Interleukin 1 beta (IL-1β) is a cytokine involved in pro-inflammatory responses. It is produced by activated macrophages, natural killer cells, monocytes, and neutrophils in response to wounds, infections, or microbial endotoxins and is processed to its active state by caspase 1. It mediates inflammatory responses and plays a role in cell proliferation, apoptosis, and differentiation. IL-1β inflammation within the central nervous system is known to result in pain and hypersensitivity. High levels of IL-1β are associated with autoinflammatory diseases, particularly the group of rare heterozygous dominant diseases known as cryopyrin-associated periodic syndromes, that often affect the skin, joints, eyes, and nervous system. Inhibition of IL-1β treats these diseases and eases symptoms in common conditions such as type 2 diabetes, cardiac failure, gout, and rheumatoid arthritis. Dysregulated IL-1β is associated with tumor formation in a wide variety of cancers.
Interleukin 1 receptor antagonist (IL-1Ra) is an acute phase protein that is a member of the Interleukin 1 family of cytokines. It blocks Interleukin 1 alpha and beta (IL-1α and IL-1β) from binding to the Interleukin 1 receptor type 1. The IL-1 family plays an important role in both adaptive and innate immunity through promoting inflammation, IL-1Ra works to reduce inflammation and fever responses. It is secreted by a variety of cell types, including immune cells, epithelial cells, and adipocytes. It is commonly used in veterinary medicine to calm inflamed soft tissue injuries. A modified version is used in human medicine to treat rheumatoid arthritis. Aberrations in IL-1Ra are associated with schizophrenia and are commonly found in high levels in schizophrenia patients.
Interleukin-2 (IL-2) cytokine signaling molecule in the immune system that mediates the activity of white blood cells, particularly lymphocytes, during an immune response. IL-2 promotes the differentiation of T cells into memory T cells after exposure to a novel pathogen, making it a critical component of the active immune system and long-term immunity to disease. In the thymus, IL-2 supports the formation of regulatory T cells, which work to prevent autoimmune diseases by eliminating overactive immune cells. Since IL-2 helps increase immune cell production and regulate large scale activities of the immune system, it is commonly used as a cancer treatment for patients with certain kinds of cancers, including kidney and skin cancers.
Interleukin 2 receptor alpha chain (IL-2R⍺), also known as CD25, is a protein that forms a component of the receptor for interleukin 2 (IL-2), a cytokine that mediates the behavior of white blood cells during an immune response. On its own, IL-2R⍺ forms homodimers to produce a low-affinity receptor. When combined with IL-2 receptor beta and gamma, it forms a high-affinity receptor for IL-2. Alterations in IL-22R⍺ are associated with many disease states. Mutations in IL-2R⍺ are a common risk factor for multiple sclerosis and higher levels of soluble IL-2R⍺ are found in the blood of MS patients. Common MS medications block the soluble form of the protein. The protozoan infection that leads to Chagas disease causes a reduction in membrane-bound IL-2R⍺ that ultimately leads to immune suppression if left untreated. Epigenetic alterations of IL-2R⍺ have been associated with childhood-onset of type I diabetes and some types of cancer.
Interleuken 6 (IL-6) has the capability to behave as both a pro-inflammatory cytokine and an anti-inflammation myokine. As a cytokine, it is secreted by macrophages in response to microbial activity, to regulate the progression of fever through raising the temperature of muscle and fat, as well as crossing the blood-brain barrier to alter the body’s temperature set point in the hypothalamus. It acts through T cells and macrophages fighting infection and causing inflammation. As a myokine, it is released by contracting muscles during exercise, and inhibits the activity of pro-inflammatory agent TNF-alpha, reducing system-wide inflammation. In addition to its functions in the immune system, IL-6 aids in bone remodeling and maintenance by stimulating the production of osteoclasts. Clinically, IL-6 is implicated in the inflammatory and autoimmune symptoms of many diseases, including diabetes, asthma, atherosclerosis, depression, Alzheimer’s disease, rheumatoid arthritis, and many cancers. High levels of IL-6 are common in advanced cancer patients and are correlated with low survival rates. IL-6 has the ability to induce epigenetic modifications of gene transcription in the brain, and these IL-6 modifications are associated with schizophrenia and major depressive disorder.
Interleukin 6 receptor (IL6R), also known as CD126, is a functional receptor for the IL-6 cytokine, that regulates many activities in the immune system, muscle tissue, and bone tissue. The receptor is commonly is expressed on hepatocytes, neutrophils, monocytes, B cells, and T cells, and in organs including muscle tissue, the heart, kidney, liver, spleen. placenta, lung, and brain. IL-6 and IL-6R have a low affinity for one another. High levels of IL-6R are often found in patients with early-stage rheumatoid arthritis. Abnormal behavior of IL-6 and/or IL-6R is associated with chronic inflammatory conditions such as Crohn’s disease, multiple myeloma, and ulcerative colitis, as well as many cancers.
Interleukin 8 (IL-8), also known as CXCL8, is a chemokine that plays a role in the recruitment and regulation of white blood cells during an innate immune response. It is a strong chemoattractant for neutrophils and other granulocytes, bringing them to the site of infection and then stimulating them to engage in phagocytosis. It is commonly secreted by macrophages that have identified a foreign pathogen but may be emitted by any cell with toll-like receptors. IL-8 plays a key role in metastasis; it was first identified as a leukocyte chemoattractant that progresses melanoma by directly inducing angiogenesis and migration of melanoma cells. Serum IL-8 levels are directly correlated with the degree of metastatic melanoma and overall tumor count. High levels of IL-8 in a pregnant mother are associated with schizophrenia in her child and high levels in adults with schizophrenia reduces the effectiveness of antipsychotic medications. IL-8 dysregulation is also involved in cystic fibrosis, where it recruits an excessive number of white blood cells to the lungs, resulting in tissue damage.
Interleukin 10 (IL-10) is a class-2 anti-inflammatory cytokine, also known as human cytokine synthesis inhibitory factor (CSIF). It impacts many areas of immunoregulation and inflammation, with numerous pleiotropic effects in the immune system. As an anti-inflammatory, it downregulates MHC class II expression, inhibits the synthesis and activity of many inflammatory cytokines, and reduces co-stimulatory factors on macrophages. It also enhances the release of other anti-inflammatory mediators by monocytes and macrophage, particularly during exercise. It enhances B cell proliferation, differentiation, survival, and antibody production. IL-10 has anti-tumor effects, reducing tumor growth and decreasing metastatic burden in the body. IL-10 deficiency is associated with chronic inflammatory and autoimmune diseases, including multiple sclerosis, Crohn’s disease, inflammatory bowel disease, psoriasis, and rheumatoid arthritis. IL-10 is currently under investigation as a potential therapeutic for many conditions, including cancer treatments and reducing symptoms in inflammatory disorders.
Interleukin 12 p70 (IL-12p70) is a subunit of interleukin 12 (IL-12) a cytokine that has a broad range of biological activities in the immune system. The complete IL-12 unit aids in the differentiation of naïve T cells into Th1 cells and regulates the activity of natural killer cells. It also stimulates the production of T cells, IFN-γ, and TNF-α. IL-12 inhibits the formation of new blood vessels and may play a role in autoimmune disorders.
Interleukin-13 is an immunoregulatory cytokine that is involved numerous immune processes and a mediator of allergic inflammation responses. It is secreted primarily by activated Th2 cells, but also by smooth muscle cells, eosinophils, basophils, NK cells, mast cells, and helper T cells in response to pathogenic detection, particularly parasitic infections. IL-13 is commonly associated with airway activity during an immune response, since it regulates mucus secretion and airway responsiveness in the respiratory tract. It also encourages the production of IgE, which confers immunity to many helminth parasites, and IL-13 induces changes in the lungs and gut that encourage the expulsion of these parasites. Its effects on the maturation and differentiation of B cells are similar to that of IL-4, which it shares similar structure and activation pathways, however IL-13 appears to be less critical to B cell function than IL-4. IL-13 also suppresses the production of pro-inflammatory cytokines by macrophages. Due to its role in airway responses, dysregulation of IL-13 is associated with asthma and severe allergic responses.
Interferon gamma (IFNγ), also known as Type II interferon, is a cytokine that plays a critical role in the innate and adaptive immune systems. It serves as protection against viral infections, as well as some bacterial and protozoal infections, and plays a role in tumor control. It is capable of inhibiting viral replication and works to modulate immunological responses to multiple kinds of pathogens, with effects including promoting natural killer cell activity, activating macrophages to destroy foreign cells, increasing antigen presentation, and inducing the expression of numerous immune defense factors. IFNγ is primarily produced by natural killer and natural killer T cells during the innate immune response and by CD4 and CD8 cytotoxic T lymphocyte effector T cells as part of an adaptive response. It has been shown to halt growth and induce apoptosis in some types of tumors. During pregnancy, IFNγ aids in the remodeling of the uterine wall and placenta to accommodate a zygote.
Interferon alpha (IFN⍺) is a member of the interferon type I family of immune system proteins that bind to the INF⍺/β receptor complex. IFN⍺ plays a role in innate viral immunity and inflammatory responses. It is produced primarily by dendritic cells and leukocytes, however, its production is inhibited by interleukin 10. There are multiple subtypes of IFN⍺ that each play unique roles in the immune system, including activating natural killer (NK) cells, stimulating B cell proliferation, promoting the production of human leukocyte antigen (HLA) types I and II, activating dendritic cells to promote an immune response. The interleukin has been found to limit the proliferation of cancer cells by halting the cell cycle and inducing apoptosis. IFN⍺ is commonly produced as a therapeutic under the name interferon alfa to treat a number of cancers and viral diseases, including leukemia, melanoma, and hepatitis B and C infections.
Tumor necrosis factor alpha (TNFα) is a prototypic ligand of the TNF superfamily. It is a versatile cytokine that plays a central role in inflammation, immune system development, apoptosis, and lipid metabolism. TNFα is an important endogenous pyrogen, its release quickly induces fever. It also causes apoptotic cell death, cachexia, inflammation, and has the ability to inhibit tumorigenesis and viral replication. It is chemoattractive to many immune cells, particularly neutrophils. Cell surface TNFα can induce the lysis of neighboring tumor cells and virus infected cells and has the ability to generate its own downstream cell signaling. It is produced chiefly by activated macrophages, although it is produced in low levels by a wide variety of immune, epithelial, endothelial, and tumor cells such as CD4+ lymphocytes, NK cells, neutrophils, mast cells, eosinophils, and neurons. TNFα also plays an important role in metabolism, with the ability to induce insulin resistance and regulate appetite through interactions with the hypothalamus. Dysregulation of TNF production has been implicated in a variety of human diseases including Alzheimer’s disease, inflammatory bowel disease, arthritis, cancer, and psoriasis.
Granulocyte-macrophage colony-stimulating factor (GM‑CSF), also known as colony-stimulating factor 2 (CSF2), is a growth factor that promotes the formation of white blood cells and is a critical component of the immune/inflammatory cascade. The growth factor is commonly used for in vitro colony formation of white blood cells. Numerous cell types produce GM-CSF in response to inflammation, particularly in the immune system, including T cells, B cells, macrophages, mast cells, endothelial cells, fibroblasts, and adipocytes. In hematopoietic cells, GM-CSF activates the functions of monocytes, macrophages, eosinophils, and granulocytes. In clinical settings, GM-CSF is capable of raising white blood cell counts in chemotherapy and bone marrow transplant patients and is being investigated as a potential cancer vaccination due to its ability to transfer targeted genetic material into tumor cells. Since GM-CSF initiates the development of an immune response, it is implicated in autoimmunity disorders and allergic inflammation. Patients with rheumatoid arthritis often have high levels of GM-CSF in their joints.
Monocyte chemoattractant protein 1 (MCP1), also known as chemokine (C-C motif) ligand 2 (CCL2) and small inducible cytokine (A2MCP-1), is a chemokine that plays a role in the body’s response to tissue injury and infection. It is produced by many cell types in response to tissue damage, and is a chemoattractant to monocytes, basophils, memory T cells, and dendritic cells. MCP-1 is commonly found at the site of tooth and bone injuries or infections, where it is expressed by osteoclasts and osteoblasts. It is also produced by cells of the nervous system and is implicated in many inflammatory neurological disorders. Elevated MCP-1 levels are often associated with sepsis, Crohn’s disease, lupus nephritis, amyotrophic lateral sclerosis, multiple sclerosis, rheumatoid arthritis, acute pancreatitis, and atherosclerosis. MCP-1 is also upregulated in several cancers including gastric carcinoma, esophageal squamous cell carcinoma, malignant glioma, and ovarian, pancreatic, bladder, and breast cancers.
Macrophage inflammatory protein 1-alpha (MIP-1α), also known as chemokine (C-C motif) ligand 3 (CCL3), is a cytokine of the immune system involved in inflammation and fever. MIP-1α and its counterpart MIP-1β are produced primarily by macrophages following exposure to a bacterial endotoxin but can also be secreted by other immune cells. It works to activate granulocyte white blood cells and stimulate the production of other pro-inflammatory cytokines. Its presence also limits the production of hematopoietic stem cells. MIP-1α has the ability to induce a rapid onset fever in response to an infection. MIP-1α is capable of suppressing HIV infection since it binds to CCR5, a common HIV coreceptor. MIP-1α is implicated in many diseases, including multiple myeloma, cystic fibrosis, and breast cancer.