The IL-10 family is a family of interleukins.
In addition to IL-10, it includes IL-19, IL-20, IL-22, IL-24 and IL-26. [1]
Some sources also include the interferons IL-28 and IL-29. [2]
The IL-10 family are helical cytokines categorized based on their specific similarities and can be classified as class 2 cytokines. [3]
The IL-10 family is one of the important types of cytokines, that can stop the inflammation. In general. these cytokines have a helical structure of homodimers. [4] The difference that the members of IL-10 family have between each other is that they have various receptor-binding residues, which help with interaction with specific cytokine receptors. [5] The features of the IL-10 family consists of their genomic structure being similar, their primary and secondary protein structures being similar, their a clustering of encoding genes, and their utilization the similar receptor complexes. [3]
Interleukin 10 is produced by regulatory T lymphocytes, B cells, and monocytes. It is a homodimer that functions through the IL-10R1 and IL-10R2 receptor complexes, activating such kinases as Janus kinase and tyrosine kinase 2. [6] IL-10R2 receptor is presented in most cells, when IL-10R1 receptor is IL-10 is also an inhibitor of expressions of CD80 and CD86 by dendritic cells (DC) and antigen-presenting cells (APC), [6] and of T cells, decreasing their cytokine production, therefore, controlling their activation. IL-10 plays a big role in regulating allergies by inhibiting cytokines responsible for allergic inflammation.
Interleukin 19 is produced mainly in monocytes, and can be found in big concentrations in patients with allergic disorders and psoriasis. IL-19 plays a big role in the CNS by regulating the inflammation process through a delayed production of it. [7]
IL-20 - induces cheratin proliferation and Stat-3 signal transduction pathway; [7] is expressed in the CNS, myeloid cells, and keratinocytes. When IL-20 is inhibited in the CNS can stop such inflammations as acute ischemic brain injury. [7] [6]
IL-22 mediates inflammation and binds class II cytokine receptor heterodimers IL-22 RA1/CRF2-4; [8] is involved in immuno-regulatory responses
IL-24 produced by activated monocytes and T-cells. [9]
IL-26 is a newly discovered cytokine produced by memory T cells and monocytes. IL-26 assist with the process of human T cell transformation after their infections. [9]
Based on the functions of the cytokine, the IL-10 family can be separated into three subfamily groups. IL-10 subfamily cytokine selects the innate and adaptive immune response and can prevent the function to reduce tissue damage. [10] The IL-20 subfamily of cytokine works on tissues in the stroma and epithelial cells to bring out the mechanism of innate defense that manages the attack of extracellular pathogens. [10] The IL-28 subfamily of cytokine are type III interferon (IFN) family. [10] This subfamily share intersecting biology and signaling pathways with type I IFN family cytokines but the difference is that the type III INF family cytokines prefer to target the tissues of the epithelial cell. [10]
Cytokines are a broad and loose category of small proteins important in cell signaling. Due to their size, cytokines cannot cross the lipid bilayer of cells to enter the cytoplasm and therefore typically exert their functions by interacting with specific cytokine receptors on the target cell surface. Cytokines have been shown to be involved in autocrine, paracrine and endocrine signaling as immunomodulating agents.
Interleukin 10 (IL-10), also known as human cytokine synthesis inhibitory factor (CSIF), is an anti-inflammatory cytokine. In humans, interleukin 10 is encoded by the IL10 gene. IL-10 signals through a receptor complex consisting of two IL-10 receptor-1 and two IL-10 receptor-2 proteins. Consequently, the functional receptor consists of four IL-10 receptor molecules. IL-10 binding induces STAT3 signalling via the phosphorylation of the cytoplasmic tails of IL-10 receptor 1 + IL-10 receptor 2 by JAK1 and Tyk2 respectively.
Interleukin 12 (IL-12) is an interleukin that is naturally produced by dendritic cells, macrophages, neutrophils, helper T cells and human B-lymphoblastoid cells (NC-37) in response to antigenic stimulation. IL-12 belongs to the family of interleukin-12. IL-12 family is unique in comprising the only heterodimeric cytokines, which includes IL-12, IL-23, IL-27 and IL-35. Despite sharing many structural features and molecular partners, they mediate surprisingly diverse functional effects.
The interleukin 4 is a cytokine that induces differentiation of naive helper T cells (Th0 cells) to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4 in a positive feedback loop. IL-4 is produced primarily by mast cells, Th2 cells, eosinophils and basophils. It is closely related and has functions similar to IL-13.
Interleukin 13 (IL-13) is a protein that in humans is encoded by the IL13 gene. IL-13 was first cloned in 1993 and is located on chromosome 5q31.1 with a length of 1.4kb. It has a mass of 13 kDa and folds into 4 alpha helical bundles. The secondary structural features of IL-13 are similar to that of Interleukin 4 (IL-4); however it only has 25% sequence identity to IL-4 and is capable of IL-4 independent signaling. IL-13 is a cytokine secreted by T helper type 2 (Th2) cells, CD4 cells, natural killer T cell, mast cells, basophils, eosinophils and nuocytes. Interleukin-13 is a central regulator in IgE synthesis, goblet cell hyperplasia, mucus hypersecretion, airway hyperresponsiveness, fibrosis and chitinase up-regulation. It is a mediator of allergic inflammation and different diseases including asthma., and atopic dermatitis.
Interleukin-15 (IL-15) is a protein that in humans is encoded by the IL15 gene. IL-15 is an inflammatory cytokine with structural similarity to Interleukin-2 (IL-2). Like IL-2, IL-15 binds to and signals through a complex composed of IL-2/IL-15 receptor beta chain (CD122) and the common gamma chain. IL-15 is secreted by mononuclear phagocytes following infection by virus(es). This cytokine induces the proliferation of natural killer cells, i.e. cells of the innate immune system whose principal role is to kill virally infected cells.
Interleukin-31 (IL-31) is a protein that in humans is encoded by the IL31 gene that resides on chromosome 12. IL-31 is an inflammatory cytokine that helps trigger cell-mediated immunity against pathogens. It has also been identified as a major player in a number of chronic inflammatory diseases, including atopic dermatitis.
Interleukin-26 (IL-26) is a protein that in humans is encoded by the IL26 gene.
Interleukin-25 (IL-25) – also known as interleukin-17E (IL-17E) – is a protein that in humans is encoded by the IL25 gene on chromosome 14. IL-25 was discovered in 2001 and is made up of 177 amino acids.
Interleukin 20 (IL20) is a protein that is in humans encoded by the IL20 gene which is located in close proximity to the IL-10 gene on the 1q32 chromosome. IL-20 is a part of an IL-20 subfamily which is a part of a larger IL-10 family.
Interleukin 17 family is a family of pro-inflammatory cystine knot cytokines. They are produced by a group of T helper cell known as T helper 17 cell in response to their stimulation with IL-23. Originally, Th17 was identified in 1993 by Rouvier et al. who isolated IL17A transcript from a rodent T-cell hybridoma. The protein encoded by IL17A is a founding member of IL-17 family. IL17A protein exhibits a high homology with a viral IL-17-like protein encoded in the genome of T-lymphotropic rhadinovirus Herpesvirus saimiri. In rodents, IL-17A is often referred to as CTLA8.
Interleukin 19 (IL-19) is an immunosuppressive protein that belongs to the IL-10 cytokine subfamily.
Interleukin-12 receptor, beta 1, or IL-12Rβ1 in short, is a subunit of the interleukin 12 receptor and the interleukin 23 receptor. IL12RB1, is the name of its human gene. IL-12Rβ1 is also known as CD212.
Interleukin 20 receptor, alpha subunit, is a subunit of the interleukin-20 receptor, the interleukin-26 receptor, and the interleukin-24 receptor. The interleukin 20 receptor, alpha subunit is also referred to as IL20R1 or IL20RA. The IL20RA receptor is involved in both pro-inflammatory and anti-inflammatory responses, signaling through the JAK-STAT pathway.
Interleukin 20 receptor, beta subunit is a subunit of the interleukin-20 receptor and interleukin-22 receptor. It is believed to be involved in both pro-inflammatory and anti-inflammatory responses.
Interleukin-28 receptor is a type II cytokine receptor found largely in epithelial cells. It binds type 3 interferons, interleukin-28 A, Interleukin-28B, interleukin 29 and interferon lambda 4. It consists of an α chain and shares a common β subunit with the interleukin-10 receptor. Binding to the interleukin-28 receptor, which is restricted to select cell types, is important for fighting infection. Binding of the type 3 interferons to the receptor results in activation of the JAK/STAT signaling pathway.
The Interleukin-1 family is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections or sterile insults.
Interleukin 23 (IL-23) is a heterodimeric cytokine composed of an IL-12B (IL-12p40) subunit and an IL-23A (IL-23p19) subunit. IL-23 is part of the IL-12 family of cytokines. The functional receptor for IL-23 consists of a heterodimer between IL-12Rβ1 and IL-23R.
Interleukin 36, or IL-36, is a group of cytokines in the IL-1 family with pro-inflammatory effects. The role of IL-36 in inflammatory diseases is under investigation.
Interleukin 17F (IL-17F) is signaling protein that is in human is encoded by the IL17F gene and is considered a pro-inflammatory cytokine. This protein belongs to the interleukin 17 family and is mainly produced by the T helper 17 cells after their stimulation with interleukin 23. However, IL-17F can be also produced by a wide range of cell types, including innate immune cells and epithelial cells.