Christian Geis

Publications of Christian Geis

• Human IgG directed against amphiphysin induces anxiety behavior in a rat model after intrathecal passive transfer.

  Authors: Christian Geis, Benedikt Grünewald, Andreas Weishaupt, Thomas Wultsch, Klaus V Toyka, Andreas Reif, Claudia Sommer

  Journal of neural transmission (Vienna, Austria : 1996). 02/2012;

  Stiff person syndrome with auto-antibodies against amphiphysin is characterized by muscular stiffness, spasms, and anxiety which is a less appreciated core symptom. Here, we report that intrathecalStiff person syndrome with auto-antibodies against amphiphysin is characterized by muscular stiffness, spasms, and anxiety which is a less appreciated core symptom. Here, we report that intrathecal application of purified immunoglobulin G-antibodies against amphiphysin from one patient induce anxiety behavior in rats. Immunostaining demonstrated binding of anti-amphiphysin antibodies to brain structures which are associated with anxiety disorders, such as the amygdala. We propose that antibody-mediated amphiphysin deficiency may account for anxiety behavior in stiff person syndrome via presynaptic dysregulation of GABAergic pathways.

• Lacosamide has protective disease modifying properties in experimental vincristine neuropathy.

  Authors: Christian Geis, Bettina K Beyreuther, Thomas Stöhr, Claudia Sommer

  Neuropharmacology. 05/2011; 61(4):600-7.

  Pain and paresthesias are the most common symptoms of chemotherapy induced painful neuropathy (CIPN). Current treatment and preventive strategies of CIPN are ineffective, and the neuropathy may leadPain and paresthesias are the most common symptoms of chemotherapy induced painful neuropathy (CIPN). Current treatment and preventive strategies of CIPN are ineffective, and the neuropathy may lead to discontinuation of anti-tumor therapy. Here we used experimental vincristine-induced neuropathy in rats to evaluate the disease modifying potential of lacosamide using a sustained release formulation and the acute treatment effects of a rapid release formulation. Pain behavior was assessed by withdrawal responses to von Frey hairs, acetone drops, the Randall-Selitto device, and to radiant heat. Neuropathy was assessed using electrophysiological recordings. Preventive lacosamide treatment (30 mg/kg subcutaneously b.i.d. for 17 days) was well tolerated, and pharmacokinetic analysis revealed a peak plasma concentration 2 h post-injection with a plasma half-life of approximately 3 h. Rats treated with lacosamide, in contrast to vehicle treated rats, did not develop vincristine-induced cold allodynia. Neurophysiology showed a delayed F-wave latency in vehicle treated rats, which was not present in lacosamide treated animals. We could thus demonstrate a protective disease modifying potency of lacosamide in an animal model of CIPN. Lacosamide may be a promising candidate for preventive treatment of CIPN in patients receiving chemotherapy with vinca alkaloids or platinum drugs.

• Human stiff-person syndrome IgG induces anxious behavior in rats.

  Authors: Christian Geis, Andreas Weishaupt, Benedikt Grünewald, Thomas Wultsch, Andreas Reif, Manfred Gerlach, Ron Dirkx, Michele Solimena, Daniela Perani, Manfred Heckmann, Klaus V Toyka, Franco Folli, Claudia Sommer

  PloS one. 01/2011; 6(2):e16775.

  Anxiety is a heterogeneous behavioral domain playing a role in a variety of neuropsychiatric diseases. While anxiety is the cardinal symptom in disorders such as panic disorder, co-morbid anxiousAnxiety is a heterogeneous behavioral domain playing a role in a variety of neuropsychiatric diseases. While anxiety is the cardinal symptom in disorders such as panic disorder, co-morbid anxious behavior can occur in a variety of diseases. Stiff person syndrome (SPS) is a CNS disorder characterized by increased muscle tone and prominent agoraphobia and anxiety. Most patients have high-titer antibodies against glutamate decarboxylase (GAD) 65. The pathogenic role of these autoantibodies is unclear. We re-investigated a 53 year old woman with SPS and profound anxiety for GABA-A receptor binding in the amygdala with (11)C-flumazenil PET scan and studied the potential pathogenic role of purified IgG from her plasma filtrates containing high-titer antibodies against GAD 65. We passively transferred the IgG fraction intrathecally into rats and analyzed the effects using behavioral and in vivo electrophysiological methods. In cell culture, we measured the effect of patient IgG on GABA release from hippocampal neurons. Repetitive intrathecal application of purified patient IgG in rats resulted in an anxious phenotype resembling the core symptoms of the patient. Patient IgG selectively bound to rat amygdala, hippocampus, and frontal cortical areas. In cultured rat hippocampal neurons, patient IgG inhibited GABA release. In line with these experimental results, the GABA-A receptor binding potential was reduced in the patient's amygdala/hippocampus complex. No motor abnormalities were found in recipient rats. The observations in rats after passive transfer lead us to propose that anxiety-like behavior can be induced in rats by passive transfer of IgG from a SPS patient positive for anti-GAD 65 antibodies. Anxiety, in this case, thus may be an antibody-mediated phenomenon with consecutive disturbance of GABAergic signaling in the amygdala region.

• The immunological basis for treatment of stiff person syndrome.

  Authors: Trygve Holmøy, Christian Geis

  Journal of neuroimmunology. 10/2010; 231(1-2):55-60.

  Antibodies against autoantigens involved in GABAergic neurotransmission are a shared feature of the different subtypes of stiff person syndrome (SPS). The autoantigens can be either presynaptic suchAntibodies against autoantigens involved in GABAergic neurotransmission are a shared feature of the different subtypes of stiff person syndrome (SPS). The autoantigens can be either presynaptic such as the smaller isoform of glutamic acid decarboxylase (GAD65), postsynaptic such as GABA-A receptor-associated protein and gephyrin, or located at the pre- and postsynaptic side such as amphiphysin. Most of these autoantigens are intracellular, and antibodies against GAD65 also occur in diabetes mellitus type 1 as well as other neurological diseases. Their pathogenic role has therefore been questioned. We here discuss the role of autoantibodies and T cells in SPS.

• Stiff person syndrome-associated autoantibodies to amphiphysin mediate reduced GABAergic inhibition.

  Authors: Christian Geis, Andreas Weishaupt, Stefan Hallermann, Benedikt Grünewald, Carsten Wessig, Thomas Wultsch, Andreas Reif, Nadiya Byts, Marcus Beck, Sibylle Jablonka, Michael K Boettger, Nurcan Üçeyler, Wernher Fouquet, Manfred Gerlach, Hans-Michael Meinck, Anna-Leena Sirén, Stephan J Sigrist, Klaus V Toyka, Manfred Heckmann, Claudia Sommer

  Brain : a journal of neurology. 09/2010; 133(11):3166-80.

  Synaptic inhibition is a central factor in the fine tuning of neuronal activity in the central nervous system. Symptoms consistent with reduced inhibition such as stiffness, spasms and anxiety occurSynaptic inhibition is a central factor in the fine tuning of neuronal activity in the central nervous system. Symptoms consistent with reduced inhibition such as stiffness, spasms and anxiety occur in paraneoplastic stiff person syndrome with autoantibodies against the intracellular synaptic protein amphiphysin. Here we show that intrathecal application of purified anti-amphiphysin immunoglobulin G antibodies induces stiff person syndrome-like symptoms in rats, including stiffness and muscle spasms. Using in vivo recordings of Hoffmann reflexes and dorsal root potentials, we identified reduced presynaptic GABAergic inhibition as an underlying mechanism. Anti-amphiphysin immunoglobulin G was internalized into neurons by an epitope-specific mechanism and colocalized in vivo with presynaptic vesicular proteins, as shown by stimulation emission depletion microscopy. Neurons from amphiphysin deficient mice that did not internalize the immunoglobulin provided additional evidence of the specificity in antibody uptake. GABAergic synapses appeared more vulnerable than glutamatergic synapses to defective endocytosis induced by anti-amphiphysin immunoglobulin G, as shown by increased clustering of the endocytic protein AP180 and by defective loading of FM 1-43, a styryl dye used to label cell membranes. Incubation of cultured neurons with anti-amphiphysin immunoglobulin G reduced basal and stimulated release of γ-aminobutyric acid substantially more than that of glutamate. By whole-cell patch-clamp analysis of GABAergic inhibitory transmission in hippocampus granule cells we showed a faster, activity-dependent decrease of the amplitude of evoked inhibitory postsynaptic currents in brain slices treated with antibodies against amphiphysin. We suggest that these findings may explain the pathophysiology of the core signs of stiff person syndrome at the molecular level and show that autoantibodies can alter the function of inhibitory synapses in vivo upon binding to an intraneuronal key protein by disturbing vesicular endocytosis.

• Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration.

  Authors: Christoph Kleinschnitz, Henrike Grund, Kirstin Wingler, Melanie E Armitage, Emma Jones, Manish Mittal, David Barit, Tobias Schwarz, Christian Geis, Peter Kraft [......] Anja Schrewe, Lore Becker, Valérie Gailus-Durner, Helmut Fuchs, Thomas Klopstock, Martin Hrabé de Angelis, Karin Jandeleit-Dahm, Ajay M Shah, Norbert Weissmann, Harald H H W Schmidt

  PLoS biology. 01/2010; 8(9).

  Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical needIschemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.

• Mild experimental autoimmune encephalitis as a tool to induce blood-brain barrier dysfunction.

  Authors: Michael Boettger, Andreas Weishaupt, Christian Geis, Klaus Toyka, Claudia Sommer

  Journal of neural transmission (Vienna, Austria : 1996). 11/2009;

  The blood-brain barrier (BBB) serves as a border limiting access of immunoglobulins from the circulation into the brain. This becomes relevant when studying the pathogenesis of antibody-mediatedThe blood-brain barrier (BBB) serves as a border limiting access of immunoglobulins from the circulation into the brain. This becomes relevant when studying the pathogenesis of antibody-mediated autoimmune CNS disorders. Here, we characterized the BBB dysfunction in a model of mild experimental adoptive transfer autoimmune encephalomyelitis (AT-EAE). We show that large molecules can readily penetrate the BBB between days 3 and 7 after EAE-induction. This model may be valuable for studying putative pathogenic effects of immunoglobulins in the central nervous system.

• TNF signaling contributes to the development of nociceptive sensitization in a tibia fracture model of complex regional pain syndrome type I.

  Authors: Ilya Sabsovich, Tian-Zhi Guo, Tzuping Wei, Rong Zhao, Xiangqi Li, David J Clark, Christian Geis, Claudia Sommer, Wade S Kingery

  Pain. 08/2008; 137(3):507-19.

  Tibia fracture in rats initiates a cascade of nociceptive, vascular, and bone changes resembling complex regional pain syndrome type I (CRPS I). Previous studies suggest that the pathogenesis ofTibia fracture in rats initiates a cascade of nociceptive, vascular, and bone changes resembling complex regional pain syndrome type I (CRPS I). Previous studies suggest that the pathogenesis of these changes is attributable to an exaggerated regional inflammatory response to injury. We postulated that the pro-inflammatory cytokine tumor necrosis factor alpha (TNF) might mediate the development of CRPS-like changes after fracture. RT-PCR and EIA assays were used to evaluate changes in TNF expression and content in skin, nerve, and bone after fracture. Bilateral hindpaw thickness, temperature, and nociceptive thresholds were determined, and bone microarchitecture was measured using microcomputed tomography. Lumbar spinal cord Fos immunostaining was performed for quantification of Fos positive neurons. After baseline testing, the distal tibia was fractured and the hindlimb casted for 4 weeks. The rats were subcutaneously injected either with a soluble TNF receptor type 1 (sTNF-R1, 5mg/kg/d) or saline every 3 days over 28 days and then were retested at 4 weeks post-fracture. Tibia fracture chronically upregulated TNF expression and protein levels in the hindpaw skin and sciatic nerve. After fracture the rats developed hindpaw mechanical allodynia and unweighting, which were reversed by sTNF-R1 treatment. Consistent with the behavioral data, spinal Fos increased after fracture and this effect was inhibited by sTNF-R1 treatment. Collectively, these data suggest that facilitated TNF signaling in the hindlimb is an important mediator of chronic regional nociceptive sensitization after fracture, but does not contribute to the hindlimb warmth, edema, and bone loss observed in this CRPS I model.

• Pentoxifylline attenuates nociceptive sensitization and cytokine expression in a tibia fracture rat model of complex regional pain syndrome.

  Authors: Tzuping Wei, Ilya Sabsovich, Tian-Zhi Guo, Xiaoyou Shi, Rong Zhao, Wenwu Li, Christian Geis, Claudia Sommer, Wade S Kingery, David J Clark

  European journal of pain (London, England). 07/2008;

  BACKGROUND: Tibia fracture in rats evokes chronic hindpaw warmth, edema, allodynia, and regional osteopenia, a syndrome resembling complex regional pain syndrome (CRPS). Previous studies suggest thatBACKGROUND: Tibia fracture in rats evokes chronic hindpaw warmth, edema, allodynia, and regional osteopenia, a syndrome resembling complex regional pain syndrome (CRPS). Previous studies suggest that the pathogenesis of some of these changes involves an exaggerated regional inflammatory response to injury and we postulated that inflammatory cytokines contribute to the development of CRPS-like changes after fracture. METHODS: The distal tibia was fractured and the hindlimb casted for 4 weeks. The rats were given drinking water with or without the cytokine inhibitor pentoxifylline (PTX) starting the day before fracture and continuing for 4 weeks, after which time the cast was removed and multiple assays were performed in the hindpaw. PCR and immunoassays were used to evaluate changes in cytokine expression. Bilateral hindpaw thickness, temperature, and nociceptive thresholds were determined, and bone microarchitecture was measured by microcomputed tomography (muCT). RESULTS: Tibia fracture chronically up-regulated TNFalpha, IL-1beta and IL-6 mRNA and protein levels in hindpaw skin and PTX treatment significantly reduced the mRNA expression and cytokine protein levels for all these cytokines. PTX inhibited the nociceptive sensitization and some vascular changes, but had insignificant effects on most of the bone-related parameters measured in these studies. Immunostaining of hindpaw skin was negative for immunocyte infiltration at 4 weeks post-fracture. CONCLUSIONS: These results suggest that pro-inflammatory cytokines contribute to the nociceptive and vascular sequelae of fracture and that PTX treatment can reverse these CRPS-like changes.

• Activation of TRPV1 contributes to morphine tolerance: involvement of the mitogen-activated protein kinase signaling pathway.

  Authors: Yong Chen, Christian Geis, Claudia Sommer

  The Journal of neuroscience : the official journal of the Society for Neuroscience. 06/2008; 28(22):5836-45.

  Tolerance to the analgesic effects of opioids occurs after their chronic administration, a pharmacological phenomenon that has been associated with the development of abnormal pain sensitivity suchTolerance to the analgesic effects of opioids occurs after their chronic administration, a pharmacological phenomenon that has been associated with the development of abnormal pain sensitivity such as hyperalgesia. In the present study, we investigated the role of TRPV1, which is crucial for the transduction of noxious chemical and thermal stimuli, in morphine tolerance and tolerance-associated thermal hyperalgesia. After chronic morphine treatment, a marked increase in TRPV1 immunoreactivity (IR) was detected in L4 dorsal root ganglion (DRG) neurons, spinal cord dorsal horn, and sciatic nerve. Real-time reverse transcription (RT)-PCR demonstrated that TRPV1 mRNA was upregulated in spinal cord and sciatic nerve but not in the DRG. Intrathecal pretreatment with SB366791 [N-(3-methoxyphenyl)-4-chlorocinnamide], a selective antagonist of TRPV1, attenuated both morphine tolerance and associated thermal hyperalgesia. Chronic morphine exposure induced increases in phosphorylation of mitogen-activated protein kinases (MAPKs), including p38 MAPK-IR, extracellular signal-regulated protein kinase (ERK)-IR, and c-Jun N-terminal kinase (JNK)-IR, in L4 DRG neurons. Intrathecal administration of the selective p38, ERK, or JNK inhibitors not only reduced morphine tolerance and associated thermal hyperalgesia but also suppressed the morphine-induced increase of TRPV1-IR in DRG neurons, spinal cord, and sciatic nerve and of mRNA levels in spinal cord and sciatic nerve. Together, we have identified a novel mechanism by which sustained morphine treatment results in tolerance and tolerance-associated thermal hyperalgesia, by regulating TRPV1 expression, in a MAPK-dependent manner. Thus, blocking TRPV1 might be a way to reduce morphine tolerance.

• Antihyperalgesic efficacy of lacosamide in a rat model for muscle pain induced by TNF.

  Authors: Bettina K Beyreuther, Christian Geis, Thomas Stöhr, Claudia Sommer

  Neuropharmacology. 05/2007; 52(5):1312-7.

  Chronic muscle pain is a problem with high prevalence in clinical practice and its pharmacological treatment is difficult. There is a lack of animal models which reliably predict analgesic activityChronic muscle pain is a problem with high prevalence in clinical practice and its pharmacological treatment is difficult. There is a lack of animal models which reliably predict analgesic activity of drugs on muscle pain. Here we used intramuscular injection of tumor necrosis factor-alpha (TNF) in rats as a model of muscle pain. In this model we tested the antihyperalgesic action of lacosamide in comparison to the analgesics pregabalin and gabapentin. Mechanical withdrawal thresholds to muscle pressure were measured with an algesimeter exerting pressure on the gastrocnemius muscles previously injected with TNF. Fore limb grip strength was measured with a digital grip force meter after TNF injection into the biceps brachii muscles. A complete reversal of hyperalgesia was seen with lacosamide at 30mg/kg. Significant effects were also seen for pregabalin at 30 and 100mg/kg and gabapentin at 100mg/kg. In biceps muscle hyperalgesia, a significant reversal of hyperalgesia was seen with lacosamide at 10mg/kg. Significant effects were also seen for pregabalin and gabapentin at 100mg/kg. We could thus demonstrate in a rat model for myalgia that lacosamide effectively reduces muscular hyperalgesia and is somewhat more potent than gabapentin and pregabalin.

• Selective increase of tumour necrosis factor-alpha in injured and spared myelinated primary afferents after chronic constrictive injury of rat sciatic nerve.

  Authors: Maria Schäfers, Christian Geis, Camilla I Svensson, Z David Luo, Claudia Sommer

  The European journal of neuroscience. 03/2003; 17(4):791-804.

  Chronic constriction of the sciatic nerve, leading to a hyperalgesic state, results in a partial lesion wherein some axons are injured and others remain intact. Here we sought to characterizeChronic constriction of the sciatic nerve, leading to a hyperalgesic state, results in a partial lesion wherein some axons are injured and others remain intact. Here we sought to characterize reactive changes which occur in DRG cell bodies of injured and uninjured axons projecting to skin and muscle. Using immunohistochemistry combined with flurorogold and fluororuby retrograde labelling to define DRG cell bodies associated with injured and uninjured axons, we analysed the DRG immunoreactivity (IR) for tumour necrosis factor-alpha (TNF), interleukin-10 (IL-10), the sensory neuron-specific channel vanilloid receptor 1 (VR1), isolectin B4 (IB4) and calcitonin-gene-related peptide (CGRP) 4 days after a unilateral chronic constriction injury (CCI) of the rat sciatic nerve. TNF IR was predominantly localized in neuronal DRG cells. In DRG with an intact nerve, TNF IR was present in 45%, IL-10 IR in 46%, VR1 IR in 44%, IB4 IR in 51% and CGRP IR in 40% of all neuronal profiles. Four days after CCI, TNF IR was increased in medium-sized neurons, whereas IR for IL-10, VR1 and IB4, predominantly present in small neurons, was reduced. Importantly, not only injured but also adjacent spared neurons contributed markedly to increased TNF IR. Neurons projecting to both muscle and skin displayed upregulated TNF IR after CCI. TNF in medium-sized neurons colocalized with neurofilament and trkB, but not with IB4, trkA or RET, suggesting a selective phenotypic switch in presumably low-threshold myelinated primary afferents. Spared myelinated fibres with intact sensory functions but upregulated TNF expression may contribute to behavioural changes observed after nerve injury.

• Anterograde transport of tumor necrosis factor-alpha in the intact and injured rat sciatic nerve.

  Authors: Maria Schäfers, Christian Geis, Dominik Brors, Tony L Yaksh, Claudia Sommer

  The Journal of neuroscience : the official journal of the Society for Neuroscience. 02/2002; 22(2):536-45.

  Tumor necrosis factor-alpha (TNF) appears as a key player at both central and peripheral terminals in early degenerative pathology and pain behavior after peripheral nerve injury. Recent studiesTumor necrosis factor-alpha (TNF) appears as a key player at both central and peripheral terminals in early degenerative pathology and pain behavior after peripheral nerve injury. Recent studies suggest that TNF may be axonally transported and thereby contribute to these central and peripheral actions. To characterize this transport, we used a double ligation (DL) procedure that distinguishes between anterograde and retrograde flow to visualize the axonal transport of endogenous TNF compared with the neurotrophin nerve growth factor (NGF) and to the neuropeptide calcitonin gene-related peptide (CGRP). In the intact nerve, TNF and CGRP immunoreactivity predominantly accumulated proximal to the DL (anterograde transport), whereas NGF displayed exclusive retrograde transport. At 20 hr after chronic constrictive injury (CCI), the anterograde transport of TNF and CGRP to the nerve injury site was dramatically increased. The results were corroborated by the analysis of axonal transport of exogenously applied 125I-TNF and 125I-NGF. After intraneural injection, 125I-TNF accumulated proximally to a DL, suggesting anterograde transport. In the unligated nerve, 125I-TNF was specifically transported anterogradely to the innervated muscle but not to skin. After CCI, 125I-TNF accumulated proximally to the peripheral nerve injury site, and endogenous TNF was exclusively increased in medium-sized and large dorsal root ganglion (DRG) neurons, suggesting that DRG neurons are a major contributing source of increased TNF traffic in the injured sciatic nerve. Our results suggest that anterograde transport of TNF plays a major role in the early neuronal response to peripheral nerve injury at sites distal to the cell body.

• Pentoxifylline attenuates nociceptive sensitization and cytokine expression in a tibia fracture rat model of complex regional pain syndrome

  Authors: Tzuping Wei, Ilya Sabsovich, Tian-Zhi Guo, Xiaoyou Shi, Rong Zhao, Wenwu Li, Christian Geis, Claudia Sommer, Wade S. Kingery, David J. Clark

  European Journal of Pain.

  BackgroundTibia fracture in rats evokes chronic hindpaw warmth, edema, allodynia, and regional osteopenia, a syndrome resembling complex regional pain syndrome (CRPS). Previous studies suggest thatBackgroundTibia fracture in rats evokes chronic hindpaw warmth, edema, allodynia, and regional osteopenia, a syndrome resembling complex regional pain syndrome (CRPS). Previous studies suggest that the pathogenesis of some of these changes involves an exaggerated regional inflammatory response to injury and we postulated that inflammatory cytokines contribute to the development of CRPS-like changes after fracture.MethodsThe distal tibia was fractured and the hindlimb casted for 4 weeks. The rats were given drinking water with or without the cytokine inhibitor pentoxifylline (PTX) starting the day before fracture and continuing for 4 weeks, after which time the cast was removed and multiple assays were performed in the hindpaw. PCR and immunoassays were used to evaluate changes in cytokine expression. Bilateral hindpaw thickness, temperature, and nociceptive thresholds were determined, and bone microarchitecture was measured by microcomputed tomography (μCT).ResultsTibia fracture chronically up-regulated TNFα, IL-1β and IL-6 mRNA and protein levels in hindpaw skin and PTX treatment significantly reduced the mRNA expression and cytokine protein levels for all these cytokines. PTX inhibited the nociceptive sensitization and some vascular changes, but had insignificant effects on most of the bone-related parameters measured in these studies. Immunostaining of hindpaw skin was negative for immunocyte infiltration at 4 weeks post-fracture.ConclusionsThese results suggest that pro-inflammatory cytokines contribute to the nociceptive and vascular sequelae of fracture and that PTX treatment can reverse these CRPS-like changes.