B cell activation factor (BAFF) is a novel adipokine that links obesity and inflammation

Immune system dysregulation in the pathogenesis of non-alcoholic steatohepatitis: unveiling the critical role of T and B lymphocytes

Non-alcoholic fatty liver disease (NAFLD), characterized by the excessive accumulation of fat within the cytoplasm of hepatocytes (exceeding 5% of liver weight) in individuals without significant alcohol consumption, has rapidly evolved into a pressing global health issue, affecting approximately 25% of the world population. This condition, closely associated with obesity, type 2 diabetes, and the metabolic syndrome, encompasses a spectrum of liver disorders ranging from simple steatosis without inflammation to non-alcoholic steatohepatitis (NASH) and cirrhotic liver disease. Recent research has illuminated the complex interplay between metabolic and immune responses in the pathogenesis of NASH, underscoring the critical role played by T and B lymphocytes. These immune cells not only contribute to necroinflammatory changes in hepatic lobules but may also drive the onset and progression of liver fibrosis. This narrative review aims to provide a comprehensive exploration of the effector mechanisms employed by T cells, B cells, and their respective subpopulations in the pathogenesis of NASH. Understanding the immunological complexity of NASH holds profound implications for the development of targeted immunotherapeutic strategies to combat this increasingly prevalent and burdensome metabolic liver disease.

Effects of belimumab on the lipid profile in systemic lupus erythematosus patients: an observational study

This study is asked to investigate the effects of belimumab on the lipid profile in systemic lupus erythematosus (SLE) patients. Forty-one SLE patients who received at least 6 months of belimumab treatment were retrospectively analyzed. The control group consisted of 56 age- and sex-matched lupus patients not treated with belimumab. The changes in lipid profile after a 6-month treatment were compared between the two groups. Generalized estimating equation (GEE) analyses were performed to examine lipid levels longitudinally during the period and the effect of clinical response variables and medication on the lipid profile in the belimumab group. In the belimumab group, high-density lipoprotein (HDL) cholesterol levels increased significantly after the 6-month treatment (P = 0.02). After 1 month, HDL, apolipoprotein A-I (apoA-I) significantly increased by 13.8 and 11.4%, compared with baseline, respectively. After 3 months, HDL and apoA-I increased by 9.0 and 7.1%, respectively. After 6 months, HDL increased by 7.6% compared with baseline. Total cholesterol, triglycerides, low-density lipoprotein cholesterol, and apolipoprotein B did not change significantly over the course of treatment. GEE analyses indicated a significant association between HDL and disease activity indexes, such as IgG, anti-dsDNA, and complement C3. Subgroup analysis revealed significant changes in HDL only in patients who had achieved a ≥ 4-point reduction in SLEDAI-2 K after 6 months of belimumab treatment. Belimumab treatment may result in a long-term increase in HDL level in SLE patients by improving control of lupus activity. This might have beneficial effects on controlling cardiovascular risk in lupus patients. Key Points • Treatment with belimumab resulted in a significant and sustained increase in the HDL levels in SLE patients. • Significant changes in HDL were observed in lupus patients treated with belimumab who had a better clinical response.

Molecular Basis of Cerebral Vasospasm: What Can We Learn from Transcriptome and Temporal Gene Expression Profiling in Intracranial Aneurysm?

Cerebral vasospasm (CV) is a significant complication following aneurysmal subarachnoid hemorrhage (aSAH), and lacks a comprehensive molecular understanding. Given the temporal trajectory of intracranial aneurysm (IA) formation, its rupture, and development of CV, altered gene expression might be a molecular substrate that runs through these clinical events, influencing both disease inception and progression. Utilizing RNA-Seq, we analyzed tissue samples from ruptured IAs with and without vasospasm to identify the dysregulated genes. In addition, temporal gene expression analysis was conducted. We identified seven dysregulated genes in patients with ruptured IA with vasospasm when compared with those without vasospasm. We found 192 common genes when the samples of each clinical subset of patients with IA, that is, unruptured aneurysm, ruptured aneurysm without vasospasm, and ruptured aneurysm with vasospasm, were compared with control samples. Among these common genes, TNFSF13B, PLAUR, OSM, and LAMB3 displayed temporal expression (progressive increase) with the pathological progression of disease that is formation of aneurysm, its rupture, and consequently the development of vasospasm. We validated the temporal gene expression pattern of OSM at both the transcript and protein levels and OSM emerges as a crucial gene implicated in the pathological progression of disease. In addition, RSAD2 and ATP1A2 appear to be pivotal genes for CV development. To the best of our knowledge, this is the first study to compare the transcriptome of aneurysmal tissue samples of aSAH patients with and without CV. The findings collectively provide new insights on the molecular basis of IA and CV and new leads for translational research.

HMGB1 mediates microbiome-immune axis dysregulation underlying reduced neutralization capacity in obesity-related post-acute sequelae of SARS-CoV-2

While obesity is a risk factor for post-acute sequelae of SARS-CoV-2 infection (PASC, "long-COVID"), the mechanism(s) underlying this phenomenon remains poorly understood. To address this gap in knowledge, we performed a 6-week longitudinal study to examine immune activity and gut microbiome dysbiosis in post-acute stage patients recovering from SARS-CoV-2 infection. Self-reported symptom frequencies and blood samples were collected weekly, with plasma assessed by ELISA and Luminex for multiple biomarkers and immune cell profiling. DNA from stool samples were collected at the early stage of recovery for baseline assessments of gut microbial composition and diversity using 16S-based metagenomic sequencing. Multiple regression analyses revealed obesity-related PASC linked to a sustained proinflammatory immune profile and reduced adaptive immunity, corresponding with reduced gut microbial diversity. In particular, enhanced signaling of the high mobility group box 1 (HMGB1) protein was found to associate with this dysregulation, with its upregulated levels in plasma associated with significantly impaired viral neutralization that was exacerbated with obesity. These findings implicate HMGB1 as a candidate biomarker of PASC, with potential applications for risk assessment and targeted therapies.

B-cell-activating factor (BAFF) and platelet-activating factor (PAF) in pregnancies complicated by maternal obesity and diabetes: a preliminary study

OBJECTIVE

In pregnancies complicated by maternal obesity and diabetes, a disruption in inflammatory mediators occurs, resulting in endothelial microvascular dysfunction, oxidative stress, tissue damage, and maternal and feto-neonatal complications. To outline this proinflammatory status, an innovative approach is represented by the measurement of proinflammatory cytokines. Among these biomarkers, B-cell-activating factor (BAFF) and platelet-activating factor (PAF) play a key role in metabolic regulation, immune response to infections, tissue homeostasis, and "food-related inflammation." The aim of the present study is to investigate the blood expression of BAFF and PAF in a cohort of pregnant women affected by obesity and diabetes compared with a control group of healthy pregnant women.

METHODS

A prospective longitudinal cohort study has been conducted on pregnant women referred to Fondazione Policlinico Universitario Gemelli IRCCS in Rome. For each pregnant woman, a capillary sample was collected with a swab in three different consecutive evaluations carried out in the three trimesters of pregnancy.

RESULTS

A total of 77 pregnant women have been enrolled. No significant differences in BAFF and PAF levels were longitudinally observed between groups. Focusing on the exposed group, in the third trimester of pregnancy, both PAF and BAFF levels were lower than the basal time. Among the selected group of patients who developed Gestational Diabetes, only PAF values were longitudinally lower when compared to other groups. The multivariate analysis showed that BAFF levels were positively correlated with thyroid-stimulating hormone levels. No macrosomia, no shoulder dystocia, no major perineal lacerations at birth, and no intrauterine growth restriction were observed in the whole population.

CONCLUSIONS

This study supports the involvement of metabolic and proinflammatory biomarkers in the mechanisms related to pregnancy complications. Improving a good metabolic environment for obese and diabetic pregnant women could break the vicious cycle connecting inflammation, oxidative stress, and metabolic disorders.

Interaction Between Adipocytes and B Lymphocytes in Human Metabolic Diseases

Diseases associated with the disorders of carbohydrate and lipid metabolism are widespread in the modern world. Interaction between the cells of adipose tissue - adipocytes - and immune system cells is an essential factor in pathogenesis of such diseases. Long-term increase in the glucose and fatty acid levels leads to adipocyte hypertrophy and increased expression of pro-inflammatory cytokines and adipokines by these cells. As a result, immune cells acquire a pro-inflammatory phenotype, and new leukocytes are recruited. Inflammation of adipose tissue leads to insulin resistance and stimulates formation of atherosclerotic plaques and development of autoimmunity. New studies show that different groups of B lymphocytes play an essential role in regulation of adipose tissue inflammation. Decrease in the number of B-2 lymphocytes suppresses development of a number of metabolic diseases, whereas decreased numbers of the regulatory B lymphocytes and B-1 lymphocytes are associated with more severe pathology. Recent studies showed that adipocytes influence B lymphocyte activity both directly and by altering activity of other immune cells. These findings provide better understanding of the molecular mechanisms of human pathologies associated with impaired carbohydrate and lipid metabolism, such as type 2 diabetes mellitus.

Subclinical Atherosclerosis Is Associated with Discrepancies in BAFF and APRIL Levels and Altered Breg Potential of Precursor-like Marginal Zone B-Cells in Long-Term HIV Treated Individuals

Chronic inflammation persists in people living with HIV (PLHIV) despite antiretrovial therapy (ART) and is involved in their premature development of cardiovascular diseases (CVD) such as atherosclerosis. We have previously reported that an excess of “B-cell activating factor” (BAFF), an important molecule for the selection and activation of first-line Marginal Zone (MZ) B-cell populations, is associated with deregulations of precursor-like MZ (MZp), whose potent B-cell regulatory (Breg) capacities are altered in PLHIV, early on and despite 1−2 years of ART. Based on these observations, and growing evidence that MZ populations are involved in atherosclerosis control, we designed a cross sectional study to explore the associations between BAFF and its analogue “A proliferation-inducing ligand” (APRIL) with subclinical CVD in long-time-treated individuals of the Canadian HIV and Aging Cohort Study (CHACS) imaging sub-study group. We also characterized the Breg profile of MZp from the blood of these individuals. Results were correlated with the total volume of atherosclerotic plaques (TPV) and with CVD risk factors and biomarkers. TPV was measured using cardiac computerised tomography angiography, and presence of CVD was defined as TPV > 0. We report that blood levels of BAFF are elevated and correlate positively with CVD and its risk factors in PLHIV from the CHACS, in contrast to APRIL levels, which correlate negatively with these factors. The expression levels of Breg markers such as NR4A3, CD39, CD73 and CD83 are significantly lower in PLHIV when compared to those of HIV-uninfected controls. In vitro experiments show that APRIL upregulates the expression of Breg markers by blood MZp from HIV-uninfected individuals, while this modulation is dampened by the addition of recombinant BAFF. Altogether, our observations suggest that strategies viewed to modulate levels of BAFF and/or APRIL could eventually represent a potential treatment target for CVD in PLHIV.

Role of B Lymphocytes in the Pathogenesis of NAFLD: A 2022 Update

Non-alcoholic fatty liver disease and its related complications are becoming one of the most important health problems globally. The liver functions as both a metabolic and an immune organ. The crosstalk between hepatocytes and intrahepatic immune cells plays a key role in coordinating a dual function of the liver in terms of the protection of the host from antigenic overload as a result of receiving nutrients and gut microbiota antigenic stimulation via facilitating immunologic tolerance. B cells are the most abundant lymphocytes in the liver. The crucial role of intrahepatic B cells in energy metabolism under different immune conditions is now emerging in the literature. The accumulating evidence has demonstrated that the antibodies and cytokines produced by B cells in the microenvironment play key and distinct roles in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Herein, we have aimed to consolidate and update the current knowledge about the pathophysiological roles of B cells as well as the underlying mechanisms in energy metabolism. Understanding how B cells can exacerbate and suppress liver damage by exploiting the antibodies and cytokines they produce will be of great importance for designing B-cell targeting therapies to treat various liver diseases.

B-Cell Activating Factor Increases Related to Adiposity, Insulin Resistance, and Endothelial Dysfunction in Overweight and Obese Subjects

Obesity (OB) is a major healthcare problem that results from long-term energy imbalance. Adipokines and pro-inflammatory cytokines facilitate adipose tissue (AT) remodeling to safely store excess nutrients. B-cell activating factor (BAFF) is a newly described adipokine whose role in enhancing adipogenesis has been reported. The present study aimed to evaluate serum BAFF association with adiposity distribution, serum adipokines, pro-inflammatory cytokines, and metabolic and endothelial dysfunction markers. The study included 124 young Mexican adults with no diagnosed comorbidities, divided according to their BMI. Anthropometric measurements, blood counts, and serum molecules (i.e., glucose, lipid profile, insulin, leptin, pro- and anti-inflammatory cytokines, von Willebrand factor (vWF), and BAFF) were assessed. The analysis showed positive correlation between BAFF and increased fat mass in all anthropometric measurements (p < 0.0001). BAFF augmentation was related to systemic inflammatory environment (p < 0.05), and linked with insulin resistance status (p < 0.05). BAFF increment was also correlated with early endothelial damage markers such as vWF (p < 0.0001). Linear regression analysis showed a role for BAFF in predicting serum vWF concentrations (p < 0.01). In conclusion, our data show that BAFF is an adipokine dynamically related to OB progression, insulin resistance status, and systemic inflammatory environment, and is a predictor of soluble vWF augmentation, in young overweight and obese Mexican subjects.

Marginal Zone B-Cell Populations and Their Regulatory Potential in the Context of HIV and Other Chronic Inflammatory Conditions

Inflammation in the context of Human Immunodeficiency Virus (HIV) establishes early and persists beyond antiretroviral therapy (ART). As such, we have shown excess B-cell activating factor (BAFF) in the blood of HIV-infected progressors, as soon as in the acute phase, and despite successful ART. Excess BAFF was associated with deregulation of the B-cell compartment; notably, with increased frequencies of a population sharing features of both transitional immature (TI) and marginal zone (MZ) B-cells, we termed Marginal Zone precursor-like (MZp). We have reported similar observations with HIV-transgenic mice, Simian Immunodeficiency Virus (SIV)-infected macaques, and more recently, with HIV-infected Beninese commercial sex workers, which suggests that excess BAFF and increased frequencies of MZp B-cells are reliable markers of inflammation in the context of HIV. Importantly, we have recently shown that in healthy individuals, MZps present an important regulatory B-cell (Breg) profile and function. Herein, we wish to review our current knowledge on MZ B-cell populations, especially their Breg status, and that of other B-cell populations sharing similar features. BAFF and its analog A Proliferation-Inducing Ligand (APRIL) are important in shaping the MZ B-cell pool; moreover, the impact that excess BAFF—encountered in the context of HIV and several chronic inflammatory conditions—may exert on MZ B-cell populations, Breg and antibody producing capacities is a threat to the self-integrity of their antibody responses and immune surveillance functions. As such, deregulations of MZ B-cell populations contribute to autoimmune manifestations and the development of MZ lymphomas (MZLs) in the context of HIV and other inflammatory diseases. Therefore, further comprehending the mechanisms regulating MZ B-cell populations and their functions could be beneficial to innovative therapeutic avenues that could be deployed to restore MZ B-cell immune competence in the context of chronic inflammation involving excess BAFF.

An insight into major signaling pathways and protein-protein interaction networks involved in the pathogenesis of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with the increase of glucose in the blood rather than being absorbed by the cells. A better understanding of the signaling pathways is necessary to understand the pathophysiology of GDM. This study provides details about a series of signaling pathways and protein-protein interactions involved in the pathogenesis of GDM and their evaluations in GDM development. Protein-protein interactions were found between proteins of several signaling pathways that suggest interlink between these signaling pathways. Protein-protein interactions were generated with high confidence interaction scores based on textmining, co-occurrence, coexpression, neighborhood, gene fusion, experiments and databases. The dysregulation of signaling pathways may also contribute to the increased risk of complications associated with GDM in the mother and child. Further, studies on signaling pathways involved in the pathogenesis of GDM would help in the development of an effective intervention to prevent GDM along with the identification of key targets for effective therapies in the future. This article is protected by copyright. All rights reserved.

Non-alcoholic fatty liver disease: the interplay between metabolism, microbes and immunity

Non-alcoholic fatty liver disease (NAFLD) has emerged pandemically across the globe and particularly affects patients with obesity and type 2 diabetes. NAFLD is a complex systemic disease that is characterised by hepatic lipid accumulation, lipotoxicity, insulin resistance, gut dysbiosis and inflammation. In this review, we discuss how metabolic dysregulation, the gut microbiome, innate and adaptive immunity and their interplay contribute to NAFLD pathology. Lipotoxicity has been shown to instigate liver injury, inflammation and insulin resistance. Synchronous metabolic dysfunction, obesity and related nutritional perturbation may alter the gut microbiome, in turn fuelling hepatic and systemic inflammation by direct activation of innate and adaptive immune responses. We review evidence suggesting that, collectively, these unresolved exogenous and endogenous cues drive liver injury, culminating in liver fibrosis and advanced sequelae of this disorder such as liver cirrhosis and hepatocellular carcinoma. Understanding NAFLD as a complex interplay between metabolism, gut microbiota and the immune response will challenge the clinical perception of NAFLD and open new therapeutic avenues.

Implications of Inflammatory States on Dysfunctional Immune Responses in Aging and Obesity

Aging and obesity are two conditions characterized by chronic, low-grade inflammation. While both conditions are also associated with dysfunctional immune responses, the shared and distinct underlying mechanisms are just starting to be uncovered. In fact, recent findings have suggested that the effects of obesity on the immune system can be thought of as a state of accelerated aging. Here we propose that chronic, low-grade inflammation seen in obesity and aging is complex, affects multiple cell types, and results in an altered basal immune state. In aging, part of this altered state is the emergence of regulatory immune populations that lead to further immune dysfunction in an attempt to reduce chronic inflammation. While in obesity, part of the altered state is the effect of expanding adipose tissue on immune cell function. Thus, in this review, we compare, and contrast altered immune states in aging and obesity and discuss their potential contribution to a shared clinical problem- decreased vaccine responsiveness.

BAFF signaling in B cell metabolism

BAFF is an essential cytokine primarily known for its role in maintaining B cell homeostasis via induction of a pro-survival gene expression profile. Additionally, recent evidence suggests that BAFF induced signaling also drives a metabolic program that is needed for homeostatic cell mass maintenance in resting B cells and which increases the cells' capacity to divide. Many components of the signaling cascades initiated by BAFF, the alternative NFκB pathway and the PI3K/AKT/mTOR pathway, are active in roles beyond their classically assigned function. These components can directly or indirectly impact metabolic reprogramming. Further exploration of the role BAFF signaling plays in B cell metabolism could help to identify metabolic vulnerabilities of hyperactive B cells in the context of autoimmunity.

A BAFF/APRIL axis regulates obesogenic diet-driven weight gain

The impact of immune mediators on weight homeostasis remains underdefined. Interrogation of resistance to diet-induced obesity in mice lacking a negative regulator of Toll-like receptor signaling serendipitously uncovered a role for B cell activating factor (BAFF). Here we show that overexpression of BAFF in multiple mouse models associates with protection from weight gain, approximating a log-linear dose response relation to BAFF concentrations. Gene expression analysis of BAFF-stimulated subcutaneous white adipocytes unveils upregulation of lipid metabolism pathways, with BAFF inducing white adipose tissue (WAT) lipolysis. Brown adipose tissue (BAT) from BAFF-overexpressing mice exhibits increased Ucp1 expression and BAFF promotes brown adipocyte respiration and in vivo energy expenditure. A proliferation-inducing ligand (APRIL), a BAFF homolog, similarly modulates WAT and BAT lipid handling. Genetic deletion of both BAFF and APRIL augments diet-induced obesity. Lastly, BAFF/APRIL effects are conserved in human adipocytes and higher BAFF/APRIL levels correlate with greater BMI decrease after bariatric surgery. Together, the BAFF/APRIL axis is a multifaceted immune regulator of weight gain and adipose tissue function.

Transglutaminases and Obesity in Humans: Association of F13A1 to Adipocyte Hypertrophy and Adipose Tissue Immune Response

Transglutaminases TG2 and FXIII-A have recently been linked to adipose tissue biology and obesity, however, human studies for TG family members in adipocytes have not been conducted. In this study, we investigated the association of TGM family members to acquired weight gain in a rare set of monozygotic (MZ) twins discordant for body weight, i.e., heavy-lean twin pairs. We report that F13A1 is the only TGM family member showing significantly altered, higher expression in adipose tissue of the heavier twin. Our previous work linked adipocyte F13A1 to increased weight, body fat mass, adipocyte size, and pro-inflammatory pathways. Here, we explored further the link of F13A1 to adipocyte size in the MZ twins via a previously conducted TWA study that was further mined for genes that specifically associate to hypertrophic adipocytes. We report that differential expression of F13A1 (ΔHeavy-Lean) associated with 47 genes which were linked via gene enrichment analysis to immune response, leucocyte and neutrophil activation, as well as cytokine response and signaling. Our work brings further support to the role of F13A1 in the human adipose tissue pathology, suggesting a role in the cascade that links hypertrophic adipocytes with inflammation.

Nutritional status impacts dengue virus infection in mice

Background

Dengue virus (DENV) is estimated to infect 390 million people annually. However, few host factors that alter disease severity are known. Malnutrition, defined as both over- and undernutrition, is a growing problem worldwide and has long been linked to dengue disease severity by epidemiological and anecdotal observations. Accordingly, we sought to establish a mouse model to assess the impact of nutritional status on DENV disease severity.

Results

Using transiently immunocompromised mice, we established a model of mild dengue disease with measurable viremia. We then applied it to study the effects of healthy weight, obese, and low-protein diets representing normal, over-, and undernutrition, respectively. Upon infection with DENV serotype 2, obese mice experienced more severe morbidity in the form of weight loss and thrombocytopenia compared to healthy weight groups. Additionally, obesity altered cytokine expression following DENV infection. Although low protein-fed mice did not lose significant weight after DENV2 infection, they also experienced a reduction in platelets as well as increased spleen pathology and viral titers.

Conclusions

Our results indicate that obese or undernourished mice incur greater disease severity after DENV infection. These studies establish a role for nutritional status in DENV disease severity.

Immunological distinctions between nonalcoholic steatohepatitis and hepatocellular carcinoma

Nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease, ranges from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is a more aggressive form characterized by hepatocyte injury, inflammation, and fibrosis. Increasing evidence suggests that NASH is a risk factor for hepatocellular carcinoma (HCC), which is the fifth most common cancer worldwide and the second most common cause of cancer-related death. Recent studies support a strong mechanistic link between the NASH microenvironment and HCC development. The liver has a large capacity to remove circulating pathogens and gut-derived microbial compounds. Thus, the liver is a central player in immunoregulation. Altered immune responses are tightly associated with the development of NASH and HCC. The objective of this study was to differentiate the roles of specific immune cell subsets in NASH and HCC pathogenesis.

Clarifying the role of specific cells in the immune system in the transition from non-alcoholic fatty liver disease (NAFLD) to liver cancer will help to understand disease progression and may open avenues towards new preventive and therapeutic strategies. NAFLD is the most common chronic liver disease. Growing evidence suggests that its most aggressive form, non-alcoholic steatohepatitis (NASH), can promote the development of liver cancer, the second most common cause of cancer deaths worldwide. Chang-Woo Lee and colleagues at Sungkyunkwan University, Suwon, South Korea review the immunological distinction between NASH and liver cancer, focusing on the levels and activities of six key types of immune system cells. Chronic inflammation mediated by the immune system can create conditions for NAFLD, NASH and liver cancer to develop and worsen.

Ezh2 Ameliorates Osteoarthritis by Activating TNFSF13B

Epigenetic regulation is highly correlated with osteoarthritis (OA) development, whereas its role and detailed mechanisms remain elusive. In this study, we explored the expression of EZH2, an H3K27me3 transferase, in human OA cartilages and its roles in regulating OA pathogenesis. Here, we found EZH2 was highly expressed in both mice and human OA cartilage samples by using histological analysis and RNA sequencing (RNA-Seq). The medial meniscectomy (MMx) OA model results indicated the conditional knockout of Ezh2 deteriorated OA pathological conditions. Furthermore, we showed the positive role of Ezh2 in cartilage wound healing and inhibition of hypertrophy through activating TNFSF13B, a member of the tumor necrosis factor superfamily. Further, we also indicated that the effect of TNFSF13B, increased by Ezh2, might boost the healing of chondrocytes through increasing the phosphorylation of Akt. Taken together, our results uncovered an EZH2-positive subpopulation existed in OA patients, and that EZH2-TNFSF13B signaling was responsible for regulating chondrocyte healing and hypertrophy. Thus, EZH2 might act as a new potential target for OA diagnosis and treatment. © 2020 American Society for Bone and Mineral Research.

Methylglyoxal, Glycated Albumin, PAF, and TNF-α: Possible Inflammatory and Metabolic Biomarkers for Management of Gestational Diabetes

Background: In gestational diabetes mellitus (GDM), pancreatic β-cell breakdown can result from a proinflammatory imbalance created by a sustained level of cytokines. In this study, we investigated the role of specific cytokines, such as B-cell activating factor (BAFF), tumor necrosis factor α (TNF-α), and platelet-activating factor (PAF), together with methylglyoxal (MGO) and glycated albumin (GA) in pregnant women affected by GDM. Methods: We enrolled 30 women whose inflammation and metabolic markers were measured at recruitment and after 12 weeks of strict dietetic therapy. We compared these data to the data obtained from 53 randomly selected healthy nonpregnant subjects without diabetes, hyperglycemia, or any condition that can affect glycemic metabolism. Results: In pregnant women affected by GDM, PAF levels increased from 26.3 (17.4–47.5) ng/mL to 40.1 (30.5–80.5) ng/mL (p < 0.001). Their TNF-α levels increased from 3.0 (2.8–3.5) pg/mL to 3.4 (3.1–5.8) pg/mL (p < 0.001). The levels of methylglyoxal were significantly higher in the women with GDM (p < 0.001), both at diagnosis and after 12 weeks (0.64 (0.46–0.90) μg/mL; 0.71 (0.47–0.93) μg/mL, respectively) compared to general population (0.25 (0.19–0.28) μg/mL). Levels of glycated albumin were significantly higher in women with GDM (p < 0.001) only after 12 weeks from diagnosis (1.51 (0.88–2.03) nmol/mL) compared to general population (0.95 (0.63–1.4) nmol/mL). Conclusion: These findings support the involvement of new inflammatory and metabolic biomarkers in the mechanisms related to GDM complications and prompt deeper exploration into the vicious cycle connecting inflammation, oxidative stress, and metabolic results.

Circulatory levels of B-cell activating factor of the TNF family in patients with diabetic foot ulcer: Association with disease progression

Enhanced and prolonged expression of tumor necrosis factor alpha (TNF-α), a potent pro-inflammatory cytokine is evidenced during the chronic wound healing process of infected diabetic foot ulcer (IDFU). B-cell activating factor (BAFF) is the member of TNF-α family, which implicit in B-cell dysfunction. This study was aimed to evaluate the role of BAFF in diabetic foot ulcer (DFU) patients and to correlate its association with other family of inflammatory cytokines. Circulating levels of BAFF and other cytokines were measured in IDFU (n = 44) and non-IDFU patients (n = 40) using multiplexed bead-based cytokine immunoassay. A stepwise significant increase was observed in both circulatory BAFF and C-reactive protein (CRP) during the disease progression. The area under the receiver operating characteristic curve (AUC_ROC ) for BAFF was found to be high (0.89; [95% CI: 0.73-1.0]), when compared to CRP (0.68; [95% CI: 0.61-0.76]). Optimum diagnostic cutoff level for BAFF was found to be ≥2.35 pg/mL with 62.0% sensitivity and 85.7% specificity. Further, BAFF levels showed a significant positive correlation with CRP among IDFU patients. With respect to other family cytokines, BAFF levels were positively correlated with TNF-α, interferon family cytokines such as IFN-α2, IL-28A/IFN-λ2, IFN-γ, and IL-10 family cytokines such as IL-19, IL-22, and IL-26 and negatively correlated with IL-6 receptor family such as gp130/sIL-6Rβ. Hence, our data suggest that devising therapeutic strategies to reduce the levels of BAFF may contribute in amelioration of IDFU.

Type 2 diabetes - An autoinflammatory disease driven by metabolic stress

Type 2 diabetes has traditionally been viewed as a metabolic disorder characterised by chronic high glucose levels, insulin resistance, and declining insulin secretion from the pancreas. Modern lifestyle, with abundant nutrient supply and reduced physical activity, has resulted in dramatic increases in the rates of obesity-associated disease conditions, including diabetes. The associated excess of nutrients induces a state of systemic low-grade chronic inflammation that results from production and secretion of inflammatory mediators from the expanded pool of activated adipocytes. Here, we review the mechanisms by which obesity induces adipose tissue dysregulation, detailing the roles of adipose tissue secreted factors and their action upon other cells and tissues central to glucose homeostasis and type 2 diabetes. Furthermore, given the emerging importance of adipokines, cytokines and chemokines in disease progression, we suggest that type 2 diabetes should now be viewed as an autoinflammatory disease, albeit one that is driven by metabolic dysregulation.

TACI-Deficient Macrophages Protect Mice Against Metaflammation and Obesity-Induced Dysregulation of Glucose Homeostasis

Transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) is a receptor for the TNF superfamily cytokines, B cell-activating factor (BAFF), and A proliferation-inducing ligand (APRIL). Here, we demonstrate that TACI-deficient mice subjected to high-fat diet (HFD) are protected from weight gain and dysregulated glucose homeostasis. Resistance to HFD-induced metabolic changes in TACI-deficient mice does not involve TACI-mediated adipogenesis. Instead, accumulation of M2 macrophages (Mϕs), eosinophils, and type 2 innate lymphoid cells in visceral adipose tissue (VAT) is implicated in the protection from obesity-induced assaults. In support of this hypothesis, adoptively transferred TACI-deficient peritoneal or adipose tissue Mϕs, but not B cells, can improve glucose metabolism in the obese host. Interestingly, the transferred TACI-deficient Mϕs not only home to host VAT but also trigger the accumulation of host M2 Mϕs and eosinophils in VAT. The increase in host M2 Mϕs in VAT is likely a result of eosinophil recruitment in response to eotaxin-2 produced by TACI-deficient Mϕs. Insulin signaling experiments revealed that IL-10 secreted by TACI-deficient Mϕs is responsible for maintaining adipocyte insulin sensitivity. Thus, the adoptive transfer experiments offer a model where TACI-deficient Mϕs accumulate in VAT and protect against metaflammation and obesity-associated dysregulation of glucose metabolism.

Maternal Serum B-Cell Activating Factor Levels

Hypertensive disorders of pregnancy are a leading cause of maternal and perinatal morbidity and mortality. Early suppression of B-cell lymphopoiesis is necessary for a normal pregnancy. Dysregulation of factors critical to B-cell survival may result in pregnancy complications, including hypertension. In this prospective observational study at a single medical center, serum levels of BAFF (B-cell activating factor) were measured in pregnant participants at each trimester, at delivery, and postpartum and in nonpregnant controls at a single time point. Comparisons were made between nonpregnant and pregnant subjects and between time periods of pregnancy. First-trimester serum BAFF levels were further tested for association with hypertensive disorders of pregnancy. The study included 149 healthy pregnant women, 25 pregnant women with chronic hypertension, and 48 nonpregnant controls. Median first-trimester serum BAFF level (ng/mL) for healthy women (0.90) was lower than median serum BAFF levels for women with chronic hypertension (0.96; P =0.013) and controls (1.00; P =0.002). Serum BAFF levels steadily declined throughout pregnancy, with the median second-trimester level lower than the corresponding first-trimester level (0.77; P =0.003) and the median third-trimester level lower than the corresponding second-trimester level (0.72; P =0.025). The median first-trimester serum BAFF level was elevated in women who subsequently developed hypertension compared with women who remained normotensive (1.02 versus 0.85; P =0.012), with the area under the receiver operating characteristic curve being 0.709. First-trimester serum BAFF level may be an early and clinically useful predictor of hypertensive disorders of pregnancy.

Verification of B-lymphocyte activating factor's involvement in the exacerbation of insulin resistance as well as an autoimmune response in patients with nonalcoholic steatohepatitis and patients with HCV-related chronic liver disease

BACKGROUND

Ten to forty percent of nonalcoholic steatohepatitis (NASH) and HCV-related chronic liver disease (CLD-C) patients have antinuclear antibodies (ANAs). However, the relationship between autoimmune response and insulin resistance remains uncertain among those patients. The primary purpose of this study was to investigate whether or not ANA status was associated with the development of insulin resistance and obesity in NASH and CLD-C patients.

METHODS

Degrees of hepatic fibrosis and steatosis were evaluated by the classification proposed by Brunt et al. Obesity and insulin resistance were estimated by calculating body mass index and the value of homeostasis model of for assessment of insulin resistance (HOMA-IR), respectively. A revised scoring system was applied to the diagnosis of autoimmune hepatitis (AIH). Serum B-lymphocyte activating factor (BAFF) levels were determined, using an ELISA technique.

RESULTS

Ten of 25 (40%) NASH patients and 9 of 22 (41%) CLD-C patients had ANAs, though the titers were weak in most patients. Only one NASH patient met the category of "definite" AIH among the enrolled patients. Serum IgG levels were significantly higher in NASH and CLD-C patients with ANAs than in those without ANAs, and NASH and CLD-C patients with ANAs had significantly higher HOMA-IR values than those without ANAs (6.81 ± 3.36 vs. 4.00 ± 2.57, p = 0.0305, 3.01 ± 1.31 vs. 1.28 ± 0.50, p = 0.0011). CLD-C patients with ANAs had more advanced hepatic fibrosis and steatosis than those without ANAs, while ANA status was not associated with hepatic fibrosis or steatosis in NASH patients. Obesity was independent of ANA status in both subjects. Serum BAFF levels were significantly higher in CLD-C patients with ANAs than those in CLD-C patients without ANAs (1303 ± 268 vs. 714 ± 143 pg/ml, p = 0.0036). A close correlation between serum BAFF level and the HOMA-IR value was observed in CLD-C patients (r = 0.467, p = 0.0485).

CONCLUSION

Our data suggest that NASH and CLD-C patients with ANAs have more severe insulin resistance than those without ANAs. More advanced insulin resistance deriving from excessive BAFF production may result in severe hepatic fibrosis and steatosis in CLD-C patients with ANAs.

Cutting Edge: BAFF Overexpression Reduces Atherosclerosis via TACI-Dependent B Cell Activation

Patients with systemic lupus erythematosus exhibit accelerated atherosclerosis, a chronic inflammatory disease of the arterial wall. The impact of B cells in atherosclerosis is controversial, with both protective and pathogenic roles described. For example, natural IgM binding conserved oxidized lipid epitopes protect against atherosclerosis, whereas anti-oxidized low-density lipoprotein (oxLDL) IgG likely promotes disease. Because BAFF promotes B cell class-switch recombination and humoral autoimmunity, we hypothesized that excess BAFF would accelerate atherosclerosis. In contrast, BAFF overexpression markedly reduced hypercholesterolemia and atherosclerosis in hyperlipidemic mice. BAFF-mediated atheroprotection required B cells and was associated with increased protective anti-oxLDL IgM. Surprisingly, high-titer anti-oxLDL IgM production and reduced atherosclerosis was dependent on the BAFF family receptor transmembrane activator and CAML interactor. In summary, we identified a novel role for B cell-specific, BAFF-dependent transmembrane activator and CAML interactor signals in atherosclerosis pathogenesis, of particular relevance to the use of BAFF-targeted therapies in systemic lupus erythematosus.

Precursor B Cells Increase in the Lung during Airway Allergic Inflammation: A Role for B Cell-Activating Factor

Background

B cells, key cells in allergic inflammation, differentiate in the bone marrow and their precursors include pro-B, pre-B and immature B cells. Eosinophil progenitor cells increase in the lung after allergen exposure. However, the existence and possible role of B cell precursors in the lung during allergic inflammation remains elusive.

Methods

A BALB/c mouse model of allergic airway inflammation was utilized to perform phenotypic and quantification analyses of pro-B and pre-B cells in the lung by flow cytometry. B cell maturation factors IL-7 and B cell-activating factor (BAFF) and their receptors (CD127 and BAFFR, BCMA, TACI, respectively) were also evaluated in the lung and serum. The effect of anti-BAFF treatment was investigated both in vivo (i.p. administration of BAFF-R-Ig fusion protein) and in vitro (colony forming cell assay). Finally, BAFF levels were examined in the bronchoalveolar lavage (BAL) of asthmatic patients and healthy controls.

Results

Precursor pro and pre-B cells increase in the lung after allergen exposure, proliferate in the lung tissue in vivo, express markers of chemotaxis (CCR10 and CXCR4) and co-stimulation (CD40, CD86) and are resistant to apoptosis (Bax). Precursor B cells express receptors for BAFF at baseline, while after allergen challenge both their ligand BAFF and the BCMA receptor expression increases in B cell precursors. Blocking BAFFR in the lung in vivo decreases eosinophils and proliferating precursor B cells. Blocking BAFFR in bone marrow cultures in vitro reduces pre-B colony formation units. BAFF is increased in the BAL of severe asthmatics.

Conclusion

Our data support the concept of a BAFF-mediated role for B cell precursors in allergic airway inflammation.

Role of intrahepatic B cells in non-alcoholic fatty liver disease by secreting pro-inflammatory cytokines and regulating intrahepatic T cells

OBJECTIVE

To investigate the alterations and functions of intrahepatic B (IHB) cells in non-alcoholic fatty liver disease (NAFLD) model induced by high-fat diet (HFD).

METHODS

C57BL/6 J mice were fed with HFD for 16 weeks to induce NAFLD. Flow cytometry was used to analyze lymphocytes from liver, spleen and peripheral blood mononuclear cells (PBMC). Real-time polymerase chain reaction and immunofluorescence stain were applied to investigate cytokine expression in the intrahepatic lymphocytes and IHB cells. CD4(+) intrahepatic T (IHT) cells and IHB cells were enriched by a magnetic-activated cell sorting method and cultured in vitro. The cytokines and immunoglobulin (Ig) levels in the plasma, cultural supernatants and liver homogenates were monitored with cytometric bead arrays or multiplex immunoassays.

RESULTS

The percentage of IHB cells in CD45(+) cells was significantly higher in the NAFLD group than in the control group (P < 0.05). IHB cells expressed higher levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in the NAFLD group, and produced higher levels of IL-6 and TNF-α under the stimulation of lipopolysaccharide (LPS) than the control group. IgG2a levels were higher in the plasma, liver homogenates and the culture supernatants of IHB cells after stimulated by LPS and anti-CD40/IgM in the NAFLD group than in the control group. Moreover, IHB cells enhanced the activation of CD4(+) IHT cells and promoted the differentiation into T helper (Th) 1 cells in the NAFLD group.

CONCLUSION

IHB cells might be involved in NAFLD both by inducing the secretion of IL-6, TNF-α and IgG2a and by enhancing the activation of CD4(+) IHT cells and their differentiation into Th1 cells.

The effect of lipopolysaccharide-induced obesity and its chronic inflammation on influenza virus-related pathology

Obese individuals show increased susceptibility to infection, low vaccine efficacy, and worse pathophysiology. However, it is unclear how obesity affects these events. The aim of this study was to investigate the effect of obesity-triggered chronic inflammation on immune cells after influenza virus infection. Control and lipopolysaccharide mice, in which an osmotic pump continually released Tween saline or lipopolysaccharide, were prepared and 3 weeks later were infected with pandemic H1N1 2009 influenza A virus. In lipopolysaccharide mice, we found a reduction in macrophage activation markers in the steady state, and reduced production of pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6, in restimulated peritoneal macrophages. Interestingly, lipopolysaccharide-triggered chronic inflammation exacerbated the severity of pathological symptoms in the lungs after challenge with influenza virus. Taken together, the increased severity of virus-induced symptoms in obese individuals with chronic inflammation may be, at least partially, caused by macrophage dysfunction.

The interplay between inflammation and metabolism in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by extensive synovitis resulting in erosions of articular cartilage and marginal bone that lead to joint destruction. The autoimmune process in RA depends on the activation of immune cells, which use intracellular kinases to respond to external stimuli such as cytokines, immune complexes, and antigens. An intricate cytokine network participates in inflammation and in perpetuation of disease by positive feedback loops promoting systemic disorder. The widespread systemic effects mediated by pro-inflammatory cytokines in RA impact on metabolism and in particular in lymphocyte metabolism. Moreover, RA pathobiology seems to share some common pathways with atherosclerosis, including endothelial dysfunction that is related to underlying chronic inflammation. The extent of the metabolic changes and the types of metabolites seen may be good markers of cytokine-mediated inflammatory processes in RA. Altered metabolic fingerprints may be useful in predicting the development of RA in patients with early arthritis as well as in the evaluation of the treatment response. Evidence supports the role of metabolomic analysis as a novel and nontargeted approach for identifying potential biomarkers and for improving the clinical and therapeutical management of patients with chronic inflammatory diseases. Here, we review the metabolic changes occurring in the pathogenesis of RA as well as the implication of the metabolic features in the treatment response.

B Cell Activating Factor (BAFF) and BAFF Receptor Expression in Autoimmune and Nonautoimmune Thyroid Diseases

BACKGROUND

The B cell activating factor (BAFF) is a member of the tumor necrosis factor family, which controls the survival/proliferation of B cells and is involved in the pathogenesis of a number of autoimmune diseases. The objective of the present study was to investigate the expression of BAFF and BAFF receptor (BAFF-R) in the thyroid tissue of patients affected with autoimmune thyroid disorders (AITD) or multinodular goiter (MNG) compared with those with normal thyroids.

METHODS

Immunohistochemistry was performed using a panel of antibodies against BAFF, BAFF-R, CD3, CD4, CD8, CD20, CD34, CD79a, CD1a, CD68, and CD163 on the thyroid sections of 27 patients affected with Graves' disease (GD), 23 with Hashimoto's thyroiditis (HT), 16 with nontoxic nodular goiter (NTG), and 15 with toxic nodular goiter (TG), submitted to total thyroidectomy between 2000 and 2011.

RESULTS

The overall BAFF-R expression in thyrocytes was weak and not different in AITD and MNG. Conversely, a stronger BAFF expression was observed in MNG compared with AITD. BAFF and BAFF-R expression in the infiltrating lymphocytes was higher in AITD compared with MNG. Interestingly, in lymphocytes of follicular-like structures observed in HT, BAFF and BAFF-R were localized in the germinal center or in the mantle, respectively.

CONCLUSIONS

This study shows that BAFF and BAFF-R are expressed in the thyrocytes derived from patients with either AITD or MNG, in addition to the expected expression of BAFF and its receptor in the infiltrating immune cells of GD and HT. These findings suggest a possible involvement of BAFF and its receptors in the pathophysiology of AITD.

B-Cell Activating Factor as a Cancer Biomarker and Its Implications in Cancer-Related Cachexia

B-cell activating factor (BAFF) is a cytokine and adipokine of the TNF ligand superfamily. The main biological function of BAFF in maintaining the maturation of B-cells to plasma cells has recently made it a target of the first FDA-approved selective BAFF antibody, belimumab, for the therapy of systemic lupus erythematosus. Concomitantly, the role of BAFF in cancer has been a subject of research since its discovery. Here we review BAFF as a biomarker of malignant disease activity and prognostic factor in B-cell derived malignancies such as multiple myeloma. Moreover, anti-BAFF therapy seems to be a promising approach in treatment of B-cell derived leukemias/lymphomas. In nonhematologic solid tumors, BAFF may contribute to cancer progression by mechanisms both dependent on and independent of BAFF's proinflammatory role. We also describe ongoing research into the pathophysiological link between BAFF and cancer-related cachexia. BAFF has been shown to contribute to inflammation and insulin resistance which are known to worsen cancer cachexia syndrome. Taking all the above together, BAFF is emerging as a biomarker of several malignancies and a possible hallmark of cancer cachexia.

Lymphocyte roles in metabolic dysfunction: of men and mice

Type 2 diabetes (T2D) is a metabolic disease associated with obesity-related insulin resistance (IR) and chronic inflammation. Animal studies indicate that IR can be caused and/or exacerbated by systemic and/or tissue-specific alterations in lymphocyte differentiation and function. Human studies also indicate that obesity-associated inflammation promotes IR. Nevertheless, clinical trials with anti-inflammatory therapies have yielded modest impacts on established T2D. Unlike mouse models, where obesity is predominantly associated with IR, 20-25% of obese humans are metabolically healthy with high insulin sensitivity. The uncoupling of obesity from IR in humans but not in animal models advocates for a more comprehensive understanding of mediators and mechanisms of human obesity-promoted IR, and better integration of knowledge from human studies into animal experiments to efficiently pursue T2D prevention and treatment.

BAFF knockout improves systemic inflammation via regulating adipose tissue distribution in high-fat diet-induced obesity

Obesity is recognized as a chronic low-grade inflammatory state due to adipose tissue expansion being accompanied by an increase in the production of proinflammatory adipokines. Our group is the first to report that B-cell-activating factor (BAFF) is produced from adipocytes and functions as a proinflammatory adipokine. Here, we investigated how loss of BAFF influenced diet-induced obesity in mice by challenging BAFF^−/− mice with a high-fat diet for 10 weeks. The results demonstrated that weight gain in BAFF^−/− mice was >30% than in control mice, with a specific increase in the fat mass of the subcutaneous region rather than the abdominal region. Expression of lipogenic genes was examined by quantitative real-time PCR, and increased lipogenesis was observed in the subcutaneous adipose tissue (SAT), whereas lipogenesis in the epididymal adipose tissue (EAT) was reduced. A significant decrease in EAT mass resulted in the downregulation of inflammatory gene expression in EAT, and more importantly, overall levels of inflammatory cytokines in the circulation were reduced in obese BAFF^−/− mice. We also observed that the macrophages recruited in the enlarged SAT were predominantly M2 macrophages. 3T3-L1 adipocytes were cultured with adipose tissue conditioned media (ATCM), demonstrating that EAT ATCM from BAFF^−/− mice contains antilipogenic and anti-inflammatory properties. Taken together, BAFF^−/− improved systemic inflammation by redistributing adipose tissue into subcutaneous regions. Understanding the mechanisms by which BAFF regulates obesity in a tissue-specific manner would provide therapeutic opportunities to target obesity-related chronic diseases.

Delivery of an miR155 inhibitor by anti-CD20 single-chain antibody into B cells reduces the acetylcholine receptor-specific autoantibodies and ameliorates experimental autoimmune myasthenia gravis

MicroRNA-155 (miR155) is required for antibody production after vaccination with attenuated Salmonella. miR155-deficient B cells generated reduced germinal centre responses and failed to produce high-affinity immunoglobulin (Ig)G1 antibodies. In this study, we observed up-regulation of miR155 in the peripheral blood mononuclear cells (PBMCs) of patients with myasthenia gravis (MG), and miR155 was also up-regulated in torpedo acetylcholine receptor (T-AChR)-stimulated B cells. We used an inhibitor of miR155 conjugated to anti-CD20 single-chain antibody to treat both the cultured B cells and the experimental autoimmune MG (EAMG) mice. Our results demonstrated that silencing of miR155 by its inhibitor impaired the B cell-activating factor (BAFF)-R-related signalling pathway and reduced the translocation of nuclear factor (NF)-κB into the nucleus. Additionally, AChR-specific autoantibodies were reduced, which may be related to the altered amounts of marginal zone B cells and memory B cells in the spleens of EAMG mice. Our study suggests that miR155 may be a promising target for the clinical therapy of MG.

B Lymphocyte Stimulator (BLyS) is expressed in human adipocytes in vivo and is related to obesity but not to insulin resistance

Inflammation and metabolism have been shown to be evolutionary linked and increasing evidence exists that pro-inflammatory factors are involved in the pathogenesis of obesity and type 2 diabetes. Until now, most data suggest that within adipose tissue these factors are secreted by cells of the innate immune system, e. g. macrophages. In the present study we demonstrate that B lymphocyte stimulator (BLyS) is increased in human obesity. In contrast to several pro-inflammatory factors, we found the source of BLyS in human adipose tissue to be the adipocytes rather than immune cells. In grade 3 obese human subjects, expression of BLyS in vivo in adipose tissue is significantly increased (p<0.001). Furthermore, BLyS serum levels are elevated in grade 3 human obesity (862.5+222.0 pg/ml vs. 543.7+60.7 pg/ml in lean controls, p<0.001) and are positively correlated to the BMI (r = 0.43, p<0.0002). In the present study, bariatric surgery significantly altered serum BLyS concentrations. In contrast, weight loss due to a very-low-calorie-formula-diet (800 kcal/d) had no such effect. To examine metabolic activity of BLyS, in a translational research approach, insulin sensitivity was measured in human subjects in vivo before and after treatment with the human recombinant anti-BLyS antibody belimumab. Since BLyS is known to promote B-cell proliferation and immunoglobulin secretion, the present data suggest that adipocytes of grade 3 obese human subjects are able to activate the adaptive immune system, suggesting that in metabolic inflammation in humans both, innate and adaptive immunity, are of pathophysiological relevance.

Adipose tissue as an endocrine organ

Obesity is one of the most important health challenges faced by developed countries and is increasingly affecting adolescents and children. Obesity is also a considerable risk factor for the development of numerous other chronic diseases, such as insulin resistance, type 2 diabetes, heart disease and nonalcoholic fatty liver disease. The epidemic proportions of obesity and its numerous comorbidities are bringing into focus the highly complex and metabolically active adipose tissue. Adipose tissue is increasingly being considered as a functional endocrine organ. This article discusses the endocrine effects of adipose tissue during obesity and the systemic impact of this signaling.

Wrist Circumference: An Independent Predictor of Both Insulin Resistance and Chronic Kidney Disease in an Elderly Population

Background and aim: It was recently reported that wrist circumference is associated with insulin resistance (IR) both in children and adults. We aimed to evaluate whether wrist circumference is a useful anthropometrical parameter for the evaluation of IR in an elderly population. Material and method: We performed a study on 40 subjects, 20 with type 2 diabetes (T2D) and 20 control subjects. IR was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR). We measured the following anthropometrical parameters: weight, height, waist circumference (WC), hip circumference, wrist circumference, waist to hip ratio (WHR), waist to height ratio (WHtR), body mass index (BMI) and body adiposity index (BAI). Results: We found statistically significant differences between the subjects with T2D and the control group for all the analyzed parameters. Statistically significant correlations between all the anthropometrical parameters and HOMA-IR were observed. However, only WC was an independent predictor of IR. Wrist circumference was the only parameter negatively correlated with the estimated glomerular filtration rate (eGFR). Furthermore, this measurement was an independent predictor of chronic kidney disease (CKD) in the studied subjects. Conclusion: Wrist circumference can be used in the general practice as a surrogate marker of IR in the elderly, being both easily determined and a cost-free method

B cell activating factor-dependent expression of vascular endothelial growth factor in MH7A human synoviocytes stimulated with tumor necrosis factor-α

Angiogenesis in rheumatoid arthritis (RA) is one of the histological hallmarks, which is mediated by expression of vascular endothelial growth factor (VEGF) in RA synovium. VEGF expression is enhanced by TNF-α, the main pro-inflammatory cytokine in RA. B cell activating factor (BAFF) which plays a role in maturation and maintenance of B cells is also associated with autoimmune RA. Here, we investigated whether BAFF could regulate VEGF expression in TNF-α-stimulated synovium using MH7A synovial cells that are established by transfection with the SV40 T antigen. Changes in hBAFF and hVEGF were measured by western blotting, RT-PCR and luciferase promoter assay. When MH7A cells were treated with TNF-α, we observed that TNF-α increased the expression of hBAFF and hVEGF. TNF-α also increased transcriptional activity of hBAFF and hVEGF as judged by luciferase promoter assay. Inhibition of hBAFF expression with BAFF-siRNA decreased transcriptional level and activity of hVEGF. In addition, when c-fos expression was inhibited by the transfection of MH7A cells with c-fos-siRNA, data showed that transcriptional level and activity of both hBAFF and hVEGF were attenuated by the activation with TNF-α. Our results demonstrate for the first time that VEGF-mediated angiogenesis in RA could be controlled by TNF-α-induced BAFF expression through c-Fos. Data suggest that TNF-α-induced BAFF expression and BAFF-mediated VEGF expression in synovium may cooperate to maintain the capacity of such cells to protect B cells from apoptosis and the supply of nutrients and oxygen in inflammatory microenvironments.

B cell activating factor in obesity is regulated by oxidative stress in adipocytes

Adipose tissue functions as a key endocrine organ by releasing multiple bioactive substances, and plays a key role in the integration of systemic metabolism. We have previously shown that B cell activating factor is produced mainly in visceral adipose tissue and affects insulin sensitivity in obese individuals. In this study, we identified the signals that lead to production of B cell activating factor in adipocytes. 3T3-L1 and C3H/10T 1/2-clone 8 cells showed increased B cell activating factor expression upon exposure to hydrogen peroxide, and these changes were inhibited by treatment with the antioxidant N-acetyl-cysteine. B cell activating factor levels in both serum and visceral adipose tissue were increased in high fat diet-fed mice, and these increases were correlated with oxidative stress. In addition, serum BAFF levels in high fat diet-fed mice were reduced by N-acetyl-cysteine treatment. We also found that oxidative stress-induced B cell activating factor expression in adipocytes was regulated by NF-κB activation. These data indicate that control of the redox state in visceral adipose tissue is a potentially useful target for treating metabolic syndromes through regulation of adipokine production.

B-cell-activating factor is a regulator of adipokines and a possible mediator between adipocytes and macrophages

3T3-L1 adipocytes express the B-cell-activating factor (BAFF) and three different BAFF receptors (BAFF-Rs). Furthermore, BAFF expression is regulated by inflammatory modulators, such as tumor necrosis factor-α and rosiglitazone. Here we investigated the function of BAFF in 3T3-L1 adipocytes and RAW 264.7 macrophages. We examined adipokine expression in 3T3-L1 adipocytes treated with 10 ng ml⁻¹ BAFF. We also examined inflammatory molecule expression in RAW 264.7 macrophages treated with 10 or 100 ng ml⁻¹ BAFF. We examined BAFF expression in the coculture of 3T3-L1 adipocytes and RAW 264.7 macrophages, as well as in white adipose tissue (WAT) of diet-induced obese (DIO) mice. We found that BAFF decreases leptin and adiponectin expression, but increases the expression of proinflammatory adipokines monocyte chemotactic protein-1, interleukin-6 (IL-6), cyclooxygenase-2 (COX-2) and haptoglobin. Coculturing the two cell types resulted in increased BAFF mRNA and protein expression, as well as modulation of BAFF-R mRNA expression in both cell types. These data indicate that BAFF might mediate adipocyte and macrophage interaction. When RAW 264.7 macrophages were treated with BAFF, BAFF-R expression was modulated as in coculture, and nitric oxide synthase and IL-6 expression increased. BAFF expression also increased in WAT of DIO mice. We propose that BAFF can regulate adipokine expression and possibly mediate adipocyte and macrophage interaction.

Pro-apoptotic effect of epigallo-catechin-3-gallate on B lymphocytes through regulating BAFF/PI3K/Akt/mTOR signaling in rats with collagen-induced arthritis

To investigate the role of PI3K/Akt/mTOR signaling mediated by B cell-activating factor belonging to the TNF family (BAFF) involved in anti-apoptosis of B lymphocytes in rats with collagen-induced arthritis (CIA) and the regulation of epigallo-catechin-3-gallate (EGCG). Sprague-Dawley rats were immunized to induce CIA. CIA rats were randomly separated into different groups and treated with EGCG (40, 80 mg/kg), Paeoniflorin (100mg/kg) from day 18 to day 38 after immunization. The effects of EGCG on B lymphocytes were evaluated by the levels of BAFF, anti-CII antibody, IgA, IgG and IgM, and the expressions of BAFF receptor, P110δ, p-Akt, mTORC1, Bcl-xL and Bim. B lymphocyte proliferations were analyzed by MTT assay. Apoptosis of B lymphocyte were assayed by flow cytometry. Results showed that, in CIA rats, the levels of BAFF, anti-CII antibody, IgA, IgG and IgM enhanced. BAFF receptor, P110δ, p-AKT, mTORC1 and Bcl-xL were expressed highly, while Bim expression decreased. EGCG (40, 80 mg/kg) and Paeoniflorin decreased the levels of BAFF, anti-CII antibody, IgA, IgG, IgM and the expressions of BAFF receptor, P110δ, p-AKT, mTORC1, Bcl-xL in CIA rats, and increased Bim expression. Further studies showed that EGCG could reduce the expression of P110δ and mTORC1 in vitro. EGCG inhibited B lymphocyte proliferation and induced B lymphocyte apoptosis. In conclusion, BAFF/BAFF receptor might regulate B cell anti-apoptosis through PI3K/Akt/mTOR pathway. EGCG had therapeutic effects on CIA rats, which might be relative to the inhibition effects of EGCG on BAFF and PI3K/Akt/mTOR signaling, and then the apoptosis of B lymphocytes was promoted further.

BAFF/BAFF-R involved in antibodies production of rats with collagen-induced arthritis via PI3K-Akt-mTOR signaling and the regulation of paeoniflorin

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (Pae) is extracted from the root of paeonia lactiflora which have attracted attention for anti-rheumatic and immune modulating properties.

AIM OF THE STUDY

To investigate the role of PI3K/Akt/mTOR signaling mediated by BAFF/BAFF-R in antibodies production and the regulation of Pae on the signaling pathway in rats with collagen-induced arthritis (CIA).

MATERIALS AND METHODS

CIA rats were randomly separated into different groups and treated with Pae (25, 100mg/kg) from day 18 to day 38 after immunization. The effects of Pae on B lymphocytes of CIA rats were evaluated by the levels of BAFF, anti-CII antibody, IgA, IgG and IgM, and the expressions of BAFF-R, PI3K, p-Akt and mTOR.

RESULTS

In CIA rats, the levels of anti-CII antibody, IgA, IgG and IgM in serum enhanced, BAFF, BAFF-R, PI3K, p-Akt and mTOR were highly expressed. Pae (100mg/kg) obviously decreased arthritis score, relieved ankle and paw swelling, improved spleen histopathology in CIA rats, decreased the levels of IgA, IgM, IgG and anti-CII antibody, and significantly decreased the expressions of BAFF, BAFF-R, PI3K, p-Akt and mTOR.

CONCLUSION

PI3K/Akt/mTOR signaling mediated by BAFF/BAFF-R participates in antibodies production by B lymphocytes of CIA rats. Pae had therapeutic effects on rats with CIA. These effects might be relative to regulating PI3K/Akt/mTOR signal mediated by BAFF/BAFF-R, and down regulate the antibodies production further.

Protein kinase C stimulates human B cell activating factor gene expression through reactive oxygen species-dependent c-Fos in THP-1 pro-monocytic cells

BAFF is associated with various immunological diseases. Previously, we have reported that mouse B cell activating factor (mBAFF) expression was dependent on nuclear localization of co-activator, p300 and the activation of transcription factors including NF-κB and CREB. Here, we investigated whether transcription factor, c-Fos, regulates human (h) BAFF expression through promoter activation by PMA-induced reactive oxygen species (ROS) production. We cloned hBAFF promoter into luciferase-expressing pGL3-basic vector. The activity of 1.0 kb hBAFF promoter was higher than that in 0.75, 0.5 or 0.25 kb hBAFF promoter. The existence of three AP-1 binding motifs was computer-analyzed in hBAFF promoter. The stimulation with PMA and ionomycin (IOM) increased 1.0 kb hBAFF promoter activity, time-dependently. PMA/IOM-stimulation rapidly enhanced c-Fos expression in THP-1 human pro-monocytic cells. Binding of c-Fos to hBAFF promoter was detected by chromatin immunoprecipitation (ChIP) assay. hBAFF expression and its promoter activity were decreased by the transfection with small interference (si) RNA of c-Fos. ROS production in THP-1 cells was increased by PMA/IOM-stimulation. In addition, hBAFF activity stimulated by PMA/IOM was reduced by N-acetyl-cysteine (NAC), a well-known ROS scavenger. Serum starvation (0.5% FBS) producing ROS and the exogenous H(2)O(2) treatment also enhanced hBAFF promoter activity. c-Fos expression and AP-1 binding to oligonucleotide were reduced by the treatment with NAC. H(2)O(2) was not able to induce hBAFF expression in the presence of staurosporine, PKC inhibitor. Data suggest that hBAFF expression could be regulated by promoter activation through c-Fos association, which might be dependent on PMA-induced ROS production.

B cell-activating factor is associated with the histological severity of nonalcoholic fatty liver disease

PURPOSE

B cell-activating factor (BAFF) is expressed in adipocytes and affects lipogenesis and insulin sensitivity. In addition, the BAFF receptor is expressed in visceral adipose tissue and liver. The aim of this study was to analyze serum BAFF levels in patients with nonalcoholic steatohepatitis (NASH) and simple steatosis (SS) and to compare their respective clinical and histological findings.

METHODS

A total of 96 patients with nonalcoholic fatty liver disease (20 with SS and 76 with NASH) were enrolled and their serum BAFF levels were analyzed. Comprehensive blood chemistry analysis and histological examination of liver samples were also conducted.

RESULTS

Serum BAFF levels were higher in patients with NASH than in those with SS (p = 0.016). NASH patients with ballooning hepatocytes and advanced fibrosis had higher levels of BAFF in sera (p = 0.016 and p = 0.006, respectively). In addition, the prevalence of NASH increased significantly as the serum BAFF level increased (p = 0.004). Higher serum BAFF levels were found to be an independent risk factor for development of NASH (OR 1.003, 95% CI 1.0003-1.006; p = 0.047).

CONCLUSIONS

Nonalcoholic steatohepatitis patients had higher levels of serum BAFF than patients with SS, and higher levels were associated with the presence of hepatocyte ballooning and advanced fibrosis. The serum BAFF level may be a useful tool for distinguishing NASH from SS.

Adipogenic differentiation alters the immunoregulatory property of mesenchymal stem cells through BAFF secretion

Although it has been widely demonstrated that mesenchymal stem cells (MSCs) exert potent immunosuppressive effect, there is little information as to whether adipogenic-differentiated MSCs (adi-MSCs) share the same property. Here, adi-MSCs enhanced alloantigen or mitogen-stimulated lymphocyte proliferation, whereas undifferentiated MSCs (ud-MSCs) inhibited the proliferation. Transwell experiment showed that the stimulatory effect of adi-MSCs was cell-cell contact-independent, and required soluble factors. Furthermore, the supernatant of cultured adi-MSCs could effectively costimulate T and B-lymphocyte proliferation and activation in the presence of anti-CD3 and anti-mu chain treatment, respectively. Production of cytokines interferon-gamma and tumor necrosis factor-alpha by T cells, and Ig secretion by B cells also were increased by the supernatant of cultured adi-MSCs. Mechanism conducted showed that the mRNA and protein expression of costimulatory molecule B-cell activating factor (BAFF) was upregulated, and soluble BAFF was secreted in MSCs after adipogenic differentiation. By blocking the BAFF molecule with specific monoclonal antibody in the culture, T and B-lymphocyte proliferation and activation was stimulated by adi-MSCs or the supernatants were greatly reduced. In conclusion, adipogenic differentiation may alter the immunoregulatory property of MSCs, leading to stimulation of lymphocytes response. The BAFF molecule secreted by the adi-MSCs was responsible for this event.

Regulation of B cell activating factor (BAFF) receptor expression by NF-ΚB signaling in rheumatoid arthritis B cells

B cells play an important role in the pathogenesis of rheumatoid arthritis (RA). High levels of B cell activating factor (BAFF) are detected in autoimmune diseases. BAFF and BAFF receptor (BAFF-R) are expressed in B and T cells of RA synovium. The study was undertaken to identify the NF-ΚB signal pathway involved in the induction of BAFF-R in human B cells. Immunohistochemical staining of NF-ΚB p65, NF-ΚB p50, BAFF, and BAFF-R was performed on sections of synovium from severe and mild RA and osteoarthritis (OA) patients. Peripheral blood mononuclear cells (PBMCs) were isolated from control and RA patients and B cells were isolated from controls. BAFF-R was analyzed by flow cytometry, realtime PCR and confocal staining after treatment with NF-ΚB inhibitors. NF-ΚB p65, NF-ΚB p50, BAFF, and BAFF-R were highly expressed in severe RA synovium relative to mild RA synovium or OA synovium. BAFF-R expression was reduced by NF-ΚB inhibitors in PBMCs and B cells from normal controls. We also showed reduction in expression of BAFF-R via inhibition of the NF-ΚB pathway in PBMCs of RA patients. BAFF/BAFF-R signaling is an important mechanism of pathogenesis in RA and that BAFF-R reduction by NF-ΚB blocking therapy is another choice for controlling B cells in autoimmune diseases such as RA.

B cell-activating factor controls the production of adipokines and induces insulin resistance

Visceral adipose tissue (VAT) inflammation has been linked to the pathogenesis of insulin resistance and metabolic syndrome. VAT has recently been established as a new component of the immune system and is involved in the production of various adipokines and cytokines. These molecules contribute to inducing and accelerating systemic insulin resistance. In this report, we investigated the role of B cell-activating factor (BAFF) in the induction of insulin resistance. We investigated BAFF levels in the sera and VAT of obese mice. In obese mice, the BAFF levels were preferentially increased in VAT and sera compared to these levels in normal control mice. Next, we treated mice with BAFF to analyze its influence on insulin sensitivity. BAFF impaired insulin sensitivity in normal mice. Finally, we investigated the mechanisms underlying insulin resistance induced by BAFF in adipocytes. BAFF also induced alterations in the expression levels of genes related to insulin resistance in adipocytes. In addition, BAFF directly affected the glucose uptake and phosphorylation of insulin receptor substrate-1 in adipocytes. We propose that autocrine or paracrine BAFF and BAFF-receptor (BAFF-R) interaction in VAT leads to impaired insulin sensitivity via inhibition of insulin signaling pathways and alterations in adipokine production.