Anti-Toxoplasma gondii antibodies as a risk factor for the prevalence and severity of systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by the presence of numerous autoantibodies. The interaction of infectious agents (viruses, bacteria and parasites) and a genetically susceptible host may be a key mechanism for SLE. Toxoplasma gondii is a widespread intracellular parasite that has been implicated in the pathogenesis of autoimmune diseases. However, the relationship between T. gondii infection and the increased risk of SLE in Chinese populations remains unclear. METHODS: The seroprevalence of T. gondii infection was assessed in 1771 serum samples collected from Chinese individuals (908 healthy controls and 863 SLE patients) from different regions of China using an enzyme-linked immunosorbent assay. Serum autoantibodies and clinical information were obtained and analysed. RESULTS: Our observations revealed a higher prevalence of anti-T. gondii antibodies (ATxA) immunoglobulin G (IgG) in serum samples from SLE patients (144/863, 16.7%) than in those from the healthy controls (53/917, 5.8%; P < 0.0001), indicating a 2.48-fold increased risk of SLE in the ATxA-IgG+ population, after adjustment for age and sex (95% confidence interval [CI] 1.70-3.62, P < 0.0001). ATxA-IgG+ SLE patients also showed a 1.75-fold higher risk of developing moderate and severe lupus symptoms (95% CI 1.14-2.70, P = 0.011) compared to ATxA-IgG- patients. Relative to ATxA-IgG- patients, ATxA-IgG+ patients were more likely to develop specific clinical symptoms, including discoid rash, oral ulcer, myalgia and alopecia. Seven antibodies, namely anti-ribosomal RNA protein (rRNP), anti-double stranded DNA (dsDNA), anti-cell membrane DNA (cmDNA), anti-scleroderma-70 (Scl-70), anti-cardiolipin (CL), anti-beta2-glycoprotein-I (B2GPI) and rheumatoid factor (RF), occurred more frequently in ATxA-IgG+ patients. When combined with anti-dsDNA and RF/anti-rRNP/anti-cmDNA/ESR, ATxA-IgG significantly increased the risk for severe lupus. CONCLUSIONS: Our results suggest that ATxA-IgG may be a significant risk factor for SLE prevalence and severity in Chinese populations.

Aureane-type sesquiterpene tetraketides as a novel class of immunomodulators with interleukin-17A inhibitory activity.

Interleukin (IL)-17A, a pro-inflammatory cytokine, is a fundamental function in the onset and advancement of multiple immune diseases. To uncover the primary compounds with IL-17A inhibitory activity, a large-scale screening of the library of traditional Chinese medicine constituents and microbial secondary metabolites was conducted using splenic cells from IL-17A-GFP reporter mice cultured under Th17-priming conditions. Our results indicated that some aureane-type sesquiterpene tetraketides isolated from a wetland mud-derived fungus, Myrothecium gramineum, showed remarkable IL-17A inhibitory activity. Nine new aureane-type sesquiterpene tetraketides, myrogramins A-I (1, 4-11), and two known ones (2 and 3) were isolated and identified from the strain. Compounds 1, 3, 4, 10, and 11 exhibited significant IL-17A inhibitory activity. Among them, compound 3, with a high fermentation yield dose-dependently inhibited the generation of IL-17A and suppressed glycolysis in splenic cells under Th17-priming conditions. Strikingly, compound 3 suppressed immunopathology in both IL-17A-mediated animal models of experimental autoimmune encephalomyelitis and pulmonary hypertension. Our results revealed that aureane-type sesquiterpene tetraketides are a novel class of immunomodulators with IL-17A inhibitory activity, and hold great promise applications in treating IL-17A-mediated immune diseases.

IL-27 signalling promotes adipocyte thermogenesis and energy expenditure.

Thermogenesis in brown and beige adipose tissue has important roles in maintaining body temperature and countering the development of metabolic disorders such as obesity and type 2 diabetes1,2. Although much is known about commitment and activation of brown and beige adipose tissue, its multiple and abundant immunological factors have not been well characterized3-6. Here we define a critical role of IL-27-IL-27Rα signalling in improving thermogenesis, protecting against diet-induced obesity and ameliorating insulin resistance. Mechanistic studies demonstrate that IL-27 directly targets adipocytes, activating p38 MAPK-PGC-1α signalling and stimulating the production of UCP1. Notably, therapeutic administration of IL-27 ameliorated metabolic morbidities in well-established mouse models of obesity. Consistently, individuals with obesity show significantly decreased levels of serum IL-27, which can be restored after bariatric surgery. Collectively, these findings show that IL-27 has an important role in orchestrating metabolic programs, and is a highly promising target for anti-obesity immunotherapy.

Roux-en-Y Gastric Bypass Improved Insulin Resistance via Alteration of the Human Gut Microbiome and Alleviation of Endotoxemia.

BACKGROUND: Obesity is a main contributing factor for the development of glucose intolerance and type 2 diabetes mellitus (T2D). Roux-en-Y gastric bypass (RYGB) is believed to be one of the most effective treatments to reduce body weight and improve glucose metabolism. In this study, we sought to explore the underlying mechanisms of weight reduction and insulin resistance improvement after RYGB. METHODS: This was a prospective observational study using consecutive samples of 14 obese subjects undergoing bariatric surgery. Main assessments were serum indexes (blood metabolites, glucose-lipid regulating hormones, trimethylamine-N-oxide (TMAO), and lipopolysaccharide-binding protein (LBP), fecal short-chain fatty acids (SCFAs), and gut microbiota. Correlation analysis of the factors changed by RYGB was used to indicate the potential mechanism by which surgery improves insulin resistance. RESULTS: The subjects showed significant improvement on indices of obesity and insulin resistance and a correlated change of gut microbiota components at 1 month, 3 months, and 6 months post-RYGB operation. In particular, the abundance of a counterobese strain, Akkemansia muciniphila, had gradually increased with the postoperative time. Moreover, these changes were negatively correlated to serum levels of LBP and positively correlated to serum TMAO and fecal SCFAs. CONCLUSIONS: Our findings uncovered links between intestinal microbiota alterations, circulating endotoxemia, and insulin resistance. This suggests that the underlying mechanism of protection of the intestine by RYGB in obesity may be through changing the gut microbiota.

Pregnancy Induces an Immunological Memory Characterized by Maternal Immune Alterations Through Specific Genes Methylation.

During pregnancy, the maternal immune system undergoes major adaptive modifications that are necessary for the acceptance and protection of the fetus. It has been postulated that these modifications are temporary and limited to the time of pregnancy. Growing evidence suggests that pregnancy has a long-term impact on maternal health, especially among women with pregnancy complications, such as preeclampsia (PE). In addition, the presence of multiple immunological-associated changes in women that remain long after delivery has been reported. To explain these long-term modifications, we hypothesized that pregnancy induces long-term immunological memory with effects on maternal well-being. To test this hypothesis, we evaluated the immunological phenotype of circulating immune cells in women at least 1 year after a normal pregnancy and after pregnancy complicated by PE. Using multiparameter flow cytometry (FCM) and whole-genome bisulfite sequencing (WGBS), we demonstrate that pregnancy has a long-term effect on the maternal immune cell populations and that this effect differs between normal pregnancy and pregnancy complicated by PE; furthermore, these modifications are due to changes in the maternal methylation status of genes that are associated with T cell and NK cell differentiation and function. We propose the existence of an "immunological memory of pregnancy (IMOP)" as an evolutionary advantage for the success of future pregnancies and the proper adaptation to the microchimeric status established during pregnancy. Our findings demonstrate that the type of immune cell populations modified during pregnancy may have an impact on subsequent pregnancy and future maternal health.

Inflammation is associated with decreased functional connectivity of insula in unmedicated bipolar disorder.

BACKGROUND: Systemic inflammation and immune dysregulation have been considered as risk factors in the pathophysiology of mood disorders including bipolar disorder (BD). Previous neuroimaging studies have demonstrated metabolic, structural and functional abnormalities in the insula in BD, proposed that the insula played an important role in BD. We herein aimed to explore neural mechanisms underlying inflammation-induced in the insular subregions functional connectivity (FC) in patients with BD. METHODS: Brain resting-state functional magnetic resonance imaging (rs-fMRI) data were acquired from 41 patients with unmedicated BD II (current episode depressed), 68 healthy controls (HCs). Three pairs of insular seed regions were selected: the bilateral anterior insula (AI), the bilateral middle insula (MI) and the bilateral posterior insula (PI), and calculated the whole-brain FC for each subregion. Additionally, the serum levels of pro-inflammatory cytokines in patients and HCs, including IL-6 and TNF-α, were detected. Then the partial correlation coefficients between the abnormal insular subregions FC values and pro-inflammatory cytokines levels in patients with BD II depression were calculated. RESULTS: The BD II depression group exhibited decreased FC between the right PI and the left postcentral gyrus, and increased FC between the left AI and the bilateral insula (extended to the right putamen) when compared with the HC group. Moreover, the patients with BD II depression showed higher IL-6 and TNF-α levels than HCs, and IL-6 level was negatively correlated with FC of the right PI to the left postcentral gyrus. CONCLUSIONS: Our results demonstrated that abnormal FC between the bilateral insula, and between the insula and sensorimotor areas in BD. Moreover, disrupted FC between the insula and sensorimotor areas was associated with elevated pro-inflammatory cytokine levels of IL-6 in BD.

Perforin Acts as an Immune Regulator to Prevent the Progression of NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is one of the main causes of cirrhosis and major risk factors for hepatocellular carcinoma and liver-related death. Despite substantial clinical and basic research, the pathogenesis of obesity-related NAFLD remains poorly understood. In this study, we show that perforin can act as an immune regulator to prevent the progression of NAFLD. Aged perforin-deficient (Prf-/-) mice have increased lipid accumulation in the liver compared to WT mice. With high-fat diet (HFD) challenge, Prf-/- mice have increased liver weight, more severe liver damage, and increased liver inflammation when compared with WT controls. Mechanistic studies revealed that perforin specifically regulates intrinsic IFN-γ production in CD4 T cells, not CD8 T cells. We found that CD4 T cell depletion reduces liver injury and ameliorates the inflammation and metabolic morbidities in Prf-/- mice. Furthermore, improved liver characteristics in HFD Prf-/- and IFN-γR-/- double knockout mice confirmed that IFN-γ is a key factor for mediating perforin regulation of NAFLD progression. Overall, our findings reveal the important regulatory role perforin plays in the progression of obesity-related NAFLD and highlight novel strategies for treating NAFLD.

Uric acid induces stress resistance and extends the life span through activating the stress response factor DAF-16/FOXO and SKN-1/NRF2.

Uric acid is a common metabolite found in mammals' serum. Recently, several metabolites have been identified that modulate aging, and uric acid levels are positively correlated with mammals' lifespan. However, the molecular mechanisms underlying this are largely undefined. Here we show that uric acid, an end product of purine metabolism, enhances the resistance of oxidative stress and extends the life span of Caenorhabditis elegans (C. elegans). We show that uric acid enhances a variety of pathways and leads to the upregulation of genes that are required for uric acid-mediated life span extension. We find that the transcription factors DAF-16/FOXO, SKN-1/NRF2 and HSF-1 contribute to the beneficial longevity conferred by uric acid. We also show that uric acid induced life span extension by regulating the reproductive signaling and insulin/IGF-1 signaling (IIS) pathways. In addition, we find that mitochondrial function plays an important role in uric acid-mediated life span extension. Taken together, these data suggest that uric acid prolongs the life span of C. elegans, in part, because of its antioxidative activity, which in turn regulates the IIS and the reproductive signaling pathways, thereby activating the function of the transcription factors DAF-16, HSF-1 and SKN-1.

Roles of mTORC1 and mTORC2 in controlling γδ T1 and γδ T17 differentiation and function.

The metabolism-controlled differentiation of αß T cells has been well documented; however, the role of a metabolism program in γδ T cell differentiation and function has not been clarified. Here, using CD2-cre; mTORC1 Raptor-f/f, and mTORC2 Rictor-f/f mice (KO mice), we found that mTORC1, but not mTORC2, was required for the proliferation and survival of peripheral γδ T cells, especially Vγ4 γδ T cells. Moreover, mTORC1 was essential for both γδ T1 and γδ Τ17 differentiation, whereas mTORC2 was required for γδ T17, but not for γδ Τ1, differentiation. We further studied the underlying molecular mechanisms and found that depletion of mTORC1 resulted in the increased expression of SOCS1, which in turn suppressed the key transcription factor Eomes, consequentially reducing IFN-γ production. Whereas the reduced glycolysis resulted in impaired γδ Τ17 differentiation in Raptor KO γδ T cells. In contrast, mTORC2 potentiated γδ Τ17 induction by suppressing mitochondrial ROS (mitoROS) production. Consistent with their cytokine production profiles, the Raptor KO γδ T cells lost their anti-tumor function both in vitro and in vivo, whereas both Raptor and Rictor KO mice were resistant to imiquimod (IMQ)-induced psoriasis-like skin pathogenesis. In summary, we identified previously unknown functions of mTORC1 and mTORC2 in γδ T cell differentiation and clarified their divergent roles in mediating the activity of γδ T cells in tumors and autoimmunity.

Intermediate metabolites of the pyrimidine metabolism pathway extend the lifespan of C. elegans through regulating reproductive signals.

The pyrimidine metabolism pathway has important biological functions; it not only maintains appropriate pyrimidine pools but also produces bioactive intermediate metabolites. In a previous study, we identified that the pyrimidine metabolism pathway is associated with aging regulation. However, the molecular mechanism by which the pyrimidine metabolism pathway regulates aging remains unclear. Here, we investigated the longevity effect of pyrimidine intermediates on Caenorhabditis elegans (C. elegans). Our results demonstrated that the supplementation of some pyrimidine intermediates could extend the lifespan of C. elegans. In addition, the RNAi knockdown of essential enzymes involved in pyrimidine metabolism could also significantly affect lifespan. We further investigated the molecular mechanism by which a representative intermediate metabolite, thymine, extends the lifespan of worms and found that thymine-induced longevity required the nuclear receptors DAF-12 and NHR-49, and the transcription factor DAF-16/FOXO. Further pathway analysis revealed that the longevity effect of thymine depended on the inhibition of reproductive signals. Additionally, we found that other pyrimidine intermediates functioned in a manner similar to thymine to prolong lifespan in C. elegans. Taken together, our results revealed that pyrimidine intermediates increased lifespan by inhibiting reproductive signals and subsequently inducing the function of DAF-12, NHR-49 and DAF-16 in C. elegans.

NK007 helps in mitigating paclitaxel resistance through p38MAPK activation and HK2 degradation in ovarian cancer.

Ovarian cancer resistance to available medicines is a huge challenge in dire need of a solution, which makes its recurrence and mortality rate further exacerbated. A promising approach to overcome chemoresistance is drug screening from natural products. Here, we report that NK007, a (±)-tylophorine malate isolated from the Asclepiadaceae family, selectively inhibited the proliferation of A2780 and A2780 (Taxol) cells and migration of paclitaxel-sensitive and -resistant ovarian cancer cells. Interestingly, the decline of cell viability, including cell multiplication, clonality, and migration capacity was independent on cell apoptosis. At the molecular level, NK007 considerably induced G1/S arrest and upregulated the expression of phospho-p38 mitogen-activated protein kinase (p-p38MAPK). In addition, hexokinase 2 (HK2) protein degradation was considerably elevated in the presence of NK007, which resulted in the reduction of oxygen consumption rate and extracellular acidification rate. Altogether, our results indicate that NK007, an analog of tylophorine, can overcome paclitaxel (PTX) resistance through p38MAPK activation and HK2 degradation. As an effective, alternative antiresistance agent, NK007 exhibits a promising potential to treat PTX-resistant ovarian cancer.

Mitochondrial ROS activate interleukin-1ß expression in allergic rhinitis.

Allergic rhinitis (AR) is the most common cause of inflammation of the nasal mucosa. It is also the most common form of non-infectious rhinitis associated with an immunoglobulin E (IgE)-mediated immune response against allergens. Previous studies have indicated that interleukin-1ß (IL-1ß) has a pathological role in the development of allergic asthma. The present study was designed to assess whether IL-1ß participates in the pathogenesis of AR. A total of 45 patients with AR were enrolled in the present study and were identified to have increased IL-1ß expression expressed by peripheral blood mononuclear cells (PBMCs), and the mitochondrial reactive oxygen species (ROS) and NLRP3 are required for IL-1ß synthesis in monocytes/macrophages and PBMCs from patients with AR. The levels of IL-1ß and interleukin-17 (IL-17) were increased in patients with AR and were positively correlated with each other. The results of the present study suggested that patients with AR have raised mitochondrial ROS levels, which may upregulate the expression of IL-1ß, affecting IL-17-production and serving a role in the pathogenesis of AR.

Transmembrane domain dependent inhibitory function of FcγRIIB.

FcγRIIB, the only inhibitory IgG Fc receptor, functions to suppress the hyper-activation of immune cells. Numerous studies have illustrated its inhibitory function through the ITIM motif in the cytoplasmic tail of FcγRIIB. However, later studies revealed that in addition to the ITIM, the transmembrane (TM) domain of FcγRIIB is also indispensable for its inhibitory function. Indeed, recent epidemiological studies revealed that a non-synonymous single nucleotide polymorphism (rs1050501) within the TM domain of FcγRIIB, responsible for the I232T substitution, is associated with the susceptibility to systemic lupus erythematosus (SLE). In this review, we will summarize these epidemiological and functional studies of FcγRIIB-I232T in the past few years, and will further discuss the mechanisms accounting for the functional loss of FcγRIIB-I232T. Our review will help the reader gain a deeper understanding of the importance of the TM domain in mediating the inhibitory function of FcγRIIB and may provide insights to a new therapeutic target for the associated diseases.

Correction: Forkhead Box C1 Regulates Human Primary Keratinocyte Terminal Differentiation.

[This corrects the article DOI: 10.1371/journal.pone.0167392.].

γδ T cells provide the early source of IFN-γ to aggravate lesions in spinal cord injury.

Immune responses and neuroinflammation are critically involved in spinal cord injury (SCI). γδ T cells, a small subset of T cells, regulate the inflammation process in many diseases, yet their function in SCI is still poorly understood. In this paper, we demonstrate that mice deficient in γδ T cells (TCRδ-/- ) showed improved functional recovery after SCI. γδ T cells are detected at the lesion sites within 24 hours after injury and are predominantly of the Vγ4 subtype and express the inflammatory cytokine IFN-γ. Inactivating IFN-γ signaling in macrophages results in a significantly reduced production of proinflammatory cytokines in the cerebrospinal fluid (CSF) of mice with SCIs and improves functional recovery. Furthermore, treatment of SCI with anti-Vγ4 antibodies has a beneficial effect, similar to that obtained with anti-TNF-α. In SCI patients, γδ T cells are detected in the CSF, and most of them are IFN-γ positive. In conclusion, manipulation of γδ T cell functions may be a potential approach for future SCI treatment.

Long-term consumption of caffeine-free high sucrose cola beverages aggravates the pathogenesis of EAE in mice.

Epidemiological data provide strong evidence of dramatically increasing incidences of many autoimmune diseases in the past few decades, mainly in western and westernized countries. Recent studies clearly revealed that 'Western diet' increases the risk of autoimmune diseases at least partially via disrupting intestinal tight junctions and altering the construction and metabolites of microbiota. However, the role of high sucrose cola beverages (HSCBs), which are one of the main sources of added sugar in the western diet, is barely known. Recently, a population study showed that regular consumption of sugar-sweetened beverages is associated with increased risk of seropositive rheumatoid arthritis in women, which provokes interest in the genuine effects of these beverages on the pathogenesis of autoimmune diseases and the underlying mechanisms. Here we showed that long-term consumption of caffeine-free HSCBs aggravated the pathogenesis of experimental autoimmune encephalomyelitis in mice in a microbiota-dependent manner. Further investigation revealed that HSCBs altered community structure of microbiota and increased Th17 cells. High sucrose consumption had similar detrimental effects while caffeine contamination limited the infiltrated pathogenic immune cells and counteracted these effects. These results uncovered a deleterious role of decaffeinated HSCBs in aggravating the pathogenesis of experimental autoimmune encephalomyelitis in mice.

Forkhead Box C1 Regulates Human Primary Keratinocyte Terminal Differentiation.

The epidermis serves as a critical protective barrier between the internal and external environment of the human body. Its remarkable barrier function is established through the keratinocyte (KC) terminal differentiation program. The transcription factors specifically regulating terminal differentiation remain largely unknown. Using a RNA-sequencing (RNA-seq) profiling approach, we found that forkhead box c 1 (FOXC1) was significantly up-regulated in human normal primary KC during the course of differentiation. This observation was validated in human normal primary KC from several different donors and human skin biopsies. Silencing FOXC1 in human normal primary KC undergoing differentiation led to significant down-regulation of late terminal differentiation genes markers including epidermal differentiation complex genes, keratinization genes, sphingolipid/ceramide metabolic process genes and epidermal specific cell-cell adhesion genes. We further demonstrated that FOXC1 works down-stream of ZNF750 and KLF4, and upstream of GRHL3. Thus, this study defines FOXC1 as a regulator specific for KC terminal differentiation and establishes its potential position in the genetic regulatory network.

SLC25A13 cDNA cloning analysis using peripheral blood lymphocytes facilitates the identification of a large deletion mutation: Molecular diagnosis of an infant with neonatal intrahepatic cholestasis caused by citrin deficiency.

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is an autosomal recessive disorder resulting from biallelic mutations of the SLC25A13 gene. Due to the lack of well­recognized clinical or biochemical diagnostic criteria, the definitive diagnosis of this disease relies on the genetic analysis of SLC25A13 at present. As novel large deletion/insertion mutations of the SLC25A13 gene are difficult to detect using routine DNA analytic approaches, the timely diagnosis of patients with these types of mutations remains a challenge. The present study aimed to examine SLC25A13 mutations in an infant with a suspected diagnosis of NICCD. DNA was extracted from blood samples, and SLC25A13 mutations were examined by screening for high­frequency mutations and Sanger sequencing. Reverse transcription-polymerase chain reaction and cDNA cloning analyses were then performed using peripheral blood lymphocytes (PBLs) to identify the obscure mutation. The results demonstrated that the infant was heterozygous for a paternally­inherited mutation, c.851_854del4, and a maternally­inherited large deletion, c.1019_1177+893del, which has not been reported previously. A positive diagnosis of NICCD was made, and the infant responded favorably to a galactose­free and medium­chain triglyceride­enriched formula. The present study confirmed the effectiveness of this formula in NICCD therapy, enriched the SLC25A13 mutational spectrum and supported the feasibility of cDNA cloning analysis using PBLs as a molecular tool for facilitating the identification of large SLC25A13 deletions.

mTOR inhibition potentiates cytotoxicity of Vγ4 γδ T cells via up-regulating NKG2D and TNF-α.

γδ T cells play a critical role in early anti-tumor immunity and perform cytotoxicity via NKG2D for recognition and multiple cytotoxic factors for tumor killing. Recent studies have demonstrated pivotal roles of mTOR-mediated metabolism in the maturation, differentiation, and effector function of diverse immune cells, including DCs, NK cells, CD4+ T cell subsets, and CD8+ T cells, but the role of mTOR signaling in γδ T cells is barely known. Here, we showed that suppressing mTOR signaling in in vitro-expanded Vγ4 γδ T cells via the mechanistic inhibitor rapamycin enhanced their cytotoxicity against multiple tumor cell lines, and these cells performed better tumor-suppressing effects upon adoptive therapy. Further investigation revealed that elevated cytotoxicity was a result of up-regulation of NKG2D and TNF-α. Moreover, rapamycin treatment significantly decreased the expression of CISH and increased pSTAT5. The inhibition of STAT5 pathways via siRNA interference or a specific inhibitor eliminated the up-regulation of NKG2D and TNF-α in rapamycin-treated Vγ4 γδ T cells. These results uncovered an important role of mTOR signaling in the cytotoxic effector function of γδ T cells and provided a potential strategy to improve γδ T cell-based cancer immunotherapy.