The interleukin 4 (IL4, IL-4) is a
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
that induces differentiation of naive helper T cells (
Th0 cells) to
Th2 cells. Upon activation by IL-4, T
h2 cells subsequently produce additional IL-4 in a
positive feedback
Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the ...
loop. IL-4 is produced primarily by mast cells, T
h2 cells, eosinophils and basophils. It is closely related and has functions similar to
IL-13.
Function
Interleukin 4 has many biological roles, including the stimulation of activated
B cell
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or ...
and
T cell
A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
proliferation, and the differentiation of B cells into
plasma cell
Plasma cells, also called plasma B cells or effector B cells, are white blood cells that originate in the lymphoid organs as B lymphocytes and secrete large quantities of proteins called antibodies in response to being presented specific substan ...
s. It is a key regulator in
humoral
Humoral immunity is the aspect of immunity that is mediated by macromolecules - including secreted antibodies, complement proteins, and certain antimicrobial peptides - located in extracellular fluids. Humoral immunity is named so because it invo ...
and
adaptive immunity
The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system ...
. IL-4 induces B cell
class switching
Immunoglobulin class switching, also known as isotype switching, isotypic commutation or class-switch recombination (CSR), is a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the ...
to
IgE
Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig) " isotype") that has been found only in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε c ...
, and up-regulates
MHC class II
MHC Class II molecules are a class of major histocompatibility complex (MHC) molecules normally found only on professional antigen-presenting cells such as dendritic cells, mononuclear phagocytes, some endothelial cells, thymic epithelial ce ...
production. IL-4 decreases the production of
Th1 cells, macrophages,
IFNγ
Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock ...
, and
dendritic cell
Dendritic cells (DCs) are antigen-presenting cells (also known as ''accessory cells'') of the mammalian immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. ...
s
IL-12.
Overproduction of IL-4 is associated with
allergies
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...
.
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Inflammation and wound repair
Tissue macrophages play an important role in chronic
inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
and
wound repair
Wound healing refers to a living organism's replacement of destroyed or damaged tissue by newly produced tissue.
In undamaged skin, the epidermis (surface, epithelial layer) and dermis (deeper, connective layer) form a protective barrier again ...
. 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
Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other sign ...
that result in a diminution of pathological inflammation. Release of
arginase
Arginase (, ''arginine amidinase'', ''canavanase'', ''L-arginase'', ''arginine transamidinase'') is a manganese-containing enzyme. The reaction catalyzed by this enzyme is:
: arginine + H2O → ornithine + urea
It is the final enzyme of the ure ...
,
proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the prot ...
, polyaminases and TGF-β by the activated M2 cell is tied with wound repair and
fibrosis
Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
.
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
Interleukin 13 receptor, alpha 1, also known as IL13RA1 and CD213A1 (cluster of differentiation 213A1), is a human gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of here ...
. These type 2 receptors have the ability to bind both IL-4 and IL-13, two cytokines with closely related biological functions.
Structure
IL-4 has a compact, globular
fold (similar to other
cytokines
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
), stabilised by 3
disulphide bonds
In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...
.
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
The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...
.
Discovery
This cytokine was co-discovered by Maureen Howard and
William E. Paul
William Erwin Paul (June 12, 1936 – September 18, 2015) was an American immunologist. He and Maureen Howard discovered interleukin 4, while an independent team led by Ellen Vitetta did the same in 1982. Paul worked on AIDS research for much of ...
as well as by
Ellen Vitetta
Ellen S. Vitetta is the director of the Cancer Immunobiology Center at the University of Texas Southwestern Medical Center in Dallas.Mak, Tak W. & Mary E. Saudners. ''Primer to the Immune Response.'' Burlington, MA: Academic Press, 2008. ix.
B ...
and her research group in 1982.
The
nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...
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).
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
Signal transducer and activator of transcription 6 (STAT6) is a transcription factor that belongs to the Signal Transducer and Activator of Transcription (STAT) family of proteins. The proteins of STAT family transmit signals from a receptor com ...
in an experimental
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
model in adult zebrafish brain.
Clinical significance
IL-4 has also been shown to drive
mitogenesis
A mitogen is a small bioactive protein or peptide that induces a cell to begin cell division, or enhances the rate of division (mitosis). Mitogenesis is the induction (triggering) of mitosis, typically via a mitogen. The mechanism of action of a ...
,
dedifferentiation
Dedifferentiation (pronounced dē-ˌdi-fə-ˌren-chē-ˈā-shən) is a transient process by which cells become less specialized and return to an earlier cell state within the same lineage. This suggests an increase in a cell potency, meaning that a ...
, and
metastasis
Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...
in
rhabdomyosarcoma
Rhabdomyosarcoma (RMS) is a highly aggressive form of cancer that develops from mesenchymal cells that have failed to fully differentiate into myocytes of skeletal muscle. Cells of the tumor are identified as rhabdomyoblasts.
There are four subt ...
.
IL-4, along with other Th2 cytokines, is involved in the airway inflammation observed in the lungs of patients with allergic
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, cou ...
.
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
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.
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 – receptors per cell depending on tumor type.
IL-4 can primitively motivate tumor cells and increase their apoptosis resistance by increasing tumor growth.
Nervous system
Brain tissue tumors such as
astrocytoma
Astrocytomas are a type of brain tumor. They originate in a particular kind of glial cells, star-shaped brain cells in the cerebrum called astrocytes. This type of tumor does not usually spread outside the brain and spinal cord and it does not usu ...
,
glioblastoma
Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality ch ...
,
meningioma
Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing o ...
, and
medulloblastoma
Medulloblastoma is a common type of primary brain cancer in children. It originates in the part of the brain that is towards the back and the bottom, on the floor of the skull, in the cerebellum, or posterior fossa.
The brain is divided into two ...
overexpress receptors for various growth factors including
epidermal growth factor receptor
The epidermal growth factor receptor (EGFR; ErbB-1; HER1 in humans) is a transmembrane protein that is a receptor for members of the epidermal growth factor family (EGF family) of extracellular protein ligands.
The epidermal growth factor recept ...
, FGFR-1 (
fibroblast growth factor receptor 1
Fibroblast growth factor receptor 1 (FGFR1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast ...
), TfR (
transferrin receptor
Transferrin receptor (TfR) is a carrier protein
A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membr ...
), 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.
HIV
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 T
h2 cells. Increased IL-4 production by T
h2 cells has been demonstrated in people infected with HIV.
See also
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STAT6
Signal transducer and activator of transcription 6 (STAT6) is a transcription factor that belongs to the Signal Transducer and Activator of Transcription (STAT) family of proteins. The proteins of STAT family transmit signals from a receptor com ...
References
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Further reading
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External links
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Interleukin-4from
Gentaur
Recombinant Human Interleukin-4from
Cornell University
Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach an ...
Interleukin-4 from Allergy Glossaryat
Health On the Net Foundation
Health On the Net Foundation (HON) is a Geneva, Switzerland-based not-for-profit organization which promotes a code of conduct for websites providing health information and offers certificates to those in compliance.
In September 2022, Health On ...
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{{Authority control
Protein domains
Interleukins