|SCOP2||2int / SCOPe / SUPFAM|
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. It is closely related and has functions similar to IL-13.
Interleukin 4 has many biological roles, including the stimulation of activated B cell and T cell proliferation, and the differentiation of B cells into plasma cells. It is a key regulator in humoral and adaptive immunity. IL-4 induces B cell class switching to IgE, and up-regulates MHC class II production. IL-4 decreases the production of Th1 cells, macrophages, IFNγ, and dendritic cells IL-12. IL-4 signaling determines the levels of CD20 on the surface of normal and malignant B lymphocytes via activation of transcription factor STAT6. IL4 is an important signal supporting the survival of malignant B cells in chronic lymphocytic leukemia (CLL) underscoring the need for CLL-T cell interactions. 
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.
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.
IL-4 has a compact, globular fold (similar to other cytokines), stabilised by 3 disulphide bonds. One half of the structure is dominated by a 4 alpha-helix bundle with a left-handed twist. The helices are anti-parallel, with 2 overhand connections, which fall into a 2-stranded anti-parallel beta-sheet.
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.
IL-4 has also been shown to drive mitogenesis, dedifferentiation, and metastasis in rhabdomyosarcoma. IL-4, along with other Th2 cytokines, is involved in the airway inflammation observed in the lungs of patients with allergic asthma.
Illnesses associated with IL-4
IL-4 plays an important role in the development of certain immune disorders, particularly allergies and some autoimmune 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 VCAM-1 molecules (vascular cell adhesion molecule 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.
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.
IL-4 can primitively motivate tumor cells and increase their apoptosis resistance by increasing tumor growth.
Brain tissue tumors such as astrocytoma, glioblastoma, meningioma, and medulloblastoma overexpress receptors for various growth factors including epidermal growth factor receptor, FGFR-1 (fibroblast growth factor receptor 1), TfR (transferrin receptor), IL-13R. Most human meningiomas massively expresses IL-4 receptors, indicating its role in cancer progression. They express IL-4Rα and IL13Rα-1-1, but not the surface γc chain, suggesting that most human meningiomas express IL-4 type II.
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.
- "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- Gadani, Sachin P.; Cronk, James C.; Norris, Geoffrey T.; Kipnis, Jonathan (2012-11-01). "Interleukin-4: A Cytokine to Remember". Journal of Immunology. 189 (9): 4213–4219. doi:10.4049/jimmunol.1202246. ISSN 0022-1767. PMC 3481177. PMID 23087426.
- Sandova V, Pavlasova GM, Seda V, Cerna KA, Sharma S, Palusova V, Brychtova Y, Pospisilova S, Fernandes SM, Panovska A, Doubek M, Davids MS, Brown JR, Mayer J, Mraz M (July 1, 2021). "IL4-STAT6 signaling induces CD20 in chronic lymphocytic leukemia and this axis is repressed by PI3Kδ inhibitor idelalisib". Haematologica. X (X): X. doi:10.3324/haematol.2021.278644. PMID 34196167.
- Hoferkova E, Kadakova S, Mraz M (June 2022). "In Vitro and In Vivo Models of CLL-T Cell Interactions: Implications for Drug Testing". Cancers. 14 (13): 3087. doi:10.3390/cancers14133087. PMID 32482755.
- Hershey GK, Friedrich MF, Esswein LA, Thomas ML, Chatila TA (December 1997). "The association of atopy with a gain-of-function mutation in the alpha subunit of the interleukin-4 receptor". N. Engl. J. Med. 337 (24): 1720–5. doi:10.1056/NEJM199712113372403. PMID 9392697.
- Lay summary in: "Scientists Identify Strong Genetic Link To Allergies". EurekAlert.org (Press release). December 10, 1997.
- Jon Aster; Vinay Kumar; Abul K. Abbas; Nelson Fausto (2009). Robbins & Cotran Pathologic Basis of Disease (8th ed.). Philadelphia: Saunders. p. 54. ISBN 978-1-4160-3121-5.
- Maes T, Joos GF, Brusselle GG (September 2012). "Targeting interleukin-4 in asthma: lost in translation?". Am. J. Respir. Cell Mol. Biol. 47 (3): 261–70. doi:10.1165/rcmb.2012-0080TR. PMID 22538865.
- Chatila TA (October 2004). "Interleukin-4 receptor signaling pathways in asthma pathogenesis". Trends Mol Med. 10 (10): 493–9. doi:10.1016/j.molmed.2004.08.004. PMID 15464449.
- Carr C, Aykent S, Kimack NM, Levine AD (February 1991). "Disulfide assignments in recombinant mouse and human interleukin 4". Biochemistry. 30 (6): 1515–23. doi:10.1021/bi00220a011. PMID 1993171.
- Walter MR, Cook WJ, Zhao BG, Cameron RP, Ealick SE, Walter RL, Reichert P, Nagabhushan TL, Trotta PP, Bugg CE (October 1992). "Crystal structure of recombinant human interleukin-4". J. Biol. Chem. 267 (28): 20371–6. doi:10.2210/pdb2int/pdb. PMID 1400355. S2CID 2310949.
- Howard M, Paul WE (1982). "Interleukins for B lymphocytes". Lymphokine Res. 1 (1): 1–4. PMID 6985399.
- Yokota T, et al. (1986). "Isolation and characterization of a human interleukin cDNA clone, homologous to mouse B-cell stimulatory factor 1, that expresses B-cell- and T-cell-stimulating activities". Proc. Natl. Acad. Sci. U.S.A. 83 (16): 5894–8. Bibcode:1986PNAS...83.5894Y. doi:10.1073/pnas.83.16.5894. PMC 386403. PMID 3016727.
- Bhattarai P, Thomas AK, Cosacak MI, Papadimitriou C, Mashkaryan V, Froc C, Reinhardt S, Kurth T, Dahl A, Zhang Y, Kizil C (2016). "IL4/STAT6 Signaling Activates Neural Stem Cell Proliferation and Neurogenesis upon Amyloid-β42 Aggregation in Adult Zebrafish Brain". Cell Reports. 17 (4): 941–8. doi:10.1016/j.celrep.2016.09.075. PMID 27760324.
- Hosoyama T, Aslam MI, Abraham J, Prajapati SI, Nishijo K, Michalek JE, Zarzabal LA, Nelon LD, Guttridge DC, Rubin BP, Keller C (May 2011). "IL-4R Drives Dedifferentiation, Mitogenesis, and Metastasis in Rhabdomyosarcoma". Clin Cancer Res. 17 (9): 2757–2766. doi:10.1158/1078-0432.CCR-10-3445. PMC 3087179. PMID 21536546.
- Gour N, Wills-Karp M (2015). "IL-4 and IL-13 signaling in allergic airway disease". Cytokine. 75 (1): 68–78. doi:10.1016/j.cyto.2015.05.014. PMC 4532591. PMID 26070934.
- Steinke, John W.; Borish, Larry (19 February 2001). "Th2 cytokines and asthma — Interleukin-4: its role in the pathogenesis of asthma, and targeting it for asthma treatment with interleukin-4 receptor antagonists". Respiratory Research. 2 (2): 66–70. doi:10.1186/rr40. PMC 59570. PMID 11686867.
- Ul-Haq, Zaheer; Naz, Sehrish; Mesaik, M. Ahmed (2016). "Interleukin-4 receptor signaling and its binding mechanism: A therapeutic insight from inhibitors tool box". Cytokine & Growth Factor Reviews. 32: 3–15. doi:10.1016/j.cytogfr.2016.04.002. PMID 27165851.
- Li, Z.; Jiang, J.; Wang, Z.; Zhang, J.; Xiao, M.; Wang, C.; Lu, Y.; Qin, Z. (1 November 2008). "Endogenous Interleukin-4 Promotes Tumor Development by Increasing Tumor Cell Resistance to Apoptosis". Cancer Research. 68 (21): 8687–8694. doi:10.1158/0008-5472.CAN-08-0449. PMID 18974110.
- Puri, Sachin; Joshi, Bharat H.; Sarkar, Chitra; Mahapatra, Ashok Kumar; Hussain, Ejaz; Sinha, Subrata (15 May 2005). "Expression and structure of interleukin 4 receptors in primary meningeal tumors". Cancer. 103 (10): 2132–2142. doi:10.1002/cncr.21008. PMID 15830341. S2CID 42324572.
- Meyaard, L; Hovenkamp, E; Keet, IP; Hooibrink, B; de Jong, IH; Otto, SA; Miedema, F (15 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): 2712–8. PMID 8805678.
- Zhu H, Wang Z, Yu J, Yang X, He F, Liu Z, Che F, Chen X, Ren H, Hong M, Wang J (March 2019). "Role and mechanisms of cytokines in the secondary brain injury after intracerebral hemorrhage". Prog. Neurobiol. 178: 101610. doi:10.1016/j.pneurobio.2019.03.003. PMID 30923023. S2CID 85495400.
- Apte SH, Baz A, Kelso A, Kienzle N (2008). "Interferon-gamma and interleukin-4 reciprocally regulate CD8 expression in CD8+ T cells". Proc Natl Acad Sci U S A. 105 (45): 17475–80. Bibcode:2008PNAS..10517475A. doi:10.1073/pnas.0809549105. PMC 2580749. PMID 18988742.
- Kay AB, Barata L, Meng Q, et al. (1997). "Eosinophils and eosinophil-associated cytokines in allergic inflammation". Int. Arch. Allergy Immunol. 113 (1–3): 196–9. doi:10.1159/000237545. PMID 9130521.
- Marone G, Florio G, Petraroli A, de Paulis A (2001). "Dysregulation of the IgE/Fc epsilon RI network in HIV-1 infection". J. Allergy Clin. Immunol. 107 (1): 22–30. doi:10.1067/mai.2001.111589. PMID 11149986.
- Marone G, Florio G, Triggiani M, et al. (2001). "Mechanisms of IgE elevation in HIV-1 infection". Crit. Rev. Immunol. 20 (6): 477–96. doi:10.1615/critrevimmunol.v20.i6.40. PMID 11396683.
- Maeda S, Yanagihara Y (2001). "[Inflammatory cytokines (IL-4, IL-5 and IL-13)]". Nippon Rinsho. 59 (10): 1894–9. PMID 11676128.
- Izuhara K, Arima K, Yasunaga S (2003). "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): 263–9. doi:10.2174/1568010023344661. PMID 14561191.
- Copeland KF (2006). "Modulation of HIV-1 transcription by cytokines and chemokines". Mini Reviews in Medicinal Chemistry. 5 (12): 1093–101. doi:10.2174/138955705774933383. PMID 16375755.
- Olver S, Apte S, Baz A, Kienzle N (2007). "The duplicitous effects of interleukin 4 on tumour immunity: how can the same cytokine improve or impair control of tumour growth?". Tissue Antigens. 69 (4): 293–8. doi:10.1111/j.1399-0039.2007.00831.x. PMID 17389011.
- Sokol CL; Chu NQ; Shuang Yu; Simone Nish; Terri Laufer; Ruslan Medzhitov (2009). "Basophils function as antigen-presenting cells for an allergen-induced T helper type 2 response". Nature Immunology. 10 (7): 713–720. doi:10.1038/ni.1738. PMC 3252751. PMID 19465907.
- Sokol CL, Chu NQ, Yu S, Nish SA, Laufer TM, Medzhitov R (July 2009). "Basophils function as antigen-presenting cells for an allergen-induced T helper type 2 response". Nat. Immunol. 10 (7): 713–20. doi:10.1038/ni.1738. PMC 3252751. PMID 19465907.
- Interleukin-4 at the US National Library of Medicine Medical Subject Headings (MeSH)
- Interleukin-4 from Gentaur
- Recombinant Human Interleukin-4 from Cornell University
- Interleukin-4 from Allergy Glossary at Health On the Net Foundation
- Overview of all the structural information available in the PDB for UniProt: P05112 (Interleukin-4) at the PDBe-KB.