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So, A., De Smedt, T., Revaz, S. & Tschopp, J. A pilot study of IL-1 inhibition by anakinra in acute gout. Arthritis Res. Ther. 9, R28


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Monosodium urate crystals stimulate monocytes and macrophages to release IL-1beta through the NALP3 component of the inflammasome. The effectiveness of IL-1 inhibition in hereditary autoinflammatory syndromes with mutations in the NALP3 protein suggested that IL-1 inhibition might also be effective in relieving the inflammatory manifestations of acute gout. The effectiveness of IL-1 inhibition was first evaluated in a mouse model of monosodium urate crystal-induced inflammation. IL-1 inhibition prevented peritoneal neutrophil accumulation but TNF blockade had no effect. Based on these findings, we performed a pilot, open-labeled study (trial registration number ISRCTN10862635) in 10 patients with gout who could not tolerate or had failed standard antiinflammatory therapies. All patients received 100 mg anakinra daily for 3 days. All 10 patients with acute gout responded rapidly to anakinra. No adverse effects were observed. IL-1 blockade appears to be an effective therapy for acute gouty arthritis. The clinical findings need to be confirmed in a controlled study.
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Vol 9 No 2
Research article
A pilot study of IL-1 inhibition by anakinra in acute gout
Alexander So1, Thibaut De Smedt2, Sylvie Revaz1 and Jürg Tschopp3
1Service of Rhumatologie, Department of Medicine, Centre Hospitalier Universtaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
2Apoxis SA, Avenue de Sévelin 18-20, 1004 Lausanne, Switzerland
3Institute of Biochemistry, University of Lausanne, chemin de Boveresses 155, 1066 Epalinges, Switzerland
Corresponding author: Alexander So,
Received: 13 Feb 2007 Revisions requested: 1 Mar 2007 Revisions received: 5 Mar 2007 Accepted: 12 Mar 2007 Published: 12 Mar 2007
Arthritis Research & Therapy 2007, 9:R28 (doi:10.1186/ar2143)
This article is online at:
© 2007 So et al., licensee BioMed Central Ltd.
This is an open access article distributed under the terms of the Creative Commons Attribution License (,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Monosodium urate crystals stimulate monocytes and
macrophages to release IL-1β through the NALP3 component
of the inflammasome. The effectiveness of IL-1 inhibition in
hereditary autoinflammatory syndromes with mutations in the
NALP3 protein suggested that IL-1 inhibition might also be
effective in relieving the inflammatory manifestations of acute
gout. The effectiveness of IL-1 inhibition was first evaluated in a
mouse model of monosodium urate crystal-induced
inflammation. IL-1 inhibition prevented peritoneal neutrophil
accumulation but TNF blockade had no effect. Based on these
findings, we performed a pilot, open-labeled study (trial
registration number ISRCTN10862635) in 10 patients with
gout who could not tolerate or had failed standard
antiinflammatory therapies. All patients received 100 mg
anakinra daily for 3 days. All 10 patients with acute gout
responded rapidly to anakinra. No adverse effects were
observed. IL-1 blockade appears to be an effective therapy for
acute gouty arthritis. The clinical findings need to be confirmed
in a controlled study.
Acute gout is a common cause of arthritis, affecting approxi-
mately 1% of the adult population, and epidemiological evi-
dence suggests that its prevalence is increasing [1]. Current
treatments during an acute attack include nonsteroidal antiin-
flammatory drugs (NSAIDs), colchicine and corticosteroids.
Although these agents are generally effective, they also
present significant risks in patients who have pre-existing
renal, cardiovascular and gastrointestinal diseases.
Gouty inflammation is due to monosodium urate (MSU) crys-
tal-induced release of proinflammatory cytokines from leuko-
cytes. Among the many cytokines implicated [2,3], IL-1 may
have a special role in the inflammatory network, as MSU crys-
tals stimulate IL-1 release by monocytes and synovial mononu-
clear cells [4]. The MSU crystals trigger IL-1 release through
innate immune pathways, which include TLR-2 and TLR-4,
found on the surface of monocytes and macrophages, as well
as the 'inflammasome' complex that leads to IL-1β activation
[5,6]. The inflammasome acts as an intracellular sensor of
inflammatory stimuli and regulates the activation of caspase-1.
On assembly of the inflammasome, which consists of a mem-
ber of the nucleotide-binding oligomerization domain-leucine
rich repeat protein family (such as NALP1, NALP2, NALP3, or
IPAF), the adaptor protein ASC and caspase-1 [7], caspase-1
becomes active and cleaves pro-IL-1β to release the mature
p17 form of IL-1β. Activators of the NALP3 inflammasome
include ATP, the microbial cell-wall component muramyl
dipeptide and bacterial RNAs [8-10]. MSU and calcium pyro-
phosphate dihydrate crystals directly activate the inflammas-
ome via NALP3 in monocytes or macrophages to release
active IL-1β and cause neutrophil influx into the peritoneal
space when administered by intraperitoneal injection. These
responses were abrogated in ASC-/- or caspase-1-/- mice [6].
Spontaneous activation of the NALP3 inflammasome due to
mutations in the NALP3 gene has been implicated in heredi-
tary autoinflammatory syndromes such as Muckle–Wells syn-
drome and chronic infantile neurologic cutaneous articular
[11]. Affected patients respond dramatically to IL-1 inhibition
[12,13], suggesting that IL-1β plays a crucial role in the patho-
genesis of inflammation in these conditions. Based on these
IL = interleukin; mAb = monoclonal antibody; MSU = monosodium urate; NALP = Nacht, LRR and Pyrin domain containing protein; NSAID = nons-
teroidal antiinflammatory drug; PBS = phosphate-buffered saline; TLR = Toll-like receptor; TNF = tumor necrosis factor.
Arthritis Research & Therapy Vol 9 No 2 So et al.
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findings, we questioned whether IL-1 inhibition may also have
a beneficial effect in gouty inflammation.
As treatment with drugs currently used in acute gout is not
always well tolerated or is contraindicated due to coexistent
medical problems, we investigated the validity of IL-1 blockade
as therapy in acute gout. We first analyzed the effects of IL-1
inhibition using the mouse peritoneal model of MSU-induced
inflammation and then assessed the effects of anakinra in
patients with acute gout who presented contraindications or
were refractory to standard treatment in an open study.
MSU crystals were prepared based on the method described
previously [14]. Briefly, 1.68 g uric acid was dissolved in 500
ml of 0.01 M NaOH and heated to 70°C. NaOH was added as
required to maintain the pH between 7.1 and 7.2, and the solu-
tion was filtered and incubated at room temperature with little
stirring slowly and continuously 24 hours.
Animal studies
BALB/C mice were treated intraperitoneally with PBS or 0.5
mg MSU crystals in 0.5 ml sterile PBS. Some mice were
injected intraperitoneally with 200 μg anti-IL-1RI mAb (clone
35F5; BD Pharmingen, San Jose, CA, USA) or with 200 μg
anti-TNF mAb (clone TN3-19.12; BD Pharmingen) or with 200
μg anakinra (Kineret; Amgen, Thousand Oaks, CA, USA) at
the time of MSU injection. Mice were euthanized after 6 hours
by CO2 exposure and the peritoneal cavities were washed
with 10 ml cold PBS. The lavage fluids were analyzed for neu-
trophil recruitment by fluorescence-activated cell sorting using
the neutrophil markers Ly-6G and CD11b (BD Pharmingen).
Five mice per group were used for study.
Human studies
The diagnosis of gout arthritis was based on clinical and labo-
ratory features. All patients fulfilled the American College of
Rheumatology criteria for acute gouty arthritis [15], but all had
a long previous history of either recurrent gouty attacks or
tophaceous gout. Patients were treated with anakinra on an
open-label basis. All subjects had either failed conventional
treatment with NSAIDs, colchicine or corticosteroids for at
least 48 hours or had developed significant side-effects on
these drugs in the past. Patients with an active untreated infec-
tion, with uncontrolled diabetes, with uncontrolled heart or res-
piratory failure or with chronic renal failure with a creatinine
clearance <30 ml/min were not eligible. Joint infection was
excluded by prior bacterial culture in all cases that underwent
joint aspiration.
All patients consented to receive anakinra. Treatment was
administered daily at a dose of 100 mg subcutaneously for 3
days. On starting anakinra, the NSAID or colchicine therapy
was discontinued. Patients who were already on low-dose cor-
ticosteroids continued their treatment at the same dose. Clin-
ical efficacy was assessed by clinical examination of the
swollen and tender joint count as well as the patient's evalua-
tion of the efficacy of treatment in terms of pain reduction after
3 days of therapy in comparison with their symptoms before
treatment. All patients were followed up for >1 month. During
follow-up, patients were evaluated for side-effects related to
the treatment and for joint symptoms related to gout. All
patients were followed by physicians responsible for this study
(AS and SR). The study protocol was approved by the local
institution's ethics committee and has the ISRTCN trial regis-
tration number 10862635.
MSU-induced peritoneal inflammation and its inhibition
by anakinra or anti-IL-1RI mAb
To study the inflammatory response to MSU crystals in vivo,
we used a well-described model of neutrophil infiltration in the
peritoneal cavity subsequent to MSU crystal administration. In
previous experiments we determined that intraperitoneal
administration of MSU crystals induced a dose-dependent
neutrophil accumulation at the site of crystal deposition, with a
plateau effect observed at 500 μg (data not shown), and this
dose was therefore used in subsequent experiments. We went
on to determine whether IL-1 blockade reduced the inflamma-
tory response in the same model. Coadministration of MSU
crystals with two different IL-1 inhibitors (anti-IL-1RI mAb or IL-
1R antagonist (anakinra)) had similar and marked inhibitory
effects on neutrophil recruitment (Figure 1a). This effect was
not observed when anti-TNF blocking mAb was administered
in the same fashion as the IL-1 inhibitors (Figure 1b). The dif-
ferences were statistically significant in comparison with the
positive MSU control.
The same dose of TNF inhibitor was effective in suppressing
liver inflammation induced by concavalin A administration, a
model of hepatitis dependent on TNF production (data not
Effects of anakinra in gout patients
The effectiveness of IL-1 inhibition in suppressing the symp-
toms of acute gout was assessed in 10 patients who could not
tolerate or did not respond to standard antiinflammatory treat-
ments. A summary of the medical histories is presented in
Table 1. All patients responded rapidly to the drug, with the
most rapid onset observed within 24 hours. In all patients, sub-
jective symptoms of gout were greatly relieved by 48 hours
after the first injection. No side-effects were observed during
the study period. Clinical examination of affected joints
showed complete resolution of signs of arthritis in 9/10
patients on day 3 after initiation of treatment.
Case 1
A 72-year-old woman with a 13-year history of chronic topha-
ceous gout and hyperuricemia was treated with rasburicase.
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The patient previously had a severe cutaneous reaction to
allopurinol, and uricosuric treatment with benzbromazone
caused renal stones. During previous gout flares, medical
treatment was unsatisfactory. She could only tolerate a low
dose of diclofenac (50–100 mg/day), as higher doses caused
gastrointestinal side-effects including one episode of gastroin-
testinal hemorrhage. Colchicine at 1 mg/day provoked intoler-
able diarrhea, and oral corticosteroid caused severe
abdominal pain.
Uricase treatment was commenced (14 mg intravenously daily
for 5 days) and resulted in rapid lowering of the patient's uric
acid levels. On the fourth day of treatment, arthritis developed
in her hand and foot joints. As treatment with diclofenac during
previous flares took more than 1 week to relieve her
symptoms, treatment with anakinra was started. Her arthritis
responded rapidly and she was able to continue the course of
uricase. No acute flares were observed during the following 2
Case 2
A 70-year-old man with an 8-year history of chronic topha-
ceous gout was assessed for hypouricemic treatment. The
patient's past medical history included congestive cardiac fail-
ure, severe ischemic heart disease, hypertension and renal
insufficiency (serum creatinine, 202 μmol/l; normal range, 44–
80 μmol/l). Previous trials of treatment with allopurinol had to
be abandoned because acute gout developed after the first
dose, which did not respond to small doses of NSAIDs. Higher
doses of NSAIDs were contraindicated because of renal fail-
ure. Colchicine at low doses (<1 mg/day) provoked rapid
onset of diarrhea.
The patient was again started on a low dose of allopurinol
(100 mg), and after the first dose developed acute arthritis of
the right foot and ankle. Anakinra was administered for 3 days
with rapid and complete resolution of signs and symptoms of
arthritis. The patient continued on allopurinol 100 mg daily,
and at follow-up 2 months later he had no further flare-ups
while continuing on the same dose of allopurinol.
Case 3
A 72-year-old man with a past history of diabetes, hyperten-
sion, renal failure and ischemic heart disease presented with
polyarticular gout. Arthritis involved the knees, the right ankle
and the right tarsal joints. MSU crystals were detected in the
knee joint aspirate.
Owing to renal impairment and a history of rectal bleeding on
colchicine, treatment with oral prednisone at 30 mg daily was
started with a tapering dose over 7 days. Despite steroids, the
arthritis remained active and the patient could not walk. After
Figure 1
Inhibition of monosodium urate-induced peritoneal neutrophil influx by anti-IL-1 treatmentInhibition of monosodium urate-induced peritoneal neutrophil influx by anti-IL-1 treatment. (a) BALB/C mice were injected intraperitoneally with 0.5
mg monosodium urate (MSU) crystals together with PBS or anti-IL-1RI mAb (200 μg) or anakinra (200 μg). (b) BALB/C mice were injected intra-
peritoneally with 0.5 mg MSU crystals together with PBS or anti-TNF mAb (200 μg) or anakinra (200 μg). Neutrophil influx in the peritoneum was
quantified 6 hours later. Values are the mean ± standard error of the mean of five mice per group. An unpaired Student's t test was used to calculate
the P value.
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steroids were stopped, the patient received a 3-day course of
anakinra, with complete resolution of arthritis by the second
day. There had been no recurrence of arthritis at follow-up 1
month later.
Case 4
A 50-year-old man with a 20-year history of polyarticular gout
principally involving the right ankle and big toe sought medical
advice because of increasingly frequent gout attacks. He had
started allopurinol but could not continue treatment because it
induced flare-ups of arthritis. NSAIDs caused severe gastroin-
testinal pain, and colchicine at 1 mg daily was ineffective.
Higher doses of colchicine provoked diarrhea. On examina-
tion, he had arthritis of the right ankle joint and MSU crystals
were identified in the joint aspirate.
A trial of anakinra was initiated at the same time as starting
allopurinol (300 mg/day). The patient's arthritis responded
rapidly and he continued on allopurinol. He was asymptomatic
2 months later.
Case 5
A 40-year-old man with a 12-year history of gout presented
with recurrent podagra of the right big toe. The attacks
occurred approximately once every 2 months, and responded
normally to indomethacin 150 mg daily over 7 days. The
patient was taking allopurinol 300 mg daily and his uric acid
level was stable at 322 μmol/l. He could not tolerate colchi-
cine, which induced diarrhea when given at doses above 1.5
mg daily.
The patient consulted after another attack, which did not
respond to indomethacin over 2 days. Joint aspiration con-
firmed the presence of urate crystals in the joint fluid. The
patient received anakinra and his symptoms completely
resolved 36 hours after the first injection. He has had no fur-
ther attacks at the 6-week follow-up.
Case 6
A 73-year-old female presented with acute gout involving the
big toes of both feet for the first time. She had a past medical
history of hypertension and knee osteoarthritis. On examina-
tion, both metatarsophalangeal-1 joints were red and swollen
and tender to the touch. The joint aspirate did not yield any
fluid. Serum uric acid was raised at 572 μmol/l and serum cre-
atinine was normal at 72 μmol/l. A presumptive diagnosis of
acute gout was made because of the patient's clinical presen-
tation and the hyperuricemia.
The patient's symptoms had not responded to 2 days of treat-
ment with diclofenac (100 mg daily), so anakinra was started.
Her joint pains were 50% improved by 24 hours and 80% by
36 hours after the injections. No further recurrence was
reported on follow-up at 1 month. The patient was started sub-
sequently on allopurinol.
Case 7
A 76-year-old man developed polyarticular gout affecting his
right ankle, the right tarsal joint and both big toe joints during
hospitalization for acute cholecystitis and bacterial sepsis. The
patient had a past medical history of cardiovascular disease
treated with low-dose aspirin and nitrates, of hypertension, of
obstructive airway disease and of cirrhosis. On examination,
Table 1
Clinical summary of the 10 patients studied and their response to treatment
Patient Clinical
Affected joints Serum uric acid
(normal range,
160–390 μmol/l)
Serum creatinine
(normal range,
44–80 μmol/l)
Effect of
assessment of
improvement in
pain (%)
Case 1 (female, 72 years old) Chronic
tophaceous gout,
renal stones
Fingers, toes 637 79 Uricase 36 70
Case 2 (male, 70 years old) Chronic
tophaceous gout
Ankle, toes 564 202 Allopurinol 24 90
Case 3 (male, 72 years old) Acute gout Knee, ankle, foot 482 121 Allopurinol 24 90
Case 4 (male, 51 years old) Acute gout Ankle, toe 396 84 Allopurinol 24 100
Case 5 (male, 40 years old) Acute gout Ankle, toe 322 113 Allopurinol 36 100
Case 6 (female, 72 years old) Acute gout Feet, toe 572 72 None 36 80
Case 7 (male, 76 years old) Acute gout Ankle, foot 338 79 None 36 100
Case 8 (male, 70 years old) Acute gout Wrist, elbow, hand 779 406 None 48 50
Case 9 (male, 53 years old) Chronic
tophaceous gout
Elbow, finger, foot,
660 84 Allopurinol 48 50
Case 10 (male, 38 years old) Acute gout Wrist, finger 540 84 None 24 60
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joint inflammation was observed at the aforementioned
affected sites. Aspiration of the ankle joint revealed uric acid
Owing to a lack of response to NSAIDs over 48 hours, anak-
inra treatment was started. The patient responded after the
first injection, and the symptoms and signs of gout were com-
pletely abolished 48 hours afterwards.
Case 8
A 70-year-old man developed arthritis of his right wrist, elbow,
hand and shoulder. The patient's past medical history included
chronic renal failure, diabetes, and cardiovascular disease
with atrial fibrillation. Gout was suspected because of hyperu-
ricemia and he was treated with colchicine, which provoked
rectal bleeding and a worsening of renal failure. The patient's
serum urate was raised at 779 μmol/l and his serum creatinine
was 258 μmol/l. The joint aspiration of the left elbow revealed
MSU crystals.
A trial of treatment with prednisone caused a decompensation
of the patient's diabetes. Anakinra was started and on review,
after completing the injections, the symptoms of arthritis of the
knee and elbow were greatly reduced, but the right wrist and
hand remained moderately painful.
Case 9
A 53-year-old male presented with severe tophaceous gout of
17 years' duration. In the past, treatment with allopurinol and
uricosurics had been attempted but discontinued because
treatment provoked acute attacks of gout that were not well
controlled by NSAIDs. Colchicine caused severe diarrhea at a
dose of 1 mg/day. There was a positive family history of gout.
On examination, tophi were detected over the elbows, fingers,
knees, ankles and feet, with signs of inflammation in the hands,
knees and right foot. The patient's serum urate was increased
at 660 μmol/l and his renal function was normal.
Owing to the patient's prior intolerance of NSAIDs and colch-
icine, a further attempt to start allopurinol was made under
cover of anakinra, given at 100 mg daily over 3 days. On start-
ing anakinra, the patient reported a 50% decrease in joint
pains after 2 days and he started allopurinol 200 mg daily and
acetametacin 90 mg daily without complications. On follow-up
1 month later, the patient had one minor attack of gout and the
allopurinol was continued.
Case 10
A 38-year-old male presented with painful arthritis of the left
wrist. In the past, the left wrist was fractured in a road traffic
accident and the patient also had a past history of gout affect-
ing the ankles and the left knee. Aspiration of the left wrist
showed MSU crystals. Colchicine (2 mg/day) over 5 days was
not effective in controlling the symptoms of gout.
Anakinra was administered and there was a rapid clinical
response. On follow-up at day 7 after the first injection, the left
wrist was still slightly swollen and tender but the ankle and
knee were asymptomatic. The patient was subsequently
started on allopurinol.
MSU crystals induce tissue inflammation via multiple mecha-
nisms. The release of monocyte-derived cytokines, triggered
by urate crystals, can in turn modulate endothelial expression
of adhesion molecules that enhance neutrophil recruitment to
the site of inflammation [16]. Within the joint, the release of
chemokines, prostanoids as well as kinins further amplifies the
inflammatory response [17]. The recent finding that MSU crys-
tals induce IL-1 release by activation of the NALP3 inflammas-
ome led us to investigate whether IL-1 blockade could inhibit
inflammation provoked by MSU. Our results from animal stud-
ies confirmed the effectiveness of IL-1 inhibition in preventing
neutrophil trafficking to the peritoneum, whereas TNF inhibi-
tion did not have any effect. Indeed, TNF inhibition aggravated
neutrophil influx. At present we do not have any simple expla-
nation for the apparent increase in neutrophil accumulation in
mice treated with the anti-TNF mAb. This observation was
made in the two separate experiments performed with five ani-
mals per group. The anti-TNF agent employed inhibited con-
cavalin A-induced hepatitis, demonstrating that the reagent is
biologically active.
The latter results differed from those reported by Chapman
and colleagues, who found that anti-TNF inhibited MSU-
induced endothelial activation, as evidenced by scintigraphy,
in a porcine monoarthritis model [16]. These differences may
be due to the different species employed in the animal models
as well as to the differences in the cytokine inhibitors tested.
Apart from the inflammasome, IL-1 secretion by macrophages
in contact with MSU can also be induced through a TLR-
dependent mechanism [5]. In the current experiments, IL-1
inhibitors would block the effects of activation via both the TLR
and the inflammasome pathways.
As proof of concept that IL-1 inhibition may be clinically effec-
tive, we performed an open-label study of anakinra treatment
in patients with acute gout. All patients had acute excacerba-
tions of longstanding gout and three had severe tophaceous
gout. All the patients had either not responded adequately to
standard treatment with NSAIDs, colchicine or steroids (n = 7)
or had significant comorbidities that made use of these treat-
ments hazardous (n = 4). Three patients could not continue
hypouricemic treatment with allopurinol because of the acute
flares provoked at the start of treatment. Only three daily injec-
tions were administered, and in all cases the symptoms of gout
responded rapidly. All patients had responded within 48
hours, and in four patients (cases 2, 3, 4 and 10) the symp-
toms improved within 24 hours. Patients' subjective assess-
ment of pain due to gout was positive, and the mean
Arthritis Research & Therapy Vol 9 No 2 So et al.
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diminution of pain was 79% by day 3 after the first injection.
Not all patients responded so well, particularly in two of the
patients who had tophaceous gout. They had a moderate
response, although still with >50% reduction of pain. As IL-1
blockade may increase the risk of infection, we excluded any
patient who had proven or clinically suspected active infection.
When appropriate, joint aspiration was performed to exclude
septic arthritis. No treatment-related side-effects were
observed during therapy and there were no infectious
complications. On follow-up, three patients who had topha-
ceous gout reported mild joint pains but no acute flare during
the first month.
Although these findings are positive, we have to stress that
this was an open-label study and confirmation of these results
would require a randomized controlled trial to prove that IL-1
inhibition is effective in acute gout. If the effectiveness of IL-1
is confirmed, then a short course of IL-1 inhibition may prove
to be a valid addition to the therapeutic arsenal when the phy-
sician is confronted with complicated cases of gouty arthritis.
In this pilot study involving 10 patients with gouty arthritis
refractory to conventional therapies, anakinra given at 100 mg
daily for 3 days rapidly relieved the inflammatory symptoms of
gout. These results reinforce the findings that implicate IL-1β
in the pathophysiology of gout and need to be confirmed by
randomized controlled trials. IL-1 inhibition may be a promising
therapeutic target in crystal-induced arthritis.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
The study was conceived by AS and JT. TDS performed the
animal studies. AS and SR performed the clinical study.
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... Commonly used drugs to treat acute gout attacks include nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine, and glucocorticoids (Terkeltaub, 2003). Several biologically targeted agents have also been developed, such as IL-1/1β antagonists, anakinra, rilonacept, canakinumab (So et al., 2007;Terkeltaub et al., 2009;Neogi, 2010;So et al., 2010). In addition, patients with gout require a combination of long-term treatments to lower uric acid levels, such as allopurin, probenecid, and sulfinpyrazone (Terkeltaub, 2003). ...
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Hyperuricemia and gout are complex diseases mediated by genetic, epigenetic, and environmental exposure interactions. The incidence and medical burden of gout, an inflammatory arthritis caused by hyperuricemia, increase every year, significantly increasing the disease burden. Genetic factors play an essential role in the development of hyperuricemia and gout. Currently, the search on disease-associated genetic variants through large-scale genome-wide scans has primarily improved our understanding of this disease. However, most genome-wide association studies (GWASs) still focus on the basic level, whereas the biological mechanisms underlying the association between genetic variants and the disease are still far from well understood. Therefore, we summarized the latest hyperuricemia-and gout-associated genetic loci identified in the Global Biobank Meta-analysis Initiative (GBMI) and elucidated the comprehensive potential molecular mechanisms underlying the effects of these gene variants in hyperuricemia and gout based on genetic perspectives, in terms of mechanisms affecting uric acid excretion and reabsorption, lipid metabolism, glucose metabolism, and nod-like receptor pyrin domain 3 (NLRP3) inflammasome and inflammatory pathways. Finally, we summarized the potential effect of genetic variants on disease prognosis and drug efficacy. In conclusion, we expect that this summary will increase our understanding of the pathogenesis of hyperuricemia and gout, provide a theoretical basis for the innovative development of new clinical treatment options, and enhance the capabilities of precision medicine for hyperuricemia and gout treatment.
... The major role of IL-1β in gout and pseudogout has been confirmed by the efficacy of blocking agents against IL-1 signaling. Anakinra, IL-1Ra recombinant, and canakinumab, an anti-IL-1β monoclonal antibody, have been found to reduce acute arthritis [131][132][133]. ...
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Inflammation is a pivotal response to a variety of stimuli, and inflammatory molecules such as cytokines have central roles in the pathogenesis of various diseases, including bone and joint diseases. Proinflammatory cytokines are mainly produced by immune cells and mediate inflammatory and innate immune responses. Additionally, proinflammatory cytokines accelerate bone resorption and cartilage destruction, resulting in the destruction of bone and joint tissues. Thus, proinflammatory cytokines are involved in regulating the pathogenesis of bone and joint diseases. Interleukin (IL)-1 is a representative inflammatory cytokine that strongly promotes bone and cartilage destruction, and elucidating the regulation of IL-1 will advance our understanding of the onset and progression of bone and joint diseases. IL-1 has two isoforms, IL-1α and IL-1β. Both isoforms signal through the same IL-1 receptor type 1, but the activation mechanisms are completely different. In particular, IL-1β is tightly regulated by protein complexes termed inflammasomes. Recent research using innovative technologies has led to a series of discoveries about inflammasomes. This review highlights the current understanding of the activation and function of the NLRP3 (NOD-like receptor family, pyrin domain-containing 3) inflammasome in bone and joint diseases.
... It triggers inflammation by inducing cell death and release of pro-inflammatory cytokines that recruit and activate other myeloid cells. Thus, it is of major interest to investigate whether mice lacking components of the NLRP3 inflammasome pathway may be protected in murine models of RA, especially following reports of increased NLRP3 and IL-1β levels in the synovium of patients with RA [222][223][224][225][226]. Additionally, it is known that monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals, responsible for acute-gout arthritis and inflammation in joints, activate the NLRP3 inflammasome [227], where anti-IL-1β therapy significantly improves symptoms in patients [228][229][230][231]. ...
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About thirty years ago, a new form of pro-inflammatory lytic cell death was observed and termed pyroptosis. Only in 2015, gasdermins were defined as molecules that create pores at the plasma membrane and drive pyroptosis. Today, we know that gasdermin-mediated death is an important antimicrobial defence mechanism in bacteria, yeast and mammals as it destroys the intracellular niche for pathogen replication. However, excessive and uncontrolled cell death also contributes to immunopathology in several chronic inflammatory diseases, including arthritis. In this review, we discuss recent findings where pyroptosis contributes to tissue damage and inflammation with a main focus on injury-induced and autoimmune arthritis. We also review novel functions and regulatory mechanisms of the pyroptotic executors gasdermins. Finally, we discuss possible models of how pyroptosis may contribute to the cross-talk between fibroblast and macrophages, and also how this cross-talk may regulate inflammation by modulating inflammasome activation and pyroptosis induction.
... However, such traditional therapy is difficult to conduct in patients with certain underlying diseases or for long-term periods due to the risk of side effects. Previous animal model studies using anakinra (IL-1R antagonist) suggested the possibility of targeting IL-1β to modulate MSU-induced inflammation (Martin et al., 2009;Torres et al., 2009), and early clinical studies also demonstrated efficacy in the treatment of acute and chronic gout patients (Mcgonagle et al., 2007;So et al., 2007;McGonagle et al., 2008). With the increased understanding of the pathophysiology of gout, new methods of gout treatment in relation to the inflammatory process have been introduced. ...
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Gout is the most common form of inflammatory arthritis. It occurs when monosodium urate crystals (MSU) are deposited within joints due to hyperuricemia and persistent elevations of serum uric acid levels. Traditional gout treatment such as urate-lowering therapy is difficult to continue for a long period of time due to the risk of side effects. Recent studies have shown that the modulation of MSU-induced inflammatory responses is dependent on the inflammatory cytokine IL-1β, which has a central role in a chain of processes involving multiple cytokines and mediators. In this regard, the NLRP3 inflammasome is known to play a crucial part and thus has been proposed as a novel target in the treatment for gout. However, the biochemical mechanism for NLRP3 inflammasome activation has not yet been clearly elucidated. Therefore, this report can provide an overview of natural extractions targeted to prevent or treat NLRP3 inflammasome-mediated gout in the MSU-induced gout model. In addition, the research and development of such natural products are suggested as a potential strategy in the treatment of gout.
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Our research group has been developing a series of biological drugs produced by coculture techniques with M2-polarized macrophages with different primary tissue cells and/or mesenchymal stromal cells (MSC), generally from fat, to produce anti-inflammatory and anti-fibrotic effects, avoiding the overexpression of pro-inflammatory cytokines by the innate immune system at a given time. One of these products is the drug PRS CK STORM, a medium conditioned by allogenic M2-polarized macrophages, from coculture, with those macrophages M2 with MSC from fat, whose composition, in vitro safety, and efficacy we studied. In the present work, we publish the results obtained in terms of safety (pharmacodynamics and pharmacokinetics) and efficacy of the intravenous application of this biological drug in a murine model of cytokine storm associated with severe infectious processes, including those associated with COVID-19. The results demonstrate the safety and high efficacy of PRS CK STORM as an intravenous drug to prevent and treat the cytokine storm associated with infectious processes, including COVID-19.
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Gout, a chronic inflammatory arthritis disease, is characterized by hyperuricemia and caused by interactions between genetic, epigenetic, and metabolic factors. Acute gout symptoms are triggered by the inflammatory response to monosodium urate crystals, which is mediated by the innate immune system and immune cells (e.g., macrophages and neutrophils), the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation, and pro-inflammatory cytokine (e.g., IL-1β) release. Recent studies have indicated that the multiple programmed cell death pathways involved in the inflammatory response include pyroptosis, NETosis, necroptosis, and apoptosis, which initiate inflammatory reactions. In this review, we explore the correlation and interactions among these factors and their roles in the pathogenesis of gout to provide future research directions and possibilities for identifying potential novel therapeutic targets and enhancing our understanding of gout pathogenesis.
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Recently developed cell-based therapies have shown potential for graft-versus-host disease (GvHD) mitigation. Our team previously developed a protocol to generate human monocyte-derived suppressor Cells (HuMoSC), a subpopulation of CD33+ suppressor cells of monocytic origin. CD33+HuMoSC successfully reduced xenoGvHD severity in NOD/SCID/IL-2Rγc -/- (NSG) mice. While CD33+ HuMoSC culture supernatant inhibits T cell activation and proliferation, the recovery of CD33+ HuMoSC immunosuppressive cells and the subsequent production of their supernatant is limited. An attractive solution would be to use both the CD33+ and the large number of CD14+ cells derived from our protocol. Here, we assessed the immunoregulatory properties of the CD14+HuMoSC supernatant and demonstrated that it inhibited both CD4 and CD8 T cell proliferation and decreased CD8 cytotoxicity. In vivo , injection of CD14+HuMoSC supernatant reduced xenoGvHD in NSG mice. Furthermore, CD14+HuMoSC supernatant maintained its immunoregulatory properties in an inflammatory environment. Proteomic and multiplex analyses revealed the presence of immunosuppressive proteins such as GPNMB, galectin-3 and IL-1R(A) Finally, CD14+HuMoSC supernatant can be produced using good manufacturing practices and be used as complement to current immunosuppressive drugs. CD14+HuMoSC supernatant is thus a promising therapy for preventing GvHD.
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Aakash V Patel,1 Angelo L Gaffo2,3 1Tinsley Harrison Internal Medicine Residency Program, University of Alabama at Birmingham, Birmingham, AL, USA; 2Division of Rheumatology and Clinical Immunology, University of Alabama at Birmingham, Birmingham, AL, USA; 3Birmingham VA Medical Center, Birmingham, AL, USACorrespondence: Angelo L Gaffo, Division of Rheumatology and Clinical Immunology, University of Alabama at Birmingham, 1825 Shelby Biomedical Building, Birmingham, AL, 35294, USA, Tel +1 205-933-8101, Fax +1 205-996-6788, Email agaffo@uabmc.eduAbstract: Gout is a common inflammatory arthritis that tends to affect significantly more men than women. However, female gout patients are more likely to have comorbidities such as hypertension, diabetes mellitus, and renal dysfunction. Furthermore, they experience a greater disease burden due to gout than males. While nonbiological causes may possibly contribute to this sex discrepancy in burden, this raises questions regarding whether current gout pharmacotherapies are as efficacious in females as they are in males. In this review, we examine how the clinical profile of female gout patients differs from male patients; we then survey the literature for data on outcomes for female gout patients treated with urate-lowering therapies for chronic management of gout as well as commonly used agents for acute flares. We also discuss considerations for managing gout in women during pregnancy and lactation.Keywords: gout, women, treatment, flare, prophylaxis, pregnancy
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Familial Mediterranean fever (FMF) is a monogenic autoinflammatory disease characterized by recurrent episodes of fever and serositis. Colchicine (Col) has a crucial role in the prevention of amyloidosis and FMF attacks. The effect of Col on innate immune cells is based on the inhibition of the microtubule system. The microtubule system is also very important for neurosecretory functions. The inhibitory effect of Col on neurosecretory functions is an overlooked issue. Considering that the neuroimmune cross-talk process plays a role in the development of inflammatory diseases, the effect of Col on the neuronal system becomes important. FMF attacks are related to emotional stress. Therefore, the effect of Col on stress mediators is taken into consideration. In this hypothetical review, we discuss the possible effects of Col on the central nervous systems (CNS) and peripheral nervous systems (PNS) in light of mostly experimental study findings using animal models. Studies to be carried out on this subject will shed light on the pathogenesis of FMF attacks and the other possible mechanisms of action of Col apart from the anti-inflammatory features.
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The interleukin-1 receptor type 1 (IL-1R1) holds pivotal roles in the immune system, as it is positioned at the "epicenter" of the inflammatory signaling networks. Increased levels of the cytokine IL-1 are a recognized feature of the immune response in the central nervous system (CNS) during injury and disease, i.e., neuroinflammation. Despite IL-1/IL-1R1 signaling within the CNS having been the subject of several studies, the roles of IL-1R1 in the CNS cellular milieu still cause controversy. Without much doubt, however, the persistent activation of the IL-1/IL-1R1 signaling pathway is intimately linked with the pathogenesis of a plethora of CNS disease states, ranging from Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS), all the way to schizophrenia and prion diseases. Importantly, a growing body of evidence is showing that blocking IL-1R1 signaling via pharmacological or genetic means in different experimental models of said CNS diseases leads to reduced neuroinflammation and delayed disease progression. The aim of this paper is to review the recent progress in the study of the biological roles of IL-1R1, as well as to highlight key aspects that render IL-1R1 a promising target for the development of novel disease-modifying treatments for multiple CNS indications.
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Missense mutations in the CIAS1 gene cause three autoinflammatory disorders: familial cold autoinflammatory syndrome, Muckle-Wells syndrome and neonatal-onset multiple-system inflammatory disease(1). Cryopyrin (also called Nalp3), the product of CIAS1, is a member of the NOD-LRR protein family that has been linked to the activation of intracellular host defence signalling pathways(2,3). Cryopyrin forms a multi-protein complex termed 'the inflammasome', which contains the apoptosis-associated speck-like protein (ASC) and caspase-1, and promotes caspase-1 activation and processing of pro-interleukin (IL)-1 beta (ref. 4). Here we show the effect of cryopyrin deficiency on inflammasome function and immune responses. Cryopyrin and ASC are essential for caspase-1 activation and IL-1 beta and IL-18 production in response to bacterial RNA and the imidazoquinoline compounds R837 and R848. In contrast, secretion of tumour-necrosis factor-alpha and IL-6, as well as activation of NF-kappa B and mitogen-activated protein kinases (MAPKs) were unaffected by cryopyrin deficiency. Furthermore, we show that Toll-like receptors and cryopyrin control the secretion of IL-1 beta and IL-18 through different intracellular pathways. These results reveal a critical role for cryopyrin in host defence through bacterial RNA-mediated activation of caspase-1, and provide insights regarding the pathogenesis of autoinflammatory syndromes.
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Crystals of monosodium urate (MSU) provide a dose-dependent stimulus for the production by human blood monocytes of tumor necrosis factor (TNF), a cytokine with proinflammatory properties; TNF activity was inhibited selectively by monoclonal antibody to TNF alpha. Biologically active cell-associated TNF activity peaked at 3 h and was exceeded at 6 h by extracellular activity, which peaked at 12-18 h. Comparable kinetics were observed with immunoreactive TNF alpha. TNF alpha mRNA accumulation in monocytes stimulated with MSU crystals appeared as a single peak at 2-4 h, kinetics compatible with rapid production of a short half-life transcript. In contrast, crystals of calcium pyrophosphate or of hydroxyapatite did not stimulate significant production of TNF or of message. Fresh tophaceous material from a patient with gout contained significant levels of TNF alpha and cells cultured from the tophus produced TNF alpha in vitro. In rheumatoid synovial cells, spontaneous release of TNF alpha was increased by in vitro exposure to MSU crystals. Taken together with earlier work, these results support an expanded view of gouty inflammation in which the crystal-stimulated production of cytokines provides a crucial link between crystal deposition and many of the clinical and pathological facts of both acute and chronic gouty arthritis.
The physical interaction of particulates with resident mononuclear phagocytes is a consistent feature in certain forms of crystal-induced inflammation. In this study, we observed that monosodium urate crystals stimulated the rapid release of neutrophil chemotactic activity from monocytes, and that this activity steadily increased over 24 hours. Because the release of monocyte-derived neutrophil chemotactic activity was markedly diminished by pretreatment of the monocytes with cycloheximide, and was completely removed from conditioned media by adsorption to heparin-agarose, we addressed the possibility that monocyte-derived neutrophil chemotactic factor/interleukin-8 (IL-8), a heparin-binding neutrophil-activating polypeptide, might modulate these activities. Urate crystal-induced IL-8 secretion from monocytes was verified by radioimmuno-assay. In addition, an IL-8–specific antibody markedly inhibited the neutrophil-activating capacity of the conditioned media from monocytes activated by urate crystals, as well as by inflammatory silica crystals. Last, IL-8 was significantly increased in gouty synovial fluids (range 3.0–16.8 ng/ml, mean 8.4 ng/ml, n = 6) relative to osteoarthritic synovial fluids (range 1.1–1.7 ng/ml, mean 1.5 ng/ml, n = 6) (P = 0.006). We conclude that microcrystal-induced secretion of IL-8 by mononuclear phagocytes may mediate a number of forms of crystal-induced inflammation.
The American Rheumatism Association subcommittee on classification criteria for gout analyzed data from more than 700 patients with gout, pseudogout, rheumatoid arthritis, or septic arthritis. Criteria for classifying a patient as having gout were a) the presence of characteristic urate crystals in the joint fluid, and/or b) a tophus proved to contain urate crystals by chemical or polarized light microscopic means, and/or c) the presence of six of the twelve clinical, laboratory, and X-ray phenomena listed in Table 5.
Objective. There is relatively little direct evidence for the roles of interleukin-1 (IL-1) and tumor necrosis factor α (TNFα) in activating endothelium in vivo. The aim of this study was to use in vitro and in vivo models to investigate the contribution of these cytokines to both E-selectin expression and the recruitment of polymor-phonuclear cells (PMN) in monosodium urate monohydrate (MSU) crystal-induced inflammation. Methods. MSU crystals were incubated with freshly isolated mononuclear cells, after which the harvested supernatants were tested for their ability to induce E-selectin expression during coculture with human umbilical vein endothelial cells. Subsequent experiments were performed with the addition of neutralizing anticytokine antibodies/antisera. The role of TNFα was then studied in an MSU crystal-induced monarthritis model, in the presence or absence of anti-TNFα (5 mg/kg intravenously). 99mtechnetium (99mTc)-labeled PMN cells and 111indium (111In)-labeled anti-E-selectin monoclonal antibody (MAb) 1.2B6 were intravenously administered 4 hours after intraarticular injection to quantify PMN recruitment and E-selectin expression in inflamed joints. Results. MSU crystals were a potent stimulus for IL-1 and TNFα production by monocytes in vitro, and these cytokines fully accounted for MSU crystalstimulated, monocyte-mediated endothelial activation. In the MSU crystal-induced monarthritis model, TNFα blockade was very effective in suppressing both E-selectin expression and PMN emigration into the inflamed joints, as judged by gamma-camera image analysis and postmortem tissue counting following the intravenous injection of 99mTc-PMN and 111In-anti-E-selectin MAb. Conclusion. IL-1 and TNFα appear to be the only factors released by monocytes following incubation with MSU crystals, which induce E-selectin expression in vitro. Anti-TNFα is effective in suppressing endothelial activation and PMN recruitment in vivo E-selectin imaging can be used to assess the endothelial response to therapy and may prove useful for clinical studies.
We found previously that crystals of sodium urate and silicon dioxide (silica) can stimulate the production of endogenous pyrogen (EP), now called interleukin-1 (IL-1), the polypeptide mediator of fever and other aspects of inflammation. We have confirmed and extended the work with urate crystals and have examined 2 other crystals associated with joint problems, hydroxyapatite (HA) and calcium pyrophosphate dihydrate (CPPD). The crystals were added to suspensions of human blood leukocytes (2.5 X 10(6) monocytes/dose, with 10% fresh autologous plasma); after 18 hours of incubation, the EP content of the supernatants was assayed in the rabbit pyrogen test. HA and CPPD crystals neither induced EP production nor reduced the amount of staphylococci-induced EP. Presized (10 - 40 micron) urate crystals were pyrogenic, but less so than the unsized and aggregated urate crystals investigated previously and reexamined here. On ultrasonication, the aggregated urate crystals became first more pyrogenic and then less so as the crystals were dispersed and broken down. Ultrasound did not impart pyrogenicity to HA or CPPD crystals: their failure to stimulate EP/IL-1 production from leukocytes in vitro indicates a difference in their phlogistic properties, compared with crystals of urate or silica. The results with urate crystals have pathogenetic implications in a number of areas of gouty inflammation: initiation of the acute attack, other aspects of the acute-phase response, polyarticular involvement, and the inflammatory consequences of chronic stimulation by tophaceous material.
We reported before that monosodium urate (MSU) crystals were potent stimulators of endogenous pyrogen (EP) production from human and rabbit mononuclear phagocytes, and proposed that this property of MSU crystals may be important in the pathogenesis of gout. EP activity is now attributed to interleukin 1 (IL 1) peptides but IL 1 is not the only pyrogenic monocyte-derived cytokine, since both interferon-alpha (alpha-IFN) and tumor necrosis factor (TNF) are also pyrogenic in rabbits. Using a T cell comitogenic assay based on a murine helper T cell clone that does not respond to IFN or TNF, we now report the release of IL 1 activity from human blood monocytes and synovial fluid mononuclear cells (MNC), following stimulation with MSU crystals. MSU-induced supernatants with IL 1 activity were neutralized with rabbit antiserum to human IL 1 and also stimulated the growth ([3H]thymidine incorporation) of long-term fibroblast-like cell lines derived from human synovial rheumatoid exudate. Two other crystals associated with articular inflammation were tested: hydroxyapatite was a much less potent stimulus compared with MSU crystals, and calcium pyrophosphate dihydrate did not stimulate IL 1 release from human monocytes or synovial fluid MNC. As a model for the inflammatory consequences of acute and chronic overproduction of IL 1, gout is the only sterile inflammatory disease where the local and systemic pathology is compatible with such overproduction; raised IL 1 levels have been found at the site of inflammation, and a necessary etiologic agent, crystalline urate, has been shown unequivocally to be a direct activator of mononuclear IL 1 release.
Proteins binding monosodium urate (MSU) crystals alter their phlogistic potential in vitro and in vivo. These proteins and other materials capable of interacting with crystals could enter the joint space from the circulation and/or could be produced locally. Using the rat subcutaneous air pouch synovium-like model, we observed different effects of collected pouch fluid supernatants from acute (6 h) and from subsiding (72 h) inflammation, and from autologous rat serum on MSU crystal induced inflammation in new air pouches. Plain crystals at 6 h produced a mean leukocyte count (WBC) of 18,156/mm3 with 12% of cells showing phagocytosis of MSU; reaction to plain crystals at 72 h had subsided to only 75 WBC/mm3 and 1% phagocytosis; new crystals preincubated in supernatant from acutely inflamed 6 h air pouches produced higher numbers of WBC in new pouches at 6 h (34,044/mm3); while crystals preincubated in 72 h supernatant gave only 9,825/mm3 and 7% phagocytosis; crystals preincubated in rat serum produced similar pouch WBC to plain crystals at 6 h, but resulted in only 2% phagocytosis. Our study provides evidence that components generated locally during subsiding inflammation as well as serum components could bind to MSU crystals and affect the generation of chemotactic factors and/or crystal phagocytosis contributing in the self-limited nature of acute gouty arthritis.
There is relatively little direct evidence for the roles of interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) in activating endothelium in vivo. The aim of this study was to use in vitro and in vivo models to investigate the contribution of these cytokines to both E-selectin expression and the recruitment of polymorphonuclear cells (PMN) in monosodium urate monohydrate (MSU) crystal-induced inflammation. MSU crystals were incubated with freshly isolated mononuclear cells, after which the harvested supernatants were tested for their ability to induce E-selectin expression during coculture with human umbilical vein endothelial cells. Subsequent experiments were performed with the addition of neutralizing anticytokine antibodies/antisera. The role of TNF alpha was then studied in an MSU crystal-induced monarthritis model, in the presence or absence of anti-TNF alpha (5 mg/kg intravenously). 99mtechnetium (99mTc)-labeled PMN cells and (111)indium (111In)-labeled anti-E-selectin monoclonal antibody (MAb) 1.2B6 were intravenously administered 4 hours after intraarticular injection to quantify PMN recruitment and E-selectin expression in inflamed joints. MSU crystals were a potent stimulus for IL-1 and TNF alpha production by monocytes in vitro, and these cytokines fully accounted for MSU crystal-stimulated, monocyte-mediated endothelial activation. In the MSU crystal-induced monarthritis model, TNF alpha blockade was very effective in suppressing both E-selectin expression and PMN emigration into the inflamed joints, as judged by gamma-camera image analysis and postmortem tissue counting following the intravenous injection of 99mTc-PMN and 111In-anti-E-selectin MAb. IL-1 and TNF alpha appear to be the only factors released by monocytes following incubation with MSU crystals, which induce E-selectin expression in vitro. Anti-TNF alpha is effective in suppressing endothelial activation and PMN recruitment in vivo E-selectin imaging can be used to assess the endothelial response to therapy and may prove useful for clinical studies.