Interleukin-22 (IL-22m) is a signaling molecule, known as a cytokine, that plays a part in the body’s immune system. It influences various biological processes, contributing to defense mechanisms and the upkeep of different tissues.
Understanding IL-22m
IL-22m is a member of the IL-10 cytokine family. It is primarily produced by several types of immune cells, including T helper 17 (Th17) and Th22 cells, natural killer (NK) cells, CD8+ cytotoxic T cells, γδ T cells, and innate lymphoid cells (ILCs). Activated macrophages can also produce IL-22m.
IL-22m’s effects are observed in specific cells and tissues throughout the body, as its unique receptor, composed of IL-22Rα and IL-10Rβ subunits, is mainly found on non-hematopoietic cells. These include epithelial cells in organs like the skin, digestive tract, respiratory tract, liver, kidney, and pancreas. This means IL-22m primarily acts on the cells lining these organs rather than directly on immune cells.
Key Roles in Immunity and Tissue Repair
IL-22m has a role in maintaining the integrity of various bodily barriers, such as those in the gut, skin, and lungs. It helps protect these surfaces from infections by promoting the production of antimicrobial peptides like β-defensin and RegIIIγ. These peptides directly combat pathogens, contributing to innate immune defense.
Beyond its antimicrobial actions, IL-22m also supports tissue repair and regeneration. It can stimulate the proliferation of epithelial cells and protect them from damage. This cytokine also influences inflammatory responses, helping to resolve inflammation and restore tissue balance. It can induce the production of mucins, further ensuring protection and maintenance of the epithelial layer.
IL-22m and Disease
Dysregulation of IL-22m activity is linked to various diseases. In inflammatory bowel disease (IBD), IL-22m has a beneficial role by enhancing the gut’s barrier integrity and promoting epithelial innate immunity. It can induce the proliferation and repair of mucosal epithelial cells in the intestinal tract, helping to repair damaged tissue and prevent microorganism penetration.
In contrast, IL-22m can exacerbate conditions like psoriasis. It can work with other pro-inflammatory cytokines to induce pathological changes in keratinocytes, contributing to the progression of the skin disease. Its imbalance is also implicated in certain liver diseases and can play a role in host defense against specific infections. For instance, while generally protective, IL-22m has been shown to promote intestinal inflammation in some parasitic infections, such as Toxoplasma gondii.
Therapeutic Potential
Scientists are exploring IL-22m as a target for new treatments. One approach involves using recombinant IL-22m to promote healing. This is beneficial in conditions like inflammatory bowel disease or liver injury, where its tissue-protective and regenerative properties aid recovery. Recombinant IL-22m can activate pathways that lead to cell proliferation and protection against apoptosis.
Another strategy focuses on blocking IL-22m activity when it is overactive, as seen in certain autoimmune conditions like adenomyosis. Neutralizing antibodies against IL-22m are being investigated to inhibit its pro-inflammatory or pro-proliferative effects in such contexts. Clinical trials are also investigating IL-22m’s efficacy in conditions like COVID-19, with some studies suggesting it shortens intensive care unit stays. This highlights IL-22m as an active area of research for future therapeutic interventions.