NOD-like receptors and inflammation

Recombinant SpTransformer proteins are functionally diverse for binding and phagocytosis by three subtypes of sea urchin phagocytes

Introduction

The California purple sea urchin, Strongylocentrotus purpuratus, relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular defenses is the SpTransformer (SpTrf) gene family that is upregulated in response to immune challenge. The gene sequences are highly variable both within and among animals and likely encode thousands of SpTrf isoforms within the sea urchin population. The native SpTrf proteins bind foreign targets and augment phagocytosis of a marine Vibrio. A recombinant (r)SpTrf-E1-Ec protein produced by E. coli also binds Vibrio but does not augment phagocytosis.

Methods

To address the question of whether other rSpTrf isoforms function as opsonins and augment phagocytosis, six rSpTrf proteins were expressed in insect cells.

Results

The rSpTrf proteins are larger than expected, are glycosylated, and one dimerized irreversibly. Each rSpTrf protein cross-linked to inert magnetic beads (rSpTrf::beads) results in different levels of surface binding and phagocytosis by phagocytes. Initial analysis shows that significantly more rSpTrf::beads associate with cells compared to control BSA::beads. Binding specificity was verified by pre-incubating the rSpTrf::beads with antibodies, which reduces the association with phagocytes. The different rSpTrf::beads show significant differences for cell surface binding and phagocytosis by phagocytes. Furthermore, there are differences among the three distinct types of phagocytes that show specific vs. constitutive binding and phagocytosis.

Conclusion

These findings illustrate the complexity and effectiveness of the sea urchin innate immune system driven by the natSpTrf proteins and the phagocyte cell populations that act to neutralize a wide range of foreign pathogens.

Mitochondrial damage and clearance in retinal pigment epithelial cells

Age-related macular degeneration (AMD) is a devastating eye disease that causes permanent vision loss in the central part of the retina, known as the macula. Patients with such severe visual loss face a reduced quality of life and are at a 1.5 times greater risk of death compared to the general population. Currently, there is no cure for or effective treatment for dry AMD. There are several mechanisms thought to underlie the disease, for example, ageing-associated chronic oxidative stress, mitochondrial damage, harmful protein aggregation and inflammation. As a way of gaining a better understanding of the molecular mechanisms behind AMD and thus developing new therapies, we have created a peroxisome proliferator-activated receptor gamma coactivator 1-alpha and nuclear factor erythroid 2-related factor 2 (PGC1α/NFE2L2) double-knockout (dKO) mouse model that mimics many of the clinical features of dry AMD, including elevated levels of oxidative stress markers, damaged mitochondria, accumulating lysosomal lipofuscin and extracellular drusen-like structures in retinal pigment epithelial cells (RPE). In addition, a human RPE cell-based model was established to examine the impact of non-functional intracellular clearance systems on inflammasome activation. In this study, we found that there was a disturbance in the autolysosomal machinery responsible for clearing mitochondria in the RPE cells of one-year-old PGC1α/NFE2L2-deficient mice. The confocal immunohistochemical analysis revealed an increase in autophagosome marker microtubule-associated proteins 1A/1B light chain 3B (LC3B) as well as multiple mitophagy markers such as PTE-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase (PARKIN), along with signs of damaged mitochondria. However, no increase in autolysosome formation was detected, nor was there a colocalization of the lysosomal marker LAMP2 or the mitochondrial marker, ATP synthase β. There was an upregulation of late autolysosomal fusion Ras-related protein (Rab7) in the perinuclear space of RPE cells, together with autofluorescent aggregates. Additionally, we observed an increase in the numbers of Toll-like receptors 3 and 9, while those of NOD-like receptor 3 were decreased in PGC1α/NFE2L2 dKO retinal specimens compared to wild-type animals. There was a trend towards increased complement component C5a and increased involvement of the serine protease enzyme, thrombin, in enhancing the terminal pathway producing C5a, independent of C3. The levels of primary acute phase C-reactive protein and receptor for advanced glycation end products were also increased in the PGC1α/NFE2L2 dKO retina. Furthermore, selective proteasome inhibition with epoxomicin promoted both nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondrial-mediated oxidative stress, leading to the release of mitochondrial DNA to the cytosol, resulting in potassium efflux-dependent activation of the absent in melanoma 2 (AIM2) inflammasome and the subsequent secretion of interleukin-1β in ARPE-19 cells. In conclusion, the data suggest that there is at least a relative decrease in mitophagy, increases in the amounts of C5 and thrombin and decreased C3 levels in this dry AMD-like model. Moreover, selective proteasome inhibition evoked mitochondrial damage and AIM2 inflammasome activation in ARPE-19 cells.

NLRP10 promotes AGEs-induced NLRP1 and NLRP3 inflammasome activation via ROS/MAPK/NF-κB signaling in human periodontal ligament cells

Diabetes mellitus (DM), characterized by production and accumulation of advanced glycation end products (AGEs), induces and promotes chronic inflammation in tissues, including periodontal tissue. Increasing amount of epidemiological and experimental evidence demonstrated that more extensive inflammatory reaction and bone resorption occurred in periodontal tissues in diabetic patients with periodontitis, which is speculated to be related to NLRP3 inflammasome. NLRP10 is the only NOD-like receptor protein lacking leucine-rich repeats, suggesting that NLRP10 may be a regulatory protein. The aim of this study was to investigate the regulatory role of NLRP10 on NLRP1 and NLRP3 inflammasome in human periodontal ligament cells (HPDLCs) under AGEs treatment. Expression of NLRP10 in HPDLCs stimulated with 100 ug/mL AGEs for 24 h was observed. Detection of TRIM31 is conducted, and in TRIM31-overexpressed HPDLCs, the interaction between NLRP10 with TRIM31 as well as NLRP10 with ubiquitination were explored by immunoprecipitation. Under AGEs stimulation, the activation of reactive oxidative stress (ROS) and inflammatory signaling pathway (NF-κB, MAPK pathway) was detected by biomedical microscope and western blot (WB), respectively. After stimulation with AGEs for 24 h with or without silencing NLRP10, inflammatory cytokines (IL-6 and IL-1β), NF-κB, MAPK pathway, ROS, and components of inflammasome were assessed. In HPDLCs, we found AGEs induced NLRP10 and inhibited TRIM31. TRIM31 overexpression significantly enhanced interaction between TRIM31 and NLRP10, then induced proteasomal degradation of NLRP10. Moreover, under AGEs stimulation, NLRP10 positively regulates NLRP1, NLRP3 inflammasomes by activating NF-κB, MAPK pathway, and increasing ROS, finally promoting the expression of inflammatory cytokines. Together, we, for the first time, confirmed that NLRP10 could promote inflammatory response induced by AGEs in HPDLCs via activation of NF-κB, and MAPK pathway and increasing ROS.

Hyperoxia Provokes Time- and Dose-Dependent Gut Injury and Endotoxemia and Alters Gut Microbiome and Transcriptome in Mice

Background: Oxygen therapy usually exposes patients to hyperoxia, which induces injuries in the lung, the heart, and the brain. The gut and its microbiome play key roles in critical illnesses, but the impact of hyperoxia on the gut and its microbiome remains not very clear. We clarified the time- and dose-dependent effects of hyperoxia on the gut and investigated oxygen-induced gut dysbiosis and explored the underlying mechanism of gut injury by transcriptome analysis. Methods: The C57BL/6 mice were randomly divided into the control group and nine different oxygen groups exposed to hyperoxia with an inspired O₂ fraction (FiO₂) of 40, 60, and 80% for 24, 72, and 168 h (7 days), respectively. Intestinal histopathological and biochemical analyses were performed to explore the oxygen-induced gut injury and inflammatory response. Another experiment was performed to explore the impact of hyperoxia on the gut microbiome by exposing the mice to hyperoxia (FiO₂ 80%) for 7 days, with the 16S rRNA sequencing method. We prolonged the exposure (up to 14 days) of the mice to hyperoxia (FiO₂ 80%), and gut transcriptome analysis and western blotting were carried out to obtain differentially expressed genes (DEGs) and signaling pathways related to innate immunity and cell death. Results: Inhaled oxygen induced time- and dose-dependent gut histopathological impairment characterized by mucosal atrophy (e.g., villus shortening: 80% of FiO₂ for 24 h: P = 0.008) and enterocyte death (e.g., apoptosis: 40% of FiO₂ for 7 days: P = 0.01). Administered time- and dose-dependent oxygen led to intestinal barrier dysfunction (e.g., endotoxemia: 80% of FiO₂ for 72 h: P = 0.002) and potentiated gut inflammation by increasing proinflammatory cytokines [e.g., tumor necrosis factor alpha (TNF-α): 40% of FiO₂ for 24 h: P = 0.003)] and reducing anti-inflammatory cytokines [Interleukin 10 (IL-10): 80% of FiO₂ for 72 h: P < 0.0001]. Hyperoxia induced gut dysbiosis with an expansion of oxygen-tolerant bacteria (e.g., Enterobacteriaceae). Gut transcriptome analysis identified 1,747 DEGs and 171 signaling pathways and immunoblotting verified TLR-4, NOD-like receptor, and apoptosis signaling pathways were activated in oxygen-induced gut injury. Conclusions: Acute hyperoxia rapidly provokes gut injury in a time- and dose-dependent manner and induces gut dysbiosis, and an innate immune response is involved in an oxygen-induced gut injury.

The integrated analysis of circRNAs, miRNAs and mRNAs revealed the potential role in the TGF-β and TNF-α signaling pathways of OPLL

Ossification of the posterior longitudinal ligament (OPLL), one of spinal disease causing myelopathy, is characterized by the ectopic ossification and narrowing of the spinal cord. However, the pathogenesis of OPLL is largely unclear. In this study, transcriptome expression profiles (circRNAs, lncRNAs, and mRNAs) were identified via high-throughput sequencing using peripheral blood mononuclear cells (PBMCs) from OPLL and non-OPLL patients. We found that 1150 mRNAs, 331 circRNAs, and 1429 lncRNAs were significantly differentially expressed in the PBMCs of OPLL patients. GO and KEGG enrichment analyses revealed that most mRNAs were associated with inflammation. The co-expression networks indicated that circRNAs and lncRNAs could regulate the mRNAs through influencing the inflammation of OPLL. The circRNA-miRNA-mRNA integrated network showed that circRNA-regulated mRNAs associated with TGF-β and TNF-α signaling pathways. These analyses indicate that circRNAs, lncRNAs, and mRNAs from PBMCs might contribute to inflammation in OPLL.

The role of dietary polyphenols in inflammatory bowel disease: A possible clue on the molecular mechanisms involved in the prevention of immune and inflammatory reactions

Inflammatory bowel disease (IBD) is one of the major complications of the gastrointestinal tract, characterized by chronic inflammation, which disturbs the quality of life of the affected individuals. Genetic predisposition, immune, inflammatory, and enzyme-mediated signaling cascades are the primary mechanisms involved in the pathogenesis of the disease. Currently, the treatment strategy involves the maintenance of remission and induction of inflammation by anti-inflammatory agents and immune suppressants. Polyphenol-containing diets, including fruits and vegetables of regular use, possess anti-inflammatory, and antioxidant potential through the inhibition of major contributing pathways to IBD. This review discusses the role of these dietary polyphenols in downregulating the major signaling cascades in IBD. Our review encourages the development of nutritional strategies to improve the efficiency of current therapies for IBD and reduce the risks of side effects associated with conventional therapy. PRACTICAL APPLICATIONS: At present, almost every third person in society is under stress and having chronic disorders like diabetes, arthritis, allergy, cardiovascular disease, IBD, etc. This insists on the direct/indirect role of changes in the lifestyle for such deterioration in society. This review would emphasize the medicinal value of polyphenols present in fruits and vegetables for chronic inflammatory disorders. This concept portrays the food components which have the potential to promote health, improve general well-being, and reduce the risk of IBD. We propose to add fruits with bioactive polyphenols in the regular diet to help in preventing the immune-mediated intestinal chronic inflammatory syndrome and reduce the risks of colorectal cancer development.

Nucleotide-binding oligomerization domain 1 is dispensable for host immune responses against pulmonary infection of Acinetobacter baumannii in mice

Nucleotide-binding domain 1 (Nod1) is a cytosolic receptor that is responsible for the recognition of a bacterial peptidoglycan motif containing meso-diaminophimelic acid. In this study, we sought to identify the role of Nod1 in host defense in vivo against pulmonary infection by multidrug resistant Acinetobacter baumannii. Wildtype (WT) and Nod1-deficient mice were intranasally infected with 3×10⁷ CFU of A. baumannii and sacrificed at 1 and 3 days post-infection (dpi). Bacterial CFUs, cytokines production, histopathology, and mouse β-defensins (mBD) in the lungs of infected mice were evaluated. The production of cytokines in response to A. baumannii was also measured in WT and Nod1-deficient macrophages. The bacterial clearance in the lungs was not affected by Nod1 deficiency. Levels of IL-6, TNF-α, and IL-1β in the lung homogenates were comparable at days 1 and 3 between WT and Nod1-deficient mice, except the TNF-α level at day 3, which was higher in Nod1-deficient mice. There was no significant difference in lung pathology and expression of mBDs (mBD1, 2, 3, and 4) between WT and Nod1-deficient mice infected with A. baumannii. The production of IL-6, TNF-α, and NO by macrophages in response to A. baumannii was also comparable in WT and Nod1-deficient mice. Our results indicated that Nod1 does not play an important role in host immune responses against A. baumannii infection.

Characterization of the immune response following in vitro mayaro and chikungunya viruses (Alphavirus, Togaviridae) infection of mononuclear cells

Two Alphaviruses stand out for their clinical importance in Brazil: chikungunya (CHIKV) and mayaro (MAYV) viruses. Few studies exist on the mechanisms of the immune response after infection by these viruses and neither a treatment nor a vaccine for these pathogens are available. Although their infection does not have a high mortality rate, they can lead to a joint involvement that can persist for months. The aims of this work were the study of the mechanisms of antiviral immune response following in vitro (U937 cells) infection with these viruses; to investigate the characteristics of the infection by these viruses; and to determine possible molecular targets that could serve as antiviral therapies against these pathogens. Several genes were modulated after infection by these viruses, and the three antiviral detection and response pathways were activated (Toll-like, RIG-I and NOD-like). Eotaxin and IL-6 were induced in all experiments. The cellular immune response profile found for each virus was different, with CHIKV activating primarily an inflammatory response (Th1 and Th17) and MAYV inducing a regulatory/suppressive response, an important feature to contain the inflammation resulting from infection. The data acquired by this study could provide an explanation why CHIKV infections, due to activation of the inflammatory response, are more clinically relevant than MAYV infections, which generates mostly an anti-inflammatory response after infection.

Our gut microbiota: a long walk to homeostasis

The microbiome of the human gastrointestinal tract (GIT) consists of billions of bacteria, fungi and viruses, of which bacteria play the most important role in nutrition, immune development, production of vitamins and maintaining a well-balanced (homeostatic) microbial population. Many papers have been published on the microbiota in the human GIT, but little is known about the first group of bacteria that colonises an infant. The intestinal tract of an unborn is, despite general belief, not sterile, but contains bacteria that have been transferred from the mother. This opens a new research field and may change our understanding about the role bacteria play in early life, the selection of strains with probiotic properties and the treatment of diseases related to bacterial infections. Differences in bacterial populations isolated from meconia may provide answers to the prevention of certain forms of diabetes. More research is now focusing on the effect that a genetically diverse group, versus a much simpler microbial population, may have on the development of a homeostatic gut microbiome. The effect different bacterial species have on the gut-associated lymphoid tissue and cascade of immune responses has been well researched, but we still fail in identifying the ideal group of intestinal bacteria and if we do, it will certainly not be possible to maintain homeostasis with so many challenges the gut faces. Changes in diet, antibiotics, food preservatives and stress are some of the factors we would like to control, but more than often fail to do so. The physiology and genetics of the GIT changes with age and so the microbiome. This review summarises factors involved in the regulation of a gut microbiome.

The emerging role of ECM crosslinking in T cell mobility as a hallmark of immunosenescence in humans

Immunosenescence is thought to result from cellular aging and to reflect exposure to environmental stressors and antigens, including cytomegalovirus (CMV). However, not all of the features of immunosenescence are consistent with this view, and this has led to the emergence of the sister theory of "inflammaging". The recently discovered diffuse tissue distribution of resident memory T cells (T_RM) which don't recirculate, calls these theories into question. These cells account for most T cells residing in barrier epithelia which sit in and travel through the extracellular matrix (ECM). With almost all studies to date carried out on peripheral blood, the age-related changes of the ECM and their consequences for T cell mobility, which is crucial for the function of these cells, have been largely ignored. We propose an update of the theoretical framework of immunosenescence, based on a novel hypothesis: the increasing stiffness and cross-linking of the senescent ECM lead to a progressive immunodeficiency due to an age-related decrease in T cell mobility and eventually the death of these cells. A key element of this mechanism is the mechanical stress to which the cell cytoplasm and nucleus are subjected during passage through the ECM. This hypothesis is based on an "evo-devo" perspective bringing together some major characteristics of aging, to create a single interpretive framework for immunosenescence.

Ultrasonographic assessment reveals detailed distribution of synovial inflammation in Blau syndrome

INTRODUCTION

Arthritis is the most frequent manifestation of Blau syndrome, an autoinflammatory disorder caused by the genetic mutation of NOD2. However, detailed information on arthritis in Blau syndrome on which the therapeutic strategy should be based on is lacking. This multi-center study aimed to accurately characterize the articular manifestation of Blau syndrome and also to demonstrate the utility of musculoskeletal ultrasound in Blau syndrome.

METHODS

Patients who had been diagnosed with Blau syndrome by genetic analysis of NOD2 were recruited. A total of 102 synovial sites in 40 joints were assessed semiquantitatively by ultrasound for gray-scale synovitis and synovial power Doppler (PD) signal.

RESULTS

In total, 10 patients whose age ranged from 10 months to 37 years enrolled in this study. Although only 4 joints (0.8%) were tender on physical examination, 81 joints (16.9%) were clinically swollen. Moreover, 240 (50.0%), and 124 (25.8%) joints showed gray-scale (GS) synovitis and synovial PD signal on ultrasound, respectively. Importantly, GS synovitis was present in 168 out of 399 non-swollen joints, in which 61 also exhibited synovial PD signal. Among 40 joint regions, the ankle, the wrist, and the proximal interphalangeal joints were the most frequently and severely affected joints. Comparisons between different synovial tissues demonstrated a significantly higher proportion of the joints with tenosynovitis as compared with that with intra-articular synovitis (41.5% versus 27.9%, P < 0.0001). In respect of age and treatment, synovial PD signals were minimal in the youngest patient and in the oldest two patients, and were relatively mild in patients receiving treatment with methotrexate plus TNF antagonists. In two patients who underwent the second ultrasound examination, total PD scores markedly decreased after initiating the treatment with a tumor necrosis factor (TNF) antagonist.

CONCLUSIONS

The detailed information on synovial inflammation obtained by ultrasound confirms the dissociation between pain and inflammation and the frequently involved joint regions and synovial tissue in the arthritis of Blau syndrome. Our data also demonstrate that ultrasonography can be a potent tool in monitoring the activity of synovial inflammation and in investigating the pathophysiology of arthritis in this rare but archetypical autoinflammatory condition.

Pyrin- and CARD-only Proteins as Regulators of NLR Functions

Upon activation Nod-like receptors (NLRs) assemble into multi-protein complexes such as the NODosome and inflammasome. This process relies upon homo domain interactions between the structurally related Pyrin and caspase-recruitment (CARD) domains and adaptor proteins, such as ASC, or effector proteins, such as caspase-1. Although a variety of NLRP and NLRC complexes have been described along with their activating stimuli and associated proteins, less familiar are processes limiting assembly and/or promoting dissociation of NLR complexes. Given the importance of limiting harmful, chronic inflammation, such regulatory mechanisms are significant and likely numerous. Proteins comprised of a solitary Pyrin domain (Pyrin-only) or CARD domain (CARD-only) posses an obvious potential ability to act as competitive inhibitors of NLR complexes. Indeed, both Pyrin-only proteins (POPs) and CARD-only proteins (COPs) have been described as regulators of caspase-1 and/or NLR-inflammasome activation and not surprisingly as factors mediating pathogenesis. Although clear examples of pathogen encoded POPs are currently limited to members of the poxviridae, the human genome likely encodes three POPs (POP1, POP2, and a potential POP3), of which only POP2 is known to prevent NLR:ASC interaction, and three COPs (COP/Pseudo-ICE, INCA, and ICEBERG), initially described for their ability to inhibit caspase-1 activity. Surprisingly, among eukaryotic species POPs and COPs appear to be evolutionarily recent and restricted to higher primates, suggesting strong selective pressures driving their emergence. Despite the importance of understanding the regulation of NLR functions, relatively little attention has been devoted to revealing the biological impact of these intriguing proteins. This review highlights the current state of our understanding of POPs and COPs with attention to protein interaction, functions, evolution, implications for health and disease, and outstanding questions.

Research progress on the NLRP3 inflammasome and its role in the central nervous system

The NLRP3 inflammasome, which consists of the NLRP3 (nucleotide-binding oligomerization domain (Nod)-like receptor 3) scaffold, the ASC (apoptosis-associated speck-like protein containing a CARD) adaptor and procaspase- 1, is assembled after the cytoplasmic LRRs (leucine-rich repeats) of NLRP3 sense pathogens or danger signals. The NLRP3 inflammasome controls the activation of the proteolytic enzyme caspase-1. Caspase-1 in turn regulates the maturation of the proinflammasome cytokines IL-1β and IL-18, which leads to an inflammatory response. The inflammasome plays an important role in the development of Alzheimer's disease and bacterial meningitis, and the NLRP3 inflammasome may become a new target for the prevention and treatment of central nervous system diseases.

Extracellular matrix from porcine small intestinal submucosa (SIS) as immune adjuvants

Porcine small intestinal submucosa (SIS) of Cook Biotech is licensed and widely used for tissue remodeling in humans. SIS was shown to be highly effective as an adjuvant in model studies with prostate and ovarian cancer vaccines. However, SIS adjuvanticity relative to alum, another important human-licensed adjuvant, has not yet been delineated in terms of activation of innate immunity via inflammasomes and boosting of antibody responses to soluble proteins and hapten-protein conjugates. We used ovalbumin, and a hapten-protein conjugate, phthalate-keyhole limpet hemocyanin. The evaluation of SIS was conducted in BALB/c and C57BL/6 mice using both intraperitoneal and subcutaneous routes. Inflammatory responses were studied by microarray profiling of chemokines and cytokines and by qPCR of inflammasomes-related genes. Results showed that SIS affected cytokine and chemokines microenvironments such as up-regulation of IL-4 and CD30-ligand and activation of chemotactic factors LIX and KC (neutrophil chemotactic factors), MCP-1 (monocytes chemotactic factors), MIP 1-α (macrophage chemotactic factor) and lymphotactin, as well as, growth factors like M-CSF. SIS also promoted gene expression of Nod-like receptors (NLR) and associated downstream effectors. However, in contrast to alum, SIS had no effects on pro-inflammatory cytokines (IL-6, IL-1β, TNF-α) or NLRP3, but it appeared to promote both Th1 and Th2 responses under different conditions. Lastly, it was as effective as alum in engendering a lasting and specific antibody response, primarily of IgG1 type.

Variation in NOD2 augments Th2- and Th17 responses to myelin basic protein in multiple sclerosis

Variations in the gene for the nucleotide-binding oligomerisation domain (NOD) 2 have been associated with Crohn's disease but not multiple sclerosis (MS). Here we investigate the effect of three polymorphisms in the NOD2 gene (rs5743277, rs2066842 and rs5743291) on cytokine production and CD4+ T cell proliferation elicited by human myelin basic protein (MBP) in blood mononuclear cell (MNC) cultures from 29 patients with MS. No polymorphism was observed at rs5743277. No associations with the rs2066842 polymorphism were found. Concerning rs5743291, none were homozygous for the minor allele. Seven of 29 (24%) patients were heterozygous, and five of these (71%) exhibited increased MBP-induced CD4+ T cell proliferation versus four of 22 (18%), who were homozygous for the major allele (p<0.04). Interleukin (IL)-5 was induced by MBP in MNC from the same five carriers versus two (9%) homozygotes (p<0.004); four carriers (57%) versus three non-carriers (14%) exhibited IL-17 responses to MBP (p<0.04). By contrast, we found no association between the polymorphisms investigated and interferon-gamma-, tumor necrosis factor-alpha-, IL-2, -4- or IL-10 responses to MBP. These results indicate that the rs5743291 polymorphism influences T helper (Th) cell 2- and Th17 cell responses in MNC from MS patients.

Fungal pathogen recognition by scavenger receptors in nematodes and mammals

Macrophages are important cells in the host resistance to fungal infections, and fungal recognition by macrophages triggers phagocytosis, intracellular killing, induction of inflammatory cytokines and chemokines, and initiation of the adaptive immune response. All of the receptors that mediate binding and engulfment of fungal pathogens and the signaling pathways triggered by fungal pathogens that regulate anti-fungal immunity are not fully understood. Using an RNAi screen we recently demonstrated that the C. elegans receptors CED-1 and C03F11.3, and their mammalian orthologues, the scavenger receptors SCARF1 and CD36 mediate host defense against the fungal pathogen, Cryptococcus neoformans. Finally, SCARF1 and CD36 function as co-receptors by binding and engulfing fungal pathogens to facilitate Toll-like receptor 2 signaling. Here we will summarize and expand upon our previous findings.

Distribution of 42-bp variable tandem repeat polymorphism of the cold-induced autoinflammatory syndrome 1 (CIAS1) gene in eight human populations

We recently identified a 42bp Variable Number of Tandem Repeats polymorphism in intron 4 of Cold-induced autoinflammatory syndrome 1 gene (CIAS1 42bp-VNTR), which are associated with CIAS1 gene expression and some inflammatory disease. The aim of our study is to investigate whether variability of CIAS1 42bp-VNTR allele is difference among races. A total of 1291 subjects from 7 populations (178 Chinese, 95 Korean, 614 Mongolian, 49 Bangladesh, 72 Sri Lanka, 192 African and 91 European) was genotyped on CIAS1 42bp-VNTR polymorphism, which was also compared to previous genotyping data from 508 Japanese subjects. A total of 11 genotypes and 5 alleles were found in 8 populations. The range of allele frequencies of CIAS1∗6, CIAS1∗7, CIAS1∗9, CIAS1∗12, and CIAS1∗13 were 0.000-0.167, 0.056-0.248, 0.008-0.203, 0.570-0.923, and 0.000-0.104 in eight populations. The CIAS1∗12 was the most common allele among all populations. The longest allele CIAS1∗13 in African population was extremely high frequent at 0.104 compared to other population. While shortest allele CIAS1∗6 was not observed Sri Lankan and African. Frequency (0.924) in the Sri Lankan population. These results showed that the CIAS1 42bp-VNTR polymorphism could represent genetic diversity among different human populations.

[Insulin resistance as a mechanism of adaptation during human evolution]

The recent application of concepts of evolution to human disease is proving useful to understand certain pathophysiological mechanisms of different entities that span genomic alterations of immunity, respiratory and hormone function, and the circulatory and neural systems. However, effort has concentrated on explaining the keys to adaptation that define human metabolism and, since the early 1960s, several theories have been developed. This article reviews some of the hypotheses postulated in recent years on the potential benefit of insulin resistance and discusses the most recent knowledge. The concept of the thrifty gene seems to have been definitively refuted by current knowledge. The current paradigm describes an interaction between the metabolic and the immune systems resulting from their coevolution, promoted by evolutionary pressures triggered by fasting, infection and intake of different foods. The activation and regulation of these ancient mechanisms in integrated and interdependent areas defines insulin resistance as a survival strategy that is critical during fasting and in the fight against infection. The relationship with some components of the diet and, particularly, with the symbiotic intestinal microflora points to new paradigms in understanding the pathophysiology of obesity, metabolic syndrome and type 2 diabetes mellitus.

The nucleotide-binding oligomerization domain-like receptor NLRC5 is involved in IFN-dependent antiviral immune responses

Nucleotide-binding oligomerization domain-like receptors (NLRs) are a group of intracellular proteins that mediate recognition of pathogen-associated molecular patterns or other cytosolic danger signals. Mutations in NLR genes have been linked to a variety of inflammatory diseases, underscoring their pivotal role in host defense and immunity. This report describes the genomic organization and regulation of the human NLR family member NLRC5 and aspects of cellular function of the encoded protein. We have analyzed the tissue-specific expression of NLRC5 and have characterized regulatory elements in the NLRC5 promoter region that are responsive to IFN-gamma. We show that NLRC5 is upregulated in human fibroblasts postinfection with CMV and demonstrate the role of a JAK/STAT-mediated autocrine signaling loop involving IFN-gamma. We demonstrate that overexpression and enforced oligomerization of NLRC5 protein results in activation of the IFN-responsive regulatory promoter elements IFN-gamma activation sequence and IFN-specific response element and upregulation of antiviral target genes (e.g., IFN-alpha, OAS1, and PRKRIR). Finally, we demonstrate the effect of small interfering RNA-mediated knockdown of NLRC5 on a target gene level in the context of viral infection. We conclude that NLRC5 may represent a molecular switch of IFN-gamma activation sequence/IFN-specific response element signaling pathways contributing to antiviral defense mechanisms.

Missense mutations in the MEFV gene are associated with fibromyalgia syndrome and correlate with elevated IL-1beta plasma levels

Background

Fibromyalgia syndrome (FMS), a common, chronic, widespread musculoskeletal pain disorder found in 2% of the general population and with a preponderance of 85% in females, has both genetic and environmental contributions. Patients and their parents have high plasma levels of the chemokines MCP-1 and eotaxin, providing evidence for both a genetic and an immunological/inflammatory origin for the syndrome (Zhang et al., 2008, Exp. Biol. Med. 233: 1171–1180).

Methods and Findings

In a search for a candidate gene affecting inflammatory pathways, among five screened in our patient samples (100 probands with FMS and their parents), we found 10 rare and one common alleles for MEFV, a gene in which various compound heterozygous mutations lead to Familial Mediterranean Fever (FMF). A total of 2.63 megabases of genomic sequence of the MEFV gene were scanned by direct sequencing. The collection of rare missense mutations (all heterozygotes and tested in the aggregate) had a significant elevated frequency of transmission to affecteds (p = 0.0085, one-sided, exact binomial test). Our data provide evidence that rare missense variants of the MEFV gene are, collectively, associated with risk of FMS and are present in a subset of 15% of FMS patients. This subset had, on average, high levels of plasma IL-1β (p = 0.019) compared to FMS patients without rare variants, unaffected family members with or without rare variants, and unrelated controls of unknown genotype. IL-1β is a cytokine associated with the function of the MEFV gene and thought to be responsible for its symptoms of fever and muscle aches.

Conclusions

Since misregulation of IL-1β expression has been predicted for patients with mutations in the MEFV gene, we conclude that patients heterozygous for rare missense variants of this gene may be predisposed to FMS, possibly triggered by environmental factors.