Biology:T helper cell 22
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T helper cell 22, also known as the Th22 cell, are a type of immune cell. Th22 cells are a subset of naïve CD4+ T cells induced by the ligand activation of the transcription factor aryl hydrocarbon receptor (AhR),[1] which uses environmental, metabolic, microbial, and dietary cues to control complex transcriptional programmes.[2] Th22 cell function is mediated by its ligand specific cytokine interleukin-22 (IL-22).[3]
Differentiation and cytokine expression
Th22 cells were distinguished as their own class of T helper cells due to their production of IL-22, setting them apart from the key expression cytokines of IFN-gamma, IL-4, or IL-17 that are associated with Th1, Th2, and Th17 cells respectively.[1][4] Th22 cell differentiation is stimulated by IL-6 and TNF-alpha, but others have found Th22 can be stimulated using Langerhans cells and dermal dendritic cells.[3] Th22 cells are known to secrete IL-22, IL-13, IL-26, TNF-α, and granzyme B.[5]
In the immune response
Th22 cells express the chemokine receptors CCR4, CCR6, and CCR10 which direct the cells to barrier surfaces such as the skin and mucosal tissue.[3][5][6] Th22 cells are also associated with the release of chemokines CXCL1, CXCL5, and CXCL9, which are associated with the recruitment of other inflammatory cells to the area.[7]
IL-22 expression stimulates the growth of keratinocytes and epithelial cells, helping to maintain the innate barrier of skin and other organs.[7] Similarly, IL-22, the characteristic cytokine produced by Th22 cells has little effect on immune cells and instead acts on mucosal barriers.[5] Due to mucosal barrier interactions Th22 and subsequently IL-22 play a significant role in a variety of skin diseases, intestinal diseases, autoimmune diseases, and allergy conditions. Many of these diseases are characterized by increased circulation of Th22 cells and concomitant increased IL-22 expression.[3]
In psoriasis, there is a positive feedback loop between Th22 and IL-22 expression.[3] Increased expression of IL-22 is observed during lesion formation that augments the expression of anti-microbials and induces chemokine ligand (CCL)-20 recruiting CCR6, which is expressed on Th22 cells increasing their concentration in the lesion.[3] Similarly, Th22 cells are found throughout the intestinal wall in irritable bowel diseases, facilitating IL-22 secretion and subsequent induction of tissue specific genes.[3][8] Interestingly, Th22 cells induced expression of IL-22 in allergic asthma has been seen to have a protective effect against lung hypertension and tissue damage in murine models.[3]
References
- ↑ 1.0 1.1 "Identification of a human helper T cell population that has abundant production of interleukin 22 and is distinct from T(H)-17, T(H)1 and T(H)2 cells". Nature Immunology 10 (8): 864–871. August 2009. doi:10.1038/ni.1770. PMID 19578368.
- ↑ "The aryl hydrocarbon receptor: an environmental sensor integrating immune responses in health and disease". Nature Reviews. Immunology 19 (3): 184–197. March 2019. doi:10.1038/s41577-019-0125-8. PMID 30718831.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "The Biology and Functions of Th22 Cells". T Helper Cell Differentiation and Their Function. Advances in Experimental Medicine and Biology. 841. Dordrecht: Springer Netherlands. 2014. pp. 209–230. doi:10.1007/978-94-017-9487-9_8. ISBN 978-94-017-9487-9.
- ↑ "Production of interleukin 22 but not interleukin 17 by a subset of human skin-homing memory T cells". Nature Immunology 10 (8): 857–863. August 2009. doi:10.1038/ni.1767. PMID 19578369.
- ↑ 5.0 5.1 5.2 "Role of Th22 Cells in the Pathogenesis of Autoimmune Diseases". Frontiers in Immunology 12. 2021. doi:10.3389/fimmu.2021.688066. PMID 34295334.
- ↑ "The Potential Role of T Helper Cell 22 and IL-22 in Immunopathogenesis of Multiple Sclerosis". Innovations in Clinical Neuroscience 13 (7–8): 30–36. July 2016. PMID 27672486.
- ↑ 7.0 7.1 "The role of Th22 cells, from tissue repair to cancer progression". Cytokine 149. January 2022. doi:10.1016/j.cyto.2021.155749. PMID 34739898.
- ↑ "Role of interleukin-22 in inflammatory bowel disease". World Journal of Gastroenterology 20 (48): 18177–18188. December 2014. doi:10.3748/wjg.v20.i48.18177. PMID 25561785.
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