Low-Salt Diet Attenuates B-Cell- and Myeloid-Cell-Driven Experimental Arthritides by Affecting Innate as Well as Adaptive Immune Mechanisms

A link between high sodium chloride (salt) intake and the development of autoimmune diseases was previously reported. These earlier studies demonstrated exacerbation of experimental autoimmune encephalomyelitis and colitis by excess salt intake associated with Th17- and macrophage-mediated mechanisms. Little is known about the impact of dietary salt intake on experimental arthritides. Here, we investigated if salt restriction can exert beneficial effects on collagen-induced arthritis (CIA) and K/BxN serum transfer-induced arthritis (STIA). CIA depends on both adaptive and innate immunity, while STIA predominantly mimics the innate immune cell-driven effector phase of arthritis. In both models, low salt (LS) diet significantly decreased arthritis severity compared to regular salt (RS) and high salt (HS) diet. We did not observe an aggravation of arthritis with HS diet compared to RS diet. Remarkably, in STIA, LS diet was as effective as IL-1 receptor blocking treatment. Complement-fixing anti-CII IgG2a antibodies are associated with inflammatory cell infiltration and cartilage destruction. LS diet reduced anti-CII IgG2a levels in CIA and decreased the anti-CII IgG2a/IgG1 ratios pointing toward a more Th2-like response. Significantly less inflammatory joint infiltrates and cartilage breakdown associated with reduced protein concentrations of IL-1 beta (CIA and STIA), IL-17 (CIA), and the monocyte chemoattractant protein-1 (MCP-1) (CIA) were detected in mice receiving LS diet compared to HS diet. However, we did not find a reduced IL-17A expression in CD4+ T cells upon salt restriction in CIA. Analysis of mRNA transcripts and immunoblots revealed a link between LS diet and inhibition of the p38 MAPK (mitogen-activated protein kinase)/NFAT5 (nuclear factor of activated T-cells 5) signaling axis in STIA. Further experiments indicated a decreased leukodiapedesis under LS conditions. In conclusion, dietary salt restriction ameliorates CIA and STIA, indicating a beneficial role of LS diet during both the immunization and effector phase of immune-mediated arthritides by predominantly modulating the humoral immunity and the activation status of myeloid lineage cells. Hence, salt restriction might represent a supportive dietary intervention not only to reduce cardiovascular risk, but also to improve human inflammatory joint diseases like rheumatoid arthritis.

Talin1 controls dendritic cell activation by regulating TLR complex assembly and signaling

Talin critically controls integrin-dependent cell migration, but its regulatory role in skin dendritic cells (DCs) during inflammatory responses has not been investigated. Here, we show that talin1 regulates not only integrin-dependent Langerhans cell (LC) migration, but also MyD88-dependent Toll-like receptor (TLR)-stimulated DC activation. Talin1-deficient LCs failed to exit the epidermis, resulting in reduced LC migration to skin-draining lymph nodes (sdLNs) and defective skin tolerance induction, while talin1-deficient dermal DCs unexpectedly accumulated in the dermis despite their actomyosin-dependent migratory capabilities. Furthermore, talin1-deficient DCs exhibited compromised chemotaxis, NFκB activation, and proinflammatory cytokine production. Mechanistically, talin1 was required for the formation of preassembled TLR complexes in DCs at steady state via direct interaction with MyD88 and PIP5K. Local production of PIP2 by PIP5K then recruited TIRAP to the preassembled complexes, which were required for TLR signalosome assembly during DC activation. Thus, talin1 regulates MyD88-dependent TLR signaling pathways in DCs through a novel mechanism with implications for antimicrobial and inflammatory immune responses.

IL-1R Regulates Disease Tolerance and Cachexia in Toxoplasma gondii Infection

Toxoplasma gondii is an obligate intracellular parasite that establishes life-long infection in a wide range of hosts, including humans and rodents. To establish a chronic infection, pathogens often exploit the trade-off between resistance mechanisms, which promote inflammation and kill microbes, and tolerance mechanisms, which mitigate inflammatory stress. Signaling through the type I IL-1R has recently been shown to control disease tolerance pathways in endotoxemia and Salmonella infection. However, the role of the IL-1 axis in T. gondii infection is unclear. In this study we show that IL-1R-/- mice can control T. gondii burden throughout infection. Compared with wild-type mice, IL-1R-/- mice have more severe liver and adipose tissue pathology during acute infection, consistent with a role in acute disease tolerance. Surprisingly, IL-1R-/- mice had better long-term survival than wild-type mice during chronic infection. This was due to the ability of IL-1R-/- mice to recover from cachexia, an immune-metabolic disease of muscle wasting that impairs fitness of wild-type mice. Together, our data indicate a role for IL-1R as a regulator of host homeostasis and point to cachexia as a cost of long-term reliance on IL-1-mediated tolerance mechanisms.

DIGIRR as a member of the toll/IL-1R family negative regulates NF-κB signaling pathway in miiuy croaker

The double-Ig-IL-1R related molecule (DIGIRR) is a member of the TIR (Toll -Interleukin-1 receptor) superfamily and plays an important role in the immune system, it is also as a negative regulator of the IL-1 signaling pathway. In this study, we identified and characterized the miiuy croaker DIGIRR (mmi-DIGIRR) gene. The results of gene structure analysis indicated that there were differences between the mmi-DIGIRR and mammalian SIGIRR, which there were two immunoglobulin (Ig) domains contained in extracellular region of mmi-DIGIRR. Sequence alignment analysis showed that fish DIGIRR shared some conserved sequences with other vertebrates and the evolution was relatively conservative. In order to further validate the function of mmi-DIGIRR and its expression levels in various tissues of fish, qRT-PCR has been conducted. The results showed DIGIRR has significant expression levels in liver, skin and muscle while expression levels in heart are low. The LPS-induced NF-κB activation was inhibited by overexpression of DIGIRR significantly. In conclusion, the evolution and function of mmi-DIGIRR were comprehensively analyzed in this study, which would provide a theoretical basis for the future research of fish DIGIRR.

Bacteria-induced IL-1β and its receptors in snakehead (Channa argus): Evidence for their involvement in antibacterial innate immunity

As a central pro-inflammatory cytokine, interleukin-1β (IL-1β) plays critical roles in the inflammatory response, pathogen infection, and immunological challenges in mammals. Although fish IL-1β has been confirmed to participate in inflammatory response to pathogen infection, few studies have been performed to characterize the antibacterial and bactericidal functions of fish IL-1β. In this study, snakehead (Channa argus) IL-1β (shIL-1β) and its receptors, shIL-1R1 and shIL-1R2, were cloned and functionally characterized. ShIL-1β contained the IL-1 family signature domain, and a potential cutting site at Asp⁹⁶ that presented in all vertebrate IL-1β sequences. ShIL-1R1 had three extracellular IG-like domains and one intracellular signal TIR domain, while shIL-1R2 had three extracellular IG-like domain but lacked the intracellular signal TIR domain. ShIL-1β, shIL-1R1, and shIL-1R2 were constitutively expressed in all tested tissues, and their expressions could be induced by Aeromonas schubertii and Nocardia seriolae in the head kidney and spleen in vivo, and by LTA, LPS, and Poly (I:C) in head kidney leukocytes (HKLs) in vitro. Moreover, recombinant shIL-1β upregulated the expression of endogenous shIL-1β, shIL-R1, and shIL-R2 in snakehead HKLs, and enhanced intracellular bactericidal activity. Taken together, this study found that, like IL-1β and its receptors in mammals, shIL-1β and its receptors play crucial roles in antibacterial innate immunity. This provides new insight into the evolution of IL-1β function in vertebrates.

Yersinia ruckeri strain SC09 disrupts proinflammatory activation via Toll/IL-1 receptor-containing protein STIR-3

Virulent pathogenic microorganisms often enhance their infectivity through immune evasion mechanisms. Our research on the integrative and conjugative element (ICE(r2)) of the virulent fish pathogen Yersinia ruckeri SC09 led to the identification of genes related to immune evasion (designated stir-1, stir-2, stir-3 and stir-4), among which stir-1 and stir-2 were determined as the key contributors to bacterial toxicity and immune evasion. Here, we further examined the ability of stir-3 to mediate immune evasion based on detailed bioinformatic analysis of ICE(r2) from Y. ruckeri SC09. Interactions among the translated STIR-1, STIR-2, STIR-3 and STIR-4 proteins in the secretory process were additionally explored. STIR-3 was positively correlated with bacterial toxicity and inhibited host toll-like receptor (TLR) signaling by interacting with MyD88, thereby facilitating bacterial survival in host cells. Importantly, our data showed co-secretion of STIR-1, STIR-2 and STIR-3 as a complex, with secretion failure occurring in the absence of any one of these proteins. While stir-1, stir-2, stir-3 and stir-4 genes werespecific to Y. ruckeri SC09, the ICE(r2) region where these genes were located is a mobile component widely distributed in bacteria. Therefore, the potential transmission risk of these immune evasion genes requires further research attention.

Inflammasome activation and IL-1 signaling during placental malaria induce poor pregnancy outcomes

Placental malaria (PM) is associated with severe inflammation leading to abortion, preterm delivery, and intrauterine growth restriction. Innate immunity responses play critical roles, but the mechanisms underlying placental immunopathology are still unclear. Here, we investigated the role of inflammasome activation in PM by scrutinizing human placenta samples from an endemic area and ablating inflammasome components in a PM mouse model. The reduction in birth weight in babies from infected mothers is paralleled by increased placental expression of AIM2 and NLRP3 inflammasomes. Using genetic dissection, we reveal that inflammasome activation pathways are involved in the production and detrimental action of interleukin-1β (IL-1β) in the infected placenta. The IL-1R pharmacological antagonist Anakinra improved pregnancy outcomes by restoring fetal growth and reducing resorption in an experimental model. These findings unveil that IL-1β-mediated signaling is a determinant of PM pathogenesis, suggesting that IL-1R antagonists can improve clinical outcomes of malaria infection in pregnancy.

Transcriptomic Analysis of Stem Cells Treated with Moringin or Cannabidiol: Analogies and Differences in Inflammation Pathways

Inflammation is a common feature of many neurodegenerative diseases. The treatment of stem cells as a therapeutic approach to repair damage in the central nervous system represents a valid alternative. In this study, using Next-Generation Sequencing (NGS) technology, we analyzed the transcriptomic profile of human Gingival Mesenchymal Stem Cells (hGMSCs) treated with Moringin [4-(α-l-ramanosyloxy)-benzyl isothiocyanate] (hGMSCs-MOR) or with Cannabidiol (hGMSCs-CBD) at dose of 0.5 or 5 µM, respectively. Moreover, we compared their transcriptomic profiles in order to evaluate analogies and differences in pro- and anti-inflammatory pathways. The hGMSCs-MOR selectively downregulate TNF-α signaling from the beginning, reducing the expression of TNF-α receptor while hGMSCs-CBD limit its activity after the process started. The treatment with CBD downregulates the pro-inflammatory pathway mediated by the IL-1 family, including its receptor while MOR is less efficient. Furthermore, both the treatments are efficient in the IL-6 signaling. In particular, CBD reduces the effect of the pro-inflammatory JAK/STAT pathway while MOR enhances the pro-survival PI3K/AKT/mTOR. In addition, both hGMSCs-MOR and hGMSCs-CBD improve the anti-inflammatory activity enhancing the TGF-β pathway.

Toxin-Triggered Interleukin-1 Receptor Signaling Enables Early-Life Discrimination of Pathogenic versus Commensal Skin Bacteria

The host must develop tolerance to commensal microbes and protective responses to infectious pathogens, yet the mechanisms enabling a privileged relationship with commensals remain largely unknown. Skin colonization by commensal Staphylococcus epidermidis facilitates immune tolerance preferentially in neonates via induction of antigen-specific regulatory T cells (Tregs). Here, we demonstrate that this tolerance is not indiscriminately extended to all bacteria encountered in this early window. Rather, neonatal colonization by Staphylococcus aureus minimally enriches for antigen-specific Tregs and does not prevent skin inflammation upon later-life exposure. S. aureus α-toxin contributes to this response by stimulating myeloid cell production of IL-1β, which limits S. aureus-specific Tregs. Loss of α-toxin or the IL-1 receptor increases Treg enrichment, whereas topical application of IL-1β or α-toxin diminishes tolerogenic responses to S. epidermidis. Thus, the preferential activation of a key alarmin pathway facilitates early discrimination of microbial "foe" from "friend," thereby preventing tolerance to a common skin pathogen.

Anti-interleukin-1 treatment in patients with rheumatoid arthritis and type 2 diabetes (TRACK): A multicentre, open-label, randomised controlled trial

BACKGROUND

The inflammatory contribution to type 2 diabetes (T2D) has suggested new therapeutic targets using biologic drugs designed for rheumatoid arthritis (RA). On this basis, we aimed at investigating whether interleukin-1 (IL-1) inhibition with anakinra, a recombinant human IL-1 receptor antagonist, could improve both glycaemic and inflammatory parameters in participants with RA and T2D compared with tumour necrosis factor (TNF) inhibitors (TNFis).

METHODS AND FINDINGS

This study, designed as a multicentre, open-label, randomised controlled trial, enrolled participants, followed up for 6 months, with RA and T2D in 12 Italian rheumatologic units between 2013 and 2016. Participants were randomised to anakinra or to a TNFi (i.e., adalimumab, certolizumab pegol, etanercept, infliximab, or golimumab), and the primary end point was the change in percentage of glycated haemoglobin (HbA1c%) (EudraCT: 2012-005370-62 ClinicalTrial.gov: NCT02236481). In total, 41 participants with RA and T2D were randomised, and 39 eligible participants were treated (age 62.72 ± 9.97 years, 74.4% female sex). The majority of participants had seropositive RA disease (rheumatoid factor and/or anticyclic citrullinated peptide antibody [ACPA] 70.2%) with active disease (Disease Activity Score-28 [DAS28]: 5.54 ± 1.03; C-reactive protein 11.84 ± 9.67 mg/L, respectively). All participants had T2D (HbA1c%: 7.77 ± 0.70, fasting plasma glucose: 139.13 ± 42.17 mg). When all the enrolled participants reached 6 months of follow-up, the important crude difference in the main end point, confirmed by an unplanned ad interim analysis showing the significant effects of anakinra, which were not observed in the other group, led to the study being stopped for early benefit. Participants in the anakinra group had a significant reduction of HbA1c%, in an unadjusted linear mixed model, after 3 months (β: -0.85, p < 0.001, 95% CI -1.28 to -0.42) and 6 months (β: -1.05, p < 0.001, 95% CI -1.50 to -0.59). Similar results were observed adjusting the model for relevant RA and T2D clinical confounders (male sex, age, ACPA positivity, use of corticosteroids, RA duration, T2D duration, use of oral antidiabetic drug, body mass index [BMI]) after 3 months (β: -1.04, p < 0.001, 95% CI -1.52 to -0.55) and 6 months (β: -1.24, p < 0.001, 95% CI -1.75 to -0.72). Participants in the TNFi group had a nonsignificant slight decrease of HbA1c%. Assuming the success threshold to be HbA1c% ≤ 7, we considered an absolute risk reduction (ARR) = 0.42 (experimental event rate = 0.54, control event rate = 0.12); thus, we estimated, rounding up, a number needed to treat (NNT) = 3. Concerning RA, a progressive reduction of disease activity was observed in both groups. No severe adverse events, hypoglycaemic episodes, or deaths were observed. Urticarial lesions at the injection site led to discontinuation in 4 (18%) anakinra-treated participants. Additionally, we observed nonsevere infections, including influenza, nasopharyngitis, upper respiratory tract infection, urinary tract infection, and diarrhoea in both groups. Our study has some limitations, including open-label design and previously unplanned ad interim analysis, small size, lack of some laboratory evaluations, and ongoing use of other drugs.

CONCLUSIONS

In this study, we observed an apparent benefit of IL-1 inhibition in participants with RA and T2D, reaching the therapeutic targets of both diseases. Our results suggest the concept that IL-1 inhibition may be considered a targeted treatment for RA and T2D.

TRIAL REGISTRATION

The trial is registered with EU Clinical Trials Register, EudraCT Number: 2012-005370-62 and with ClinicalTrial.gov, number NCT02236481.

IL-38 has an anti-inflammatory action in psoriasis and its expression correlates with disease severity and therapeutic response to anti-IL-17A treatment

IL-36 cytokines, a subgroup of IL-1 family, comprise IL-36α, IL-36β, and IL-36γ agonists, abundantly expressed in psoriatic skin, and IL-36RA and IL-38 antagonists. In psoriatic skin, IL-36 cytokines interfere with keratinocyte cornification programs and induce the release of antimicrobial peptides and chemokines active on neutrophils and Th17 lymphocytes. To date, the role of IL-38 antagonist in psoriasis remains to be defined. Here, we demonstrate that skin and circulating IL-38 levels are reduced in psoriatic patients and in other skin diseases characterized by neutrophilic infiltrate. In psoriasis, the balance of IL-36γ agonist/IL-38 antagonist serum levels is in favor of agonists and is closely associated with disease severity. Interestingly, IL-38 is upregulated by anti-IL-17A biological treatment and positively correlates with the therapeutic efficacy of secukinumab in psoriatic patients. The downregulation of IL-38 expression is strictly related to keratinocyte de-differentiation triggered by the inflammatory cytokines IL-36γ, IL-17, and IL-22. Finally, we demonstrate that administration of recombinant full-length IL-38 counteracts in vitro the biological processes induced by IL-36γ in human keratinocytes and endothelial cells and attenuates in vivo the severity of the psoriasiform phenotype induced by IMQ in mice. Such effects are achieved by restoring the physiological programs of keratinocyte proliferation and differentiation, and reducing the immune cell infiltrates.

GPR108, an NF-κB activator suppressed by TIRAP, negatively regulates TLR-triggered immune responses

Higher vertebrates have evolved innate and adaptive immune systems to defend against foreign substances and pathogens. Sophisticated regulatory circuits are needed to avoid inappropriate immune responses and inflammation. GPR108 is a seven-transmembrane family protein that activates NF-κB strongly when overexpressed. Surprisingly, its action in a physiological context is that of an antagonist of Toll-like receptor (TLR)-mediated signaling. Cells from Gpr108-null mice exhibit enhanced cytokine secretion and NF-κB and IRF3 signaling, whereas Gpr108-null macrophages reconstituted with GPR108 exhibit blunted signaling. Co-expression of TLRs and GPR108 reduces NF-κB and IFNβ promoter activation compared to expression of either TLRs or GPR108 alone. Upon TLR stimulation GPR108 abundance increases and the protein engages TLRs and their partners to reduce MyD88 expression and interfere with its binding to TLR4 through blocking MyD88 ubiquitination. In turn GPR108 is antagonized by TIRAP, an adaptor protein for TLR and MyD88. The interrelationships between GPR108 and innate immune signaling components are multifactorial and point to a membrane-associated signaling structure of significant complexity.

The ABP Dendrimer, a Drug-Candidate against Inflammatory Diseases That Triggers the Activation of Interleukin-10 Producing Immune Cells

The ABP dendrimer, which is built on a phosphorus-based scaffold and bears twelve azabisphosphonate groups at its surface, is one of the dendrimers that has been shown to display immuno-modulatory and anti-inflammatory effects towards the human immune system. Its anti-inflammatory properties have been successfully challenged in animal models of inflammatory disorders. In this review, we trace the discovery and the evaluation of the therapeutic effects of the ABP dendrimer in three different animal models of both acute and chronic inflammatory diseases. We emphasize that its therapeutic effects rely on the enhancement of the production of Interleukin-10, the paradigm of anti-inflammatory cytokines, by different subsets of immune cells, such as monocytes/macrophages and CD4+ T lymphocytes.

IL-1R8 is a checkpoint in NK cells regulating anti-tumour and anti-viral activity

Interleukin-1 receptor 8 (IL-1R8, also known as single immunoglobulin IL-1R-related receptor, SIGIRR, or TIR8) is a member of the IL-1 receptor (ILR) family with distinct structural and functional characteristics, acting as a negative regulator of ILR and Toll-like receptor (TLR) downstream signalling pathways and inflammation. Natural killer (NK) cells are innate lymphoid cells which mediate resistance against pathogens and contribute to the activation and orientation of adaptive immune responses. NK cells mediate resistance against haematopoietic neoplasms but are generally considered to play a minor role in solid tumour carcinogenesis. Here we report that IL-1R8 serves as a checkpoint for NK cell maturation and effector function. Its genetic blockade unleashes NK-cell-mediated resistance to hepatic carcinogenesis, haematogenous liver and lung metastasis, and cytomegalovirus infection.

Mast cell in innate immunity mediated by proinflammatory and antiinflammatory IL-1 family members

Innate immunity consists of physical and chemical barriers which provide the early defense against infections. Innate immunity orchestrates the defense of the host with cellular and biochemical proteins. Mast cells (MCs) are involved in innate and adaptive immunity and are the first line of defense which generates multiple inflammatory cytokines/chemokines in response to numerous antigens. MC-activated antigen receptor Fc-RI provokes a number of important biochemical pathways with secretion of numerous vasoactive, chemoattractant and inflammatory compounds which participate in allergic and inflammatory diseases. MCs can also be activated by Th1 cytokines and generate pre-formed and de novo inflammatory mediators, including TNF. IL-37 is an anti-inflammatory cytokine which binds IL-18R-alpha chain and reduces the production of inflammatory IL-1 family members. IL-37 down-regulates innate immunity by inhibiting macrophage response and its accumulation and reduces the cytokines that mediate inflammatory diseases. Here, we discuss the relationship between MCs, innate immunity, and pro-inflammatory and anti-inflammatory cytokines.

Sputum transcriptomics reveal upregulation of IL-1 receptor family members in patients with severe asthma

BACKGROUND

Sputum analysis in asthmatic patients is used to define airway inflammatory processes and might guide therapy.

OBJECTIVE

We sought to determine differential gene and protein expression in sputum samples from patients with severe asthma (SA) compared with nonsmoking patients with mild/moderate asthma.

METHODS

Induced sputum was obtained from nonsmoking patients with SA, smokers/ex-smokers with severe asthma, nonsmoking patients with mild/moderate asthma (MMAs), and healthy nonsmoking control subjects. Differential cell counts, microarray analysis of cell pellets, and SOMAscan analysis of sputum analytes were performed. CRID3 was used to inhibit the inflammasome in a mouse model of SA.

RESULTS

Eosinophilic and mixed neutrophilic/eosinophilic inflammation were more prevalent in patients with SA compared with MMAs. Forty-two genes probes were upregulated (>2-fold) in nonsmoking patients with severe asthma compared with MMAs, including IL-1 receptor (IL-1R) family and nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 (NRLP3) inflammasome members (false discovery rate < 0.05). The inflammasome proteins nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain containing 1 (NLRP1), NLRP3, and nucleotide-binding oligomerization domain (NOD)-like receptor C4 (NLRC4) were associated with neutrophilic asthma and with sputum IL-1β protein levels, whereas eosinophilic asthma was associated with an IL-13-induced T_H2 signature and IL-1 receptor-like 1 (IL1RL1) mRNA expression. These differences were sputum specific because no activation of NLRP3 or enrichment of IL-1R family genes in bronchial brushings or biopsy specimens in patients with SA was observed. Expression of NLRP3 and of the IL-1R family genes was validated in the Airway Disease Endotyping for Personalized Therapeutics cohort. Inflammasome inhibition using CRID3 prevented airway hyperresponsiveness and airway inflammation (both neutrophilia and eosinophilia) in a mouse model of severe allergic asthma.

CONCLUSION

IL1RL1 gene expression is associated with eosinophilic SA, whereas NLRP3 inflammasome expression is highest in patients with neutrophilic SA. T_H2-driven eosinophilic inflammation and neutrophil-associated inflammasome activation might represent interacting pathways in patients with SA.

Heterotrimeric complex of p38 MAPK, PKCδ, and TIRAP is required for AP1 mediated inflammatory response

Inflammation could be described as a physiological response of the body to tissue injury, pathogen invasion, and irritants. During the inflammatory phase, cells of both the innate as well as adaptive immune system are activated and recruited to the site of inflammation. These mediators are downstream targets for the transcription factors; activator protein-1 (AP1), nuclear factor kappa-light-chain-enhancer (NF-κB), signal transducers and activators of transcription factors (STAT1), as well as interferon regulatory factors (IRFs), which control the expression of most immunomodulatory genes. There is a significant increase in active p38 mitogen-activated protein kinase (p38MAK) immediately after lipopolysaccharide (LPS) stimulation, which results in the activation of AP-1 transcription factor and expression of proinflammatory cytokines, IL-12 and IL-23. We studied the novel mechanism of p38 MAPK activation through the formation of a heterotrimeric complex of Protein kinase C delta type (PKCδ), Toll-Interleukin 1 Receptor (TIR) Domain Containing Adaptor Protein (TIRAP), and p38 proteins. TIRAP serves as an adaptor molecule which brings PKCδ and p38 in close proximity. The complex facilitates the activation of p38MAPK by PKCδ. Therefore, we propose that disruption of the heterotrimeric complex may be a good strategy to dampen the inflammatory response. Structure-based design of small molecules or peptides targetting PKCδ-TIRAP or TIRAP-p38 interfaces would be beneficial for therapy in AP1 mediated inflammatory diseases.

lnterleukin-1 Receptor Antagonist

The interleukin-1 receptor antagonist (IL-lra) is unusual in that it is the only known naturally occurring, cytokine receptor antagonist with no apparent agonist function. Over the last 5 years, since the cloning of the IL-lra cDNA sequence, there has been intensive research on the genetics, regulation, and potential therapeutic value of this protein. The later discovery of a second form of IL-lra in 1991 has complicated the picture. Whereas the originally described IL-lra is predominantly glycosylated and secreted (sIL-lra), the alternative isoform is unglycosylated and intracellular (icIL-lra). Although the biological roles of the two forms are still open to question, IL-lra is likely to be of great importance in the pathogenesis of both acute and chronic inflammatory diseases. A large body of evidence for this conclusion has come from animal models of inflammatory disease that respond well to administration of exogenous IL-lra. A role for recombinant IL-lra in the management of human disease is still under investigation. The two forms of IL-lra are encoded by a single gene by alternative usage of two first exons. Expression of sIL-lra and icIl-lra is regulated by two promoters. In this review I explore the genetics of the gene encoding IL-lra (IL-1RN) and the mechanisms of IL-lra gene activation to produce sIL-lra and icIL-lra. Also, possible biological roles for these immunomodulators in health and disease are discussed.

Macrophage-dependent IL-1β production induces cardiac arrhythmias in diabetic mice

Diabetes mellitus (DM) encompasses a multitude of secondary disorders, including heart disease. One of the most frequent and potentially life threatening disorders of DM-induced heart disease is ventricular tachycardia (VT). Here we show that toll-like receptor 2 (TLR2) and NLRP3 inflammasome activation in cardiac macrophages mediate the production of IL-1β in DM mice. IL-1β causes prolongation of the action potential duration, induces a decrease in potassium current and an increase in calcium sparks in cardiomyocytes, which are changes that underlie arrhythmia propensity. IL-1β-induced spontaneous contractile events are associated with CaMKII oxidation and phosphorylation. We further show that DM-induced arrhythmias can be successfully treated by inhibiting the IL-1β axis with either IL-1 receptor antagonist or by inhibiting the NLRP3 inflammasome. Our results establish IL-1β as an inflammatory connection between metabolic dysfunction and arrhythmias in DM.

IL-1 Coordinates the Neutrophil Response to C. albicans in the Oral Mucosa

Mucosal infections with Candida albicans belong to the most frequent forms of fungal diseases. Host protection is conferred by cellular immunity; however, the induction of antifungal immunity is not well understood. Using a mouse model of oropharyngeal candidiasis (OPC) we show that interleukin-1 receptor (IL-1R) signaling is critical for fungal control at the onset of infection through its impact on neutrophils at two levels. We demonstrate that both the recruitment of circulating neutrophils to the site of infection and the mobilization of newly generated neutrophils from the bone marrow depended on IL-1R. Consistently, IL-1R-deficient mice displayed impaired chemokine production at the site of infection and defective secretion of granulocyte colony-stimulating factor (G-CSF) in the circulation in response to C. albicans. Strikingly, endothelial cells were identified as the primary cellular source of G-CSF during OPC, which responded to IL-1α that was released from keratinocytes in the infected tissue. The IL-1-dependent crosstalk between two different cellular subsets of the nonhematopoietic compartment was confirmed in vitro using a novel murine tongue-derived keratinocyte cell line and an established endothelial cell line. These data establish a new link between IL-1 and granulopoiesis in the context of fungal infection. Together, we identified two complementary mechanisms coordinating the neutrophil response in the oral mucosa, which is critical for preventing fungal growth and dissemination, and thus protects the host from disease.

The opportunistic pathogen Candida albicans is a major risk factor for immunosuppressed individuals, and oropharyngeal candidiasis (OPC) is a frequent complication in patients with weakened cellular immunity. The cytokine interleukin-17 (IL-17) plays a critical role for antifungal host defense and was proposed to act by regulating neutrophil recruitment to the oral mucosa. However, although IL-17 can promote neutrophil trafficking in some situations, we recently showed in a mouse model that this is not the case during OPC. Thus, the mechanism governing the neutrophil response to C. albicans remained to be determined. Here, we demonstrate an essential role of IL-1 receptor (IL-1R) signaling in the recruitment of neutrophils from the circulation to the infected tissue via enhanced secretion of chemokines and increased output of neutrophils from the bone marrow. We found that IL-1α is released from keratinocytes upon invasion of C. albicans and acts on endothelial cells to induce the production of granulocyte colony-stimulating factor (G-CSF), a key trigger of emergency granulopoiesis. Thereby, IL-1R signaling translates the local response to the fungus in the oral mucosa into a systemic response that critically contributes to protection from infection.

Cytokine decoy and scavenger receptors as key regulators of immunity and inflammation

IL-1R2 was the first decoy receptor to be described. Subsequently receptors which act as pure decoys or scavengers or trigger dampening of cytokine signaling have been described for cytokines and chemokines. Here we review the current understanding of the mode of action and significance in pathology of the chemokine atypical receptor ACKR2, the IL-1 decoy receptor IL-1R2 and the atypical IL-1 receptor family IL-1R8. Decoy and scavenger receptors with no or atypical signaling have emerged as a general strategy conserved in evolution to tune the action of cytokines, chemokines and growth factors.

Low Vitamin-D Levels Combined with PKP3-SIGIRR-TMEM16J Host Variants Is Associated with Tuberculosis and Death in HIV-Infected and -Exposed Infants

Background

This study examined the associations of 25-hydroxyvitamin D and specific host genetic variants that affect vitamin D levels or its effects on immune function, with the risk of TB or mortality in children.

Methods

A case-cohort sample of 466 South African infants enrolled in P1041 trial (NCT00080119) underwent 25-hydroxyvitamin D testing by chemiluminescent immunoassay. Single nucleotide polymorphisms (SNPs) that alter the effect of vitamin D [e.g. vitamin D receptor (VDR)], vitamin D levels [e.g. vitamin D binding protein (VDBP)], or toll like receptor (TLR) expression (SIGIRR including adjacent genes PKP3 and TMEM16J) were identified by real-time PCR. Outcomes were time to TB, and to the composite of TB or death by 192 weeks of follow-up. Effect modification between vitamin D status and SNPs for outcomes was assessed.

Findings

Median age at 25-hydroxyvitamin D determination was 8 months; 11% were breastfed, 51% were HIV-infected and 26% had low 25-hydroxyvitamin D (<32ng/mL). By 192 weeks, 138 incident TB cases (43 definite/probable, and 95 possible) and 26 deaths occurred. Adjusting for HIV status and potential confounders, low 25-hydroxyvitamin D was associated with any TB (adjusted hazard ratio [aHR] 1.76, 95% CI 1.01–3.05; p = 0.046) and any TB or death (aHR 1.76, 95% CI 1.03–3.00; p = 0.038). Children with low 25-hydroxyvitamin D and TMEM 16J rs7111432-AA or PKP3 rs10902158-GG were at increased risk for probable/definite TB or death (aHR 8.12 and 4.83, p<0.05) and any TB or death (aHR 4.78 and 3.26, p<0.005) respectively; SNPs in VDBP, VDR, and vitamin D precursor or hydroxylation genes were not. There was significant interaction between low 25-hydroxyvitamin D and, TMEM 16J rs7111432-AA (p = 0.04) and PKP3 rs10902158-GG (p = 0.02) SNPs.

Conclusions

Two novel SNPs, thought to be associated with innate immunity, in combination with low vitamin D levels were identified as increasing a young child’s risk of developing TB disease or death. Identifying high-risk children and providing targeted interventions such as vitamin D supplementation may be beneficial.

Trial Registration

ClinicalTrials.gov NCT00080119

Expression of aryl hydrocarbon receptor and ATG16L1 protein in experimental oxazolone-induced colitis in rats

We studied the expression of AhR and ATG16L1 protein in experimental oxazolone-induced colitis in rats and anti-inflammatory action of recombinant antagonist of IL-1 receptors (ARIL-1) and simvastatin. The immunopositive cells were determined using an indirect immunofluorescence technique with using a monoclonal rat antibody. It has been established that development of colitis was accompanied by an increase of total number of ATG16L1-lymphocytes (by 30%, P < 0.05) in lymphoid structures of the colon. However the amount of AhR(+)-lymphocytes has not changed. At the same time has increased the concentration of ATG16L1 protein (by 4-11%, P < 0.05) in immunopositive cells. Administration of simvastatin and ARIL-1 during the development of experimental pathology was accompanied by decrease of total number of AhR(+) (by 24-38%, P < 0.05) and ATG16L1(+)-lymphocytes (by 43% - 2 fold, P < 0.05) in the colon.

Interleukin-1 (IL-1) signaling in intestinal stromal cells controls KC/ CXCL1 secretion, which correlates with recruitment of IL-22- secreting neutrophils at early stages of Citrobacter rodentium infection

Attaching and effacing pathogens, including enterohemorrhagic Escherichia coli in humans and Citrobacter rodentium in mice, raise serious public health concerns. Here we demonstrate that interleukin-1 receptor (IL-1R) signaling is indispensable for protection against C. rodentium infection in mice. Four days after infection with C. rodentium, there were significantly fewer neutrophils (CD11b+ Ly6C+ Ly6G+) in the colons of IL-1R−/− mice than in wild-type mice. Levels of mRNA and protein of KC/CXCL1 were also significantly reduced in colon homogenates of infected IL-1R−/− mice relative to wild-type mice. Of note, infiltrated CD11b+ Ly6C+ Ly6G+ neutrophils were the main source of IL-22 secretion after C. rodentium infection. Interestingly, intestinal stromal cells isolated from IL-1R−/− mice secreted lower levels of KC/CXCL1 than stromal cells from wild-type mice during C. rodentium infection. Similar effects were found when mouse intestinal stromal cells and human nasal polyp stromal cells were treated with IL-1R antagonists (i.e., anakinra) in vitro. These results suggest that IL-1 signaling plays a pivotal role in activating mucosal stromal cells to secrete KC/CXCL1, which is essential for infiltration of IL-22-secreting neutrophils upon bacterial infection.

Yersinia pestis activates both IL-1β and IL-1 receptor antagonist to modulate lung inflammation during pneumonic plague

Pneumonic plague is the most rapid and lethal form of Yersinia pestis infection. Increasing evidence suggests that Y. pestis employs multiple levels of innate immune evasion and/or suppression to produce an early “pre-inflammatory” phase of pulmonary infection, after which the disease is highly inflammatory in the lung and 100% fatal. In this study, we show that IL-1β/IL-18 cytokine activation occurs early after bacteria enter the lung, and this activation eventually contributes to pulmonary inflammation and pathology during the later stages of infection. However, the inflammatory effects of IL-1β/IL-1-receptor ligation are not observed during this first stage of pneumonic plague. We show that Y. pestis also activates the induction of IL-1 receptor antagonist (IL-1RA), and this activation likely contributes to the ability of Y. pestis to establish the initial pre-inflammatory phase of disease.

Inhalation of respiratory droplets containing Yersinia pestis results in a rapidly developing and lethal pneumonia. Interestingly, early interactions between Y. pestis and host cells in the lung contribute to significant immune evasion, but also ultimately result in severe innate immune activation. Our results demonstrate that Y. pestis activates pro-inflammatory cytokines IL-1β and IL-18 in the lung early during infection. However, there is very little early pulmonary inflammation while Y. pestis continues to multiply in the lung compartment. We show that the host protein IL-1RA is activated concurrently with IL-1β, attenuating early immune activation by this cytokine. We propose that this allows the organism to replicate to high titers, eventually triggering a vigorous inflammatory response and facilitating aerosol transmission. Therefore, evaluating early host activation of IL-1RA by Y. pestis may provide therapeutic targets against pneumonic plague.

Interleukin-1: Ariadne's Thread in Autoinflammatory and Autoimmune Disorders

Autoinflammatory and autoimmune disorders are characterized by chronic activation of the immune system, which leads to systemic self-directed inflammation in genetically predisposed individuals. Mutations in inflammasome-related proteins have been associated with autoinflammatory disorders, and the link between inflammasome and autoimmune disorders is becoming increasingly clear. As researchers learn more about these two areas, other disorders that were once thought to be autoimmune are now being considered autoinflammatory, or as having at least an autoinflammatory component. This review depicts the role of interleukin-1 as "Ariadne's thread" on the path through the labyrinth of autoinflammatory and autoimmune disorders and emphasizes the blurred boundary between innate and adaptive immune systems.

Blockade of IL-36 receptor signaling does not prevent from TNF-induced arthritis

Introduction

Interleukin (IL)-36α is a newly described member of the IL-1 cytokine family with a known inflammatory and pathogenic function in psoriasis. Recently, we could demonstrate that the receptor (IL-36R), its ligand IL-36α and its antagonist IL-36Ra are expressed in synovial tissue of arthritis patients. Furthermore, IL-36α induces MAP-kinase and NFκB signaling in human synovial fibroblasts with subsequent expression and secretion of pro-inflammatory cytokines.

Methods

To understand the pathomechanism of IL-36 dependent inflammation, we investigated the biological impact of IL-36α signaling in the hTNFtg mouse. Also the impact on osteoclastogenesis by IL-36α was tested in murine and human osteoclast assays.

Results

Diseased mice showed an increased expression of IL-36R and IL-36α in inflamed knee joints compared to wildtype controls. However, preventively treating mice with an IL-36R blocking antibody led to no changes in clinical onset and pattern of disease. Furthermore, blockade of IL-36 signaling did not change histological signs of TNF-induced arthritis. Additionally, no alteration on bone homeostasis was observed in ex vivo murine and human osteoclast differentiation assays.

Conclusion

Thus we conclude that IL-36α does not affect the development of inflammatory arthritis.

A novel mouse model of Campylobacter jejuni gastroenteritis reveals key pro-inflammatory and tissue protective roles for Toll-like receptor signaling during infection

Campylobacter jejuni is a major source of foodborne illness in the developed world, and a common cause of clinical gastroenteritis. Exactly how C. jejuni colonizes its host's intestines and causes disease is poorly understood. Although it causes severe diarrhea and gastroenteritis in humans, C. jejuni typically dwells as a commensal microbe within the intestines of most animals, including birds, where its colonization is asymptomatic. Pretreatment of C57BL/6 mice with the antibiotic vancomycin facilitated intestinal C. jejuni colonization, albeit with minimal pathology. In contrast, vancomycin pretreatment of mice deficient in SIGIRR (Sigirr^−/−), a negative regulator of MyD88-dependent signaling led to heavy and widespread C. jejuni colonization, accompanied by severe gastroenteritis involving strongly elevated transcription of Th1/Th17 cytokines. C. jejuni heavily colonized the cecal and colonic crypts of Sigirr^−/− mice, adhering to, as well as invading intestinal epithelial cells. This infectivity was dependent on established C. jejuni pathogenicity factors, capsular polysaccharides (kpsM) and motility/flagella (flaA). We also explored the basis for the inflammatory response elicited by C. jejuni in Sigirr^−/− mice, focusing on the roles played by Toll-like receptors (TLR) 2 and 4, as these innate receptors were strongly stimulated by C. jejuni. Despite heavy colonization, Tlr4^−/−/Sigirr^−/− mice were largely unresponsive to infection by C. jejuni, whereas Tlr2^−/−/Sigirr^−/− mice developed exaggerated inflammation and pathology. This indicates that TLR4 signaling underlies the majority of the enteritis seen in this model, whereas TLR2 signaling had a protective role, acting to promote mucosal integrity. Furthermore, we found that loss of the C. jejuni capsule led to increased TLR4 activation and exaggerated inflammation and gastroenteritis. Together, these results validate the use of Sigirr^−/− mice as an exciting and relevant animal model for studying the pathogenesis and innate immune responses to C. jejuni.

Research into the key virulence strategies of the bacterial pathogen Campylobacter jejuni, as well as the host immune responses that develop against this microbe have, in many ways, been limited by the lack of relevant animal models. Here we describe the use of Sigirr deficient (^−/−) mice as a model for C. jejuni pathogenesis. Not only do Sigirr^−/− mice develop significant intestinal inflammation in response to colonization by C. jejuni, but the ability of this pathogen to trigger gastroenteritis was dependent on key virulence factors. We also found that the induction of the inflammatory and Th1/Th17 immune responses to infection in these mice depended on specific Toll-like receptors, principally TLR4, which we identified as the main driver of inflammation. In contrast, TLR2 signaling was found to protect mucosal integrity, with Tlr2^−/−/Sigirr^−/− mice suffering exaggerated mucosal damage and inflammation. Notably, we found that C. jejuni's capsule helped conceal it from the host's immune system as its loss led to significantly increased activation of host TLRs and exaggerated gastroenteritis. Our research shows that the increased sensitivity of Sigirr^−/− mice can be used to generate a unique and exciting model that facilitates the study of C. jejuni pathogenesis as well as host immunity to this enteric pathogen.

Genetic polymorphisms in the Toll-like receptor signalling pathway in Helicobacter pylori infection and related gastric cancer

BACKGROUND

Gastric cancer (GC) is a progressive process initiated by Helicobacter pylori-induced inflammation. Initial recognition of H. pylori involves Toll-like receptors (TLRs), central molecules in the host inflammatory response. Here, we investigated the association between novel polymorphisms in genes involved in the TLR signalling pathway, including TLR2, TLR4, LBP, MD-2, CD14 and TIRAP, and risk of H. pylori infection and related GC.

METHODS

A case-control study comprising 310 ethnic Chinese individuals (87 non-cardia GC cases and 223 controls with functional dyspepsia) was conducted. Twenty-five polymorphisms were detected by MALDI-TOF mass spectrometry, PCR, PCR-RFLP and real-time PCR.

RESULTS

Seven polymorphisms showed significant associations with GC (TLR4 rs11536889, TLR4 rs10759931, TLR4 rs1927911, TLR4 rs10116253, TLR4 rs10759932, TLR4 rs2149356 and CD14 -260 C/T). In multivariate analyses, TLR4 rs11536889 remained a risk factor for GC (OR: 3.58, 95% CI: 1.20-10.65). TLR4 rs10759932 decreased the risk of H. pylori infection (OR: 0.59, 95% CI: 0.41-0.86). Statistical analyses assessing the joint effect of H. pylori infection and the selected polymorphisms revealed strong associations with GC (TLR2, TLR4, MD-2, LBP and TIRAP polymorphisms).

CONCLUSIONS

Novel polymorphisms in TLR2, TLR4, MD-2, LBP, CD14 and TIRAP, genes encoding important molecules of the TLR signalling pathway, showed clear associations with H. pylori-related GC in Chinese.

Association of IL33-IL-1 receptor-like 1 (IL1RL1) pathway polymorphisms with wheezing phenotypes and asthma in childhood

BACKGROUND

Genome-wide association studies identified IL33 and IL-1 receptor-like 1 (IL1RL1)/IL18R1 as asthma susceptibility loci. IL33 and IL1RL1 constitute a single ligand-receptor pathway.

OBJECTIVE

In 2 birth cohorts, the Prevalence and Incidence of Asthma and Mite Allergy (PIAMA) study and Avon Longitudinal Study of Parents and Children (ALSPAC), we analyzed associations of longitudinal wheezing phenotypes and asthma with single nucleotide polymorphisms (SNPs) of 8 genes encoding IL-33, IL1RL1, its coreceptor IL1RAcP, its adaptors myeloid differentiation primary response gene 88 (MyD88) and Toll-IL-11 receptor domain containing adaptor protein (TIRAP), and the downstream IL-1 receptor-associated kinase 1, IL-1 receptor-associated kinase 4, and TNF receptor-associated factor 6 (TRAF6). Furthermore, we investigated whether SNPs in this pathway show replicable evidence of gene-gene interaction.

METHODS

Ninety-four SNPs were investigated in 2007 children in the PIAMA study and 7247 children in ALSPAC. Associations with wheezing phenotypes and asthma at 8 years of age were analyzed in each cohort and subsequently meta-analyzed. Gene-gene interactions were assessed through model-based multifactor dimensionality reduction in the PIAMA study, and gene-gene interactions of 10 SNP pairs were further evaluated.

RESULTS

Intermediate-onset wheeze was associated with SNPs in several genes in the IL33-IL1RL1 pathway after applying multiple testing correction in the meta-analysis: 2 IL33 SNPs (rs4742170 and rs7037276), 1 IL-1 receptor accessory protein (IL1RAP) SNP (rs10513854), and 1 TRAF6 SNP (rs5030411). Late-onset wheeze was associated with 2 IL1RL1 SNPs (rs10208293 and rs13424006), and persistent wheeze was associated with 1 IL33 SNP (rs1342326) and 1 IL1RAP SNP (rs9290936). IL33 and IL1RL1 SNPs were nominally associated with asthma. Three SNP pairs showed interaction for asthma in the PIAMA study but not in ALSPAC.

CONCLUSIONS

IL33-IL1RL1 pathway polymorphisms are associated with asthma and specific wheezing phenotypes; that is, most SNPs are associated with intermediate-onset wheeze, a phenotype closely associated with sensitization. We speculate that IL33-IL1RL1 pathway polymorphisms affect development of wheeze and subsequent asthma through sensitization in early childhood.

A20-deficient mast cells exacerbate inflammatory responses in vivo

Mast cells, best known as effector cells in pathogenic immunoglobulin-mediated responses, can sense a variety of “danger” signals; if manipulated to enhance their resulting inflammatory responses, they also exacerbate inflammatory diseases such as arthritis and lung inflammation.

Mast cells are implicated in the pathogenesis of inflammatory and autoimmune diseases. However, this notion based on studies in mast cell-deficient mice is controversial. We therefore established an in vivo model for hyperactive mast cells by specifically ablating the NF-κB negative feedback regulator A20. While A20 deficiency did not affect mast cell degranulation, it resulted in amplified pro-inflammatory responses downstream of IgE/FcεRI, TLRs, IL-1R, and IL-33R. As a consequence house dust mite- and IL-33-driven lung inflammation, late phase cutaneous anaphylaxis, and collagen-induced arthritis were aggravated, in contrast to experimental autoimmune encephalomyelitis and immediate anaphylaxis. Our results provide in vivo evidence that hyperactive mast cells can exacerbate inflammatory disorders and define diseases that might benefit from therapeutic intervention with mast cell function.

Mast cells mediate allergic and anaphylactic immune reactions. They are also equipped with innate pattern recognition, cytokine, and alarmin receptors, which induce inflammatory responses. Correlative studies in human patients hinted at roles for mast cells in autoimmune and inflammatory diseases. However, studies using mast cell-deficient mice have yielded contradictory results in this context. In this study we determined that A20, the negative feedback regulator, restricts inflammation downstream of the mast cell antigen (allergen) receptor module, innate pattern recognition receptors, and the alarmin receptor IL-33R. By mast cell–specific ablation of A20 we established a mouse model for exaggerated inflammatory but normal anaphylactic mast cell signaling. With these mice we evaluated the impact of increased mast cell-mediated inflammation under experimental conditions aimed at mimicking several inflammatory human diseases. Our results demonstrated that the lack of A20 from mast cells exacerbated disease in mouse models for rheumatoid arthritis and innate forms of asthma, but did not impact disease progression in a mouse model for multiple sclerosis. Our data provide direct evidence that enhanced inflammatory mast cell responses can contribute to disease pathology and do so via sensing and amplifying local inflammatory reactions driven by “danger” stimuli and/or tissue damage that leads to the release of alarmins.

[Role of Helicobacter pylori eradication in the prevention of gastric cancer]

The review deals with the current aspects of prevention of non-cardia gastric cancer (GC). Helicobacter pylori is the most common cause of non-cardia GC. The Correa cascade remains a major pattern of the pathogenesis of non-cardia GC as before. The key moments in gastric carcinogenesis are H. pylori infection; genes associated with cell recognition of bacteria; an immune response and the activation of an inflammatory response. The prevention of GC requires H. pylori eradication as primary prevention in combination with screening for this pathology as secondary prevention of gastric malignancies. Standard three-component therapy is a first-line major regimen for H. pylori eradication.

Genetic susceptibility to Chagas disease cardiomyopathy: involvement of several genes of the innate immunity and chemokine-dependent migration pathways

BACKGROUND

Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is, by far, the most important clinical consequence of T. cruzi infection. The others remain asymptomatic (ASY). A possible genetic component to disease progression was suggested by familial aggregation of cases and the association of markers of innate and adaptive immunity genes with CCC development. Migration of Th1-type T cells play a major role in myocardial damage.

METHODS

Our genetic analysis focused on CCR5, CCL2 and MAL/TIRAP genes. We used the Tag SNPs based approach, defined to catch all the genetic information from each gene. The study was conducted on a large Brazilian population including 315 CCC cases and 118 ASY subjects.

RESULTS

The CCL2rs2530797A/A and TIRAPrs8177376A/A were associated to an increase susceptibility whereas the CCR5rs3176763C/C genotype is associated to protection to CCC. These associations were confirmed when we restricted the analysis to severe CCC, characterized by a left ventricular ejection fraction under 40%.

CONCLUSIONS

Our data show that polymorphisms affecting key molecules involved in several immune parameters (innate immunity signal transduction and T cell/monocyte migration) play a role in genetic susceptibility to CCC development. This also points out to the multigenic character of CCC, each polymorphism imparting a small contribution. The identification of genetic markers for CCC will provide information for pathogenesis as well as therapeutic targets.

Evaluation of innate immune responses in bovine forestomachs

Previous studies had indicated an active role of bovine forestomachs in the response to alimentary disorders as well as to inflammatory and infectious processes in both the gastro-intestinal (GI) tract and elsewhere. We investigated the potential of bovine forestomachs to receive, elaborate and produce signals and mediators of the innate immune response. Indeed, we detected the expression of Toll IL-1R8/single Ig IL-1-related receptor (TIR8/SIGIRR) and other receptors and cytokines, such as Toll-like receptor (TLR)4, interleukin (IL)-1β, IL-10 and Caspase-1 in the forestomach walls of healthy cows. Their presence suggests an active role of forestomachs in inflammatory disorders of the GI tract and other body compartments. Moreover, interferon (IFN)-γ was revealed in ruminal content. We confirmed and further characterized the presence of leukocytes in the rumen fluids. In particular, T-, B-lymphocytes and myeloid lineage cells were detected in the ruminal content of both rumen-fistulated heifers and diseased cows. An acidogenic diet based on daily supplements of maize was shown to inhibit leukocyte accumulation, as opposed to a control, hay-based diet, with or without a soy flour (protein) supplement. On the whole, results indicate that bovine forestomachs can receive and elaborate signals for the immune cells infiltrating the rumen content or other organs. Forestomachs can thus participate in a cross-talk with the lymphoid tissues in the oral cavity and promote regulatory actions at both regional and systemic levels; these might include the control of dry matter intake as a function of fundamental metabolic requirements of ruminants.

Relationship between the induction of inflammatory processes and infectious diseases in patients with ischemic stroke

Pro-inflammatory cytokines participate in the induction of ischemic stroke. So far, their participation in the cerebral ischemia was proven for the tumor necrosis factor TNF-α, interleukin-1 (IL-1), and interleukin-6 (IL-6). The release of the pro-inflammatory cytokines into the extracellular space causes the enlargement of the brain damage region, and consequently increases the neurological deficit and negatively affects the survival rate prognoses. That is confirmed by the increased concentration of pro-inflammatory cytokines in blood and the cerebrospinal fluid of patients with brain stroke, as well as by the research on the induced/experimental cerebral ischemia in animals. The pro-inflammatory cytokines participate in the migration of the reactive T lymphocytes to the regions of brain ischemia where they enhance the nerve tissue damage by down-regulation of microcirculation, induce the pro-thrombotic processes and release other neurotoxic cytokines. Also, in the early stage of cerebral ischemia, cytokines activate the axis hypothalamus-pituitary gland-adrenal cortex and increase the cortisol concentration in blood, what results in the decreased resistance to infectious diseases. Administration of the inhibitor of the interleukin-1 receptor (IL-1Ra) inhibits the inflammatory processes in the region of brain ischemia, and subsequently improves the prognosis for the size of the neurological deficit and the survival rate, as well as resistance to infectious diseases.

Soluble interleukin-1 receptor, a potential negative regulator of orange-spotted grouper Epinephelus coioides interleukin-1 system

In this study, the cDNA sequence encoding interleukin-1 (Il-1) receptor-like protein of orange-spotted grouper Epinephelus coioides was obtained. The newly identified sequence was named soluble type I Il-1 receptor (sIl-1rI) owing to its structural composition, which had two Ig-like domains, lack of transmembrane region and the Toll/interleukin-1 receptor (TIR) domain, similar to the brown rat Rattus norvegicus soluble Il-1rI. In addition, sequence comparison and phylogenetic analysis indicated that E. coioides sequence had a closer relationship with Il-1rI than Il-1rII. Real-time PCR revealed that sil-1rI mRNA expression presented a process of decrease, restoration and increase in Cryptocaryon irritans-infected E. coioides. The negative correlation between Il-1β and sil-1rI mRNA in C. irritans-infected head-kidney implied the potential negative regulatory role of sil-1rI in E. coioides Il-1 system. The leucocytes incubated with lipopolysaccharide or polyriboinosinic polyribocytidylic acid exhibited different expression profiles of sil-1rI. Recombinant Il-1β (rIl-1β) protein was capable of inducing sil-1rI mRNA under the concentration of 100 ng ml(-1) , suggesting that high dosage or excess Il-1β would stimulate the expression of sil-1rI to maintain the homoeostasis of E. coioides Il-1 system. For the first time, the role of teleost Il-1rI in parasite infection has been identified, and soluble Il-1r was found in fish.

Therapeutic potential of SIGIRR in systemic lupus erythematosus

Single immunoglobulin IL-1-related receptor (SIGIRR), which is also known as Toll/interleukin-1 receptor 8, is a member of the interleukin-1 receptor (IL-1R) family. Different from other typical IL-1R superfamily members, SIGIRR seems to exert negatively modulates in immune responses. Several previous studies demonstrated that SIGIRR influences chronic inflammatory or autoimmune diseases, such as intestinal inflammation, rheumatoid arthritis and psoriatic arthritis. Recent work has explored the role of SIGIRR in systemic lupus erythematosus (SLE), for example, the role of SIGIRR protects the mice from hydrocarbon oil-induced lupus has been reported. These results indicate that SIGIRR may represent a novel target for the treatment of SLE. In this review, we will discuss the SIGIRR and the therapeutic potential of modulating the pathway in SLE.

Intracellular function of interleukin-1 receptor antagonist in ischemic cardiomyocytes

Background

Loss of cardiac myocytes due to apoptosis is a relevant feature of ischemic heart disease. It has been described in infarct and peri-infarct regions of the myocardium in coronary syndromes and in ischemia-linked heart remodeling. Previous studies have provided protection against ischemia-induced cardiomyocyte apoptosis by the anti-inflammatory cytokine interleukin-1 receptor-antagonist (IL-1Ra). Mitochondria triggering of caspases plays a central role in ischemia-induced apoptosis. We examined the production of IL-1Ra in the ischemic heart and, based on dual intra/extracellular function of some other interleukins, we hypothesized that IL-1Ra may also directly inhibit mitochondria-activated caspases and cardiomyocyte apoptosis.

Methodology/Principal Findings

Synthesis of IL-1Ra was evidenced in the hearts explanted from patients with ischemic heart disease. In the mouse ischemic heart and in a mouse cardiomyocyte cell line exposed to long-lasting hypoxia, IL-1Ra bound and inhibited mitochondria-activated caspases, whereas inhibition of caspase activation was not observed in the heart of mice lacking IL-1Ra (Il-1ra−/−) or in siRNA to IL-1Ra-interfered cells. An impressive 6-fold increase of hypoxia-induced apoptosis was observed in cells lacking IL-1Ra. IL-1Ra down-regulated cells were not protected against caspase activation and apoptosis by knocking down of the IL-1 receptor, confirming the intracellular, receptor-independent, anti-apoptotic function of IL-1Ra. Notably, the inhibitory effect of IL-1Ra was not influenced by enduring ischemic conditions in which previously described physiologic inhibitors of apoptosis are neutralized.

Conclusions/Significance

These observations point to intracellular IL-1Ra as a critical mechanism of the cell self-protection against ischemia-induced apoptosis and suggest that this cytokine plays an important role in the remodeling of heart by promoting survival of cardiomyocytes in the ischemic regions.

Psoriasiform dermatitis is driven by IL-36-mediated DC-keratinocyte crosstalk

Psoriasis is a chronic inflammatory disorder of the skin affecting approximately 2% of the world's population. Accumulating evidence has revealed that the IL-23/IL-17/IL-22 pathway is key for development of skin immunopathology. However, the role of keratinocytes and their crosstalk with immune cells at the onset of disease remains poorly understood. Here, we show that IL-36R-deficient (Il36r-/-) mice were protected from imiquimod-induced expansion of dermal IL-17-producing γδ T cells and psoriasiform dermatitis. Furthermore, IL-36R antagonist-deficient (Il36rn-/-) mice showed exacerbated pathology. TLR7 ligation on DCs induced IL-36-mediated crosstalk with keratinocytes and dermal mesenchymal cells that was crucial for control of the pathological IL-23/IL-17/IL-22 axis and disease development. Notably, mice lacking IL-23, IL-17, or IL-22 were less well protected from disease compared with Il36r-/- mice, indicating an additional distinct activity of IL-36 beyond induction of the pathological IL-23 axis. Moreover, while the absence of IL-1R1 prevented neutrophil infiltration, it did not protect from acanthosis and hyperkeratosis, demonstrating that neutrophils are dispensable for disease manifestation. These results highlight a central and unique IL-1-independent role for IL-36 in control of the IL-23/IL-17/IL-22 pathway and development of psoriasiform dermatitis.

The largely normal response to Toll-like receptor 7 and 9 stimulation and the enhanced expression of SIGIRR by B cells in systemic lupus erythematosus

Background

Altered Toll-like receptor (TLR) signaling has been implicated in the pathogenesis of systemic lupus erythematosus (SLE). The present study was undertaken to characterize responses of B cells from SLE patients to TLR7 and TLR9 stimulation and to explore the potential role of single immunoglobulin interleukin-1 receptor related molecule (SIGIRR) in the regulation of TLR-mediated responses of SLE B cells.

Methodology/Principal Findings

Peripheral blood mononuclear cells (PBMC) were isolated from 64 patients with SLE and 37 healthy donors. CD19+ B cells purified using microbeads were cultured with TLR7 or TLR9 agonists. Cell proliferation was measured by thymine incorporation and the frequency of antibody-secreting cells was determined by ELISPOT assay. SIGIRR expression in PBMCs and B cells was analyzed using flow cytometry analysis. In contrast to the enhanced proliferation following B cell receptor (BCR) engagement, B cells from SLE patients exhibited a virtually normal proliferative response to TLR7 or TLR9 stimulation. Moreover, B cells from SLE patients and healthy donors were almost equally competent to differentiate into antibody-secreting cells upon TLR engagement except for a reduction in the generation of IgG-secreting cells by TLR9-stimulated lupus B cells. In line with these somehow unexpected observations, SLE B cells were found to express a significantly higher level of SIGIRR than normal B cells.

Conclusions/Significance

Despite the reported upregulation of TLR7 and TLR9 expression in B cell from SLE patients, their responses to TLR stimulation were largely normal. The increased expression of the negative regulator SIGIRR may be partly responsible for the “balance of terror”.

Bacterial TIR-containing proteins and host innate immune system evasion

The innate immune system provides the first line of host defence against invading pathogens. Key to upregulation of the innate immune response are Toll-like receptors (TLRs), which recognize pathogen-associated molecular patterns (PAMPs) and trigger a signaling pathway culminating in the production of inflammatory mediators. Central to this TLR signaling pathway are heterotypic protein-protein interactions mediated through Toll/interleukin-1 receptor (TIR) domains found in both the cytoplasmic regions of TLRs and adaptor proteins. Pathogenic bacteria have developed a range of ingenuous strategies to evade the host immune mechanisms. Recent work has identified a potentially novel evasion mechanism involving bacterial TIR domain proteins. Such domains have been identified in a wide range of pathogenic bacteria, and there is evidence to suggest that they interfere directly with the TLR signaling pathway and thus inhibit the activation of NF-κB. The individual TIR domains from the pathogenic bacteria Salmonella enterica serovar Enteritidis, Brucella sp, uropathogenic E. coli and Yersinia pestis have been analyzed in detail. The individual bacterial TIR domains from these pathogenic bacteria seem to differ in their modes of action and their roles in virulence. Here, we review the current state of knowledge on the possible roles and mechanisms of action of the bacterial TIR domains.

Description of an Atlantic salmon (Salmo salar L.) type II interleukin-1 receptor cDNA and analysis of interleukin-1 receptor expression in amoebic gill disease-affected fish

Previously, we showed that IL-1β transcription is induced in the gills of amoebic gill disease (AGD)-affected fish in an AGD lesion-restricted fashion. However, in this environment, there is very little evidence of inflammation on histopathological or transcriptional levels and we hypothesised that aberrant signalling may occur. As a first step in investigating this issue, we cloned and sequenced the Atlantic salmon IL-1 receptor type II (IL-1RII) mRNA, and then examined the expression of both the IL-1RI (IL-1 receptor-like protein) and II during Neoparamoeba perurans infection. In gill lesions from AGD-affected fish, a step-wise temporal increase in the relative expression of IL-1β coincided with a significant reduction in IL-1RI, whereas the IL-1RII mRNA remained unchanged. Down-regulation of IL-1RI could explain the paucity of inflammation in affected tissue, although simultaneous up-regulation of IL-1β-inducible transcripts indicated that this is not due to a complete blockage of the IL-1RI pathway. Rather, it appears that IL-1RI transcription is reduced and this rate limits the effects of chronic IL-1β over-expression.

IFN-λ3 inhibits HIV infection of macrophages through the JAK-STAT pathway

BACKGROUND

Interferon lambda 3 (IFN-λ3) is a newly identified cytokine with antiviral activity, and its single nucleotide polymorphisms are strongly associated with the treatment effectiveness and development of chronic hepatitis C virus infection. We thus examined the potential of IFN-λ3 to inhibit HIV replication and the possible mechanisms of the anti-HIV action by IFN-λ3 in human macrophages.

PRINCIPAL FINDINGS

Under different conditions (before, during, and after HIV infection), IFN-λ3 significantly inhibited viral replication in macrophages, which was associated with the induction of multiple antiviral cellular factors (ISG56, MxA, OAS-1, A3G/F and tetherin) and IFN regulatory factors (IRF-1, 3, 5, 7 and 9). This anti-HIV action of IFN-λ3 could be compromised by the JAK-STAT inhibitor. In addition, IFN-λ3 treatment of macrophages induced the expression of toll-like receptor 3 (TLR3) and two key adaptors (MyD88 and TRIF) in type I IFN pathway activation. However, HIV infection compromised IFN-λ3-mediated induction of the key elements in JAK-STAT signaling pathway.

CONCLUSIONS

These data indicate that IFN-λ3 exerts its anti-HIV function by activating JAK-STAT pathway-mediated innate immunity in macrophages. Future in vivo studies are necessary in order to explore the potential for developing IFN-λ3-based therapy for HIV disease.

A review: inflammatory process in Alzheimer's disease, role of cytokines

Alzheimer's disease (AD) is the most common neurodegenerative disorder to date. Neuropathological hallmarks are β-amyloid (Aβ) plaques and neurofibrillary tangles, but the inflammatory process has a fundamental role in the pathogenesis of AD. Inflammatory components related to AD neuroinflammation include brain cells such as microglia and astrocytes, the complement system, as well as cytokines and chemokines. Cytokines play a key role in inflammatory and anti-inflammatory processes in AD. An important factor in the onset of inflammatory process is the overexpression of interleukin (IL)-1, which produces many reactions in a vicious circle that cause dysfunction and neuronal death. Other important cytokines in neuroinflammation are IL-6 and tumor necrosis factor (TNF)-α. By contrast, other cytokines such as IL-1 receptor antagonist (IL-1ra), IL-4, IL-10, and transforming growth factor (TGF)-β can suppress both proinflammatory cytokine production and their action, subsequently protecting the brain. It has been observed in epidemiological studies that treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) decreases the risk for developing AD. Unfortunately, clinical trials of NSAIDs in AD patients have not been very fruitful. Proinflammatory responses may be countered through polyphenols. Supplementation of these natural compounds may provide a new therapeutic line of approach to this brain disorder.

Peli: a family of signal-responsive E3 ubiquitin ligases mediating TLR signaling and T-cell tolerance

E3 ubiquitin ligases play a crucial role in regulating immune receptor signaling and modulating immune homeostasis and activation. One emerging family of such E3s is the Pelle-interacting (Peli) proteins, characterized by the presence of a cryptic forkhead-associated domain involved in substrate binding and an atypical RING domain mediating formation of both lysine (K) 63- and K48-linked polyubiquitin chains. A well-recognized function of Peli family members is participation in the signal transduction mediated by Toll-like receptors (TLRs) and IL-1 receptor. Recent gene targeting studies have provided important insights into the in vivo functions of Peli1 in the regulation of TLR signaling and inflammation. These studies have also extended the biological functions of Peli1 to the regulation of T-cell tolerance. Consistent with its immunoregulatory functions, Peli1 responds to different immune stimuli for its gene expression and catalytic activation. In this review, we discuss the recent progress, as well as the historical perspectives in the regulation and biological functions of Peli.

The composition and signaling of the IL-35 receptor are unconventional

Interleukin 35 (IL-35) belongs to the IL-12 family of heterodimeric cytokines but has a distinct functional profile. IL-35 suppresses T cell proliferation and converts naive T cells into IL-35-producing induced regulatory T cells (iTr35 cells). Here we found that IL-35 signaled through a unique heterodimer of receptor chains IL-12Rβ2 and gp130 or homodimers of each chain. Conventional T cells were sensitive to IL-35-mediated suppression in the absence of one receptor chain but not both receptor chains, whereas signaling through both chains was required for IL-35 expression and conversion into iTr35 cells. Signaling through the IL-35 receptor required the transcription factors STAT1 and STAT4, which formed a unique heterodimer that bound to distinct sites in the promoters of the genes encoding the IL-12 subunits p35 and Ebi3. This unconventional mode of signaling, distinct from that of other members of the IL-12 family, may broaden the spectrum and specificity of IL-35-mediated suppression.