Background & Aims
Rheumatoid arthritis (RA) is an autoimmune disease, characterized by chronic joint inflammation and pain. A diverse community of microorganisms resides at mucosal surfaces of the gastrointestinal tract. Gut dysbiosis is one of contributing factors to the development and progression of RA[1], [2], [3]. It has been suggested that transient receptor potential/ vanilloid receptor subtype 1 (TRPV1) is involved in joint inflammation and pain[4]. Given that TRPV1 is expressed in various cells, including neurons, immune cells, synoviocytes, and epithelial cells, it is not surprised that TRPV1 could have a complex influence on RA progression. This study investigates the role of TRPV1 in shaping the gut microbiome and its impact on RA-related pain and inflammation. This work aims to provide insights into novel mechanisms underlying autoimmune diseases, potentially opening avenues for therapeutic interventions and microbiota-based therapy for RA.
Methods
Arthritis mouse model were adapted from the method by Gauldie et al. (2004). Male and female mice received weekly injections of 5 ?g CFA (Complete Freund’s Adjuvant)in the right ankle joint for four weeks. Arthritis severity was graded on a scale from 0 to 5 based on redness and swelling. Mechanical nociceptive responses were assessed using von Frey filaments. At week 12, mice were sacrificed, joint, blood, and fecal samples were collected. Blood samples were used to measure interleukin-6 (IL-6) levels using ELISA kits from the R&D system. Joint samples were fixed, waxed and sectioned for hematoxylin/eosin staining by Taiwan Mouse Clinic (Taipei, Taiwan). Microbial DNA from feces was extracted by using the QIAamp PowerFecal DNA kit. The extracted DNA was analyzed by Biotools Pvt Limited (Taipei, Taiwan) for 16S rDNA gene amplification. The QIIME2-2022.2 platform was used for microbial analysis.
Results
CFA injection induced a long-term inflammation and pain hypersensitivity in TRPV1+/+ mice. Deletion of TRPV1 reduces bilateral mechanical hyperalgesia and arthritis scores in later phase. It also reduces synovial inflammation, cartilage damage, bone erosion and IL-6 levels at 12 w after CFA . Microbiome analysis revealed significant alterations in the gut microbiota at genus level.There is a slight increase in ? diversity indices of the microbiome in TRPV1+/+ RA mice but a dramatic decrease in ? diversity in TRPV1-/- RA mice. In TRPV1+/+ RA mice, the core genera Helicobacter,Clostridium and Desulfovibrio contents are increased;while Lactobacillus, Alisteps,Odoribacter,Sporobacter, and Mucispirillium are reduced. TRPV1 deficient mice increased Lactobacillus, and Bifidobacterium; decreased Alisteps,Odoribacter. These changes in microbiome abundance could affect the levels of SCFA and metabolites,contributing to gut-barrier integrity and the balance of pro- and anti-inflammatory response.
Conclusions
This study investigates the microbiome composition in feces of CFA-induced arthritis mouse models, specifically comparing TRPV1 wild-type and knockout mice before and after RA induction. The results demonstrate significant changes at the genus level, highlighting shifts in bacteria such as Prevotella, Helicobacter, Lactobacillus, Clostridium, and Papillibacter, associated with pro-inflammatory responses indicative of RA. These alterations influence short-chain fatty acid and metabolite levels[5], gut barrier integrity[6], triggering a systemic immune response leading to inflammation and painful swelling. The study emphasizes the importance of understanding bacterial interactions with host mucus in the gut and TRPV1 modulation in specific microbiota, providing insights for developing innovative microbiota-based therapies for RA.
References
[1]X. Zhang et al., “The oral and gut microbiomes are perturbed in rheumatoid arthritis and partly normalized after treatment,” Nat Med, vol. 21, no. 8, pp. 895–905, Aug. 2015, doi: 10.1038/nm.3914.
[2]M.-N. Tsetseri, A. J. Silman, D. J. Keene, and S. G. Dakin, “The role of the microbiome in rheumatoid arthritis: a review,” Rheumatol Adv Pract, vol. 7, no. 2, Apr. 2023, doi: 10.1093/rap/rkad034.
[3]N. T. Nguyen, W.-H. Sun, T.-H. Chen, P.-C. Tsai, C.-C. Chen, and S.-L. Huang, “Gut Mucosal Microbiome Is Perturbed in Rheumatoid Arthritis Mice and Partly Restored after TDAG8 Deficiency or Suppression by Salicylanilide Derivative,” Int J Mol Sci, vol. 23, no. 7, p. 3527, Mar. 2022, doi: 10.3390/ijms23073527.
[4]W.-S. Hsieh, C.-C. Kung, S.-L. Huang, S.-C. Lin, and W.-H. Sun, “TDAG8, TRPV1, and ASIC3 involved in establishing hyperalgesic priming in experimental rheumatoid arthritis,” Sci Rep, vol. 7, no. 1, p. 8870, Aug. 2017, doi: 10.1038/s41598-017-09200-6.
[5]L. Xu et al., “Metabolomics in rheumatoid arthritis: Advances and review,” Front Immunol, vol. 13, Aug. 2022, doi: 10.3389/fimmu.2022.961708.
[6]D. E. Matei et al., “Intestinal barrier dysfunction plays an integral role in arthritis pathology and can be targeted to ameliorate disease,” Med, vol. 2, no. 7, pp. 864-883.e9, Jul. 2021, doi: 10.1016/j.medj.2021.04.013.
Presenting Author
Samarth Gupta
Poster Authors
Topics
- Specific Pain Conditions/Pain in Specific Populations: Rheumatology, Arthritis, and Other