Part 2 of a two-part Deep GUNA Research series on cytokine biology, for practitioners.
This article is written for a practitioner audience and draws directly on GUNA's own published clinical reference material on cytokines. It is educational in nature, summarising cytokine immunology as background to GUNA's low-dose cytokine product range, and does not replace clinical judgement or personalised medical advice.
Part 1 of this series covered general cytokine immunology, the Th1/Th2 balance, and a full reference to IL-1 through IL-5. This article continues the reference from IL-6 through IL-12 — the complete range GUNA offers as individual low-dose interleukin remedies — then covers the interferon and tumour necrosis factor families, colony-stimulating factors, transforming and epidermal growth factors, adhesion molecules, and closes with GUNA's own clinical-use table.
IL-6
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IL-6 is derived from macrophages, fibroblasts, bone marrow, vascular endothelium, some T cells, and IL-1-stimulated B cells, antigens, mitogens and endotoxins. It inhibits macrophage IL-1 and IFN-γ production, forming a feedback loop, and stimulates immunoglobulin-producing B cells and thymic/peripheral T-cell proliferation. Together with IL-1, it induces "killer" T lymphocyte differentiation, and it stimulates liver acute phase proteins — fibrinogen, serum amyloid A, α2-macroglobulin. It activates NK cells and plays a role in osteoclastogenesis and bone metabolism.
IL-6 is upregulated in type 1 diabetes, inflammatory thyroid disease, rheumatoid arthritis, systemic sclerosis, psoriasis, and various cancers. It affects cancer progression via cell adhesion and motility, thrombopoiesis, tumour antigen expression, and cancer cell proliferation — tumours stimulated by IL-6 include melanoma, renal cell carcinoma, prostate carcinoma, Kaposi's sarcoma, ovarian carcinoma, lymphoma, leukaemia and multiple myeloma.
Ageing-associated disorders linked to IL-6 include Alzheimer's disease, arteriosclerosis and thyroiditis; IL-6 correlates with ageing across species, and dietary restriction and DHEA reduce the age-associated rise in IL-6. IL-6 is also implicated in HIV, rheumatoid arthritis, Castleman's disease, the paraneoplastic symptoms of cardiac myxoma, sepsis, and inflammatory joint disease (elevated synovial IL-6 is seen in RA).
The hormonal relationship runs both ways: glucocorticoids inhibit IL-6 expression, but stress and inflammation raise IL-6, which induces corticotrophin-releasing factor, elevating corticosteroids in a negative feedback loop. Oestrogen also inhibits IL-6 expression — menopause and ovariectomy both increase IL-6 serum levels and secretion by mononuclear cells, and oestradiol inhibits bone marrow stromal cell and osteoblastic cell production.
IL-7, IL-8, IL-9
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IL-7 is derived from bone marrow and thymus stromal cells. It stimulates B-cell progenitor proliferation, mature T cells, and cytotoxicity.
IL-8 is derived from mononuclear phagocytes, activated T cells, endothelial and epithelial cells, and neutrophils. It's a chemotactic activator of neutrophils, monocytes, lymphocytes, basophils and eosinophils, stimulates granulocyte activity, and upregulates ELAM-1 and ICAM-1, enhancing neutrophil adherence and diapedesis.
IL-9 comes from CD4 T-helper cells and some B lymphomas, and is dependent on IL-4, IL-10 and IL-2. It promotes CD8 T-cell proliferation, inhibits IFN-γ-producing CD4+ T-cell lymphokine production, and increases immunoglobulin production and mast cell proliferation.
IL-10, IL-11, IL-12
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IL-10 is generated from CD4 T cells, activated CD8+ T lymphocytes, B-lymphocytes, macrophages, activated mast cells and epidermal cells. It's anti-inflammatory, working alongside IL-4 and IL-13: it downregulates macrophage production of IL-1, IFN-γ and TNF-α, inhibits IL-2-induced IFN-γ production by NK cells, and inhibits IL-4/IFN-γ-induced MHC class II expression on monocytes. It stimulates B-cell proliferation, inhibits nitric oxide production, and suppresses peripheral blood lymphocyte activity — a property that matters clinically in graft rejection.
IL-11 comes from bone stromal cells and fibroblasts, and functions as a homologue of IL-6 — it can substitute for IL-6 in inducing acute phase proteins in the liver. It promotes lymphopoiesis and haemopoietic cell growth, T-cell-dependent B-cell immunoglobulin secretion, and platelet production, and induces IL-6 expression by CD4+ T cells.
IL-12 is produced by T and B lymphocytes, NK cells and macrophages; its production is inhibited by IL-4 and IL-10. It promotes Th1 development (antagonised by IL-4), induces IFN-γ production by NK and T cells (further enhancing Th1 formation), and inhibits IgE synthesis via IFN-γ. It stimulates NK cells, and acts as a growth factor for activated T cells and a maturation factor for cytotoxic T cells.
The Interferons
GUNA's individual interleukin range runs from IL-1 through IL-12; interleukins beyond IL-12 (IL-13 and higher) aren't offered as individual GUNA low-dose remedies and aren't covered in this practitioner reference.
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Two T-cell types anchor the interferon response: cytotoxic "killer" T cells, which screen for infection and malignancy and secrete toxic molecules, and "helper" T cells, which cooperate with bone-marrow-matured B lymphocytes to produce antibody. Helper T cells produce interferon and cytokines in response to antigen challenge. At the broadest level: interferon fights infectious disease, increases the phagocytic activity of macrophages, and increases the cytotoxic activity of lymphocytes.
IFN-α and IFN-β are generated by leukocytes and fibroblasts respectively. Both have antiviral properties, activate phagocytes, are anti-proliferative, and up-regulate MHC class I expression.
IFN-γ is generated by T lymphocytes and NK cells. It's antiviral, drives Th1 development from Th0 while inhibiting Th2, and is the most powerful macrophage-activating factor in the body. It increases MHC type I and II expression — enhancing antigen presentation — stimulates VCAM expression and cytotoxic T-cell differentiation, antagonises IL-4's actions, and promotes IgG2 synthesis by activated T cells.
Cytotoxins: TNF-α and TNF-β
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TNF-α is generated by macrophages, mast cells and T lymphocytes — macrophages are stimulated by IFN-γ, and TNF-α is also produced when interferon triggers migration inhibition factor (MIF), or when T lymphocytes are stimulated by endotoxin. At high, endotoxin-induced concentrations, effects are pyrogenic (via PGE₂ or IL-1 release), drive acute phase protein production, and stimulate nitric oxide production; prolonged high levels cause cachexia. At low concentrations, TNF-α up-regulates the inflammatory response, induces ICAM-1, VCAM-1 and E-selectin expression, enhances killing of intracellular organisms such as Leishmania and M. tuberculosis, and activates leukocytes to produce IL-6 and further TNF-α.
TNF-β is produced by activated T cells. It induces apoptosis in transformed, virally infected or tumour cells, stimulates PMN (polymorphonuclear neutrophil) effector functions, and lyses tumour cells directly.
Colony Stimulating Factors and TGF
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G-CSF and GM-CSF — Granulocyte-Colony Stimulating Factor and Granulocyte-Macrophage-CSF — are derived from monocytes, T lymphocytes, fibroblasts and endothelial cells. They participate in acute inflammation and stimulate neutrophils; GM-CSF additionally activates eosinophil and mononuclear phagocyte effector functions. Alveolar macrophages may be a source of GM-CSF, producing two to three times more than control macrophages, and T lymphocytes present in the airways are another source — airway inflammation in asthma involves IL-4, IL-13, GM-CSF, IL-3 and IL-5 in a cycle that perpetuates eosinophil activation. TNF-β activates neutrophils and increases leukocyte adhesion to vascular endothelium.
Transforming Growth Factor (TGF-β) exists as a family of five isoforms — TGF-β1, β2 and β3 arise from separate genes but bind the same high-affinity receptor. These are trophic polypeptides that stimulate the proliferation and differentiation of different cell types, derived from T cells, platelets, NK cells and monocytes; TGF-β inhibits T-cell and NK-cell proliferation and activation. At injury sites, TGF-β released from platelets attracts monocytes and activates their degranulation, up-regulates IL-1, fibroblast growth factor (FGF), platelet-derived growth factor (PDGF) and TNF-α, and inhibits collagenase production. If TGF-β expression is prolonged, the result is progressive fibrosis — a mechanism implicated in mesangial proliferative glomerulonephritis, diabetic nephropathy, pulmonary fibrosis, and systemic sclerosis. TGF-β also regulates adhesion molecule, integrin and extracellular matrix production.
Epidermal and Fibroblast Growth Factors
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Epidermal Growth Factor (EGF) is related to TGF, around 50 amino acids in length, and a member of a larger protein family that also includes certain viral proteins. It's a trophic polypeptide stimulating proliferation and differentiation of cell types, and a potent stimulator of astrocyte proliferation. EGF isn't synthesised by developing neuronal cells, though its homologue TGF-α is expressed in the brain; it's detectable in tissue and blood during gliogenesis, affects astrocyte morphology, and induces glutamine upregulation.
Fibroblast Growth Factors (FGFs) occur throughout peripheral tissues as potent mitogens; the brain and pituitary are particularly rich sources of basic FGF.
Cell Surface Molecules and Adhesion Molecules
Around 300 different cell surface structures have been identified. As a collective term, this includes adhesion molecules, MHC complexes, and cytokine receptors — ligands bind these via a lock-and-key principle, though the underlying signal transduction mechanism is, for many, still not well understood. Receptor expression can occur within minutes of a stimulus; receptor density typically peaks at 2–6 hours and returns to normal within 24 hours, with receptors either shed from the cell surface or reabsorbed after use.
Altered inflammation triggers secretion of intracellular adhesion molecules (ICAMs), and each cell type carries characteristic surface molecules for adhesion — CD4 and CD8, for instance, identify specific immune cell populations. Several key inflammatory steps require this cell-to-cell adhesion contact directly: antigen recognition and presentation, induction of the humoral immune response, cytotoxic T-cell and macrophage activation, and immune cell migration. Up- or down-regulation of adhesion receptors occurs via stimulatory or inhibitory cytokines secreted locally.
Adhesion molecules play a documented role in chronic inflammatory disease, autoimmune disease, and the pathogenesis of metastasis. Chronic toxin exposure induces an excess supply of adhesion receptors, increasing immunocyte migration into affected areas. In arterial walls specifically, ICAMs allow macrophages and monocytes to bind and become foam cells; these foam cells release oxidants that convert LDL into atherogenic oxidised LDL, altering gene expression, producing benign tumour-like monoclonal hyperplasia, and ultimately atheroma.
Two broad types of adhesion molecule are recognised: selectins — lectin-like proteins present when the endothelium is stimulated by bacterial endotoxins, IL-1, thrombin or TNF-α — and members of the immunoglobulin super-family, including VCAM, ICAM-1 and ICAM-2 (stimulated by IL-1/TNF-α), integrins, and cartilage link proteins.
Inflammatory activity correlates directly with adhesion molecule expression density. Selectin over-expression drives a substantial increase in neutrophilic cell migration, contributing to chronic inflammation; ICAM-1 over-expression on endothelium in affected areas perpetuates inflammation, and — notably — enables lymphocyte passage through the blood-brain barrier in multiple sclerosis patients. GUNA's material summarises the clinical picture of ICAM over-expression as: (1) associated with increased risk of heart disease; (2) upregulates the inflammatory response in multiple sclerosis; (3) worth checking for a challenge against giardia, helicobacter or chlamydia; (4) worth checking inflammatory biomarkers and supplementing accordingly.
Clinical Use Table
GUNA's reference booklet closes its cytokine section with a table of possible clinical (treatment or diagnostic) uses by cytokine:
A Note on Multiple Sclerosis and the Interferons
GUNA's reference material closes with a note relevant to interferon selection specifically: multiple sclerosis is an autoimmune disease in which T cells attack myelin basic protein (MBP) and proteolipid protein (PLP); an MS-like disease can be induced in animals with MBP or PLP plus an adjuvant, and there is a possible link to the measles virus given its myelin-like configuration. MS is more common and more severe in women, typically chronic and progressive, and affects an estimated 300,000 Americans. It's treated mainly with diet and exercise, with steroids and immunosuppressants reserved for acute exacerbations. Interferon-γ trials for MS were disappointing — stimulating the immune system in a way that exacerbated the disease — while Interferon-β has appeared more promising, inhibiting the hyperactive immune system and moderating γ-interferon activity.
Separately, GUNA's footnotes note that interferon α-2 was the first pure human protein shown effective in cancer treatment, and served as the prototype for IL-2 and other growth-regulating cytokines — used in chronic myelogenous leukaemia, and, combined with retinoids, able to induce regression in squamous carcinomas. It also inhibits vascular and endothelial proliferation, relevant to melanoma, hypernephroma and haemangioma treatment, and has potential diagnostic and imaging applications in ovarian and colorectal carcinoma.
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Related reading
- Cytokines: How the Immune System's Messengers Work
- The GUNA Method: Understanding Physiological Regulating Medicine
Source: GUNA, *Cytokines* clinical reference booklet, pages 20–38.
Tags: Deep Guna Research, Guna Articles, Cytokines