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Summary: A hallmark of obesity is chronic low‐grade inflammation, which plays a major role in the process of atherosclerotic cardiovascular disease (ACVD). Gut microbiota is one of the factors influencing systemic immune responses, and profound changes have been found in its composition and metabolic function in individuals with obesity. This systematic review assesses the association between the gut microbiota and markers of low‐grade inflammation in humans. We identified 14 studies which were mostly observational and relatively small (n = 10 to 471). The way in which the microbiome is analysed differed extensively between these studies. Lower gut microbial diversity was associated with higher white blood cell counts and high sensitivity C‐reactive protein (hsCRP) levels. The abundance of Bifidobacterium, Faecalibacterium, Ruminococcus and Prevotella were inversely related to different markers of low‐grade inflammation such as hsCRP and interleukin (IL)‐6. In addition, this review speculates on possible mechanisms through which the gut microbiota can affect low‐grade inflammation and thereby ACVD. We discuss the associations between the microbiome and the inflammasome, the innate immune system, bile acids, gut permeability, the endocannabinoid system and TMAO. These data reinforce the importance of human research into the gut microbiota as potential diagnostic and therapeutic strategy to prevent ACVD. [ABSTRACT FROM AUTHOR]

Background STAT1 mutations cause chronic mucocutaneous candidiasis ( CMC), while STAT3 mutations cause hyper-IgE syndrome ( HIES). CMC and HIES patients have T helper (Th) 17 defects suffering from mucosal Candida infections, but only patients with HIES show an allergic phenotype with eczema, eosinophilia and high IgE levels. Objective We investigated whether differential Th2 and Th9 responses may explain the clinical differences. Methods Peripheral blood mononuclear cells of patients with CMC ( n = 4), patients with HIES ( n = 4), patients with atopic dermatitis ( n = 4) and healthy volunteers ( n = 13) were stimulated with Candida and Staphylococcus aureus, with and without IL-4. The cytokines IL-5, IL-13, IL-9, IL-17 and TGFβ and regulatory T cells were measured in cell culture supernatants by ELISA or flow cytometry, respectively. Results Peripheral blood mononuclear cells of patients with CMC showed a significantly impaired production of the Th2 cytokines IL-5 and IL-13, especially in the presence of IL-4. Moreover, IL-9 production was significantly lower in patients with CMC compared to healthy controls. In contrast, patients with HIES and patients with AD showed normal IL-5 and IL-13 production, while IL-9 production was significantly lower in patients with HIES compared to healthy controls. Although TGFβ was involved in the IL-4-induced IL-9 production, TGFβ levels and the frequency of regulatory T cells did not differ between patients with HIES and controls. Flow cytometry analysis demonstrated an IL-9+ IL-17+ CD4+ subset in healthy controls after stimulation with Candida which was less present in patients with HIES. Conclusion Patients with CMC have a general Th defect including Th2 and Th9, while patients with HIES have normal Th2 cytokines. These differences are in line with their clinical presentation. Surprisingly, the allergic cytokine IL-9 was deficient in both HIES and CMC, suggesting a Th-17-derived origin. [ABSTRACT FROM AUTHOR]

Adaptive immunity towards tuberculosis (TB) has been extensively studied for many years. In addition, in recent years the profound contribution of innate immunity to host defence against this disease has become evident. The discovery of pattern recognition receptors, which allow innate immunity to tailor its response to different infectious agents, has challenged the view that this arm of immunity is nonspecific. Evidence is now accumulating that innate immunity can remember a previous exposure to a microorganism and respond differently during a second exposure. Although the specificity and memory of innate immunity cannot compete with the highly sophisticated adaptive immune response, its contribution to host defence against infection and to vaccine-induced immunity should not be underestimated and needs to be explored. Here, we present the concept of trained immunity and discuss how this may contribute to new avenues for control of TB. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to determine the genetic and immunological defects underlying familial manifestations of an autoimmune disorder. Methods Whole-exome sequencing was performed on the index patient with various manifestations of autoimmunity, including hypothyroidism, vitiligo and alopecia. Peripheral blood mononuclear cells and DNA of family members were used for functional and genetic testing of the candidate variants obtained by Sanger sequencing. Results Exome sequencing identified 233 rare, coding and nonsynonymous variants in the index patient; five were highly conserved and affect genes that have a possible role in autoimmunity. Only a heterozygous missense mutation in the suppressor of cytokine signalling 4 gene ( SOCS4) cosegregated with the autoimmune disorder in the family. SOCS4 is a known inhibitor of epidermal growth factor ( EGF) receptor signalling, and functional studies demonstrated specific upregulation of EGF-dependent immune stimulation in affected family members. Conclusion We present a family with an autoimmune disorder, probably resulting from dysregulated immune responses due to mutations in SOCS4. [ABSTRACT FROM AUTHOR]

Background Allergic bronchopulmonary aspergillosis ( ABPA) is characterised by an exaggerated Th2 response to Aspergillus fumigatus, but the immunological pathways responsible for this effect are unknown. Objective The aim of this study was to decipher the pattern recognition receptors ( PRRs) and cytokines involved in the Aspergillus-specific Th2 response and to study Aspergillus-induced responses in healthy controls and ABPA patients. Methods Peripheral blood mononuclear cells ( PBMCs) were stimulated with heat-killed Aspergillus conidia, various other pathogens, or PRR ligands. PRRs and cytokine pathways were blocked with PRR-blocking reagents, anti-TNF (Etanercept or Adalimumab), IL-1Ra (Anakinra) or IFNγ (IFN-gamma). ELISA and FACS were used to analyse cytokine responses. Results Aspergillus was the only pathogen that stimulated the Th2 cytokines IL-5 and IL-13, while Gram-negative bacteria, Gram-positive bacteria, Candida albicans, chitin, β-glucan or Toll-like receptor ( TLR) ligands did not. Depletion of CD4+ cells abolished IL-13 production. Blocking complement receptor 3 ( CR3) significantly reduced IL-5 and IL-13, while blocking TLR2, TLR4 or dectin-1 had no effect. ABPA patients displayed increased Aspergillus-induced IL-5 and IL-13 and decreased IFNγ production compared with healthy controls. All biological agents tested showed the capability to inhibit Th2 responses, but also decreased Aspergillus-induced IFNγ. Conclusions and Clinical Relevance Aspergillus conidia are unique in triggering Th2 responses in human PBMCs, through a CR3-dependent pathway. ABPA patients display a significantly increased Aspergillus-induced Th2/Th1 ratio that can be modulated by biologicals. These data provide a rationale to explore IFNγ therapy in ABPA as a corticosteroid-sparing treatment option, by dampening Th2 responses and supplementing the IFNγ deficiency at the same time. [ABSTRACT FROM AUTHOR]

Inflammation at the level of the β cell appears to be involved in progressive β-cell dysfunction in type 2 diabetes. We assessed the effect of blocking interleukin-1 ( IL-1) by anakinra [recombinant human interleukin-1 receptor antagonist (IL-1Ra)] on β-cell function. Sixteen participants with impaired glucose tolerance were treated with 150 mg anakinra daily for 4 weeks in a double blind, randomized, placebo-controlled cross-over study with a wash-out period of 4 weeks. At the end of each treatment period, oral glucose tolerance tests ( OGTTs) and hyperglycaemic clamps were performed. First-phase insulin secretion improved after anakinra treatment compared with placebo, 148 ± 20 versus 123 ± 14 mU/l, respectively (p = 0.03), and the insulinogenic index was higher after anakinra treatment. These results support the concept of involvement of IL-1β in the (progressive) decrease of insulin secretion capacity associated with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Primary immunodeficiencies ( PIDs) are severe defects in the capacity of the host to mount a proper immune response, and are characterized by an increased susceptibility to infections. Although classical immunodeficiencies have been characterized based on broad defects in cell populations (e.g. T/ B cells or polymorphonuclear leukocytes) or humoral factors (e.g. antibodies or complement), specific immune defects based on well-defined molecular targets have been described more recently. Among these, genetic defects in pattern recognition receptors ( PRRs), leading to impaired recognition of invading pathogens by the innate immune system, play an important role in specific defects against human pathogens. Defects have been described in three of the major families of PRRs: the Toll-like receptors, the C-type lectin receptors and the nucleotide-binding domain leucine-rich repeat-containing receptors. By contrast, no defects in the intracellular viral receptors of the RigI helicase family have been described to date. Defects in the PRRs show a broad variation in severity, have a narrow specificity for certain classes of pathogens, and often decrease in severity with age; these characteristics distinguish them from other forms of PIDs. Their discovery has led to important insights into the pathophysiology of infections, and may offer potential novel therapeutic targets for immunotherapy. [ABSTRACT FROM AUTHOR]

Macrophage migration inhibitory factor (MIF) has recently been implicated in the pathogenesis of malarial anaemia. However, field studies have reported contradictory results on circulating MIF concentrations in patients with clinically overt Plasmodium falciparum malaria. We determined plasma MIF levels over time in 10 healthy volunteers during experimental P. falciparum infection. Under fully controlled conditions, MIF levels decreased significantly during early blood-stage infection and reached a nadir at day 8 post-infection. A decrease in the number of circulating lymphocytes, which are an important source of MIF production, paralleled the decrease in MIF levels. Monocyte/macrophage counts remained unchanged. At MIF nadir, the anti-inflammatory cytokine interleukin (IL)-10, which is an inhibitor of T-cell MIF production, was detectable in only 2 of 10 volunteers. Plasma concentrations of the pro-inflammatory cytokines IL-8 and IL-1β were only marginally elevated. We conclude that circulating MIF levels decrease early in blood-stage malaria as a result of the decline in circulating lymphocytes. [ABSTRACT FROM AUTHOR]

Background The endogenous mediators playing a role in the sensing of fatigue and cessation of exercise are yet to be characterized. We hypothesized that proinflammatory cytokines, in particular tumour necrosis factor-α (TNFα) and lymphotoxin-α (LT) transmit signals leading to fatigue. Materials and methods Mice were placed in a cage with a freely rotating exercise wheel and allowed to adapt for 24 h. The running distance was measured for two additional periods of 24 h. The effects of the administration of intravenous anti-TNF antibodies, intracerebral recombinant TNF, or intravenous lipopolysaccharide (LPS) were also determined. Results Compared to normal littermates, the voluntary daily running distance was 1·8-fold greater in mice with a disruption of the gene for TNFα, and 3-fold greater in mice with a gene disruption for both TNFα and LT. Intravenous administration of a monoclonal antibody against murine TNFα did not affect the running distance of wild-type mice, whereas administration of TNF intracerebrally reduced by 4-fold the voluntary running distance of the animals. This demonstrates that fatigue is mediated by TNFα expressed in the central nervous system (CNS) and not by increased peripheral TNFα concentrations. TNFα and LT are strong inducers of prostaglandins, but mice with disrupted prostaglandin or prostacyclin receptors exhibited running distances not significantly different from their wild-type littermates. Thus, signalling molecules other than prostaglandins mediate the effect of TNFα and LT on exercise capacity. Conclusions Our finding that exercise capacity is controlled by TNFα is the first to define the endogenous mediators of fatigue, and may have important implications for diseases with impaired exercise tolerance. [ABSTRACT FROM AUTHOR]

The autosomal-dominant (AD) form of the hyperimmunoglobulin E syndrome (HIES) has been described as a multisystem disorder including immune, skeletal and dental abnormalities. Recently, the evaluation of patients from families in which HIES was inherited in a manner more consistent with autosomal-recessive (AR) inheritance, showed that AR-HIES is a clinically distinct disease entity. In addition to classical immunologic findings of AD-HIES, the AR form presents with severe recurrent fungal and viral infections with herpes zoster, herpes simplex and characteristic mollusca contagiosa. Furthermore, cerebral vascular sequelae, including vasculitis, infarction and haemorrhage were noted. In this report, we describe the clinical picture of two patients who showed remarkable resemblance to the description of AR-HIES, but also developed fatal aneurysmal dilatation of the thoracic aorta in adolescence. This finding may further consummate the clinical picture of AR-HIES and emphasize the possibility to develop early aortitis, most likely preceding the critical aneurysm formation at older age. This process should be anticipated during childhood in cases with AR-HIES. [ABSTRACT FROM AUTHOR]

Background Hyperimmunoglobulin E syndrome (HIES) is an inborn disorder characterized by recurrent skin and respiratory tract infections, skeletal abnormalities, chronic eczema and elevated serum IgE. The nature of the host defence defect has yet to be established. The aim of this study was to investigate whether activation of the interleukin-12/interleukin-18/interferon-γ axis, known to be crucial for the activation of cellular immune responses, is impaired in patients with HIES. Materials and methods Cytokine production capacity of seven HIES patients and seven healthy controls was investigated in whole-blood cultures stimulated with heat-killed Staphylococcus aureus, Candida albicans, or a combination of interleukin (IL)-12/IL-18. Results Interferon (IFN)γ production, in addition to IFNγ/IL-10 ratios, was 10–30-fold lower in the HIES patients compared with the healthy volunteers. In contrast TNF, IL-1β and IL-8 production was normal. Conclusions These data revealed a severe dysbalance towards a Th2 phenotype in HIES patients which is likely to contribute to the specific pattern of infection susceptibility characteristic to HIES. [ABSTRACT FROM AUTHOR]

Disseminated fungal infections are increasing. However, the interactions between the body's largest population of tissue macrophages, the Kupffer cells and the fungal pathogens are scarcely understood. The aim of this study was to examine the involvement of Toll-like receptor 4 (TLR4) signalling in cytokine production, using primary cultures of rat and murine Kupffer cells exposed to Aspergillus fumigatus and Candida albicans hyphae and conidia. All fungal components induced the release of tumour necrosis factor-α (TNF-α), but with delayed kinetics compared with lipopolysaccharide (LPS). Candida albicans was the most potent inducer of TNF-α protein and mRNA and the only inducer of interleukin-10 (IL-10) in rat Kupffer cells. All fungal components induced enhanced mRNA levels of macrophage inhibitory protein-2 (MIP-2) in the cells, similar to LPS. Inhibitors of Src tyrosine kinases added to cells prior to stimulation led to attenuation in the release of both TNF-α (60%, P < 0.05) and IL-10 (70%, P < 0.05) induced by C. albicans conidia but did not influence the LPS-mediated cytokine release. Murine Kupffer cells (C57BL/10J) also released TNF-α as well as the chemokines keratinocyte-derived chemokine (KC) and MIP-2 in response to fungal component. Surprisingly, Kupffer cells from TLR4-deficient C57BL/ScCr mice exhibited significantly enhanced production of KC and MIP-2 upon stimulation by fungal components compared with control littermates ( P < 0.05). Our study demonstrates that Aspergillus and Candida components induce cytokine production in rat Kupffer cells and that the response to C. albicans conidia involves Src tyrosine kinases. The experiments with TLR4-deficient Kupffer cells suggest that the cytokine response in these cells to fungal component is not mediated by TLR4. [ABSTRACT FROM AUTHOR]

Toll-like receptor-4 (TLR4) is a major receptor for inflammatory stimuli potentially involved in the pathogenesis of atherosclerosis, such as lipopolysaccharide (LPS) and heat-shock proteins. The Asp299Gly polymorphism of the TLR4 gene has been associated with a reduced intima-media thickness (IMT) of the common carotid artery in healthy individuals. We have investigated whether the presence of the Asp299Gly polymorphism in patients with familial hypercholesterolaemia (FH) has a similar protective effect, and whether it influences the effects of HMG-CoA reductase treatment. A cohort of 293 FH patients and 200 healthy volunteers were genotyped for the presence of the Asp299Gly allele using polymerase chain reaction followed by restriction fragment length polymorphism analysis. Intima-media thickness measurements, inflammatory parameters and the effect of HMG-CoA reductase inhibitors were compared between the patients with and without Asp299Gly allele. The Asp299Gly allele was present in 10·6% of the FH patients and 11·0% of the healthy individuals. Whereas the FH patients carrying the Asp299Gly allele displayed a reduced absolute IMT value compared with the FH patients carrying the wild-type allelle, the difference did not reach statistical significance. In addition, the effect of treatment with HMG-CoA reductase inhibitors was not influenced by the presence of Asp299Gly allele. The presence of the Asp299Gly allele of the TLR4 gene does not seem to exert a major influence on the progression of atherosclerosis in patients with FH. [ABSTRACT FROM AUTHOR]

It has been suggested that abnormalities in the immune response play a role in the pathogenesis of essential hypertension (EH). The aim of this study was to assess circulating concentrations and ex vivo production of the pro-inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and of the anti-inflammatory cytokines IL-1 receptor antagonist (IL-1ra) and IL-6, in patients with EH and compare them with healthy volunteers. Plasma cytokine concentrations were measured in EH patients and control volunteers by specific radioimmunoassays and ELISA. Ex vivo cytokine production was assessed after stimulation of whole-blood with lipopolysaccharide. Circulating concentrations of TNF, IL-1 and IL-6 did not differ between EH patients and controls. In contrast, IL-1ra circulating levels were higher in EH patients. Hypertensive patients had an increased IL-1 and IL-6 production capacity when whole blood was stimulated ex vivo with lipopolysaccharide, while TNF production was lower. IL-1ra production capacity did not differ between patients and controls. Patients with EH have an altered profile of pro-and anti-inflammatory cytokines, consistent with monocyte activation in the circulation. The importance of these changes for the pathogenesis of EH and/or its secondary complications remains to be elucidated. [ABSTRACT FROM AUTHOR]

Comments on leptin and leptin-receptor concentrations in patients with end-stage renal disease. Elevation of leptin concentrations in peritoneal dialysis patients; Low level of anti-inflammatory cytokines in those patients; Shift in the balance of the cytokine network in patients undergoing peritoneal dialysis.