IL 17 (Interleukin 17)

Overview

Interleukin-17 (primarily IL-17A and IL-17F) is the signature cytokine of Th17 cells. At physiological levels, IL-17 maintains mucosal barrier defense by recruiting neutrophils and inducing antimicrobial peptide production. At pathological levels (Th17/Treg imbalance), IL-17 drives autoimmune tissue destruction — it is the therapeutic target in psoriasis (secukinumab), psoriatic arthritis, and ankylosing spondylitis.

Microbiome Regulation

  • Segmented filamentous bacteria (SFB) are the strongest known microbial inducers of IL-17-producing Th17 cells in the gut.
  • Dysbiosis-driven SCFA depletion shifts the Th17/Treg balance toward IL-17 excess (see th17 treg balance).
  • IL-17 elevation is documented across: Graves' disease [1], Hashimoto's [2], schizophrenia [3], T1D [4], MS, IBD, and psoriasis.

Cross-References

References (4)

  1. Su X, Yin X, Liu Y et al. (2020). Su et al. 2020 — Gut Dysbiosis Contributes to the Imbalance of Treg and Th17 Cells in Graves' Disease Patients by Propionic Acid. The Journal of Clinical Endocrinology & Metabolism. doi:10.1210/clinem/dgaa511
  2. Pei XQ, Wang WH, Gao YH et al. (2024). Role of immune cells in mediating the effect of gut microbiota on Hashimoto's thyroiditis: a 2-sample Mendelian randomization study. Frontiers in Microbiology. doi:10.3389/fmicb.2024.1463394
  3. Ermakov EA, Melamud MM, Buneva VN et al. (2022). Immune System Abnormalities in Schizophrenia: An Integrative View and Translational Perspectives. Frontiers in Psychiatry. doi:10.3389/fpsyt.2022.880568
  4. Xinyun Bi, Fanghong Li, Shanshan Liu et al. (2017). Bi 2017 — Omega-3 Polyunsaturated Fatty Acids Ameliorate Type 1 Diabetes and Autoimmunity. Journal of Clinical Investigation. doi:10.1172/JCI87388

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