High body mass index is associated with heightened systemic and mycobacterial antigen - Specific pro-inflammatory cytokines in latent tuberculosis

Adipose Tissue Remodeling in Pathophysiology

Rather than serving as a mere onlooker, adipose tissue is a complex endocrine organ and active participant in disease initiation and progression. Disruptions of biological processes operating within adipose can disturb healthy systemic physiology, the sequelae of which include metabolic disorders such as obesity and type 2 diabetes. A burgeoning interest in the field of adipose research has allowed for the elucidation of regulatory networks underlying both adipose tissue function and dysfunction. Despite this progress, few diseases are treated by targeting maladaptation in the adipose, an oft-overlooked organ. In this review, we elaborate on the distinct subtypes of adipocytes, their developmental origins and secretory roles, and the dynamic interplay at work within the tissue itself. Central to this discussion is the relationship between adipose and disease states, including obesity, cachexia, and infectious diseases, as we aim to leverage our wealth of knowledge for the development of novel and targeted therapeutics.

Pulmonary tuberculosis among prisoners in Southern Thailand: prevalence and its association with imprisonment status

PURPOSE

This study aims to measure the prevalence of pulmonary tuberculosis (PTB), its association with imprisonment status and to document the treatment success rate (TSR) among prisoners in Songkhla province, Southern Thailand.

DESIGN/METHODOLOGY/APPROACH

A retrospective cross-sectional study was conducted in five prisons in Songkhla province, including all prisoners in the fiscal of year 2019, who had an annual chest radiography (CXR) screening result. Information of prisoners who had been imprisoned from 1 October 2018 to 30 September 2019, were reviewed for PTB diagnosis. Imprisonment status and other associated factors with PTB were analyzed using multiple logistic regression.

FINDINGS

The prevalence of PTB was 2.72%. Prisoners having new or transfer-in status were more likely to have PTB. Those aged 40-80 years, who had smoked for ten years or more, or who were underweight, had higher odds of having PTB. TSR among prisoners with PTB in this study was 94.9%.

ORIGINALITY/VALUE

The prevalence of PTB among prisoners having annual CXR screening was high. Detection of PTB was higher among new or transfer-in prisoners; therefore, the CXR for PTB screening before admission to prison should be performed to prevent transmission to other prisoners.

Higher Serum Cholesterol Levels Are Associated With Reduced Systemic Inflammation and Mortality During Tuberculosis Treatment Independent of Body Mass Index

Background: Lipids play a central role in the pathogenesis of tuberculosis (TB). The effect of serum lipid levels on TB treatment (ATT) outcomes and their association with serum inflammatory markers have not yet been characterized. Methods: Our retrospective cohort study on drug-susceptible TB patients, at the National Taiwan University Hospital, assessed the association of baseline serum lipid levels such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC) and triglycerides (TG) with all-cause and infection-related mortality during first 9 months of ATT and baseline inflammatory markers namely C-reactive protein (CRP), total leukocyte count (WBC), and neutrophil-lymphocyte ratio (NL ratio). Results: Among 514 patients, 129 (26.6%) died due to any-cause and 72 (14.0%) died of infection. Multivariable Cox-regression showed a lower adjusted hazard ratio (aHR) of all-cause mortality in the 3rd tertiles of HDL (aHR 0.17, 95% CI 0.07-0.44) and TC (aHR 0.30, 95% CI 0.14-0.65), and lower infection-related mortality in the 3rd tertile of HDL (aHR 0.30, 95% CI 0.14-0.65) and TC (aHR 0.30, 95% CI 0.14-0.65) compared to the 1st tertile. The 3rd tertiles of LDL and TG showed no association in multivariable analysis. Similarly, 3rd tertiles of HDL and TC had lower levels of baseline inflammatory markers such as CRP, WBC, and NL ratio using linear regression analysis. Body mass index (BMI) did not show evidence of confounding or effect modification. Conclusions: Higher baseline serum cholesterol levels were associated with lower hazards of all-cause and infection-related mortality and lower levels of inflammatory markers in TB patients. BMI did not modify or confound this association.

Reconsidering the reasons for heightened inflammation in major depressive disorder

BACKGROUND

Increased circulating pro-inflammatory markers have repeatedly been associated with major depressive disorder (MDD). However, it remains unclear whether inflammation represents a causal mechanism for MDD, or whether the association is influenced by confounding factors such as body mass index (BMI).

METHODS

To better understand this complex relationship, we generated polygenic risk scores (PRS) for MDD and BMI in a population cohort and attempted to isolate the impact these potential risk factors have on adulthood inflammation. Peripheral blood samples were collected as part of the South East London Community Health study, where we generated individualized PRS for MDD and BMI and quantified inflammatory markers using multiplex ELISA-based technology. We performed linear regressions to investigate the effects of PRS for MDD and BMI on inflammatory marker levels.

RESULTS

Out of 35 inflammatory markers, we found a nominal effect of PRS for MDD on interleukin-10. We also found a significant positive effect of BMI on nine inflammatory markers, of which the two most strongly affected markers, interleukin-6 (IL-6) and C-reactive protein (CRP), were also nominally predicted by BMI PRS.

LIMITATIONS

The study utilized a cross-sectional design with a moderately sized sample.

CONCLUSIONS

Our findings suggest there may not be a shared genetic mechanism contributing to MDD and higher inflammatory marker levels. However, there may be shared genetic etiology between BMI and adulthood levels of CRP and IL-6. Therefore, polygenic risk scores for BMI may represent a useful indicator for heightened levels of inflammation in adulthood.

Low body mass index has minimal impact on plasma levels of cytokines and chemokines in tuberculous lymphadenitis

Malnutrition, due to low body mass index (LBMI), is considered to be one of the key risk factors for tuberculosis (TB) development. The link between pro and anti-inflammatory cytokines and BMI has been studied in active pulmonary TB. However, the association of BMI with cytokines and chemokines in TB lymphadenitis (TBL) has not been examined. Hence, we wanted to examine the plasma levels of different cytokines and chemokines in TBL individuals with LBMI, normal BMI (NBMI) and high BMI (HBMI). LBMI with TBL disease is associated with enhanced systemic levels of type 1 (tumor necrosis factor alpha [TNFα], interleukin-2 [IL-2]) and type 2 (IL-4, IL-13) cytokines in comparison with NBMI and/or HBMI. However, other pro-inflammatory (IFNγ, IL-1β, IL-17A, IL-6, IL-7, IL-12, G-CSF, and GM-CSF) and anti-inflammatory (IL-5 and IL-10) cytokines were not significantly different among the TBL individuals with different BMI status. Likewise, no significant differences were observed in the CC (CCL-1, CCL-2/MCP-1, CCL3/MIP1α, CCL4/MIP-1β, CCL11/eotaxin) and CXC (CXCL-1/GRO-⍺, CXCL2/GRO-β, CXCL9/MIG, CXCL10/IP-10, CXCL11/ITAC 1) chemokine profile among the TBL individuals with different BMI. Hence, our data implies that TBL individuals with LBMI are characterized by minimal effects on plasma cytokines and chemokines in TBL.

Overweight, Obesity, and Older Age Favor Latent Tuberculosis Infection among Household Contacts in Low Tuberculosis-Incidence Settings within Panama

Latent tuberculosis infection (LTBI) remains the main source of new active tuberculosis (TB) cases worldwide. Household close contacts (HCCs) are at high risk of acquiring LTBI and subsequent development of TB. In this study, we aim to identify risk factors associated with LTBI in HCCs of TB patients living in a low TB-incidence setting. Our results revealed that HCCs who are aged more than 50 years (OR = 4.05) and overweight (OR = 15.3) are at higher risk of acquiring LTBI. None of these LTBI household contacts progressed to active TB. These findings suggest that HCCs who are young adults and children with normal and low body mass index are less likely to acquire LTBI after exposure to TB patients, even in low TB-incidence settings.

Screening for pulmonary tuberculosis in high-risk groups of diabetic patients

BACKGROUND

The double burden of diabetes mellitus (DM) and tuberculosis (TB) has attracted increasing attention, because DM not only increases the risk of active TB but also affects treatment outcomes. Screening for TB among diabetic patients has been recommended, but requires real-world evidence by considering its cost-effectiveness, cost-utility ratio, and cost-benefit ratio.

METHODS

A screening program was conducted in Jiangyin City of Jiangsu Province, China. A total of 14 869 diabetic patients received regular physical examinations for three consecutive years and were followed for the diagnosis of TB. The cost of screening and the effectiveness, utility, and social benefits attributed to the program were evaluated. In addition, a matched case-control study was conducted and the nomogram was used to identify high-risk groups that could be the target population for screening.

RESULTS

Among the 14 869 diabetic patients who participated in this screening program, 22 were diagnosed with TB, resulting in an incremental cost-effectiveness ratio (ICER) of 83 910 CNY per disability-adjusted life-year (DALY) gained and a cost-benefit ratio of 0.50. If the screening program was limited to high-risk diabetic patients by considering body mass index (BMI), fasting blood glucose (FBG), and triglycerides, the ICER decreased to 34 303 CNY per DALY gained and the cost-benefit ratio increased to 1.22.

CONCLUSIONS

Screening for TB using regular chest X-ray examinations is feasible but not economical in areas with a low incidence of TB. It is recommended that diabetic patients with a low BMI, high FBG, and low triglycerides are selected as subjects for TB screening.

mTORC2/Akt activation in adipocytes is required for adipose tissue inflammation in tuberculosis

Background

Mycobacterium tuberculosis has co-evolved with the human host, adapting to exploit the immune system for persistence and transmission. While immunity to tuberculosis (TB) has been intensively studied in the lung and lymphoid system, little is known about the participation of adipose tissues and non-immune cells in the host-pathogen interaction during this systemic disease.

Methods

C57BL/6J mice were aerosol infected with M. tuberculosis Erdman and presence of the bacteria and the fitness of the white and brown adipose tissues, liver and skeletal muscle were studied compared to uninfected mice.

Findings

M. tuberculosis infection in mice stimulated immune cell infiltration in visceral, and brown adipose tissue. Despite the absence of detectable bacterial dissemination to fat tissues, adipocytes produced localized pro-inflammatory signals that disrupted adipocyte lipid metabolism, resulting in adipocyte hypertrophy. Paradoxically, this resulted in increased insulin sensitivity and systemic glucose tolerance. Adipose tissue inflammation and enhanced glucose tolerance also developed in obese mice after aerosol M. tuberculosis infection. We found that infection induced adipose tissue Akt signaling, while inhibition of the Akt activator mTORC2 in adipocytes reversed TB-associated adipose tissue inflammation and cell hypertrophy.

Interpretation

Our study reveals a systemic response to aerosol M. tuberculosis infection that regulates adipose tissue lipid homeostasis through mTORC2/Akt signaling in adipocytes. Adipose tissue inflammation in TB is not simply a passive infiltration with leukocytes but requires the mechanistic participation of adipocyte signals.

Association of body mass index with incident tuberculosis in Korea

INTRODUCTION

Overweight or obesity might be protective factors of tuberculosis (TB), but the evidence is inconclusive. The objective of study was to evaluate association between BMI and incident TB.

METHODS

The National Health Insurance database was used. Eligible participants were individuals aged 20-89 years without history of TB before 2007, and who underwent national health examinations between January 2002 and December 2006. The latest record of BMI was used as the exposure and categorized as follows: <18.5, 18.5-23, 23-25, 25-30, and ≥30 kg/m2. TB was defined as the first recorded diagnosis of TB, using ICD-10 between January 2007 and December 2013.

RESULTS

Among 301,081 individuals, 3,772 (1.26%) incident TB cases were detected. The incidence rate of the event was 19.65 per 10,000 person-years. After adjusting age, sex, household income, smoking status, alcohol use, and diabetes, incident TB was decreased as BMI was increased in an inverse dose-response relationship. However, when stratified by age and sex, BMI >30 kg/m2 did not show protective effect of TB in female under 50 years. Additionally, BMI >30 kg/m2 did not decrease incident TB in diabetics.

CONCLUSION

Our study suggests that high BMI might be associated with decreased risk of TB. However, very high BMI did not reduce the risk of TB in young females or diabetics participants with in Korean population.

Malnutrition: Modulator of Immune Responses in Tuberculosis

Nutrition plays a major role in the management of both acute and chronic diseases, in terms of body’s response to the pathogenic organism. An array of nutrients like macro- and micro-nutrients, vitamins, etc., are associated with boosting the host’s immune responses against intracellular pathogens including mycobacterium tuberculosis (M.tb). These nutrients have an immunomodulatory effects in controlling the infection and inflammation process and nutritional deficiency of any form, i.e., malnutrition may lead to nutritionally acquired immunodeficiency syndrome, which greatly increases an individual’s susceptibility to progression of infection to disease. This narrative review looks at the various mechanisms by which nutrition or its deficiency leads to impaired cell mediated and humoral immune responses, which in turn affects the ability of an individual to fight M.tb infection or disease. There is very little evidence in the literature that any specific food on its own or a specific quantity can alter the course of TB disease or be effective in the treatment of malnutrition. Further clinical trials or studies will be needed to recommend and to better understand the link between malnutrition, tuberculosis, and impaired immunity.