IFNγ is a Key Link between Obesity and Th1-Mediated AutoImmune Diseases

The role of the host-microbiome and metabolomics in sarcoidosis

Sarcoidosis is a complex inflammatory fibrotic disease that affects multiple organ systems. It is characterized by the infiltration of lymphocytes and mononuclear phagocytes, which form non-caseating granulomas in affected organs. The lungs and intrathoracic lymph nodes are the most commonly affected organs. The underlying cause of sarcoidosis is unknown, but it is believed to occur in genetically predisposed individuals who are exposed to pathogenic organisms, environmental contaminants, or self and non-self-antigens. Recent research has suggested that the microbiome may play a role in the development of respiratory conditions, including sarcoidosis. Additionally, metabolomic studies have identified potential biomarkers for monitoring sarcoidosis progression. This review will focus on recent microbiome and metabolomic findings in sarcoidosis, with the goal of shedding light on the pathogenesis and possible diagnostic and therapeutic approaches.

D-Allulose Ameliorates Dysregulated Macrophage Function and Mitochondrial NADH Homeostasis, Mitigating Obesity-Induced Insulin Resistance

D-allulose, a rare sugar, has been proposed to have potential benefits in addressing metabolic disorders such as obesity and type 2 diabetes (T2D). However, the precise mechanisms underlying these effects remain poorly understood. We aimed to elucidate the mechanisms by which D-allulose influences obesity-induced insulin resistance. We conducted gene set enrichment analysis on the liver and white adipose tissue of mice exposed to a high-fat diet (HFD) along with the white adipose tissue of individuals with obesity. Our study revealed that D-allulose effectively suppressed IFN-γ, restored chemokine signaling, and enhanced macrophage function in the livers of HFD-fed mice. This implies that D-allulose curtails liver inflammation, alleviating insulin resistance and subsequently impacting adipose tissue. Furthermore, D-allulose supplementation improved mitochondrial NADH homeostasis and translation in both the liver and white adipose tissue of HFD-fed mice. Notably, we observed decreased NADH homeostasis and mitochondrial translation in the omental tissue of insulin-resistant obese subjects compared to their insulin-sensitive counterparts. Taken together, these results suggest that supplementation with allulose improves obesity-induced insulin resistance by mitigating the disruptions in macrophage and mitochondrial function. Furthermore, our data reinforce the crucial role that mitochondrial energy expenditure plays in the development of insulin resistance triggered by obesity.

Chronic inflammation in high-fat diet-fed mice: Unveiling the early pathogenic connection between liver and adipose tissue

Obesity-induced chronic inflammation has been linked to several autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. The underlying mechanisms are not yet fully understood, but it is believed that chronic inflammation in adipose tissue can lead to the production of pro-inflammatory cytokines and chemokines, which can trigger immune responses and contribute to the development of autoimmune diseases. However, the underlying mechanisms that lead to the infiltration of immune cells into adipose tissue are not fully understood. In this study, we observed a time-dependent response to a high-fat diet in the liver and epididymal white adipose tissue using gene set enrichment analysis. Our findings revealed a correlation between early abnormal innate immune responses in the liver and late inflammatory response in the adipose tissue, that eventually leads to systemic inflammation. Specifically, our data suggest that the dysregulated NADH homeostasis in the mitochondrial matrix, interacting with the mitochondrial translation process, could serve as a sign marking the transition from liver inflammation to adipose tissue inflammation. Taken together, our study provides valuable insights into the molecular mechanisms underlying the development of chronic inflammation and associated autoimmune diseases in obesity.

Luteolin attenuates acute liver allograft rejection in rats by inhibiting T cell proliferation and regulating T cell subsets

Allograft rejection continues to be a significant cause of morbidity and graft failure for liver transplant recipients. Existing immunosuppressive regimens have many drawbacks, thus safe and effective long-term immunosuppressive regimens are still required. Luteolin (LUT), a natural component found in many plants, has a variety of biological and pharmacological effects and shows good anti-inflammatory activity in inflammatory and autoimmune diseases. Nevertheless, it remains unclear how it affects acute organ rejection after allogeneic transplantation. In this study, a rat liver transplantation model was constructed to investigate the effect of LUT on acute rejection of organ allografts. We found that LUT significantly protected the structure and function of liver grafts, prolonged recipient rat survival, ameliorated T cell infiltration, and downregulated proinflammatory cytokines. Moreover, LUT inhibited the proliferation of CD4+ T cells and Th cell differentiation but increased the proportion of Tregs, which is the key to its immunosuppressive effect. In vitro, LUT also significantly inhibited CD4+ T cell proliferation and Th1 differentiation. There may be important implications for improving immunosuppressive regimens for organ transplantation as a result of this discovery.

Leptin regulates thymic plasmacytoid dendritic cell ability to influence the thymocyte distribution in vitro

Leptin, the adipocyte-derived hormone, involved in regulating food intake and body weight, plays an important role in immunity and reproduction. Leptin signals via the specific membrane receptors expressed in most types of immune cells including dendritic cells (DCs) and thymocytes. Leptin enhances thymopoiesis and modulates T-cell-mediated immunity. Thymic plasmacytoid DCs (pDCs) are predominated in the thymus. They play an important role in thymocyte differentiation. We have analyzed whether leptin mediates its effects on human thymocytes by influencing on pDCs. We used leptin at concentration corresponding to its level during II-III trimesters of physiological pregnancy. We cultivated leptin-primed pDCs with autologous thymocytes and estimated the main thymocyte subsets expressing αβ chains of the T-cell receptor (αβTCR), natural regulatory T-cells (tTreg), natural T-helpers producing interleukin-17 (nTh17) and invariant natural killer T-cells (iNKT) in vitro. We have shown that leptin augmented CD86, CD276 expressions and depressed IL-10 productions by pDCs. Leptin-primed pDCs decreased the percentage of CD4⁺CD8⁺αβTCR⁺ thymocytes, increased CD4^hiCD8^-/loαβTCR⁺ cells. pDCs cultivated with leptin decreased the number of iNKT precursors, and did not change the number of tTreg and nTh17 precursors. Thus, leptin's important role in regulation of thymic pDC abilities to influence on the thymocyte distribution was indicated in vitro.

Low vitamin D concentrations and BMI are causal factors for primary biliary cholangitis: A mendelian randomization study

Backgrounds

Observational studies have identified associations between smoking, alcohol use, body mass index (BMI), and the levels of vitamin D with primary biliary cholangitis (PBC). However, there was a lack of randomization control studies to estimate the causal relationship. This study was to investigate the causal estimates for the effects of those risk factors on PBC.

Methods

The genetic instrument variants were extracted from genome-wide association studies in European ancestry. Two-sample mendelian randomization (MR) and multivariable mendelian randomization were used to determine genetically causal estimates. Primary analyses consisted of random-effects and fix-mode inverse-variance-weighted methods, followed by secondary sensitivity analyses to verify the results.

Results

Our study showed that BMI was a causal factor for PBC (OR 1.35; 95% CI=1.03-1.77; p=0.029). In addition, we found that serum vitamin D levels had a protective effect on PBC after adjusting for BMI (OR 0.51; 95% CI=0.32-0.84; p=0.007). However, we failed to identify evidence supporting that genetic causal effect of smoking and alcohol intake were associated with PBC in European countries.

Conclusion

Our results enriched findings from previous epidemiology studies and provided evidence from MR that serum vitamin D concentrations and BMI were independent causal factors for PBC, suggesting that ensuing vitamin D sufficiency and healthy lifestyles might be a cost-effective measure for early intervention for PBC.

Extra virgin olive oil extract rich in secoiridoids induces an anti-inflammatory profile in peripheral blood mononuclear cells from obese children

Obesity represents an important public health challenge of the twenty first century reaching epidemic proportions worldwide; this is especially true for the pediatric population. In this context, bioactive compounds from foods are crucial to counteract chronic inflammation as a typical feature of obesity. In particular, extra virgin olive oil (EVOO) is one of the most important functional foods exerting, among others, an anti-inflammatory activity not only due to its major (monounsaturated fatty acids) but also to its minor (phenolics) components, as reported in the last years. However, only a limited number of studies were performed on pediatric population, and even fewer are those focusing on EVOO phenolics that investigate the correlation of the chemical characterization with the biological function. Thus, starting from our in vitro data identifying an EVOO chemical profile characterized by a high content of secoiridoids correlating with an anti-inflammatory effect, we studied the ability of an EVOO extract with the same chemical profile to retain this function ex vivo. Specifically, peripheral blood mononuclear cells (PBMCs) collected from obese children were treated with EVOO and olive oil extracts, characterized by a low polyphenol content, to study the ability of secoiridoids to dampen the inflammatory response. A reduction of pro-inflammatory CD14⁺CD16⁺ monocytes was detected by cytofluorimetric analysis when PBMCs were treated with EVOO as compared to olive oil extracts. According to this, a down modulation of CCL2 and CCL4 chemokines involved in the recruitment of inflammatory cells, was reported in the supernatants of EVOO relative to olive oil extracts treated PBMCs. Moreover, a high-throughput gene expression analysis revealed that PBMCs molecular profile from obese children is greatly modulated after the treatment with EVOO extract in terms of metabolic and inflammatory pathways. Importantly, some of the significantly modulated genes were involved in the pathways promoting the development of severe obesity. Overall, our ex vivo data demonstrated the ability of EVOO to reduce the inflammatory milieu of PBMCs from obese children both at protein and molecular levels. Of note, a good correlation between the EVOO chemical profile and the biological modulations in terms of anti-inflammatory activity was reported.

Dietary Habits in Japanese Patients with Alopecia Areata

Purpose

Alopecia areata (AA) is characterized by non-scarring, patchy hair loss caused by autoimmune reactions to anagen hair follicles. The pathogenesis of AA may be affected by the diet. However, the dietary habits of patients with AA have not been precisely examined. Therefore, the aim of this study was to investigate the dietary habits of patients with AA in comparison to those of healthy controls.

Patients and Methods

We evaluated the dietary habits of 70 adult Japanese patients with AA using a brief-type self-administered diet history questionnaire and compared them to the habits of age- and sex-matched healthy controls.

Results

Japanese patients with AA had a higher body mass index (BMI) and higher intakes of vitamin C and fruit than the controls. Logistic regression analysis showed that AA was associated with BMI. Retinol intake was positively correlated with severity of alopecia tool (SALT) score, and linear regression analysis revealed that retinol intake was a predictor of SALT score. Retinol intake among patients with moderate to severe AA (ie, a SALT score >25) was higher than that in patients with mild AA (a SALT score ≤25). The mean age of AA patients with atopic dermatitis (AD) was lower than that of AA patients without AD; however, there were no differences in nutrient or food intake between these two groups. Logistic regression analysis showed that the comorbidity AD was negatively associated with age.

Conclusion

AA was associated with a high BMI, and high retinol intake was a predictor of SALT score. Further studies should be conducted to clarify whether dietary intervention to reduce BMI or limit retinol intake can alter the development or severity of AA.

Transglutaminase 2 mediates transcriptional regulation through BAF250a polyamination

BACKGROUND

Transglutaminase 2 (TG2) mediates protein modifications by crosslinking or by incorporating polyamine in response to oxidative or DNA-damaging stress, thereby regulating apoptosis, extracellular matrix formation, and inflammation. The regulation of transcriptional activity by TG2-mediated histone serotonylation or by Sp1 crosslinking may also contribute to cellular stress responses.

OBJECTIVE

In this study, we attempted to identify TG2-interacting proteins to better understand the role of TG2 in transcriptional regulation.

METHODS

Using a yeast two-hybrid assay to screen a HeLa cell cDNA library, we found that TG2 bound BAF250a, a core subunit of the cBAF chromatin remodeling complex, through an interaction between the TG2 barrel 1 and BAF250a C-terminal domains.

RESULTS

TG2 was pulled down with a GST-BAF250a C-term fusion protein. Moreover, TG2 and BAF250a were co-fractionated using P11 chromatography, and co-immunoprecipitated. A transamidation reaction showed that TG2 mediated incorporation of polyamine into BAF250a. In glucocorticoid response-element reporter-expressing cells, TG2 overexpression increased the luciferase reporter activity in a transamidation-dependent manner. In addition, a comparison of genome-wide gene expression between wild-type and TG2-deficient primary hepatocytes in response to dexamethasone treatment showed that TG2 further enhanced or suppressed the expression of dexamethasone-regulated genes that were identified by a gene ontology enrichment analysis.

CONCLUSION

Thus, our results indicate that TG2 regulates transcriptional activity through BAF250a polyamination.