[show abstract][hide abstract] ABSTRACT: Contralateral responses to unilateral stimuli have been well described in animal models. These range from central sensitization to peripheral inflammatory responses. Our aim was to test for contralateral responses following unilateral intradermal capsaicin injection in man.
Three groups were investigated. A healthy volunteer group (1) was injected with capsaicin into the volar aspect of one forearm. A group of patients with RA (2) was also injected with capsaicin. A control group of healthy volunteers (3) was not injected with capsaicin. All groups were tested for hyperalgesia and allodynia every 10 min for 1 h following the injection using quantitative sensory testing.
A total of 9/14 healthy volunteers (Group 1) and 10/14 patients with RA (Group 2) demonstrated contralateral sensitization that subsided within 1 h following intradermal capsaicin injection. A total of 2/23 control subjects (Group 3) demonstrated positive responses with the monofilaments. The frequency of the contralateral responses in the experimental groups compared with the control group is significant (P < 0.05). The peak hyperalgesia was relatively delayed contralaterally compared with the ipsilateral side (35 min vs 15 min). The area of sensitization, where present, was reduced compared with the ipsilateral side (5-50%).
This is the first demonstration of a contralateral response following a unilateral stimulus in man. Bilateral neural pathways mediating contralateral responses may have a role in the pathophysiology of chronically painful or inflammatory diseases and a confounding influence on using the contralateral limb as a control experimentally. We did not find that a systemic inflammatory disease sensitized for this phenomenon.
[show abstract][hide abstract] ABSTRACT: Objectives. To assess microvascular endothelial function in patients with complex regional pain syndrome type I (CRPS) compared with healthy controls, as measured by iontophoresis of vasoactive chemicals and laser Doppler imaging. Methods. Microvascular blood flow was stimulated locally in affected and contralateral limbs of patients with CRPS (n ¼ 17) and in control subjects (n ¼ 16) using iontophoresis of the endothelial-dependent vasodilator acetylcholine (ACh) and the endothelial-independent vasodilator sodium nitroprusside (NaNP). Changes in blood flow were measured using laser Doppler imaging. Comparisons were made between right and left limbs and between patients and controls. Results. No significant differences in blood flow (expressed as a median percentage increase from baseline (interquartile range)) were detected between affected and contralateral limbs in patients with CRPS for ACh (affected 237 (95-344); unaffected 251 (152-273)) or for NaNP (affected 102 (49-300); unaffected 190 (53-218)). In addition, there were no significant differences between patients and healthy controls (controls, ACh 216 (119-316); controls, NaNP: 122 (48-249)). Conclusions. In this pilot study, CRPS was not associated with impairment of microvascular endothelial function. This may be a true result or may reflect the diversity of the CRPS disease process.
[show abstract][hide abstract] ABSTRACT: Symmetry in clinical disease occurs more commonly than expected by chance and is unexplained. In this paper we focus on symmetry in arthritis and describe the neurogenic hypothesis. Neuropeptides are anatomically relevant to systemic arthritis and have been shown to have modulating effects on both the immune and circulatory systems. Neural networks project bilaterally and are involved in the development and propagation of inflammatory disease. These putative pathological neuro-feedback loops may derive from the existence of biologically protective symmetrical mechanisms.
Novartis Foundation symposium 02/2004; 260:241-52; discussion 252-7, 277-9.
[show abstract][hide abstract] ABSTRACT: Small-diameter sensory neurons are key contributors in joint pain and have been implicated in the pathogenesis of rheumatoid arthritis (RA). Small-diameter sensory neurons can be separated into at least two distinct populations, which include isolectin B4 (IB4)-binding and tyrosine receptor kinase (trk) A-expressing. While trkA-expressing neurons have been identified in the rat knee joint there are no data, we are aware of, to suggest that IB4-binding neurons are also present. We aimed to determine whether or not there exists a population of IB4-binding neurons in the rat knee joint. Retrograde nerve tracing with fluoro-gold (FG) was used to identify the complete population of knee joint afferents in the lumbar dorsal root ganglia (DRG) L3 and L4 of female Wistar rats. IB4 conjugated to fluorescein isothiocyanate (FITC) was used to identify the cell bodies of IB4-binding neurons in the DRG. Of 1096 FG-labeled cell bodies in the DRG of knee joint injected animals (n=4), none were double labeled with FITC. Injection of FG into skin over the medial aspect of the rat knee (n=3) showed 48% of these cutaneous afferents in L3 and L4 DRG were double-labeled with FG and FITC. A complete absence of IB4-binding neurons in the rat knee joint makes it unlikely that this predominantly cutaneous, IB4-binding population of afferent neurons could have any significant influence in chronic inflammatory joint disease. This suggests that trkA-expressing neurons are the sole population of small-diameter sensory neurons in the knee joint and implies a significant role for these afferents in the progression of RA.
[show abstract][hide abstract] ABSTRACT: To determine the relationship between hypoxia and the expression of Ets-1 and hypoxia-inducible factor 1alpha (HIF-1alpha) in both normal and inflamed joints. Adjuvant-induced arthritis (AIA) was used as the model system, since it mirrors many aspects of the pathology of rheumatoid arthritis.
Adjuvant arthritis was induced in a group of 10 female Lewis rats. A second group of 10 uninjected female Lewis rats served as naive controls. When a maximum clinical joint score was achieved in the AIA group, all 20 rats were injected with the specific hypoxic cell marker Hypoxyprobe-1 and subsequently killed. Hypoxyprobe-1 adducts, Ets-1, and HIF-1alpha were localized in the joints of the hind feet from these groups using immunohistochemistry.
Compared with the joints from control rats, inflamed joints contained markedly more cells with Hypoxyprobe-1 adduct immunoreactivity, Ets-1-immunoreactive nuclei, and nuclear immunoreactivity for both Ets-1 and HIF-1alpha.
Our results demonstrate the presence of hypoxia in inflamed joints in this experimental model of arthritis. The colocalization of Ets-1 and HIF-1alpha in these hypoxic areas suggests that hypoxia may induce Ets-1 and HIF-1alpha expression during joint inflammation.
[show abstract][hide abstract] ABSTRACT: Symmetry is a remarkably constant clinical feature of chronic inflammatory disease. Rheumatoid arthritis is almost by definition symmetrical (1). Osteoarthritis, psoriasis and some of its associated arthritides are also symmetrical (2-4). Pulmonary fibrosis, glomerulonephri- tis and sympathetic ophthalmia are also symmetrical inflammatory conditions. Whilst the pathophysiology behind this symmetry is unexplained, we and others have speculated that it is likely to be mediated via neurological mechanisms crossing through the spinal cord (5, 6). The two sides of the spinal column have largely been thought to function independently of each other. There are three lines of evidence to suggest that this is not true. Careful anatomical studies of the spinal cord show transmedian fibres decussating posteriorly at all levels of the spinal cord to synapse in the laminae on the contralateral dorsal horn. These neuronal connections have been seen in many different species, including several primates (Fig. 1). Szentagothai (7), using Golgi analysis on young cats and dogs, showed that neurons with their cell bodies in the substantia gelatinosa send contralateral axons that appear to synapse in the contralateral substantia gelatinosa. Perl and Light (8) corroborated these findings after they had applied horseradish peroxidase to rat, cat and monkey dorsal rootlets. They found projections into the contralateral substantia gelatinosa as well as the ventral portion of the nucleus propius. Culberson et al. (9), using cresyl violet acetate (Fink-Heimer method), identified crossed af- ferent projections throughout the spinal cord, originating and terminating in laminae III-IV, in four mammalian species. These anatomical studies provide evidence that the opportunity exists for crosstalk between the left and the right sides of the spinal column. Functional studies of decerebrate rats demonstrate that such cross-communication can produce contralat- eral responses. Electrical stimulation of contralateral peripheral nerves is known to inhibit flexor reflex pathways in the spinal cord (10) as well as the long latency of C-fibre-evoked activity in dorsal horn cells (11, 12). Contralateral dorsal horn cells are inhibited in response to noxious stimuli applied to the limb or tails of rats (13, 14). Further electrophysiological studies confirm the presence of neurons in the dorsal horn that have bilateral receptive fields. Of relevance to this article is that the number of these neurons with bilateral receptive fields increases in the presence of unilateral inflammation (15, 16). Grubb et al. (17) also showed that some of the fields onthe con tralateral side canbecome excitatory rather thaninhibitory. At what level are these contralateral responses mediated? Woolf (16) documented the persistent reduc- tioninflexor reflex thresholds con tralaterally after noxious thermal stimuli had been applied to decerebrate rats with an intact brainstem. Fitzgerald (18), using a decerebrate, spinalized rat model, showed that a contralateral effect on dorsal horn fibres need not involve such higher pathways. Although direct contra- lateral spinal pathways exist in experimental conditions, there are likely to be significant supraspinal influences in vivo. This is suggested by several studies detailing an attenuation of central sensitization and secondary hyperalgesia following spinalization or inactivation of the rostral ventral medulla in a review of rat models of
[show abstract][hide abstract] ABSTRACT: To determine the localization of 3-nitrotyrosine (3-NT), a footprint marker of peroxynitrite (ONOO-) and other reactive nitrogen species, to the inflamed human synovium and to compare this with normal synovial and nonsynovial tissue of human and animal origin.
Monoclonal and polyclonal antibodies were used to investigate for 3-NT, inducible nitric oxide synthase (iNOS), macrophage marker CD68, and the vascular smooth muscle marker alpha-actin by avidin-biotin immunocytochemistry.
In the inflamed synovium, 3-NT was found in the vascular smooth muscle and macrophages. In normal human synovium, 3-NT was present in the vascular smooth muscle and some lining cells and was not associated with immunoreactivity for iNOS. Similarly, 3-NT could be demonstrated in the vascular smooth muscle cells of normal rats and iNOS knockout mice. It was not present in the vascular smooth muscle of healthy, nonsynovial tissue.
The synovial vasculature in histologically normal human and naive rodent synovium was alone among the normal tissues studied in exhibiting iNOS-independent immunoreactivity for 3-NT. These findings suggest a physiologic role for ONOO- in normal synovial vascular function.
[show abstract][hide abstract] ABSTRACT: Objective
To determine the localization of 3-nitrotyrosine (3-NT), a footprint marker of peroxynitrite (ONOO−) and other reactive nitrogen species, to the inflamed human synovium and to compare this with normal synovial and nonsynovial tissue of human and animal origin.Methods
Monoclonal and polyclonal antibodies were used to investigate for 3-NT, inducible nitric oxide synthase (iNOS), macrophage marker CD68, and the vascular smooth muscle marker α-actin by avidin–biotin immunocytochemistry.ResultsIn the inflamed synovium, 3-NT was found in the vascular smooth muscle and macrophages. In normal human synovium, 3-NT was present in the vascular smooth muscle and some lining cells and was not associated with immunoreactivity for iNOS. Similarly, 3-NT could be demonstrated in the vascular smooth muscle cells of normal rats and iNOS knockout mice. It was not present in the vascular smooth muscle of healthy, nonsynovial tissue.Conclusion
The synovial vasculature in histologically normal human and naive rodent synovium was alone among the normal tissues studied in exhibiting iNOS-independent immunoreactivity for 3-NT. These findings suggest a physiologic role for ONOO− in normal synovial vascular function.
[show abstract][hide abstract] ABSTRACT: Angiogenesis and vascular insufficiency each may support the chronic synovial inflammation of rheumatoid arthritis. We have shown by quantitative immunohistochemistry and terminal uridyl deoxynucleotide nick end labeling that endothelial proliferation and cell death indices were each increased in synovia from patients with rheumatoid arthritis compared with osteoarthritic and noninflamed controls, whereas endothelial fractional areas did not differ significantly among disease groups. Markers of proliferation were associated with foci immunoreactive for vascular endothelial growth factor and integrin alpha(v)beta3, whereas cell death was observed in foci in which immunoreactivities for these factors were weak or absent. No association was found with thrombospondin immunoreactivity. The balance between angiogenesis and vascular regression in rheumatoid synovitis may be determined by the focal expression of angiogenic and endothelial survival factors. Increased endothelial cell turnover may contribute to microvascular dysfunction and thereby facilitate persistent synovitis.
American Journal Of Pathology 03/1998; 152(3):691-702. · 4.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Angiogenesis is an essential component of wound healing and inflammation. In the rat subcutaneous sponge implantation model, angiogenesis can be enhanced by administration of the sensory neuropeptide, substance P. We have used quantitative in vitro receptor autoradiography and immunohistochemistry to investigate the development of endogenous neurovascular regulatory systems in the newly-formed granulation tissue of this model. The fraction of endothelial cells immunoreactive for proliferating cell nuclear antigen, endothelial fractional area, and 133Xe clearance were used as measures of endothelial proliferation, neovascularization, and blood flow, respectively. Endothelial proliferation occurred predominantly in tissues surrounding the sponge, and peaked before neovascularization of sponge stroma and the establishment of sponge blood flow. Substance P-containing sensory nerves and specific, high affinity substance P binding sites with characteristics of neurokinin receptors of the NK1 subclass, were localized to microvessels surrounding the sponge at all time points. Lower density substance P binding sites were localized to newly formed microvessels within the sponge stroma, progressively increasing in density from day 4 to day 14. Nerve fibres were observed in the stroma of only 2 of 6 sponges at day 14, and none at earlier time points. These data support the hypothesis that substance P-enhanced angiogenesis in this model results from a direct action on microvascular NK1 receptors. Neovascularization is a sequential process, with early endothelial proliferation followed by new vessel formation and increased blood flow, with maturation of endogenous neurovascular regulatory systems occurring late in this process in inflamed tissues.
[show abstract][hide abstract] ABSTRACT: The transcription factor nuclear factor kappaB (NF-kappaB) has been implicated in the inflammatory response and is known to be activated by a process involving reactive oxygen intermediates. The purpose of the present study was to demonstrate the presence and distribution of activated NF-kappaB in synovium samples from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and from autopsy subjects with no known history of arthritis.
Immunohistochemical staining was performed using both polyclonal and monoclonal "activity-specific" antibodies to the Rel-A (p65) subunit of NF-kappaB (anti-Rel-A nuclear location sequences). Histologic features of inflammation were also scored.
Both antibodies demonstrated positive staining of synovial tissue, with a cellular distribution that was nuclear. The staining was associated with specific cell types within the tissue, in particular, type A synoviocytes and vascular endothelium. Notably, lymphoid aggregates were unstained. Using the monoclonal antibody, a further study was carried out to investigate the distribution of staining in tissues from patients with different disease activities and clinical diagnoses, as well as in normal control tissue obtained at autopsy. Patients with acute RA more commonly showed vessel staining (P = 0.05) and, conversely, showed less frequent staining of the synovial lining (P < 0.005) compared with OA patients. Synovial tissue from controls exhibited either no staining or only weak staining in the synovial lining.
The activation of NF-kappaB in vascular endothelium and type A synovial lining cells is a feature of synovial tissue from both RA and OA patients. The distribution of this staining appears to be related to the clinical diagnosis.
[show abstract][hide abstract] ABSTRACT: The aim of this study was to establish the effects of intra-articular capsaicin (pelargonic acid vallinylamide) on synovial innervation of the rat knee. Rats were sacrificed 1, 2, 4 and 7 days after intra-articular injection of capsaicin and joint tissues stained with either conventional haematoxylin and eosin (H and E) or with specific antibodies to the calcitonin gene-related peptide (CGRP), substance P (both of which are markers for primary afferent fibres), the C-flanking peptide of neuropeptide Y (CPON) (localised in postganglionic sympathetic fibres), or protein gene product 9.5 (a pan-neuronal marker). At lower concentrations (0.1% and 0.25%), capsaicin produced no change in peptide staining pattern or histological appearance. At 0.5% capsaicin, there was complete loss of nerve fibres showing positive staining for CGRP and substance P at all time points. Staining for CPON and protein gene product 9.5 was still present, but decreased, 1 and 2 days after treatment and virtually absent at 4 and 7 days. These findings provide evidence for partially selective denervation induced by 0.5% capsaicin, in contrast to 1% capsaicin which abolished staining for all peptide markers, indicating a total ablation of nerve fibres. A consistent but unexpected finding was the presence of a severe inflammatory response in joints treated with 0.5% and 1% capsaicin. An influx of polymorphonuclear leucocytes was found to occur within 4 h of injection, with progressive appearance of mononuclear cells after this time. We conclude that it is difficult to specifically deplete sensory nerve fibres from the synovium by means of local capsaicin injection. Although selective loss of staining for sensory nerve fibres could be achieved by injection of 0.5% capsaicin, there was progressive non-specific loss of post-ganglionic autonomic fibres which may be related to the severe inflammatory response provoked by the higher doses of capsaicin.
Journal of Chemical Neuroanatomy 03/1996; 10(1):11-8. · 2.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: Many inflammatory conditions show topographically precise symmetrical responses. In this study we assessed vascular and cellular responses of apparently normal knees following induction of monoarthritis on the opposite side. A strictly localised monoarthritis was induced in the right knee of experimental animals using intra-articular latex spheres. In both knee joints bradykinin-induced plasma extravasation was significantly enhanced increasing from 0.52 +/- 0.07 micrograms/ml Evans blue to 0.99 +/- 0.07 micrograms/ml and 0.88 +/- 0.1 micrograms/ml in the injected and uninjected, contralateral, knees respectively (P < 0.05). A bilateral increase in cellularity was also apparent with cell counts in the uninjected, and apparently normal, knee increasing from 512 +/- 42 cells/mm2 to a maximum of 812 +/- 125 cells/mm2 on day 10 (P < 0.05). Immunohistological analysis demonstrated that the infiltrating cells in both the ipsilateral and contralateral joints were predominantly macrophages. Cell counts were not increased in the other peripheral joints. Levels of the sensory neuropeptide substance P were significantly elevated in both the ipsilateral and contralateral dorsal root ganglia and prior inhibition of small unmyelinated nerve activity inhibited the cellular infiltrate on the contralateral side, suggesting that the effect was mediated, at least partially, by a specific neurogenic pathway. The data suggests the presence of a neurogenic mechanism able to induce a topographically precise response. This may serve to upregulate the cellular defences of at-risk tissues following a potentially damaging stimulus at another site.
Brain Research 09/1995; 688(1-2):72-6. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: The synovial cavity has a negative pressure in health. When the joint is exercised, vascular patency is maintained, allowing for nutrition of the avascular cartilage. In rheumatoid synovitis, the situation is altered. The cavity pressure is raised and upon movement this pressure exceeds the capillary perfusion pressure, causing collapse of the blood vessels. This leads to the production of multiple episodes of 'hypoxic-reperfusion injury' generating reactive oxygen species (ROS). Such ROS oxidise: (a) IgG, inducing rheumatoid factor production (b) Hyaluronan, leading to hyaluronan fragmentation products which may alter immune function (c) Lipids, generating aldehydes which are toxic and may alter T cell/macrophage interactions (d) lipoproteins, leading to the production of monocyte chemotactic peptides Progressive hypoxia alters immune function, predominantly by calcium mediated pathways.
British Medical Bulletin 05/1995; 51(2):419-36. · 4.36 Impact Factor
[show abstract][hide abstract] ABSTRACT: alpha-Trinositol (1D-myo-inositol 1,2,6-trisphosphate, PP56) selectively and potently inhibits the vasoconstrictor effects of neuropeptide Y (NPY). The authors used quantitative in vitro receptor autoradiography to localize and characterize [3H]alpha-trinositol binding sites in human and mammalian tissues. [3H]alpha-trinositol bound specifically to vascular and nonvascular smooth muscle in human, porcine and rat tissues. Binding was time dependent, reversible, saturable and specific for alpha-trinositol compared with inositol 1,4,5-trisphosphate, inositol 1,3,4,5-tetrakisphosphate (Ins-1,3,4,5-P4) and inositol hexakisphosphate (Ins-P6). Binding to each structure gave Kd values of 5 to 20 nM and was consistent with a homogeneous population of sites. Binding was optimal at pH 5 and at low calcium concentrations. Comparison with [125I]Bolton Hunter-labeled NPY ([125I]BH-NPY) binding in porcine tissues revealed 1) a partial colocalization but Bmax values for [3H]alpha-trinositol binding some two orders of magnitude higher than for [125I]BH-NPY and 2) failure of each of the two ligands to inhibit binding of the other. Comparison of [3H]alpha-trinositol with [3H]Ins-1,3,4,5-P4 binding in human umbilical cord revealed that both ligands bound specifically to vascular smooth muscle but that only [3H]Ins-1,3,4,5-P4 bound to arterial endothelium. Both ligands bound to sites with rank orders of affinity Ins-1,3,4,5-P4 > Ins-P6 > inositol 1,4,5-trisphosphate. alpha-Trinositol had, however, three orders of magnitude higher affinity for [3H]alpha-trinositol than [3H]Ins-1,3,4,5-P4 binding sites; Ins-1,3,4,5-P4 and Ins-P6 had higher affinity for [3H]Ins-1,3,4,5-P4 binding sites. Specific [3H]alpha-trinositol binding sites may represent receptors by which alpha-trinositol inhibits NPY effects on vascular tone.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Pharmacology and Experimental Therapeutics 04/1995; 273(1):461-9. · 3.89 Impact Factor
[show abstract][hide abstract] ABSTRACT: To investigate the time course of a monoarthritis induced with the purified protein derivative of tuberculin (PPD) or a recombinant 65 kDa heat shock protein (rhsp65) in two different strains of sensitised rats.
Wistar and Lewis rats, sensitised with heat killed Mycobacterium tuberculosis in oil, were challenged intraarticularly with PPD or rhsp65 and monitored for six weeks. Inflammation was assessed by joint swelling, histology, and radiographic studies.
Sensitised Lewis rats injected with PPD or rhsp65 showed a chronic response with recurrent spontaneous flares, while Wistar rats showed one inflammatory episode.
The Wistar strain response to PPD resembles a transient reactive arthritis, while the response of the Lewis strain mimics the relapsing nature of rheumatoid synovitis, providing an interesting model to determine dominant immunopathogenic mechanisms.
Annals of the Rheumatic Diseases 02/1995; 54(1):59-65. · 9.11 Impact Factor