| 1. |
- Agalave, Nilesh M., et al.
(author)
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Sex-dependent role of microglia in disulfide high mobility group box 1 protein-mediated mechanical hypersensitivity
- 2021
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In: Pain. - : Lippincott Williams & Wilkins. - 0304-3959 .- 1872-6623. ; 162:2, s. 446-458
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Journal article (peer-reviewed)abstract
- High mobility group box 1 protein (HMGB1) is increasingly regarded as an important player in the spinal regulation of chronic pain. Although it has been reported that HMGB1 induces spinal glial activation in a Toll-like receptor (TLR)4-dependent fashion, the aspect of sexual dimorphisms has not been thoroughly addressed. Here, we examined whether the action of TLR4-activating, partially reduced disulfide HMGB1 on microglia induces nociceptive behaviors in a sex-dependent manner. We found disulfide HMGB1 to equally increase microglial Iba1 immunoreactivity in lumbar spinal dorsal horn in male and female mice, but evoke higher cytokine and chemokine expression in primary microglial culture derived from males compared to females. Interestingly, TLR4 ablation in myeloid-derived cells, which include microglia, only protected male mice from developing HMGB1-induced mechanical hypersensitivity. Spinal administration of the glial inhibitor, minocycline, with disulfide HMGB1 also prevented pain-like behavior in male mice. To further explore sex difference, we examined the global spinal protein expression using liquid chromatography-mass spectrometry and found several antinociceptive and anti-inflammatory proteins to be upregulated in only male mice subjected to minocycline. One of the proteins elevated, alpha-1-antitrypsin, partially protected males but not females from developing HMGB1-induced pain. Targeting downstream proteins of alpha-1-antitrypsin failed to produce robust sex differences in pain-like behavior, suggesting that several proteins identified by liquid chromatography-mass spectrometry are required to modulate the effects. Taken together, the current study highlights the importance of mapping sex dimorphisms in pain mechanisms and point to processes potentially involved in the spinal antinociceptive effect of microglial inhibition in male mice.
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| 2. |
- Bersellini Farinotti, Alex, et al.
(author)
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Cartilage-binding antibodies induce pain through immune complex-mediated activation of neurons
- 2019
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In: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 216:8, s. 1904-1924
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Journal article (peer-reviewed)abstract
- Rheumatoid arthritis-associated joint pain is frequently observed independent of disease activity, suggesting unidentified pain mechanisms. We demonstrate that antibodies binding to cartilage, specific for collagen type II (CII) or cartilage oligomeric matrix protein (COMP), elicit mechanical hypersensitivity in mice, uncoupled from visual, histological and molecular indications of inflammation. Cartilage antibody-induced pain-like behavior does not depend on complement activation or joint inflammation, but instead on tissue antigen recognition and local immune complex (IC) formation. smFISH and IHC suggest that neuronal Fcgr1 and Fcgr2b mRNA are transported to peripheral ends of primary afferents. CII-ICs directly activate cultured WT but not FcRγ chain-deficient DRG neurons. In line with this observation, CII-IC does not induce mechanical hypersensitivity in FcRγ chain-deficient mice. Furthermore, injection of CII antibodies does not generate pain-like behavior in FcRγ chain-deficient mice or mice lacking activating FcγRs in neurons. In summary, this study defines functional coupling between autoantibodies and pain transmission that may facilitate the development of new disease-relevant pain therapeutics.
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| 3. |
- Goebel, Andreas, et al.
(author)
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Passive transfer of fibromyalgia symptoms from patients to mice
- 2021
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In: Journal of Clinical Investigation. - : American Society For Clinical Investigation. - 0021-9738 .- 1558-8238. ; 131:13
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Journal article (peer-reviewed)abstract
- Fibromyalgia syndrome (FMS) is characterized by widespread pain and tenderness, and patients typically experience fatigue and emotional distress. The etiology and pathophysiology of fibromyalgia are not fully explained and there are no effective drug treatments. Here we show that IgG from FMS patients produced sensory hypersensitivity by sensitizing nociceptive neurons. Mice treated with IgG from FMS patients displayed increased sensitivity to noxious mechanical and cold stimulation, and nociceptive fibers in skin-nerve preparations from mice treated with FMS IgG displayed an increased responsiveness to cold and mechanical stimulation. These mice also displayed reduced locomotor activity, reduced paw grip strength, and a loss of intraepidermal innervation. In contrast, transfer of IgG-depleted serum from FMS patients or IgG from healthy control subjects had no effect. Patient IgG did not activate naive sensory neurons directly. IgG from FMS patients labeled satellite glial cells and neurons in vivo and in vitro, as well as myelinated fiber tracts and a small number of macrophages and endothelial cells in mouse dorsal root ganglia (DRG), but no cells in the spinal cord. Furthermore, FMS IgG bound to human DRG. Our results demonstrate that IgG from FMS patients produces painful sensory hypersensitivities by sensitizing peripheral nociceptive afferents and suggest that therapies reducing patient IgG titers may be effective for fibromyalgia.
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| 4. |
- Krock, Emerson, et al.
(author)
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Fibromyalgia patients with elevated levels of anti-satellite glia cell immunoglobulin G antibodies present with more severe symptoms
- 2023
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In: Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0304-3959 .- 1872-6623. ; 164:8, s. 1828-1840
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Journal article (peer-reviewed)abstract
- Transferring fibromyalgia patient immunoglobulin G (IgG) to mice induces pain-like behaviour, and fibromyalgia IgG binds mouse and human satellite glia cells (SGCs). These findings suggest that autoantibodies could be part of fibromyalgia pathology. However, it is unknown how frequently fibromyalgia patients have anti-SGC antibodies and how anti-SGC antibodies associate with disease severity. Here, we quantified serum or plasma anti-SGC IgG levels in 2 fibromyalgia cohorts from Sweden and Canada using an indirect immunofluorescence murine cell culture assay. Fibromyalgia serum IgG binding to human SGCs in human dorsal root ganglia tissue sections was also assessed by immunofluorescence. In the cell culture assay, anti-SGC IgG levels were increased in both fibromyalgia cohorts compared with control group. Elevated anti-SGC IgG was associated with higher levels of self-reported pain in both cohorts, and higher fibromyalgia impact questionnaire scores and increased pressure sensitivity in the Swedish cohort. Anti-SGC IgG levels were not associated with fibromyalgia duration. Swedish fibromyalgia (FM) patients were clustered into FM-severe and FM-mild groups, and the FM-severe group had elevated anti-SGC IgG compared with the FM-mild group and control group. Anti-SGC IgG levels detected in culture positively correlated with increased binding to human SGCs. Moreover, the FM-severe group had elevated IgG binding to human SGCs compared with the FM-mild and control groups. These results demonstrate that a subset of fibromyalgia patients have elevated levels of anti-SGC antibodies, and the antibodies are associated with more severe fibromyalgia symptoms. Screening fibromyalgia patients for anti-SGC antibodies could provide a path to personalized treatment options that target autoantibodies and autoantibody production.
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| 5. |
- Morado Urbina, Carlos Eduardo
(author)
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Cellular and molecular mechanisms of inflammatory arthritis and fibromyalgia
- 2024
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Doctoral thesis (other academic/artistic)abstract
- In Study I, we examined the impact of the hR100E-NGF mutation on inflammatory pain and bone erosion in both female and male mice. Our findings indicate that the hR100E-NGF mutation did not affect the development of the peripheral sensory nervous system at the lumbar DRG, sciatic nerve, ankle joint, or glabrous skin. Moreover, hR100E-NGF mice displayed sensory thresholds similar to those of the hWT-NGF mice in response to mechanical, heat, or cold stimulation under normal conditions. The hR100E-NGF and hWT-NGF mice developed comparable mechanical and heat sensitivity impairments after the intra-articular injection of complete Freund’s adjuvant. Notably, the hR100E-NGF mice were insensitive to nociceptive stimulation in the deeper tissues assessed by weight bearing and gait analysis. Furthermore, mRNA analysis from the inflamed joint showed a differential sex-dependent gene expression profile between hR100E-NGF female and male mice. Finally, the hR100E-NGF female but not the male mice were protected against the CFA-bone erosion. These data collectively demonstrate that the R100E NGF mutation effectively protects against joint pain-like behaviors in both male and female mice while providing bone protection exclusively to female mice in a monoarthritis model. We propose that manipulating the signaling of NGF and its receptors in a manner similar to the R100E mutation could be a promising approach to treating chronic pain and maintaining bone health, particularly in women. Study II investigated the effects of injecting purified IgG from fibromyalgia (FM) patients and healthy controls (HC) in mice. We found that the injection of FM IgG but not IgG from healthy controls (HC) induces pressure, mechanical, and cold hypersensitivity in mice that were coupled to enhanced nociceptor responsiveness to mechanical and cold stimulation. The FM IgG-injected mice also developed impaired muscular strength and decreased locomotor activity. Moreover, FM IgG bound and stimulated satellite glial cells (SGCs) in vivo and in vitro. No FM or HC IgG accumulation was found in the brain or spinal cord of the injected mice. Our study also demonstrated that FM IgG can bind to satellite glial cells and neurons in the human DRG. In addition, we observed a significant reduction in the intraepidermal nerve fiber density in the mice 14 days after the FM IgG injection. Our results suggest that transferring FM IgG into mice can replicate some peripheral FM symptoms. This study can provide a valuable animal model for studying the peripheral physiology of FM. Our discovery could significantly advance the understanding and treatment of fibromyalgia and other related conditions. However, more research is needed to understand the cellular and molecular mechanisms involved in FM-IgG-mediated changes in mice. Study III aimed to investigate the frequency of anti-satellite glial cell (SGC) antibodies and the antibody association with the disease severity in FM patients. We used serum (Karolinska Institutet, Sweden; n=30/group) and plasma (McGill University, Canada; n=35/group) samples collected from FM patients and HCs. Our results showed a higher binding intensity of the FM IgG to SGC in vitro. Furthermore, the frequency of SGC bound to FM IgG was significantly higher than HC IgG-treated cells. These findings correlated with pain intensity and fibromyalgia impact questionnaire scores (FIQ, questionnaire was only assessed in the Karolinska cohort). Further cluster analysis separated the FM group into severe and mild groups. Additionally, we found that serum from FM patients contains IgG that binds in greater proportion to SGC in the human DRG, measured by higher signal intensity. There were no differences in the binding intensity to neuronal cell bodies or axons between FM and HC serum samples. Finally, the previous results were confirmed using an FM serum sample with high levels of anti-SGC antibodies in 5 more human DRGs. To summarize, our report indicates that levels of anti-human SGC and anti-mouse SGC antibodies are elevated in patients with FM, which are linked to a more severe form of the disease. Patient stratification based on their profile of anti-SGC antibodies might benefit from therapies aiming to decrease circulating IgG or prevent IgG binding. Our results point to the possible involvement of anti-SGC antibodies and SGCs in the severity of FM; however, more in-depth studies are necessary to elucidate the antigen or antigens expressed in the SGC that bind to the circulating anti-SGC antibodies. In Study IV, we aimed to explore the neuroimmune signature of the FM skin. We processed 16 FM and 16 HC sex-matched skin biopsies by immunohistochemistry. Using a pan-neuronal marker, we found lower intraepidermal nerve fiber density (IENFD) in the FM compared with HC skin. Moreover, the length and volume of dermal NF200+ nerve profiles were significantly elevated, but we found no changes in the length of dermal or epidermal Gap43+ nerve profiles in the FM group. Similarly, we found no changes in the total volume of CD31+ blood vessels between FM and HC skin. Our results showed that the density of non-nerve associated S100b+, CD68+, and CD163+ cells was significantly lower in the FM skin. Furthermore, the dermal CD117+FcERI+ mast cells in the dermis of FM patients were significantly increased compared with the HCs. Additionally, we found similar densities of CD207+, CD3+, or Neutrophil elastase+ cells between FM and HC skin biopsies. mRNA analysis of FM skin showed no changes in Cd68, Cd163, Cx3cr1, or FceR1 mRNA levels between FM and HC skin. In summary, this study reveals crucial dermal and epidermal changes in FM skin, particularly regarding nerve fibers and certain immune cell populations. These findings are highly relevant as they provide deeper insights into the complex interactions between the nervous and immune systems in FM. Understanding these changes could be key to developing more effective treatments for FM, focusing on both the neuropathic and immune components of the disease.
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