The interleukin 4 (IL4, IL-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.[4] It is closely related and has functions similar to IL-13.
Overproduction of IL-4 is associated with allergies.[5]
Inflammation and wound repair
Tissue macrophages play an important role in chronic inflammation and wound repair. The presence of IL-4 in extravascular tissues promotes alternative activation of macrophages into M2 cells and inhibits classical activation of macrophages into M1 cells. An increase in repair macrophages (M2) is coupled with secretion of IL-10 and TGF-β that result in a diminution of pathological inflammation. Release of arginase, proline, polyaminases and TGF-β by the activated M2 cell is tied with wound repair and fibrosis.[6]
Receptor
The receptor for interleukin-4 is known as the IL-4Rα. This receptor exists in 3 different complexes throughout the body. Type 1 receptors are composed of the IL-4Rα subunit with a common γ chain and specifically bind IL-4. Type 2 receptors consist of an IL-4Rα subunit bound to a different subunit known as IL-13Rα1. These type 2 receptors have the ability to bind both IL-4 and IL-13, two cytokines with closely related biological functions.[7][8]
Structure
IL-4 has a compact, globular fold (similar to other cytokines), stabilised by 3 disulphide bonds.[9] One half of the structure is dominated by a 4 alpha-helix bundle with a left-handed twist.[10] The helices are anti-parallel, with 2 overhand connections, which fall into a 2-stranded anti-parallel beta-sheet.[10]
Evolution
IL-4 is closely related to IL-13, and both stimulate type 2 immunity.[11] Genes of this family have also been found in fish, both in bony fish[12][13] and cartilaginous fish;[14] because at that evolutionary level they can't be distinguished as IL-4 or IL-13, they have been named IL-4/13.[13]
Discovery
This cytokine was co-discovered by Maureen Howard and William E. Paul[15] as well as by Ellen Vitetta and her research group in 1982.
The nucleotide sequence for human IL-4 was isolated four years later confirming its similarity to a mouse protein called B cell stimulatory factor-1 (BCSF-1).[16]
Animal studies
IL-4 has been found to mediate a crosstalk between the neural stem cells and neurons that undergo neurodegeneration, and initiate a regeneration cascade through phosphorylation of its intracellular effector STAT6 in an experimental Alzheimer's disease model in adult zebrafish brain.[17]
IL-4 plays an important role in the development of certain immune disorders, particularly allergies and some autoimmune diseases.
Allergic diseases
Allergic diseases are sets of disorders that are manifested by a disproportionate response of the immune system to the allergen and Th2 responses. These pathologies include, for example, atopic dermatitis, asthma, or systemic anaphylaxis. Interleukin 4 mediates important pro-inflammatory functions in asthma, including induction of isotype rearrangement of IgE, expression of vascular cell adhesion molecule 1 (VCAM-1), promoting eosinophilic transmigration through endothelium, mucus secretion and T helper type 2 (Th2) leading to cytokine release. Asthma is a complex genetic disorder that has been associated with IL-4 gene promoter polymorphism and proteins involved in IL-4 signaling.[20]
Tumors
IL-4 has a significant effect on tumor progression. Increased IL-4 production was found in breast, prostate, lung, renal cells and other types of cancer. Overexpression of IL-4R has been found in many types of cancer. Renal cells and glioblastoma modify 10000–13000 receptors per cell depending on tumor type.[21]
IL-4 can primitively motivate tumor cells and increase their apoptosis resistance by increasing tumor growth.[22]
IL-4 may also play a role in the infection and development of HIV disease. Auxiliary T cells are a key element of HIV-1 infection. Several signs of immune dysregulation such as polyclonal B cell initialization, previous cell-mediated antigen-induced response and hypergammaglobulinaemia occur in most HIV-1 infected patients and are associated with cytokines synthesized by Th2 cells. Increased IL-4 production by Th2 cells has been demonstrated in people infected with HIV.[24]
^Jon Aster; Vinay Kumar; Abul K. Abbas; Nelson Fausto (2009). Robbins & Cotran Pathologic Basis of Disease (8th ed.). Philadelphia: Saunders. p. 54. ISBN978-1-4160-3121-5.
^Chatila TA (October 2004). "Interleukin-4 receptor signaling pathways in asthma pathogenesis". Trends in Molecular Medicine. 10 (10): 493–499. doi:10.1016/j.molmed.2004.08.004. PMID15464449.
^Carr C, Aykent S, Kimack NM, Levine AD (February 1991). "Disulfide assignments in recombinant mouse and human interleukin 4". Biochemistry. 30 (6): 1515–1523. doi:10.1021/bi00220a011. PMID1993171.
^ abWalter MR, Cook WJ, Zhao BG, Cameron RP, Ealick SE, Walter RL, et al. (October 1992). "Crystal structure of recombinant human interleukin-4". The Journal of Biological Chemistry. 267 (28): 20371–20376. doi:10.2210/pdb2int/pdb. PMID1400355. S2CID2310949.
^Li JH, Shao JZ, Xiang LX, Wen Y (March 2007). "Cloning, characterization and expression analysis of pufferfish interleukin-4 cDNA: the first evidence of Th2-type cytokine in fish". Molecular Immunology. 44 (8): 2078–2086. doi:10.1016/j.molimm.2006.09.010. PMID17084456.
^ abOhtani M, Hayashi N, Hashimoto K, Nakanishi T, Dijkstra JM (July 2008). "Comprehensive clarification of two paralogous interleukin 4/13 loci in teleost fish". Immunogenetics. 60 (7): 383–397. doi:10.1007/s00251-008-0299-x. PMID18560827. S2CID24675205.
^Meyaard L, Hovenkamp E, Keet IP, Hooibrink B, de Jong IH, Otto SA, Miedema F (September 1996). "Single cell analysis of IL-4 and IFN-gamma production by T cells from HIV-infected individuals: decreased IFN-gamma in the presence of preserved IL-4 production". Journal of Immunology. 157 (6): 2712–2718. doi:10.4049/jimmunol.157.6.2712. PMID8805678. S2CID39431866.
Further reading
Zhu H, Wang Z, Yu J, Yang X, He F, Liu Z, et al. (July 2019). "Role and mechanisms of cytokines in the secondary brain injury after intracerebral hemorrhage". Progress in Neurobiology. 178: 101610. doi:10.1016/j.pneurobio.2019.03.003. PMID30923023. S2CID85495400.
Kay AB, Barata L, Meng Q, Durham SR, Ying S (1997). "Eosinophils and eosinophil-associated cytokines in allergic inflammation". International Archives of Allergy and Immunology. 113 (1–3): 196–199. doi:10.1159/000237545. PMID9130521.
Marone G, Florio G, Triggiani M, Petraroli A, de Paulis A (2001). "Mechanisms of IgE elevation in HIV-1 infection". Critical Reviews in Immunology. 20 (6): 477–496. doi:10.1615/critrevimmunol.v20.i6.40. PMID11396683.
Maeda S, Yanagihara Y (October 2001). "[Inflammatory cytokines (IL-4, IL-5 and IL-13)]". Nihon Rinsho. Japanese Journal of Clinical Medicine. 59 (10): 1894–1899. PMID11676128.
Izuhara K, Arima K, Yasunaga S (September 2002). "IL-4 and IL-13: their pathological roles in allergic diseases and their potential in developing new therapies". Current Drug Targets. Inflammation and Allergy. 1 (3): 263–269. doi:10.2174/1568010023344661. PMID14561191.
Copeland KF (December 2005). "Modulation of HIV-1 transcription by cytokines and chemokines". Mini Reviews in Medicinal Chemistry. 5 (12): 1093–1101. doi:10.2174/138955705774933383. PMID16375755.
1iti: THE HIGH RESOLUTION THREE-DIMENSIONAL SOLUTION STRUCTURE OF HUMAN INTERLEUKIN-4 DETERMINED BY MULTI-DIMENSIONAL HETERONUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
1itl: HUMAN INTERLEUKIN 4: THE SOLUTION STRUCTURE OF A FOUR-HELIX-BUNDLE PROTEIN
1itm: ANALYSIS OF THE SOLUTION STRUCTURE OF HUMAN INTERLEUKIN 4 DETERMINED BY HETERONUCLEAR THREE-DIMENSIONAL NUCLEAR MAGNETIC RESONANCE TECHNIQUES
1rcb: CRYSTAL STRUCTURE OF HUMAN RECOMBINANT INTERLEUKIN-4 AT 2.25 ANGSTROMS RESOLUTION
2b8u: Crystal structure of wildtype human Interleukin-4
2b8x: Crystal structure of the interleukin-4 variant F82D
2b8y: Crystal structure of the interleukin-4 variant T13DF82D
2b8z: Crystal structure of the interleukin-4 variant R85A
2b90: Crystal structure of the interleukin-4 variant T13DR85A
2b91: Crystal structure of the interleukin-4 variant F82DR85A
2cyk: ASPECTS OF RECEPTOR BINDING AND SIGNALLING OF INTERLEUKIN-4 INVESTIGATED BY SITE-DIRECTED MUTAGENESIS AND NMR SPECTROSCOPY
2d48: Crystal structure of the Interleukin-4 variant T13D
2int: CRYSTAL STRUCTURE OF RECOMBINANT HUMAN INTERLEUKIN-4