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.
Evidence map1 cited passagesInspect provenance +
IL-17 elevation is documented across: Graves' disease, Hashimoto's, schizophrenia, T1D, MS, IBD, and psoriasis.
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]Su et al. 2020 — Gut Dysbiosis Contributes to the Imbalance of Treg and Th17 Cells in Graves' Disease Patients by Propionic AcidSu X, Yin X, Liu Y et al. · 2020Open reference 1 ↓ Hashimoto's,[2]Role of immune cells in mediating the effect of gut microbiota on Hashimoto's thyroiditis: a 2-sample Mendelian randomization studyPei XQ, Wang WH, Gao YH et al. · 2024Open reference 2 ↓ schizophrenia,[3]Immune System Abnormalities in Schizophrenia: An Integrative View and Translational PerspectivesErmakov EA, Melamud MM, Buneva VN et al. · 2022Open reference 3 ↓ T1D,[4]Bi 2017 — Omega-3 Polyunsaturated Fatty Acids Ameliorate Type 1 Diabetes and AutoimmunityXinyun Bi, Fanghong Li, Shanshan Liu et al. · 2017Open reference 4 ↓ MS, IBD, and psoriasis.
Cross-References#
- Th17/Treg Balance—IL-17 as Th17 effector cytokine
- Interleukin-6 (IL-6)—IL-6 + TGF-beta drives Th17 (IL-17) differentiation
- TGF-beta (Transforming Growth Factor Beta)—required for Th17 differentiation (with IL-6)
- IL-10 (Interleukin-10)—anti-inflammatory counterbalance
- Immune Balance—broader immune equilibrium
References 4
Numbered by first appearance in the article, then reconciled with its declared source list.
- 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.
- 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.
- 3
Ermakov EA, Melamud MM, Buneva VN et al. (2022). Immune System Abnormalities in Schizophrenia: An Integrative View and Translational Perspectives. Frontiers in Psychiatry.
- 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.
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