Impact of TNF and IL-33 Cytokines on Mast Cells in Neuroinflammation.

Mast cells (MCs) are derived from hematopoietic progenitors, mature in vascularized tissues, and participate in innate and acquired immunity. Neuroinflammation is a highly debated topic in the biomedical literature; however, the impact of tumor necrosis factor (TNF) and IL-33 on MCs in the brain has not been widely addressed. MCs can be activated by IgE binding to FcεRI, as well as by different antigens. After activation, MCs mediate various immunological and inflammatory responses through TNF and IL-33. TNF has two receptors: TNFR1, a p55 molecule, and TNFR2, a p75 molecule. This cytokine is the only one of its kind to be stored in the granules of MCs and can also be generated by de novo synthesis via mRNA. In the central nervous system (CNS), TNF is produced almost exclusively by microglial cells, neurons, astrocytes, and, minimally, by endothelial cells. After its release into brain tissue, TNF rapidly induces the adhesion molecules endothelial leukocyte adhesion molecule 1 (ELAM-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) in endothelial cells. TNF causes the chemoattraction of neutrophils by inducing several molecules, including CXC chemokines (IL-8). Both MCs and microglial cells act as a primary barrier against foreign molecules in the CNS, producing pro-inflammatory cytokines such as IL-33. IL-33 belongs to the IL-1 family, is activated through the ST2L/IL1-RAcP receptor complex, and mediates both the innate and adaptive immune response. IL-33 is a nuclear transcription factor expressed in the brain, where it induces pro-inflammatory cytokines (TNF and IL-1) and chemokines (CCL2, CCL3, CCL5, and CXCL10). Therefore, MCs and microglia in the CNS are a source of pro-inflammatory cytokines, including TNF and IL-33, that mediate many brain diseases. The inhibition of TNF and IL-33 may represent a new therapeutic approach that could complement existing neuroinflammatory therapies.

Retinal phakomatosis and Von Hippel-Lindau peripheral capillary hemangioblastoma: proposal for staged surgery.

PURPOSE: Retinal capillary hemangioblastoma (RCH) is present in about half of the carriers of the VHL (von Hippel-Lindau) gene mutation and can lead to the evolution of blindness. Herewith is a proposal for surgical intraretinal feeder vessel ligature to induce ischemia the phakoma and to resolve the exudative secondary retinal detachment, with satisfying results at the 6 months follow-up end point. METHODS: The patient underwent a chandelier-assisted 23 G pars plana vitrectomy with valved trocars. A bimanual transretinal ligature of the hemangioblastoma's feeder vessel was performed, followed by localized endolaser to ablate the surrounding retina and capillaries, and a Polydimethylsiloxane 1000 (PDMS 1000) final tamponade. After 3 months, exchange PDMS/air/balanced salt solution (BSS), phacoemulsification, and in-the-bag intraocular lens (IOL) implantation were performed. RESULTS: At sixth month, fundus fluorescein angiography (FFA) showed a significant reduction of blood flow in the phakoma. Final best-corrected visual acuity (BCVA) was 6/6 (9 lines gain obtained compared to the baseline time). CONCLUSIONS: This surgical technique seems to be effective and promising for the treatment of VHL retinal capillary hemangioblastomas and their related retinal complications.

Activation of Mast Cells by Neuropeptides: The Role of Pro-Inflammatory and Anti-Inflammatory Cytokines.

Mast cells (MCs) are tissue cells that are derived from bone marrow stem cells that contribute to allergic reactions, inflammatory diseases, innate and adaptive immunity, autoimmunity, and mental disorders. MCs located near the meninges communicate with microglia through the production of mediators such as histamine and tryptase, but also through the secretion of IL-1, IL-6 and TNF, which can create pathological effects in the brain. Preformed chemical mediators of inflammation and tumor necrosis factor (TNF) are rapidly released from the granules of MCs, the only immune cells capable of storing the cytokine TNF, although it can also be produced later through mRNA. The role of MCs in nervous system diseases has been extensively studied and reported in the scientific literature; it is of great clinical interest. However, many of the published articles concern studies on animals (mainly rats or mice) and not on humans. MCs are known to interact with neuropeptides that mediate endothelial cell activation, resulting in central nervous system (CNS) inflammatory disorders. In the brain, MCs interact with neurons causing neuronal excitation with the production of neuropeptides and the release of inflammatory mediators such as cytokines and chemokines. This article explores the current understanding of MC activation by neuropeptide substance P (SP), corticotropin-releasing hormone (CRH), and neurotensin, and the role of pro-inflammatory cytokines, suggesting a therapeutic effect of the anti-inflammatory cytokines IL-37 and IL-38.

Mast Cell Cytokines in Acute and Chronic Gingival Tissue Inflammation: Role of IL-33 and IL-37.

Much evidence suggests autoimmunity in the etiopathogenesis of periodontal disease. In fact, in periodontitis, there is antibody production against collagen, DNA, and IgG, as well as increased IgA expression, T cell dysfunction, high expression of class II MHC molecules on the surface of gingival epithelial cells in inflamed tissues, activation of NK cells, and the generation of antibodies against the azurophil granules of polymorphonuclear leukocytes. In general, direct activation of autoreactive immune cells and production of TNF can activate neutrophils to release pro-inflammatory enzymes with tissue damage in the gingiva. Gingival inflammation and, in the most serious cases, periodontitis, are mainly due to the dysbiosis of the commensal oral microbiota that triggers the immune system. This inflammatory pathological state can affect the periodontal ligament, bone, and the entire gingival tissue. Oral tolerance can be abrogated by some cytokines produced by epithelial cells and activated immune cells, including mast cells (MCs). Periodontal cells and inflammatory-immune cells, including mast cells (MCs), produce cytokines and chemokines, mediating local inflammation of the gingival, along with destruction of the periodontal ligament and alveolar bone. Immune-cell activation and recruitment can be induced by inflammatory cytokines, such as IL-1, TNF, IL-33, and bacterial products, including lipopolysaccharide (LPS). IL-1 and IL-33 are pleiotropic cytokines from members of the IL-1 family, which mediate inflammation of MCs and contribute to many key features of periodontitis and other inflammatory disorders. IL-33 activates several immune cells, including lymphocytes, Th2 cells, and MCs in both innate and acquired immunological diseases. The classic therapies for periodontitis include non-surgical periodontal treatment, surgery, antibiotics, anti-inflammatory drugs, and surgery, which have been only partially effective. Recently, a natural cytokine, IL-37, a member of the IL-1 family and a suppressor of IL-1b, has received considerable attention for the treatment of inflammatory diseases. In this article, we report that IL-37 may be an important and effective therapeutic cytokine that may inhibit periodontal inflammation. The purpose of this paper is to study the relationship between MCs, IL-1, IL-33, and IL-37 inhibition in acute and chronic inflamed gingival tissue.

Mast Cell Cytokines IL-1, IL-33, and IL-36 Mediate Skin Inflammation in Psoriasis: A Novel Therapeutic Approach with the Anti-Inflammatory Cytokines IL-37, IL-38, and IL-1Ra.

Psoriasis (PS) is a skin disease with autoimmune features mediated by immune cells, which typically presents inflammatory erythematous plaques, and is associated with many comorbidities. PS exhibits excessive keratinocyte proliferation, and a high number of immune cells, including macrophages, neutrophils, Th1 and Th17 lymphocytes, and mast cells (MCs). MCs are of hematopoietic origin, derived from bone marrow cells, which migrate, mature, and reside in vascularized tissues. They can be activated by antigen-provoking overexpression of proinflammatory cytokines, and release a number of mediators including interleukin (IL)-1 and IL-33. IL-1, released by activated keratinocytes and MCs, stimulates skin macrophages to release IL-36-a powerful proinflammatory IL-1 family member. IL-36 mediates both innate and adaptive immunity, including chronic proinflammatory diseases such as psoriasis. Suppression of IL-36 could result in a dramatic improvement in the treatment of psoriasis. IL-36 is inhibited by IL-36Ra, which binds to IL-36 receptor ligands, but suppression can also occur by binding IL-38 to the IL-36 receptor (IL-36R). IL-38 specifically binds only to IL-36R, and inhibits human mononuclear cells stimulated with IL-36 in vitro, sharing the effect with IL-36Ra. Here, we report that inflammation in psoriasis is mediated by IL-1 generated by MCs-a process that activates macrophages to secrete proinflammatory IL-36 inhibited by IL-38. IL-37 belongs to the IL-1 family, and broadly suppresses innate inflammation via IL-1 inhibition. IL-37, in murine models of inflammatory arthritis, causes the suppression of joint inflammation through the inhibition of IL-1. Therefore, it is pertinent to think that IL-37 can play an inhibitory role in inflammatory psoriasis. In this article, we confirm that IL-38 and IL-37 cytokines emerge as inhibitors of inflammation in psoriasis, and hold promise as an innovative therapeutic tool.

Powerful anti-inflammatory action of luteolin: Potential increase with IL-38.

Luteolin belongs to the flavone family originally present in some fruits and vegetables, including olives, which decrease intracellular levels of reactive oxygen species (ROS) following the activation of various stimuli. Luteolin inhibits inflammation, a complex process involving immune cells that accumulate at the site of infectious or non-infectious injury, with alteration of the endothelium leading to recruitment of leukocytes. Cytokines have been widely reported to act as immune system mediators, and IL-1 family members evolved to assist in host defense against infections. Interleukin (IL)-1 and Toll-like receptor (TLR) are involved in the innate immunity in almost all living organisms. After being synthesized, IL-1 induces numerous inflammatory mediators including itself, other pro-inflammatory cytokines/chemokines, and arachidonic acid products, which contribute to the pathogenesis of immune diseases. Among the 11 members of the IL-1 family, there are two new cytokines that suppress inflammation, IL-37 and IL-38. IL-38 binds IL-36 receptor (IL-1R6) and inhibits several pro-inflammatory cytokines, including IL-6, through c-Jun N-terminal kinase (JNK) induction and reducing AP1 and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) activity, alleviating inflammatory diseases. Therefore, since luteolin, IL-37 and IL-38 are all anti-inflammatory molecules with different signaling pathways, it is pertinent to recommend the combination of luteolin with these anti-inflammatory cytokines in inflammation.

Advances in Mast Cell Activation by IL-1 and IL-33 in Sjögren's Syndrome: Promising Inhibitory Effect of IL-37.

Sjögren's syndrome (SS) is a chronic autoimmune inflammatory disease that affects primarily older women and is characterized by irreversible damage of the exocrine glands, including tear (xerophthalmia) and salivary glands (xerostomia). Secretory glands lose their functionality due to the infiltration of immune cells, which produce cytokines and cause inflammation. Primary SS is characterized by dry syndrome with or without systemic commitment in the absence of other pathologies. Secondary SS is accompanied by other autoimmune diseases with high activation of B lymphocytes and the production of autoantibodies, including the rheumatoid factor. Other cells, such as CD4+ T cells and mast cells (MCs), participate in SS inflammation. MCs are ubiquitous, but are primarily located close to blood vessels and nerves and can be activated early in autoimmune diseases to express a wide variety of cytokines and chemokines. In the SS acute phase, MCs react by generating chemical mediators of inflammation, tumor necrosis factor (TNF), and other pro-inflammatory cytokines such as interleukin (IL)-1 and IL-33. IL-33 is the specific ligand for ST2 capable of inducing some adaptive immunity TH2 cytokines but also has pro-inflammatory properties. IL-33 causes impressive pathological changes and inflammatory cell infiltration. IL-1 family members can have paracrine and autocrine effects by exacerbating autoimmune inflammation. IL-37 is an IL-1 family cytokine that binds IL-18Rα receptor and/or Toll-like Receptor (TLR)4, exerting an anti-inflammatory action. IL-37 is a natural inhibitor of innate and acquired immunity, and the level is abnormal in patients with autoimmune disorders. After TLR ligand activation, IL-37 mRNA is generated in the cytoplasm, with the production of pro-IL-37 and later mature IL-37 caspase-1 mediated; both precursor and mature IL-37 are biologically active. Here, we discuss, for the first time, the current knowledge of IL-37 in autoimmune disease SS and propose a new therapeutic role.

Mast Cells Mediate Rheumatoid Arthritis-Inhibitory Role of IL-37.

Rheumatoid arthritis (RA) is an autoimmune, chronic inflammatory, disabling arthropathy that severely affects the quality of life. This disease involves several proinflammatory cytokines, including interleukin (IL)-1ß and tumor necrosis factor (TNF). IL-1 induces TNF and vice versa, causing joint damage and cartilage degradation. Current antirheumatic drugs may be effective, but they possess many unwanted side effects. In recent years, inhibitors of proinflammatory cytokines have increasingly entered mainstream clinical practice. Recent evidence indicates that IL-37, which has anti-inflammatory properties, is increased in the serum and is released from white blood cells in patients with RA. Mast cells (MCs), stimulated by the neuropeptide substance P (SP) and IL-33, release IL-1ß and TNF. Recent evidence indicates that large amounts of IL-1ß and TNF can be released from human MCs, which also secrete CXCL8, which promotes migration of immune cells, causing erosion of the bone and cartilage. Treatment with IL-37 can block the MC stimulation and release of inflammatory compounds, attenuating the severity of the disease and/or altering its progression.