Introduction to the interleukin-1 family of cytokines and receptors: Drivers of innate inflammation and acquired immunity

Unveiling the hidden connection: the blood-brain barrier's role in epilepsy

Epilepsy is characterized by abnormal synchronous electrical activity of neurons in the brain. The blood-brain barrier, which is mainly composed of endothelial cells, pericytes, astrocytes and other cell types and is formed by connections between a variety of cells, is the key physiological structure connecting the blood and brain tissue and is critical for maintaining the microenvironment in the brain. Physiologically, the blood-brain barrier controls the microenvironment in the brain mainly by regulating the passage of various substances. Disruption of the blood-brain barrier and increased leakage of specific substances, which ultimately leading to weakened cell junctions and abnormal regulation of ion concentrations, have been observed during the development and progression of epilepsy in both clinical studies and animal models. In addition, disruption of the blood-brain barrier increases drug resistance through interference with drug trafficking mechanisms. The changes in the blood-brain barrier in epilepsy mainly affect molecular pathways associated with angiogenesis, inflammation, and oxidative stress. Further research on biomarkers is a promising direction for the development of new therapeutic strategies.

NETosis of psoriasis: a critical step in amplifying the inflammatory response

NETosis, a regulated form of neutrophil death, is crucial for host defense against pathogens. However, the release of neutrophil extracellular traps (NETs) during NETosis can have detrimental effects on surrounding tissues and contribute to the pro-inflammatory response, in addition to their role in controlling microbes. Although it is well-established that the IL-23-Th17 axis plays a key role in the pathogenesis of psoriasis, emerging evidence suggests that psoriasis, as an autoinflammatory disease, is also associated with NETosis. The purpose of this review is to provide a comprehensive understanding of the mechanisms underlying NETosis in psoriasis. It will cover topics such as the formation of NETs, immune cells involved in NETosis, and potential biomarkers as prognostic/predicting factors in psoriasis. By analyzing the intricate relationship between NETosis and psoriasis, this review also aims to identify novel possibilities targeting NETosis for the treatment of psoriasis.

Bif‑1 inhibits activation of inflammasome through autophagy regulatory mechanism

Inflammasome activation is a crucial mechanism in inflammatory responses. Bax‑interacting factor 1 (Bif‑1) is required for the normal formation of autophagosomes, but its ability to exert an inflammatory regulatory effect remains unclear. The aim of the present study was to explore the role of Bif‑1 in inflammation, possibly mediated through autophagy regulation. Using a lipopolysaccharide (LPS)/adenosine triphosphate (ATP)‑induced inflammatory model in J774A.1 cells, the effect of Bif‑1 on inflammasome activation and the underlying mechanisms involving autophagy regulation were investigated. Elevated levels of NLR family pyrin domain containing protein 3 inflammasome and interleukin‑1β (IL‑1β) proteins were observed in J774A.1 cells after LPS/ATP induction. Furthermore, Bif‑1 and autophagy activity were significantly upregulated in inflammatory cells. Inhibition of autophagy resulted in inflammasome activation. Silencing Bif‑1 expression significantly upregulated IL‑1β levels and inhibited autophagy activity, suggesting a potential anti‑inflammatory role of Bif‑1 mediated by autophagy. Additionally, inhibition of the nuclear factor‑κB (NF‑κB) signaling pathway downregulated Bif‑1 and inhibited autophagy activity, highlighting the importance of NF‑κB in the regulation of Bif‑1 and autophagy. In summary, the current study revealed that Bif‑1 is a critical anti‑inflammatory factor against inflammasome activation mediated by a mechanism of autophagy regulation, indicating its potential as a therapeutic target for inflammatory regulation.

Evaluation of interleukins (IL-1α, IL-1Ra, IL-12, IL-17A, IL-31, and IL-33) and chemokines (CXCL10 and CXCL16) in the serum of male patients with ankylosing spondylitis

BACKGROUND

A case-control study was performed to explore eight pro-inflammatory and anti-inflammatory cytokines, namely interleukin (IL)-1α, IL-1Ra (IL-1 receptor antagonist), IL-12, IL-17A, IL-31, IL-33, CXCL10 (C-X-C motif chemokine ligand 10), and CXCL16, with the aim to understand their role in ankylosing spondylitis (AS) pathogenesis and evaluate their utility as markers to differentiate between diseased and healthy individuals. Among these cytokines, IL-31 and CXCL16 have not been well studied in AS.

PATIENTS AND METHODS

The study included 94 male patients with AS and 91 age-matched control males. Interleukin and chemokine levels were measured using ELISA kits.

RESULTS

Serum levels of IL-17A, CXCL10, and CXCL16 were significantly elevated in patients compared to controls, while IL-31 levels were significantly decreased in patients. IL-17A, CXCL10, and CXCL16 were associated with an increased risk of AS, while IL-31 was associated with a decreased risk of disease (odds ratio = 1.22, 1.78, 1.14, and 0.89, respectively). As indicated by the area under the curve (AUC), IL-17A, IL-31, CXCL10, and CXCL16 were potential markers to differentiate between AS patients and controls (AUC = 0.877, 0.735, 0.8, and 0.7, respectively). IL-1α, IL-1Ra, IL-12, and IL-33 levels showed no significant variations between patients and controls.

CONCLUSIONS

Among the eight cytokines examined, IL-17A, CXCL10, and CXCL16 were up-regulated in the serum of AS patients, while IL-31 was down-regulated. The levels of IL-1α, IL-1Ra, IL-12, and IL-33 showed no significant differences between patients and controls. Serum levels of all cytokines were not affected by disease duration, HLA-B27 positivity, or disease activity.

New Alpha9 nAChR Ligands Based on a 5-(Quinuclidin-3-ylmethyl)-1,2,4-oxadiazole Scaffold

Several lines of evidence have indicated that nicotinic acetylcholine receptors (nAChR) that contain α9 subunits, probably in combination with α10 subunits, may be valuable targets for the management of pain associated with inflammatory diseases through a cholinergic anti-inflammatory system (CAS), which has also been associated with α7 nAChR. Both α7- and α9-containing neuronal nAChR can be pharmacologically distinguished from the high-affinity nicotinic receptors of the brain by their sensitivity to α-bungarotoxin, but in other ways, they have quite distinct pharmacological profiles. The early association of α7 with CAS led to the development of numerous new ligands, variously characterized as α7 agonists, partial agonists, or silent agonists that desensitized α7 receptors without activation. Subsequent reinvestigation of one such family of α7 ligands based on an N,N-diethyl-N'-phenylpiperazine scaffold led to the identification of potent agonists and antagonists for α9. In this paper, we characterize the α9/α10 activity of a series of compounds based on a 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazole (QMO) scaffold and identify two new potent ligands of α9, QMO-28, an agonist, and QMO-17, an antagonist. We separated the stereoisomers of these compounds to identify the most potent agonist and discovered that only the 3R isomer of QMO-17 was an α9 antagonist, permitting an in silico model of α9 antagonism to be developed. The α9 activity of these compounds was confirmed to be potentially useful for CAS management of inflammatory pain in cell-based assays of cytokine release.

Role of Microglial Modulation in Therapies for Perinatal Brain Injuries Leading to Neurodevelopmental Disorders

Neurodevelopmental disorders (NDDs) encompass various conditions stemming from changes during brain development, typically diagnosed early in life. Examples include autism spectrum disorder, intellectual disability, cerebral palsy, seizures, dyslexia, and attention deficit hyperactivity disorder. Many NDDs are linked to perinatal events like infections, oxygen disturbances, or insults in combination. This chapter outlines the causes and effects of perinatal brain injury as they relate to microglia, along with efforts to prevent or treat such damage. We primarily discuss therapies targeting microglia modulation, focusing on those either clinically used or in advanced development, often tested in large animal models such as sheep, non-human primates, and piglets-standard translational models in perinatal medicine. Additionally, it touches on experimental studies showcasing advancements in the field.

Roles of pyroptosis in atherosclerosis pathogenesis

Pyroptosis is a pro-inflammatory type of regulated cell death (RCD) characterized by gasdermin protein-mediated membrane pore formation, cell swelling, and rapid lysis. Recent studies have suggested that pyroptosis is closely related to atherosclerosis (AS). Previous studies reported that pyroptosis involving endothelial cells (ECs), macrophages, and smooth muscle cells (SMCs) plays an important role in the formation and development of AS. Pyroptosis not only causes local inflammation but also amplifies the inflammatory response and it aggravates plaque instability, leading to plaque rupture and thrombosis, eventually resulting in acute cardiovascular events. In this review, we clarified some novel pathways and mechanics and presented some potential drugs.

Deciphering the Function of New Therapeutic Targets and Prospective Biomarkers in the Management of Psoriasis

Psoriasis is an immune-mediated skin condition affecting people worldwide, presenting at any age, and leading to a substantial burden physically and mentally. The innate and adaptive immune systems interact intricately with the pathomechanisms that underlie disease. T cells can interact with keratinocytes, macrophages, and dendritic cells through the cytokines they secrete. According to recent research, psoriasis flare-ups can cause systemic inflammation and various other co-morbidities, including depression, psoriatic arthritis, and cardio-metabolic syndrome. Additionally, several auto-inflammatory and auto-immune illnesses may be linked to psoriasis. Although psoriasis has no proven treatment, care must strive by treating patients as soon as the disease surfaces, finding and preventing concurrent multimorbidity, recognising and reducing bodily and psychological distress, requiring behavioural modifications, and treating each patient individually. Biomarkers are traits that are assessed at any time along the clinical continuum, from the early stages of a disease through the beginning of treatment (the foundation of precision medicine) to the late stages of treatment (outcomes and endpoints). Systemic therapies that are frequently used to treat psoriasis provide a variety of outcomes. Targeted therapy selection, better patient outcomes, and more cost-effective healthcare would be made possible by biomarkers that reliably predict effectiveness and safety. This review is an attempt to understand the role of Antimicrobial peptides (AMP), Interleukin-38 (IL-38), autophagy 5 (ATG5) protein and squamous cell carcinoma antigen (SCCA) as biomarkers of psoriasis.

The IL-33/ST2 Pathway in Cerebral Malaria

Interleukin-33 (IL-33) is an immunomodulatory cytokine which plays critical roles in tissue function and immune-mediated diseases. IL-33 is abundant within the brain and spinal cord tissues where it acts as a key cytokine to coordinate the exchange between the immune and central nervous system (CNS). In this review, we report the recent advances to our knowledge regarding the role of IL-33 and of its receptor ST2 in cerebral malaria, and in particular, we highlight the pivotal role that IL-33/ST2 signaling pathway could play in brain and cerebrospinal barriers permeability. IL-33 serum levels are significantly higher in children with severe Plasmodium falciparum malaria than children without complications or noninfected children. IL-33 levels are correlated with parasite load and strongly decrease with parasite clearance. We postulate that sequestration of infected erythrocytes or merozoites liberation from schizonts could amplify IL-33 production in endothelial cells, contributing either to malaria pathogenesis or recovery.

Mitochondrial VDAC1: A Potential Therapeutic Target of Inflammation-Related Diseases and Clinical Opportunities

The multifunctional protein, voltage-dependent anion channel 1 (VDAC1), is located on the mitochondrial outer membrane. It is a pivotal protein that maintains mitochondrial function to power cellular bioactivities via energy generation. VDAC1 is involved in regulating energy production, mitochondrial oxidase stress, Ca²⁺ transportation, substance metabolism, apoptosis, mitochondrial autophagy (mitophagy), and many other functions. VDAC1 malfunction is associated with mitochondrial disorders that affect inflammatory responses, resulting in an up-regulation of the body’s defensive response to stress stimulation. Overresponses to inflammation may cause chronic diseases. Mitochondrial DNA (mtDNA) acts as a danger signal that can further trigger native immune system activities after its secretion. VDAC1 mediates the release of mtDNA into the cytoplasm to enhance cytokine levels by activating immune responses. VDAC1 regulates mitochondrial Ca²⁺ transportation, lipid metabolism and mitophagy, which are involved in inflammation-related disease pathogenesis. Many scientists have suggested approaches to deal with inflammation overresponse issues via specific targeting therapies. Due to the broad functionality of VDAC1, it may become a useful target for therapy in inflammation-related diseases. The mechanisms of VDAC1 and its role in inflammation require further exploration. We comprehensively and systematically summarized the role of VDAC1 in the inflammatory response, and hope that our research will lead to novel therapeutic strategies that target VDAC1 in order to treat inflammation-related disorders.

Impact of MyD88, Microbiota, and Location on Type 1 and Type 3 Innate Lymphoid Cells during Toxoplasma gondii Infection

Toxoplasma gondii induces strong IFN-γ-based immunity. Innate lymphoid cells (ILC), in particular ILC1, are an important innate source of this protective cytokine during infection. Our objective was to determine how MyD88-dependent signaling influences ILC function during peroral compared with i.p. infection with T. gondii. MyD88 +/+ and MyD88 -/- mice were orally inoculated with ME49 cysts, and small intestinal lamina propria ILC were assessed using flow cytometry. We observed T-bet+ ILC1, retinoic acid-related orphan receptor γt+ ILC3, and a population of T-bet+retinoic acid-related orphan receptor γt+ double-positive ILC. In MyD88 -/- mice, IFN-γ-producing T-bet+ ILC1 frequencies were reduced compared with wild-type. Treatment of MyD88 -/- mice with an antibiotic mixture to deplete microflora reduced IFN-γ+ ILC1 frequencies. To examine ILC responses outside of the mucosal immune system, peritoneal exudate cells were collected from wild-type and knockout mice after i.p. inoculation with ME49 cysts. In this compartment, ILC were highly polarized to the ILC1 subset that increased significantly and became highly positive for IFN-γ over the course of infection. Increased ILC1 was associated with expression of the Ki67 cell proliferation marker, and the response was driven by IL-12p40. In the absence of MyD88, IFN-γ expression by ILC1 was not maintained, but proliferation remained normal. Collectively, these data reveal new aspects of ILC function that are influenced by location of infection and shaped further by MyD88-dependent signaling.

IL-36γ is secreted through an unconventional pathway using the Gasdermin D and P2X7R membrane pores

Mucosal innate immunity functions as the first line of defense against invading pathogens. Members of the IL-1 family are key cytokines upregulated in the inflamed mucosa. Inflammatory cytokines are regulated by limiting their function and availability through their activation and secretion mechanisms. IL-1 cytokines secretion is affected by the lack of a signal peptide on their sequence, which prevents them from accessing the conventional protein secretion pathway; thus, they use unconventional protein secretion pathways. Here we show in mouse macrophages that LPS/ATP stimulation induces cytokine relocalization to the plasma membrane, and conventional secretion blockade using monensin or Brefeldin A triggers no IL-36γ accumulation within the cell. In silico modeling indicates IL-36γ can pass through both the P2X7R and Gasdermin D pores, and both IL-36γ, P2X7R and Gasdermin D mRNA are upregulated in inflammation; further, experimental blockade of these receptors’ limits IL-36γ release. Our results demonstrate that IL-36γ is secreted mainly by an unconventional pathway through membrane pores formed by P2X7R and Gasdermin D.

P2X7 receptor as a potential therapeutic target for perinatal brain injury associated with preterm birth

Inflammation-induced preterm birth is the leading cause of perinatal mortality and long-term sequelae in surviving children. IL-1β is a major contributor to inflammation-induced preterm labor and its sequelae. It has recently been demonstrated that the cytokine storm and its progression depend on IL-1β release into circulation and that the P2X7 receptor (P2X7R) is the key player of the ATP-driven NLRP3/caspase-1 activation, necessary for the cleavage of pro-IL-1β to its mature form as well as its subsequent secretion. Being a key component to the inflammatory cascade, P2X7R illuminates a new therapeutic avenue to halt progression of inflammation prior to perinatal brain injury. In this review, we summarize the basic role of the P2X7 receptor in the inflammatory signaling cascade and the possibility of it being used as a therapeutic target in perinatal brain injury. We discuss the antagonists and agonists of the receptor as well as its role in other inflammatory diseases, showing the importance of discovering the functions of the receptor.

Cross-Talk between the Cytokine IL-37 and Thyroid Hormones in Modulating Chronic Inflammation Associated with Target Organ Damage in Age-Related Metabolic and Vascular Conditions

Chronic inflammation is considered to be the main mechanism contributing to the development of age-related metabolic and vascular conditions. The phases of chronic inflammation that mediate the progression of target organ damage in these conditions are poorly known, however. In particular, there is a paucity of data on the link between chronic inflammation and metabolic disorders. Based on some of our own results and recent developments in our understanding of age-related inflammation as a whole-body response, we discuss the hypothesis that cross-talk between the cytokine IL-37 and thyroid hormones could be the key regulatory mechanism that justifies the metabolic effects of chronic tissue-related inflammation. The cytokine IL-37 is emerging as a strong natural suppressor of the chronic innate immune response. The effect of this cytokine has been identified in reversing metabolic costs of chronic inflammation. Thyroid hormones are known to regulate energy metabolism. There is a close link between thyroid function and inflammation in elderly individuals. Nonlinear associations between IL-37 and thyroid hormones, considered within the wider clinical context, can improve our understanding of the phases of chronic inflammation that are associated with target organ damage in age-related metabolic and vascular conditions.

Biology of interleukin‑37 and its role in autoimmune diseases (Review)

Autoimmune diseases (AIDs) are characterized by dysfunction and tissue destruction, and recent studies have shown that interleukin (IL)-37 expression is dysregulated in AIDs. Among cytokines of the IL-1 family, most are pro-inflammatory agents, and as an anti-inflammatory cytokine, IL-37 may have the potential to alleviate excessive inflammation and can be used as a ligand or transcription factor that is involved in regulating innate and adaptive immunity. IL-37 plays important roles in the development of AIDs. This review summarizes the biological characteristics and functions of IL-37 and discusses the potential of IL-37 as a therapeutic target for effective cytokine therapy and as a biomarker in AIDs.

Inflammasome Contribution to the Activation of Th1, Th2, and Th17 Immune Responses

Inflammasomes are cytosolic polyprotein complexes formed in response to various external and internal stimuli, including viral and bacterial antigens. The main product of the inflammasome is active caspase 1 which proteolytically cleaves, releasing functional interleukin-1 beta (IL-1β) and interleukin-18 (IL-18). These cytokines play a central role in shaping immune response to pathogens. In this review, we will focus on the mechanisms of inflammasome activation, as well as their role in development of Th1, Th2, and Th17 lymphocytes. The contribution of cytokines IL-1β, IL-18, and IL-33, products of activated inflammasomes, are summarized. Additionally, the role of cytokines released from tissue cells in promoting differentiation of lymphocyte populations is discussed.

Interleukin-1 Receptor-Like 2: One Receptor, Three Agonists, and Many Implications

The interleukin (IL)-1 superfamily of cytokines comprises 11 pro- and anti-inflammatory cytokines, which play essential roles during the immune response. Several pathogenic pathways are initiated by IL-1RL2 (interleukin 1 receptor-like 2) signaling, also known as IL-36R, in the skin, lungs, and gut. IL-36 cytokines promote the secretion of proinflammatory cytokines and chemokines, upregulation of antimicrobial peptides, proliferation mediators, and adhesion molecules on endothelial cells. In addition, the IL-36-IL-1RL2 axis has an essential role against viral infections, including a potential role in COVID-19 pathology. The evidence presented in this review highlights the importance of the axis IL-36-IL-1RL2 in the development of several inflammation-related diseases and the healing process. It suggests that IL-1RL2 ligands have specific roles depending on the tissue or cell source. However, there is still much to discover about this cytokine family, their functions in other organs, and how they accomplish a dual effect in inflammation and healing.

Immunomodulation of Skin Repair: Cell-Based Therapeutic Strategies for Skin Replacement (A Comprehensive Review)

The immune system has a crucial role in skin wound healing and the application of specific cell-laden immunomodulating biomaterials emerged as a possible treatment option to drive skin tissue regeneration. Cell-laden tissue-engineered skin substitutes have the ability to activate immune pathways, even in the absence of other immune-stimulating signals. In particular, mesenchymal stem cells with their immunomodulatory properties can create a specific immune microenvironment to reduce inflammation, scarring, and support skin regeneration. This review presents an overview of current wound care techniques including skin tissue engineering and biomaterials as a novel and promising approach. We highlight the plasticity and different roles of immune cells, in particular macrophages during various stages of skin wound healing. These aspects are pivotal to promote the regeneration of nonhealing wounds such as ulcers in diabetic patients. We believe that a better understanding of the intrinsic immunomodulatory features of stem cells in implantable skin substitutes will lead to new translational opportunities. This, in turn, will improve skin tissue engineering and regenerative medicine applications.

The anti-inflammatory and protective role of interleukin-38 in inflammatory bowel disease

Interleukin (IL)-38 exerts an anti-inflammatory function by binding to several cytokine receptors, including the IL-36 receptor. In this study, we evaluated IL-38 expression in the inflamed mucosa of patients with inflammatory bowel disease (IBD) and investigated its functions. IL-38 mRNA expression in endoscopic biopsy samples was evaluated using quantitative PCR. IL-38 protein expression was analyzed using immunohistochemical technique. Dextran sulfate sodium-induced colitis was induced in C57BL/6 background IL-38KO mice. The IL-38 mRNA and protein expression were enhanced in the active mucosa of ulcerative colitis, but not in Crohn's disease. The ratio of IL-36γ to IL-38 mRNA expression was significantly elevated in the active mucosa of UC patients. Immunofluorescence staining revealed that B cells are the major cellular source of IL-38 in the colonic mucosa. IL-38 dose-dependently suppressed the IL-36γ-induced mRNA expression of CXC chemokines (CXCL1, CXCL2, and CXCL8) in HT-29 and T84 cells. IL-38 inhibited the IL-36γ-induced activation of nuclear-factor kappa B (NF-κB) and mitogen-activated protein kinases in HT-29 cells. DSS-colitis was significantly exacerbated in IL-38KO mice compared to wild type mice. In conclusion, IL-38 may play an anti-inflammatory and protective role in the pathophysiology of IBD, in particular ulcerative colitis, through the suppression of IL-36-induced inflammatory responses.

Immunobiological Properties and Clinical Applications of Interleukin-38 for Immune-Mediated Disorders: A Systematic Review Study

Exponential growth in the usage of "cytokines" (as seroimmunobiomarkers) has facilitated more accurate prognosis, early diagnosis, novel, and efficient immunotherapeutics. Numerous studies have reported immunopathophysiological and immunopathological processes of interleukin-38 (IL-38). Therefore, in this systematic review article, the authors aimed to present an updated comprehensive overview on the immunobiological mechanisms, diagnostic, and immune gene-based therapeutic potentials of IL-38. According to our inclusion and exclusion criteria, a total of 216 articles were collected from several search engines and databases from the January 2012 to July 2021 time interval by using six main keywords. Physiologic or pathologic microenvironments, optimal dosage, and involved receptors affect the functionalities of IL-38. Alterations in serum levels of IL-38 play a major role in the immunopathogenesis of a wide array of immune-mediated disorders. IL-38 shows anti-inflammatory activities by reduction or inhibition of pro-inflammatory cytokines, supporting the therapeutic aspects of IL-38 in inflammatory autoimmune diseases. According to the importance of pre-clinical studies, it seems that manipulation of the immune system by immunomodulatory properties of IL-38 can increase the accuracy of diagnosis, and decipher optimal clinical outcomes. To promote our knowledge, more collaboration is highly recommended among laboratory scientists, internal/infectious diseases specialists, oncologists, immunologists, diseases-specific biomarkers scientists, and basic medical researchers.

IL-1/IL-1R Signaling in Head and Neck Cancer

Decades ago, the study of cancer biology was mainly focused on the tumor itself, paying little attention to the tumor microenvironment (TME). Currently, it is well recognized that the TME plays a vital role in cancer development and progression, with emerging treatment strategies focusing on different components of the TME, including tumoral cells, blood vessels, fibroblasts, senescent cells, inflammatory cells, inflammatory factors, among others. There is a well-accepted relationship between chronic inflammation and cancer development. Interleukin-1 (IL-1), a potent pro-inflammatory cytokine commonly found at tumor sites, is considered one of the most important inflammatory factors in cancer, and has been related with carcinogenesis, tumor growth and metastasis. Increasing evidence has linked development of head and neck squamous cell carcinoma (HNSCC) with chronic inflammation, and particularly, with IL-1 signaling. This review focuses on the most important members of the IL-1 family, with emphasis on how their aberrant expression can promote HNSCC development and metastasis, highlighting possible clinical applications.

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.

IL-1α and colorectal cancer pathogenesis: Enthralling candidate for anti-cancer therapy

Inflammation has been well-established as a hallmark of colorectal cancer (CRC). Interleukin-1 alpha (IL-1α) is one of the primary inflammatory mediators driving the pathogenesis of inflammation-associated CRC. This systematic review presents the roles of IL-1α in the pathogenesis of the disease. Bibliographic databases PubMed, Science Direct, Scopus and Web of Science were systematically searched for articles that addresses the relationship between IL-1α and colorectal cancer. We highlighted various mechanisms by which IL-1α promotes the pathogenesis of CRC including enhancement of angiogenesis, metastasis, resistance to therapy, and inhibition of tumour suppressive genes. We also discussed the potential mechanisms by which IL-1α expression is induced or secreted in various studies. Beyond these, the systematic review also highlights several potential therapeutic strategies which should be further explored in the future; to target IL-1α and/or its associated pathways; paving our way in finding effective treatments for CRC patients.

The Emerging Role of the Innate Immune Response in Idiosyncratic Drug Reactions

Idiosyncratic drug reactions (IDRs) range from relatively common, mild reactions to rarer, potentially life-threatening adverse effects that pose significant risks to both human health and successful drug discovery. Most frequently, IDRs target the liver, skin, and blood or bone marrow. Clinical data indicate that most IDRs are mediated by an adaptive immune response against drug-modified proteins, formed when chemically reactive species of a drug bind to self-proteins, making them appear foreign to the immune system. Although much emphasis has been placed on characterizing the clinical presentation of IDRs and noting implicated drugs, limited research has focused on the mechanisms preceding the manifestations of these severe responses. Therefore, we propose that to address the knowledge gap between drug administration and onset of a severe IDR, more research is required to understand IDR-initiating mechanisms; namely, the role of the innate immune response. In this review, we outline the immune processes involved from neoantigen formation to the result of the formation of the immunologic synapse and suggest that this framework be applied to IDR research. Using four drugs associated with severe IDRs as examples (amoxicillin, amodiaquine, clozapine, and nevirapine), we also summarize clinical and animal model data that are supportive of an early innate immune response. Finally, we discuss how understanding the early steps in innate immune activation in the development of an adaptive IDR will be fundamental in risk assessment during drug development. SIGNIFICANCE STATEMENT: Although there is some understanding that certain adaptive immune mechanisms are involved in the development of idiosyncratic drug reactions, the early phase of these immune responses remains largely uncharacterized. The presented framework refocuses the investigation of IDR pathogenesis from severe clinical manifestations to the initiating innate immune mechanisms that, in contrast, may be quite mild or clinically silent. A comprehensive understanding of these early influences on IDR onset is crucial for accurate risk prediction, IDR prevention, and therapeutic intervention.

IL-33 promotes innate lymphoid cell-dependent IFN-γ production required for innate immunity to Toxoplasma gondii

IL-33 is an alarmin required for resistance to the parasite Toxoplasma gondii, but its role in innate resistance to this organism is unclear. Infection with T. gondii promotes increased stromal cell expression of IL-33, and levels of parasite replication correlate with release of IL-33 in affected tissues. In response to infection, a subset of innate lymphoid cells (ILC) emerges composed of IL-33R+ NK cells and ILC1s. In Rag1-/-mice, where NK cells and ILC1 production of IFN-γ mediate innate resistance to T. gondii, the loss of the IL-33R resulted in reduced ILC responses and increased parasite replication. Furthermore, administration of IL-33 to Rag1-/- mice resulted in a marked decrease in parasite burden, increased production of IFN-γ, and the recruitment and expansion of inflammatory monocytes associated with parasite control. These protective effects of exogenous IL-33 were dependent on endogenous IL-12p40 and the ability of IL-33 to enhance ILC production of IFN-γ. These results highlight that IL-33 synergizes with IL-12 to promote ILC-mediated resistance to T. gondii.

Modulation of Liver Inflammation and Fibrosis by Interleukin-37

Background and Aims: Chronic inflammation induces liver fibrosis, cirrhosis and potentially liver cancer. Kupffer cells modulate hepatic stellate cells by secreting immunologically active proteins as TGF-β. TGF-β promotes liver fibrosis via the activation of Sma- and Mad-related protein 3. IL-37 broadly suppresses innate and adaptive immune responses. Intracellular IL-37 interacts with Smad3. We hypothesize that IL-37 downregulates the activation of hepatic Kupffer and stellate cells and interferes with the TGF-β signaling cascade to modulate liver fibrogenesis. Methods: The role of IL-37 on liver inflammation and fibrogenesis was assessed in three mouse models as well as isolated Kupffer- and stellate cells. Serum IL-37 was tested by ELISA in a clinical cohort and correlated with liver disease severity. Results: Transgene expression of IL-37 in mice extends survival, reduces hepatic damage, expression of early markers of fibrosis and histologically assessed liver fibrosis after bile duct ligation. IL-37tg mice were protected against CCl4-induced liver inflammation. Colitis-associated liver inflammation and fibrosis was less severe in IL-10 knockout IL-37tg mice. Spontaneous and LPS/TGF-β-induced cytokine release and profibrogenic gene expression was lower in HSC and KC isolated from IL-37tg mice and IL-37 overexpressing, IL-1β stimulated human LX-2 stellate cells. However, administration of recombinant human IL-37 did not modulate fibrosis pathways after BDL in mice, LX2 cells or murine HSCs. In a large clinical cohort, we observed a positive correlation of serum IL-37 levels with disease severity in liver cirrhosis. Conclusions: Predominantly intracellular IL-37 downregulates liver inflammation and fibrosis. The correlation of serum IL-37 with disease severity in cirrhosis suggests its potential as a novel target modulating the course of liver fibrosis.

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.

Cytotoxic and immunological responses of fish leukocytes to nodularin exposure in vitro

Nodularin (NOD) is a cyclic peptide released by bloom-forming toxic cyanobacteria Nodularia spumigena commonly occurring in brackish waters throughout the world. Although its hepatotoxic effects are well known, other negative effects of NOD have not yet been completely elucidated. The present study aims were to evaluate and compare the cytotoxic and immunotoxic effects of the toxin on primary leukocytes (from head kidney [HK]) and stable fish leukocytes (carp leucocyte cell line [CLC] cells). The cells were incubated with the cyanotoxin at concentrations of 0.001, 0.01, 0.05, or 0.1 μg/ml. After 24 h of exposure, the concentrations ≥0.05 μg/ml of toxin resulted in cytotoxicity in the primary cells, while in CLC cells, the toxic effect was obtained only with the highest concentration. Similarly, depending on the concentration, exposure to NOD causes a significant inhibition of chemotaxis of the phagocytic abilities of primary leukocytes and a significant reduction in the proliferation of lymphocytes isolated from the HKs. Moreover, CLC cells and HK leukocytes incubated with this toxin at all the mentioned concentrations showed an increased production of reactive oxygen and nitrogen species. NOD also evidently influenced the expression of genes of cytokine TNF-α and IL-10 and, to a minor extent, IL-1β and TGF-β. Notably, the observed changes in the mRNA levels of cytokines in NOD-exposed cells were evident, but not clearly dose-dependent. Interestingly, NOD did not affect the production and release of IL-1β of the CLC cells. This study provides evidence that NOD may exert cytotoxicity and immune-toxicity effects depending on cell type and toxin concentration.

Untangling Local Pro-Inflammatory, Reparative, and Regulatory Damage-Associated Molecular-Patterns (DAMPs) Pathways to Improve Transplant Outcomes

Detrimental inflammatory responses after solid organ transplantation are initiated when immune cells sense pathogen-associated molecular patterns (PAMPs) and certain damage-associated molecular patterns (DAMPs) released or exposed during transplant-associated processes, such as ischemia/reperfusion injury (IRI), surgical trauma, and recipient conditioning. These inflammatory responses initiate and propagate anti-alloantigen (AlloAg) responses and targeting DAMPs and PAMPs, or the signaling cascades they activate, reduce alloimmunity, and contribute to improved outcomes after allogeneic solid organ transplantation in experimental studies. However, DAMPs have also been implicated in initiating essential anti-inflammatory and reparative functions of specific immune cells, particularly Treg and macrophages. Interestingly, DAMP signaling is also involved in local and systemic homeostasis. Herein, we describe the emerging literature defining how poor outcomes after transplantation may result, not from just an over-abundance of DAMP-driven inflammation, but instead an inadequate presence of a subset of DAMPs or related molecules needed to repair tissue successfully or re-establish tissue homeostasis. Adverse outcomes may also arise when these homeostatic or reparative signals become dysregulated or hijacked by alloreactive immune cells in transplant niches. A complete understanding of the critical pathways controlling tissue repair and homeostasis, and how alloimmune responses or transplant-related processes disrupt these will lead to new immunotherapeutics that can prevent or reverse the tissue pathology leading to lost grafts due to chronic rejection.

NLRP3 inflammasome as a key driver of vascular disease

NLRP3 (nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3) is an intracellular innate immune receptor that recognizes a diverse range of stimuli derived from pathogens, damaged or dead cells, and irritants. NLRP3 activation causes the assembly of a large multiprotein complex termed the NLRP3 inflammasome, and leads to the secretion of bioactive interleukin (IL)-1β and IL-18 as well as the induction of inflammatory cell death termed pyroptosis. Accumulating evidence indicates that NLRP3 inflammasome plays a key role in the pathogenesis of sterile inflammatory diseases, including atherosclerosis and other vascular diseases. Indeed, the results of the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) trial demonstrated that IL-1β-mediated inflammation plays an important role in atherothrombotic events and suggested that NLRP3 inflammasome is a key driver of atherosclerosis. In this review, we will summarize the current state of knowledge regarding the role of NLRP3 inflammasome in vascular diseases, in particular in atherosclerosis, vascular injury, aortic aneurysm, and Kawasaki disease vasculitis, and discuss NLRP3 inflammasome as a therapeutic target for these disorders.

Expression of Toll-Like Receptors in the Animal Model of Bladder Outlet Obstruction

Introduction

Bladder outlet obstruction (BOO) occurs in more than 20 percent of the adult population and may lead to changes in the structure and function of the bladder. The main objective of the study was to evaluate the expression of Toll-like receptor 4 (TLR 4) and Toll-like receptor 9 (TLR 9) in the animal model of BOO as potential triggers of the inflammation phase in the bladder. In addition, the modulating effect of alpha-1 adrenergic antagonist (tamsulosin) on TLR 4 and TLR 9 expression and inflammatory markers was assessed. Material and Methods. Thirty-two male, 9-week-old Sprague Dawley rats were randomly divided into 4 groups: SOP—sham-operated rats with a placebo (water); SOB—sham-operated rats with an alpha-1 adrenergic antagonist; BOOP—rats with BOO and a placebo; and BOOB—rats with BOO and an alpha-1 adrenergic antagonist. The rats were given a placebo or alpha-1 adrenergic antagonist for 15 days. Next, urine and the bladder were collected from the rats for histopathological and biochemical study.

Results

Histopathological analysis showed chronic inflammation without acute inflammation in the bladder. TLR 4 showed positive cytoplasmic reactivity in the urothelium and the smooth muscles of the bladder. TLR 9 showed positive cytoplasmic reactivity only in the urothelium. BOO caused an increase in TLR 4 and TLR 9 expression. Furthermore, treatment with an alpha-1 adrenergic antagonist had no significant effect on TLR 4 and TLR 9 expression in rats with BOO. BOO caused a significant increase in urine concentration of interleukin 6 (IL-6), while alpha-1 antagonist reduced the urine concentration of IL-6 and the concentration of interleukin 18 (IL-18).

Conclusions

The results suggest the participation of TLR 4 and TLR 9 receptors in the induction of inflammation in the bladder, which is the first phase in the development of pathophysiological changes in BOO.

Entecavir downregulates interleukin-37 in patients with chronic active hepatitis B infection

Objectives

Interleukin-37 (IL-37) has been identified as a potent inhibitor of the immune response. This study aimed to examine IL-37 expression in patients with chronic active hepatitis B (CAHB), and explore its possible regulatory role during inflammation.

Methods

Peripheral blood mononuclear cells (PBMCs) were collected from control (n = 20) and CAHB patients (n = 30) before and after treatment with entecavir (EVT) for 24 weeks. The PBMCs were cultured with lipopolysaccharide and IL-37 expression was determined by real-time polymerase chain reaction and flow cytometry. The mRNA and protein concentrations of IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) in PBMCs were also measured.

Results

Levels of IL-37, IL-1β, IL-6, and TNF-α were significantly increased in the supernatant of PBMCs from patients with CAHB. IL-37 significantly reduced the expression of IL-1β, IL-6, and TNF-α. EVT resulted in regression of intraocular inflammation in patients with CAHB, associated with decreased production of IL-37.

Conclusion

These results suggest that increased expression of IL-37 was associated with the suppression of the inflammatory response in patients with CAHB. Furthermore, EVT treatment of CAHB was also correlated with downregulation of IL-37, indicating that EVT may partially alleviate the immune response by modulating IL-37 production.

Glycan-mediated functional assembly of IL-1RI: structural insights into completion of the current description for immune response

Interleukin 1 Receptor type I (IL-1RI) is a multi-domain transmembrane receptor that triggers the inflammatory response. Understanding its detailed mechanism of action is crucial for treating immune disorders. IL-1RI is activated upon formation of its functional assembly that occurs by binding of the IL-1 cytokine and the accessory protein (Il-1RAcP) to it. X-ray crystallography, small-Angle X-ray Scattering and molecular dynamics simulation studies showed that IL-1RI adopts two types of 'compact' and 'extended' conformational states in its dynamical pattern. Furthermore, glycosylation has shown to play a critical role in its activation process. Here, classical and accelerated atomistic molecular dynamics were carried out to examine the role of full glycosylation of IL-1RI and IL-1RAcP in arrangement of the functional assembly. Simulations showed that the 'compact' and 'extended' IL-1RI form two types of 'cytokine-inaccessible-non-signaling' and 'cytokine-accessible-signaling' assemblies with the IL-1RacP, respectively that are both abiding in the presence of glycans. Suggesting that the cytokine binding to IL-1RI is not required for the formation of IL-1RI-IL-1RAcP complex and the 'compact' complex could act as a down-regulatory mechanism. The 'extended' complex is maintained by formation of several persistent hydrogen bonds between the IL-1RI-IL-1RAcP inter-connected glycans. Taken together, it was shown that full glycosylation regulates formation of the IL-1RI functional assembly and play critical role in cytokine biding and triggering the IL-1RI involved downstream pathways in the cell.Communicated by Ramaswamy H. Sarma.

IL-1α Is Essential for Oviduct Pathology during Genital Chlamydial Infection in Mice

Chlamydia trachomatis infection of the female genital tract can lead to irreversible fallopian tube scarring. In the mouse model of genital infection using Chlamydia muridarum, IL-1R signaling plays a critical role in oviduct tissue damage. In this study, we investigated the pathologic role of IL-1α, one of the two proinflammatory cytokines that bind to IL-1R. Il1a^-/- mice infected with C. muridarum cleared infection at their cervix at the same rate as wild-type (WT) mice, but were significantly protected from end point oviduct damage and fibrosis. The contribution of IL-1α to oviduct pathology was more dramatic than observed in mice deficient for IL-1β. Although chlamydial burden was similar in WT and Il1a^-/- oviduct during peak days of infection, levels of IL-1β, IL-6, CSF3, and CXCL2 were reduced in Il1a^-/- oviduct lysates. During infection, Il1a^-/- oviducts and uterine horns exhibited reduced neutrophil infiltration, and this reduction persisted after the infection resolved. The absence of IL-1α did not compromise CD4 T cell recruitment or function during primary or secondary chlamydial infection. IL-1α is expressed predominantly by luminal cells of the genital tract in response to infection, and low levels of expression persisted after the infection cleared. Ab-mediated depletion of IL-1α in WT mice prevented infection-induced oviduct damage, further supporting a key role for IL-1α in oviduct pathology.

Cell-specific conditional deletion of interleukin-1 (IL-1) ligands and its receptors: a new toolbox to study the role of IL-1 in health and disease

The pro-inflammatory cytokine interleukin-1 (IL-1) plays a key role in many physiological processes and during the inflammatory and immune response to most common diseases. IL-1 exists as two agonists, IL-1α and IL-1β that bind to the only signaling IL-1 type 1 receptor (IL-1R1), while a second decoy IL-1 type 2 receptor (IL-1R2) binds both forms of IL-1 without inducing cell signaling. The field of immunology and inflammation research has, over the past 35 years, unraveled many mechanisms of IL-1 actions, through in vitro manipulation of the IL-1 system or by using genetically engineered mouse models that lack either member of the IL-1 family in ubiquitous constitutive manner. However, the limitation of global mouse knockout technology has significantly hampered our understanding of the precise mechanisms of IL-1 actions in animal models of disease. Here we report and review the recent generation of new conditional mouse mutants in which exons of Il1a, Il1b, Il1r1, and Il1r2 genes flanked by loxP sites (fl/fl) can be deleted in cell-/tissue-specific constitutive or inducible manner by Cre recombinase expression. Hence, IL-1αfl/fl, IL-1βfl/fl, IL-1R1fl/fl, and IL-1R2fl/fl mice constitute a new toolbox that will provide a step change in our understanding of the cell-specific role of IL-1 and its receptor in health and disease and the potential development of targeted IL-1 therapies.

New synthetic coumarinolignans as attenuators of pro-inflammatory cytokines in LPS-induced sepsis and carrageenan-induced paw oedema models

OBJECTIVES

The aim of the study was to explore the inhibition efficacy of new synthetic coumarinolignans (SCLs) against the secretion of pro-inflammatory cytokines in two in vivo models of inflammation.

METHODS

Four SCLs 1-4 were screened for their pro-inflammatory cytokine inhibitory potential through oral administration at a dose of 50 mg/kg body weight in lipopolysaccharide-induced mouse endotoxaemia and carrageenan-induced mouse paw oedema models. Levels of pro-inflammatory cytokines (IL-1β, TNFα and IL-6) in blood and paw tissue samples were estimated using ELISA. Paw oedema was measured using a plethysmometer. Results were compared with a natural coumarinolignan, cleomiscosin A (5), and the structure-activity relationship (SAR) was interpreted.

RESULTS AND DISCUSSION

Compound 2 had the greatest potential in the endotoxaemia model, exhibiting 66.41%, 62.56% and 43.15% inhibition of plasma IL-1β, TNFα and IL-6 secretions, respectively. Further dose-dependent study revealed its anti-inflammatory potential even at dose of 10 mg/kg body weight with 24.42% decline in the level of IL-1β. Nevertheless, SCLs 1, 3 and 4 showed marked inhibitory activity with 57.54%, 51.48% and 62.46% reduction in the levels of IL-1β, respectively. Moreover, compound 2 decreased the plasma TNFα and IL-1β levels to 50.03% and 36.58% along with the reduction of paw oedema volume in the local inflammation induced by carrageenan. All compounds including cleomiscosin A (5) were more effective against IL-1β. By studying SAR, the presence of dihydroxyl groups in the phenyl ring of lignans was identified to be essential for the activity. Also, esterification of lignans and presence of a 4-methyl substituent in the coumarin nucleus were found to play some role in enhancing the activity.

CONCLUSION

All four SCLs, especially compound 2, have shown vast potential to emerge out as promising anti-inflammatory drugs.

GAG positioning on IL-1RI; A mechanism regulated by dual effect of glycosylation

IL-1RI is the signaling receptor for the IL-1 family of cytokines that are involved in establishment of the innate and acquired immune systems. Glycosylated extracellular (EC) domain of the IL-1RI binds to agonist such as IL-1β or antagonist ligands and the accessory protein to form the functional signaling complex. Dynamics and ligand binding of the IL-1RI is influenced by presence of the glycosaminoglycans (GAGs) of the EC matrix. Here a combination of molecular dockings and molecular dynamics simulations of the unglycosylated, partially N-glycosylated and fully N-glycosylated IL-1RI EC domain in the apo, GAG-bound and IL-1β-bound states were carried out to explain the co-occurring dynamical effect of receptor's glycosylation and GAGs. It was shown that the IL-1RI adopts two types of "extended" and "locked" conformations in its dynamical pattern, and glycosylation maintains the receptor in the latter form. Maintaining the receptor in the locked conformation disfavors IL-1β binding by burying its two binding site on the IL-1RI EC domain. Glycosylation disfavors GAG binding to the extended IL-1RI EC domain by sterically limiting the GAGs degrees of freedom in targeting its binding site, while it favors GAG binding to the locked IL-1RI by favorable packing interactions.

Can insulin secreting pancreatic β-cells provide novel insights into the metabolic regulation of the DNA damage response?

Insulin, produced by pancreatic β-cells, is responsible for the control of whole-body glucose metabolism. Insulin is secreted by pancreatic β-cells in a tightly regulated process that is controlled by the serum level of glucose, glucose sensing and glucose oxidative metabolism. The regulation of intermediary metabolism in β-cells is unique as these cells oxidize glucose to CO₂ on substrate supply while mitochondrial oxidative metabolism occurs on demand, for the production of intermediates or energy production, in most cell types. This review discusses recent findings that the regulation of intermediary metabolism by nitric oxide attenuates the DNA damage response (DDR) and DNA damage-dependent apoptosis in a β-cell selective manner. Specific focus is placed on the mechanisms by which iNOS derived nitric oxide (low micromolar levels) regulates DDR activation via the inhibition of intermediary metabolism. The physiological significance of the association of metabolism, nitric oxide and DDR signaling for cancer biology and diabetes is discussed.

New evidence on the role of inflammation in CVD risk

PURPOSE OF REVIEW

Based on compelling data from animal and human studies, over the past few decades, the viewpoint of atherosclerosis as an exclusively lipid-driven disease, has been gradually replaced by the concept of a chronic low-grade inflammatory process of the arterial wall. This review presents a brief description on the role of inflammation in atherosclerosis, and examines selected anti-inflammatory interventions that have been tested in clinical trials designed to prevent adverse cardiovascular disease (CVD) events and excess CVD risk.

RECENT FINDINGS

The Canakinumab Anti-inflammatory Thrombosis Outcomes Study trial has provided convincing evidence that neutralization of the interleukin (IL)-1β inflammatory pathway by the selective antibody canakinumab reduces major CVD events and significantly lowers IL-1β, IL-6 and high-sensitivity C-reactive protein, without affecting low-density lipoprotein cholesterol levels. In contrast, in the latest Cardiovascular Inflammation Reduction Trial, low-dose methotrexate compared with placebo did not reduce CVD events, probably because there was no reduction in IL-1β, or in downstream inflammatory biomarker levels either.

SUMMARY

Notwithstanding the utilization of effective medical treatments including statins and proprotein convertase subtilisin/kexin type 9 inhibitors or precise revascularizations, the recurrence of CVD events remains unacceptably high. Canakinumab is, at present, the only anti-inflammatory agent that has been proven to reduce cardiovascular events in patients with elevated markers of inflammation without modifying cholesterol levels. Nevertheless, clinical application related to this new evidence and associated knowledge has not yet been implemented in daily practice.

Microglia and mast cells generate proinflammatory cytokines in the brain and worsen inflammatory state: Suppressor effect of IL-37

Brain microglia cells are responsible for recognizing foreign bodies and act by activating other immune cells. Microglia react against infectious agents that cross the blood-brain barrier and release pro-inflammatory cytokines including interleukin (IL)-1β, IL-33 and tumor necrosis factor (TNF). Mast cells (MCs) are immune cells also found in the brain meninges, in the perivascular spaces where they create a protective barrier and release pro-inflammatory compounds, such as IL-1β, IL-33 and TNF. IL-1β binds to the IL-1R1 receptor and activates a cascade of events that leads to the production of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activation of the immune system. IL-33 is a member of the IL-1 family expressed by several immune cells including microglia and MCs and is involved in innate and adaptive immunity. IL-33 is a pleiotropic cytokine which binds the receptor ST2 derived from TLR/IL-1R super family and is released after cellular damage (also called "alarmin"). These cytokines are responsible for a number of brain inflammatory disorders. Activated IL-1β in the brain stimulates microglia, MCs, and perivascular endothelial cells, mediating various inflammatory brain diseases. IL-37 also belongs to the IL-1 family and has the capacity to suppress IL-1β with an anti-inflammatory property. IL-37 deficiency could activate and enhance myeloid differentiation (MyD88) and p38-dependent protein-activated mitogenic kinase (MAPK) with an increase in IL-1β and IL-33 exacerbating neurological pathologies. In this article we report for the first time that microglia communicate and collaborate with MCs to produce pro-inflammatory cytokines that can be suppressed by IL-37 having a therapeutic potentiality.

Inflammatory and Fibrogenic Factors in Proliferative Vitreoretinopathy Development

Purpose

Proliferative vitreoretinopathy (PVR) occurs in 5%-10% of rhegmatogenous retinal detachment cases and is the principle cause for failure of retinal reattachment surgery. Although there are a number of surgical adjunctive agents available for preventing the development of PVR, all have limited efficacy. Discovering predictive molecular biomarkers to determine the probability of PVR development after retinal reattachment surgery will allow better patient stratification for more targeted drug evaluations.

Methods

Narrative literature review.

Results

We provide a summary of the inflammatory and fibrogenic factors found in ocular fluid samples during the development of retinal detachment and PVR and discuss their possible use as molecular PVR predictive biomarkers.

Conclusions

Studies monitoring the levels of the above factors have found that few if any have predictive biomarker value, suggesting that widening the phenotype of potential factors and a combinatorial approach are required to determine predictive biomarkers for PVR.

Translational Relevance

The identification of relevant biomarkers relies on an understanding of disease signaling pathways derived from basic science research. We discuss the extent to which those molecules identified as biomarkers and predictors of PVR relate to disease pathogenesis and could function as useful disease predictors. (http://www.umin.ac.jp/ctr/ number, UMIN000005604).

Inflammatory extracellular vesicles prompt heart dysfunction via TRL4-dependent NF-κB activation

Background: After myocardial infarction, necrotic cardiomyocytes release damage-associated proteins that stimulate innate immune pathways and macrophage tissue infiltration, which drives inflammation and myocardial remodeling. Circulating inflammatory extracellular vesicles play a crucial role in the acute and chronic phases of ischemia, in terms of inflammatory progression. In this study, we hypothesize that the paracrine effect mediated by these vesicles induces direct cytotoxicity in cardiomyocytes. Thus, we examined whether reducing the generation of inflammatory vesicles within the first few hours after the ischemic event ameliorates cardiac outcome at short and long time points. Methods: Myocardial infarction was induced in rats that were previously injected intraperitoneally with a chemical inhibitor of extracellular-vesicle biogenesis. Heart global function was assessed by echocardiography performed at 7, 14 and 28 days after MI. Cardiac outcome was also evaluated by hemodynamic analysis at sacrifice. Cytotoxic effects of circulating EV were evaluated ex-vivo in a Langendorff, system by measuring the level of cardiac troponin I (cTnI) in the perfusate. Mechanisms undergoing cytotoxic effects of EV derived from pro-inflammatory macrophages (M1) were studied in-vitro in primary rat neonatal cardiomyocytes. Results: Inflammatory response following myocardial infarction dramatically increased the number of circulating extracellular vesicles carrying alarmins such as IL-1α, IL-1β and Rantes. Reducing the boost in inflammatory vesicles during the acute phase of ischemia resulted in preserved left ventricular ejection fraction in vivo. Hemodynamic analysis confirmed functional recovery by displaying higher velocity of left ventricular relaxation and improved contractility. When added to the perfusate of isolated hearts, post-infarction circulating vesicles induced significantly more cell death in adult cardiomyocytes, as assessed by cTnI release, comparing to circulating vesicles isolated from healthy (non-infarcted) rats. In vitro inflammatory extracellular vesicles induce cell death by driving nuclear translocation of NF-κB into nuclei of cardiomyocytes. Conclusion: Our data suggest that targeting circulating extracellular vesicles during the acute phase of myocardial infarction may offer an effective therapeutic approach to preserve function of ischemic heart.

Relationship Between Polymorphisms of Interleukin-1 Receptor Antagonist (IL-1Ra) Genes and Susceptibility to Systemic Lupus Erythematosus in Iranian Population

OBJECTIVES

Interleukin (IL)-1 has a major role in cell destruction and inflammation. IL-1 receptor antagonist (IL-1RN or IL-1Ra) is a natural anti-inflammatory molecule that blocks IL-1. We intended to determine whether IL-1RN or IL-1Ra variable number tandem repeat (VNTR) polymorphism is associated with susceptibility to systemic lupus erythematosus (SLE) in a series of patients in the Northeastern part of Iran.

METHODS

Genomic DNA was extracted from the whole blood of 104 SLE patients and 209 subjects without SLE as a control group. The control group was matched for age and gender with SLE patients. Then, genomic DNA was genotyped by polymerase chain reaction (PCR) method for a length polymorphism in intron 2 of the IL-1RN gene.

RESULTS

Of five alleles, only allele 4 of IL-1RN had a higher frequency in healthy subjects (2.4%) compared to SLE patients (0), with a statistically significant difference (P= 0.03). Eleven kinds of polymorphisms of IL-1RN were found including 1/1, 1/2, 2/2, 3/3, 1/3, 3/5, 2/3, 2/5, 1/5, 4/4 and 1/4 in both groups. In genotype frequency, there was no statistically significant difference regarding gene polymorphism kinds between the two groups (P= 0.29).

CONCLUSION

Alleles 4 of IL-1RN may have a protective role against SLE susceptibility. However, SLE was not associated with any of the 11 kinds of genotype IL1-RN gene polymorphisms studied here.

Interleukin 1 receptor antagonist gene variable number of tandem repeats polymorphism and cutaneous melanoma

Immunity and cytokines serve crucial roles in cutaneous melanoma. The present study investigated whether a variable number tandem repeat (VNTR) polymorphism of interleukin-1 receptor antagonist (IL-1RA) gene (IL-1RN) located in intron 2 (rs2234663) is associated with cutaneous melanoma. A total of 515 subjects were studied, 133 of which were cutaneous melanoma cases (72 stage I+II non-metastatic melanoma cases and 61 stage III+IV metastatic melanoma cases), and 382 subjects were matching healthy controls from the Friuli-Venezia-Giulia Region located in Northeast Italy, an area with a high melanoma incidence. The IL-1RN-VNTR polymorphism was determined by DNA fragment length analysis following PCR amplification. According to the number of 86-bp repeats, five different IL-1RN alleles were identified: Allele 1 (4-repeats), allele 2 (2-repeats, short allele), allele 3 (5-repeats), allele 4 (3-repeats) and allele 5 (6-repeats). Alleles with three or more 86-bp repeats, i.e. allele 1, 3, 4 and 5 were collectively denoted as long (L) repeats. The present study revealed that IL-1RN-VNTR 1/2 and 2/L genotypes were more frequent among patients with cutaneous melanoma (43.6 and 45.1%, respectively) compared with healthy controls [29.6 and 30.6%, respectively; odds ratio (OR), 1.84; CI, 1.22–2.77; P=0.003; and OR, 1.66; CI, 1.24–2.79; P=0.002, respectively]. Conversely, the IL-1RN-VNTR 1/1 genotype was less frequent among melanoma cases (45.9%) compared with healthy controls (57.9%; OR, 0.62; CI, 0.41–0.92; P=0.017). Comparison of metastatic vs. non-metastatic melanoma cases identified no significant differences. The present study first demonstrated that carriage of the 1/1 IL-1RN-VNTR genotype was protective, whereas 1/2 and 2/L was a risk factor for patients with cutaneous melanoma vs. healthy controls. The short allele 2 was associated with higher expression levels of IL-1RA, a potent competitive inhibitor of the proinflammatory cytokines IL-1α and IL-1β. VNTR-IL-1RN polymorphism may affect susceptibility to melanoma and, thus, it is a potential novel diagnostic biomarker for melanoma. The present study increased the understanding of genetic melanoma susceptibility/carcinogenesis, and may indicate novel strategies in the personalized prevention of cutaneous melanoma.

P2X7 Interactions and Signaling - Making Head or Tail of It

Extracellular adenine nucleotides play important roles in cell-cell communication and tissue homeostasis. High concentrations of extracellular ATP released by dying cells are sensed as a danger signal by the P2X7 receptor, a non-specific cation channel. Studies in P2X7 knockout mice and numerous disease models have demonstrated an important role of this receptor in inflammatory processes. P2X7 activation has been shown to induce a variety of cellular responses that are not usually associated with ion channel function, for example changes in the plasma membrane composition and morphology, ectodomain shedding, activation of lipases, kinases, and transcription factors, as well as cytokine release and apoptosis. In contrast to all other P2X family members, the P2X7 receptor contains a long intracellular C-terminus that constitutes 40% of the whole protein and is considered essential for most of these effects. So far, over 50 different proteins have been identified to physically interact with the P2X7 receptor. However, few of these interactions have been confirmed in independent studies and for the majority of these proteins, the interaction domains and the physiological consequences of the interactions are only poorly described. Also, while the structure of the P2X7 extracellular domain has recently been resolved, information about the organization and structure of its C-terminal tail remains elusive. After shortly describing the structure and assembly of the P2X7 receptor, this review gives an update of the identified or proposed interaction domains within the P2X7 C-terminus, describes signaling pathways in which this receptor has been involved, and provides an overlook of the identified interaction partners.

IL-38: A New Player in Inflammatory Autoimmune Disorders

Interleukin (IL)-38, a newly discovered IL-1 family cytokine, is expressed in several tissues and secreted by various cells. IL-38 has recently been reported to exert an anti-inflammatory function by binding to several receptors, including interleukin-36 receptor (IL-36R), interleukin-1 receptor accessory protein-like 1 (IL-1RAPL1), and interleukin-1 receptor 1 (IL-1R1) to block binding with other pro-inflammatory cytokines and inhibit subsequent signaling pathways; thereby regulating the differentiation and function of T cells, peripheral blood mononuclear cells, macrophages, and dendritic cells. Inflammatory autoimmune diseases, which are common immune-mediated inflammatory syndromes, are characterized by an imbalance between T helper cells (Ths), especially Th1s and Th17s, and regulatory T cells (Tregs). Recent findings have shown that abnormal expression of IL-38 in inflammatory autoimmune diseases, such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, primary Sjogren's syndrome, psoriasis, inflammatory bowel disease, hidradenitis suppurativa, ankylosing spondylitis, and glaucoma, involves Th1s, Th17s, and Tregs. In this review, the expression, regulation, and biological function of IL-38 are discussed, as are the roles of IL-38 in various inflammatory autoimmune disorders. Current data support that the IL-38/IL-36R and/or IL-38/IL-1RAPL1 axis primarily play an anti-inflammatory role in the development and resolution of inflammatory autoimmune diseases and indicate a possible therapeutic benefit of IL-38 in these diseases.

Current perspectives on the interleukin-1 family as targets for inflammatory disease

Since the first description of interleukin-1 (IL-1) and the genesis of the field of cytokine biology, the understanding of how IL-1 and related cytokines play central orchestrating roles in the inflammatory response has been an area of intense investigation. As a consequence of these endeavours, specific strategies have been developed to target the function of the IL-1 family in human disease realizing significant impacts for patients. While the most significant advances to date have been associated with inhibition of the prototypical family members IL-1α/β, approaches to target more recently identified family members such as IL-18, IL-33 and the IL-36 subfamily are now beginning to come to fruition. This review summarizes current knowledge surrounding the roles of the IL-1 family in human disease and describes the rationale and strategies which have been developed to target these cytokines to inhibit the pathogenesis of a wide range of diseases in which inflammation plays a centrally important role.

IL-26, a Cytokine With Roles in Extracellular DNA-Induced Inflammation and Microbial Defense

Interleukin 26 (IL-26) is the most recently identified member of the IL-20 cytokine subfamily, and is a novel mediator of inflammation overexpressed in activated or transformed T cells. Novel properties have recently been assigned to IL-26, owing to its non-conventional cationic, and amphipathic features. IL-26 binds to DNA released from damaged cells and, as a carrier molecule for extracellular DNA, links DNA to inflammation. This observation suggests that IL-26 may act both as a driver and an effector of inflammation, leading to the establishment of a deleterious amplification loop and, ultimately, sustained inflammation. Thus, IL-26 emerges as an important mediator in local immunity/inflammation. The dysregulated expression and extracellular DNA carrier capacity of IL-26 may have profound consequences for the chronicity of inflammation. IL-26 also exhibits direct antimicrobial properties. This review summarizes recent advances on the biology of IL-26 and discusses its roles as a novel kinocidin.

Understanding the pathophysiology behind chairside diagnostics and genetic testing for IL-1 and IL-6

In order for chairside diagnostic testing to make an impact on dental therapy, practitioners require a better understanding of genetic mutations contributing to the pathophysiology of periodontal disease. Commensal and pathogenic bacterial colonization in oral cavity tissues produces a cascade of proinflammatory signaling pathways ultimately detrimental to host tissues. Resolving inflammation is a multifactorial process involving the downregulation of proinflammatory cytokines while allowing commensal bacterial levels to return to normal. Because of the complicated nature of commensal bacteria and oral health homeostasis, the emphasis of dental therapy should place renewed focus on limiting destructive inflammation rather than solely eliminating bacteria. Salivary diagnostics are an easy, non-invasive way to assess inflammatory markers. Inflammatory cytokine levels can help determine the subclinical health of a patient, showing the transition from health to gingivitis, or periodontitis, prior to clinical presentation. Single nucleotide polymorphism mutations can aid in determining increased risk of developing periodontitis. Taken together, and alongside regular clinical evaluations, chairside diagnostics help individualize treatment plans to slow, or halt, the progression of disease-before tissue destruction can take place. While more studies are needed analyzing specific mutations across periodontal categories, chairside diagnostics present an exciting adjunct to improve patient care.