Altered or Impaired Immune Response to Hepatitis B Vaccine in WNIN/GR-Ob Rat: An Obese Rat Model with Impaired Glucose Tolerance

Diet-induced obesity and diabetes enhance mortality and reduce vaccine efficacy for SARS-CoV-2

IMPORTANCE

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a wide spectrum of diseases in the human population, from asymptomatic infections to death. It is important to study the host differences that may alter the pathogenesis of this virus. One clinical finding in coronavirus disease 2019 (COVID-19) patients is that people with obesity or diabetes are at increased risk of severe illness from SARS-CoV-2 infection. We used a high-fat diet model in mice to study the effects of obesity and type 2 diabetes on SARS-CoV-2 infection as well as how these comorbidities alter the response to vaccination. We find that diabetic/obese mice have increased disease after SARS-CoV-2 infection and they have slower clearance of the virus. We find that the lungs of these mice have increased neutrophils and that removing these neutrophils protects diabetic/obese mice from disease. This demonstrates why these diseases have increased risk of severe disease and suggests specific interventions upon infection.

Targeting T cell (oxidative) metabolism to improve immunity to viral infection in the context of obesity

Disorders of systemic metabolism can influence immunity. Individuals with obesity are known to have increased inflammation, increased risk to select autoimmune diseases, impaired response to several infections, and impaired vaccine response. For example, over the last decade, it has become clear that individuals with obesity have increased risk of morbidity and mortality from influenza infection. Unsurprisingly, this finding is also observed in the current COVID-19 pandemic: individuals with obesity, particularly severe obesity, have increased risk of poor outcomes from SARS-CoV-2 infection, including increased rates of hospitalization, ICU admission, mechanical ventilation, and death. Several studies have now demonstrated a critical role for T cells in the context of obesity-associated immune dysfunction in response to viral infection, and one mechanism for this may be altered T cell metabolism. Indeed, recent studies have shown that activated T cells from obese mice have an altered metabolic profile characterized by increased glucose oxidation, both in vitro and in vivo following viral infection. For that reason, treatments that target abnormal immune cell metabolism in obesity may improve outcomes to viral infection. To that end, several recent studies have shown that use of the metabolic drug, metformin, can reverse abnormal T cell metabolism and restore T cell immunity, as well as survival, in response to viral infection. These findings will be discussed in detail here.

Human placental mesenchymal stromal cell therapy restores the cytokine efflux and insulin signaling in the skeletal muscle of obesity-induced type 2 diabetes rat model

Obesity poses a significant risk factor for the onset of metabolic syndrome with allied complications, wherein mesenchymal stem cell therapy is seen as a promising treatment for obesity-induced metabolic syndrome. In the present study, we aim to explore the beneficial effects of the human placental mesenchymal stromal cells (P-MSCs) on obesity-associated insulin resistance (IR) including inflammation. To understand this, we have analyzed the peripheral blood glucose, serum insulin levels by ELISA, and the glucose uptake capacity of skeletal muscle by a 2-NBDG assay using flow cytometry in WNIN/GR-Ob rats treated with and without P-MSCs. Also, we have studied insulin signaling and cytokine profile in the skeletal muscle by western blotting, dot blotting, and Multiplex-ELISA techniques. The skeletal muscle of WNIN/GR-Ob rats demonstrates dysregulation of cytokines, altered glucose uptake vis-a-vis insulin signaling. However, P-MSCs' treatment was effective in WNIN/GR-Ob rats as compared to its control, to restore HOMA-IR, re-establishes dysregulated cytokines and PI3K-Akt pathway in addition to enhanced Glut4 expression and glucose uptake studied in skeletal muscle. Overall, our data advocate the beneficial effects of P-MSCs to ameliorate inflammatory milieu, improve insulin sensitivity, and normalize glucose homeostasis underlining the Ob-T2D conditions, and we attribute for immunomodulatory, paracrine, autocrine, and multipotent functions of P-MSCs.

The Nature of Immune Responses to Influenza Vaccination in High-Risk Populations

The current pandemic has brought a renewed appreciation for the critical importance of vaccines for the promotion of both individual and public health. Influenza vaccines have been our primary tool for infection control to prevent seasonal epidemics and pandemics such as the 2009 H1N1 influenza A virus pandemic. Certain high-risk populations, including the elderly, people with obesity, and individuals with comorbidities such as type 2 diabetes mellitus, are more susceptible to increased disease severity and decreased vaccine efficacy. High-risk populations have unique microenvironments and immune responses that contribute to increased vulnerability for influenza infections. This review focuses on these differences as we investigate the variations in immune responses to influenza vaccination. In order to develop better influenza vaccines, it is critical to understand how to improve responses in our ever-growing high-risk populations.

Glucose & energy homeostasis: Lessons from animal studies

Glucose in our body is maintained within a narrow range by the humoral control and a 'lipostat' system regulated by leptin from adipose tissues, which keep our accumulated fat stores in check. Any disturbance in this delicately poised homeostasis could be disastrous as it can lead to obesity and its associated metabolic manifestations. Laboratory animals, especially rodents, have contributed to our knowledge in understanding this physiological mechanism through an array of genetic and non-genetic animals developed over the years. Two rat mutant obese models-Wistar inbred at National Institute of Nutrition (WNIN)/Ob-obese rats with normal glucose levels and WNIN/GR-Ob-obese with impaired glucose tolerance were developed in the National Centre for Laboratory Animal Sciences (Now ICMR-National Animal Resource Facility for Biomedical Research) at Hyderabad, India. These animals are unique, as, unlike the earlier models, they show all types of degenerative disorders associated with obesity, within a single system. Thus they show impairment in all the major organs of the body - liver, pancreas, kidney, bones, muscles, gonads, brain, eyes, and are sensitive to diet manipulations, have compromised immunity, often develop tumours and have reduced life span. One may argue that there are limitations to one's interpretations from animal studies to human application, but then one cannot shut one's eyes to the new lessons they have taught us in modifying our life styles.

Hepatitis B vaccine nonresponders: Possible mechanisms and solutions

OBJECTIVE

Hepatitis B (HBV) is a viral illness that chronically infects 240 million people worldwide, leads to liver disease, and increases risk of hepatocellular carcinoma. The HBV vaccine has decreased HBV infection, and it and the human papilloma virus vaccine are the only vaccines that prevent cancer. Despite the effectiveness of the HBV vaccine, some populations do not develop protective responses. The risk groups for poor response include those with immunosuppression or dialysis-dependent, end-stage renal disease. Five percent of normal people do not have a response. These subjects are deemed HBV "nonresponders." Multiple strategies to improve the immunogenicity of the HBV vaccine are currently being pursued, including vaccine adjuvants, recombinant vaccines, and immune enhancement via up-regulation of dendritic cells.

DATA SOURCES

PubMed was searched for peer-reviewed publications published from January 1980 to September 2017.

STUDY SELECTIONS

Studies retrieved for inclusion summarized potential mechanisms behind HBV vaccine nonresponsiveness and potential solutions.

RESULTS

The mechanisms behind HBV vaccine nonresponsiveness vary between each subject population. Many current and future strategies may provide protective immunity against HBV in each of these populations.

CONCLUSION

This review provides a background on the immunology of HBV infection, the possible immunologic mechanisms to explain HBV vaccine nonresponsiveness, current research aimed at improving vaccine effectiveness, and possible future approaches for providing nonresponders protection from HBV.

Differential response of rat strains to obesogenic diets underlines the importance of genetic makeup of an individual towards obesity

Obesity, a multifactorial disorder, results from a chronic imbalance of energy intake vs. expenditure. Apart from excessive consumption of high calorie diet, genetic predisposition also seems to be equally important for the development of obesity. However, the role of genetic predisposition in the etiology of obesity has not been clearly delineated. The present study addresses this problem by selecting three rat strains (WNIN, F-344, SD) with different genetic backgrounds and exposing them to high calorie diets. Rat strains were fed HF, HS, and HFS diets and assessed for physical, metabolic, biochemical, inflammatory responses, and mRNA expression. Under these conditions: significant increase in body weight, visceral adiposity, oxidative stress and systemic pro-inflammatory status; the hallmarks of central obesity were noticed only in WNIN. Further, they developed altered glucose and lipid homeostasis by exhibiting insulin resistance, impaired glucose tolerance, dyslipidemia and fatty liver condition. The present study demonstrates that WNIN is more prone to develop obesity and associated co-morbidities under high calorie environment. It thus underlines the cumulative role of genetics (nature) and diet (nurture) towards the development of obesity, which is critical for understanding this epidemic and devising new strategies to control and manage this modern malady.

Factors affecting responsiveness to hepatitis B immunization in dialysis patients

BACKGROUND

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are widespread health problems all over the world and have high morbidity and mortality. Hemodialysis patients are more frequently exposed to these viruses as they have poor immune system and frequently undergo parenteral interventions. The vaccination against HBV prevents infection and it has been recommended for the prevention of HBV infection in all susceptible dialysis patients. This study aimed to determine the seroprevalence of HBV and HCV infections and analyzed the factors affecting inadequate response to HBV vaccine in dialysis patients.

METHODS

The data for 584 dialysis patients that were followed up at seven dialysis centers were analyzed. The patients received four doses of 40 μg recombinant hepatitis B vaccine at 0, 1, 2, and 6 months and were tested for anti-HBs titer after one month of completion of vaccination. If patients showed a titer of anti-HBs <10 IU/mL, an additional 40 μg in four vaccine doses was administered immediately and they were retested for the anti-HBs following the same schedule. The patients were divided into two groups: responders and non-responders.

RESULTS

HBsAg and anti-HCV seroprevalence was 3.4% and 10.3%, respectively. After vaccination schedule, 264 (83.5%) patients had antibody response to HBV vaccine and 52 (16.5%) had no response. Hepatitis B vaccine unresponsiveness is more common in the patients with hepatitis C positivity (p = 0.011), BMI >30 (p = 0.019), over the age of 65 years (p = 0.009), and duration of dialysis treatment >5 years (p = 0.001). There was no statistically significant difference between gender, causes of renal disease, erythropoietin treatment, and the type of dialysis.

CONCLUSION

Hepatitis C infection, obesity, being elderly, and having long hemodialysis period reduced the hepatitis B vaccination response in hemodialysis patients.

Impact of Obesity and Metabolic Syndrome on Immunity

Obesity is associated with metabolic disturbances that cause tissue stress and dysfunction. Obese individuals are at a greater risk for chronic disease and often present with clinical parameters of metabolic syndrome (MetS), insulin resistance, and systemic markers of chronic low-grade inflammation. It has been well established that cells of the immune system play an important role in the pathogenesis of obesity- and MetS-related chronic diseases, as evidenced by leukocyte activation and dysfunction in metabolic tissues such as adipose tissue, liver, pancreas, and the vasculature. However, recent findings have highlighted the substantial impact that obesity and MetS parameters have on immunity and pathogen defense, including the disruption of lymphoid tissue integrity; alterations in leukocyte development, phenotypes, and activity; and the coordination of innate and adaptive immune responses. These changes are associated with an overall negative impact on chronic disease progression, immunity from infection, and vaccine efficacy. This review presents an overview of the impact that obesity and MetS parameters have on immune system function.

Impact of Obesity and Metabolic Syndrome on Immunity

Obesity is associated with metabolic disturbances that cause tissue stress and dysfunction. Obese individuals are at a greater risk for chronic disease and often present with clinical parameters of metabolic syndrome (MetS), insulin resistance, and systemic markers of chronic low-grade inflammation. It has been well established that cells of the immune system play an important role in the pathogenesis of obesity- and MetS-related chronic diseases, as evidenced by leukocyte activation and dysfunction in metabolic tissues such as adipose tissue, liver, pancreas, and the vasculature. However, recent findings have highlighted the substantial impact that obesity and MetS parameters have on immunity and pathogen defense, including the disruption of lymphoid tissue integrity; alterations in leukocyte development, phenotypes, and activity; and the coordination of innate and adaptive immune responses. These changes are associated with an overall negative impact on chronic disease progression, immunity from infection, and vaccine efficacy. This review presents an overview of the impact that obesity and MetS parameters have on immune system function.

Metabolic syndrome delays HBeAg seroclearance in Chinese patients with hepatitis B

BACKGROUND

Delayed hepatitis B e antigen (HBeAg) seroclearance increases the risk of cirrhosis and hepatocellular carcinoma (HCC). The effect of metabolic syndrome (MetS) on HBeAg seroclearance in chronic hepatitis B (CHB) patients remains unclear.

AIMS

To examine the effect of MetS on HBeAg seroclearance.

METHODS

A prospective cohort of 413 treatment-naïve HBeAg-positive CHB patients from 2005 to 2012 was studied. Clinical, virological and histological parameters were evaluated. The patients were classified into three groups according to the metabolic characteristics; normal, pre-MetS and MetS based on the International Diabetes Federation criteria. The primary outcome was age at HBeAg seroclearance.

RESULTS

The overall HBeAg seroclearance rate was 11.4% per annum during 19 351 patient-months of follow-up with no difference in HBeAg seroclearance rates between 162 treatment-free and 251 patients receiving nucleos(t)ide analogues. Patients with pre-MetS and MetS were older when HBeAg seroclearance occurred (44 ± 12 and 53 ± 7 years, respectively) than the normal patients (37 ± 9 years, all P < 0.01). Patients with pre-MetS and MetS had more advanced liver fibrosis (33.0% and 53.1%, respectively) than the normal patients (18.4%, all P < 0.05). By the age of 50, 59.3% of the metabolic normal patients, 42.1% of the pre-MetS and 18.7% of the MetS patients had achieved HBeAg seroclearance (all P < 0.05, except P = 0.07 for pre-MetS vs. MetS). In multivariate analysis, MetS and type II diabetes at baseline were predictors of delayed HBeAg seroclearance after adjusting for viral load, anti-viral therapy and necroinflammatiom.

CONCLUSION

Chinese patients with chronic hepatitis B and with pre-metabolic syndrome or metabolic syndrome have delayed HBeAg seroclearance.

Promise(s) of mesenchymal stem cells as an in vitro model system to depict pre-diabetic/diabetic milieu in WNIN/GR-Ob mutant rats

Background

Development of model systems have helped to a large extent, in bridging gap to understand the mechanism(s) of disease including diabetes. Interestingly, WNIN/GR-Ob rats (Mutants), established at National Centre for Laboratory Animals (NCLAS) of National Institute of Nutrition (NIN), form a suitable model system to study obesity with Type 2 diabetes (T2D) demonstrating several secondary complications (cataract, cardiovascular complications, infertility, nephropathy etc). The present study has been carried out to explore the potent application(s) of multipotent stem cells such as bone marrow mesenchymal stem cells (BM-MSCs), to portray features of pre-diabetic/T2D vis-à-vis featuring obesity, with impaired glucose tolerance (IGT), hyperinsulinemia (HI) and insulin resistance (IR) seen with Mutant rats akin to human situation.

Methodology/Principal Findings

Primary cultures of BM-MSCs (third passage) from Mutants, its lean littermate (Lean) and parental control (Control) were characterized for: proliferation markers, disease memory to mark obesity/T2D/HI/IR which included phased gene expression studies for adipogenic/pancreatic lineages, inflammatory markers and differentiation ability to form mature adipocytes/Insulin-like cellular aggregates (ILCAs). The data showed that BM-MSCs from Mutant demonstrated a state of disease memory, depicted by an upregulated expression of inflammatory markers (IL-6, TNFα); increased stem cell recruitment (Oct-4, Sox-2) and proliferation rates (CD90+/CD29+, PDA, ‘S’ phase of cell cycle by FACS and BrdU incorporation); accelerated preadipocyte induction (Dact-1, PPARγ2) with a quantitative increase in mature adipocyte formation (Leptin); ILCAs, which were non-responsive to high glucose did confer the Obese/T2D memory in Mutants. Further, these observations were in compliance with the anthropometric data.

Conclusions

Given the ease of accessibility and availability of MSCs, the present study form the basis to report for the first time, application of BM-MSCs as a feasible in vitro model system to portray the disease memory of pre-clinical/T2D with IR - a major metabolic disorder of global concern.