Leptin and energy metabolism in pulmonary tuberculosis

Metabolomics as a Tool to Investigate HIV/TB Co-Infection

The HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) and tuberculosis (TB) pandemics are perpetuated by a significant global burden of HIV/TB co-infection. The synergy between HIV and Mycobacterium tuberculosis (Mtb) during co-infection of a host is well established. While this synergy is known to be driven by immunological deterioration, the metabolic mechanisms thereof remain poorly understood. Metabolomics has been applied to study various aspects of HIV and Mtb infection separately, yielding insights into infection- and treatment-induced metabolic adaptations experienced by the host. Despite the contributions that metabolomics has made to the field, this approach has not yet been systematically applied to characterize the HIV/TB co-infected state. Considering that limited HIV/TB co-infection metabolomics studies have been published to date, this review briefly summarizes what is known regarding the HIV/TB co-infection synergism from a conventional and metabolomics perspective. It then explores metabolomics as a tool for the improved characterization of HIV/TB co-infection in the context of previously published human-related HIV infection and TB investigations, respectively as well as for addressing the gaps in existing knowledge based on the similarities and deviating trends reported in these HIV infection and TB studies.

Leptin and advanced glycation end products receptor (RAGE) in tuberculosis patients

Introduction

The pathogenesis of consumptive syndrome of tuberculosis (TB) is largely unknown. Leptin concentrations may be high because of the host’s inflammatory response, contributing to weight loss in patients with TB. The receptor for advanced glycation end products (RAGE) is also associated with weight loss in patients with TB and is related to enhanced mortality. The objective of this study was to evaluate the association between leptin and AGE/RAGE.

Methods

Case-control study. Leptin, AGE (carboxymethyl lysine, CML) and soluble RAGE (sRAGE) were measured from blood samples by ELISA.

Results

We included in the study 34 patients with TB and 34 controls. We found an inverse correlation between serum leptin levels and sRAGE, only in cases (r = -0.609, p < 0.0001). sRAGE levels were lower in patients with TB who died as compared with patients who survive (21.90 ± 4.24 pg/mL vs 66.14 ± 29.49 pg/mL; p = 0.045). Leptin levels were higher in patients with TB who died as compared with patients who survive (14.11 [7.48–14.11] ng/mL vs 3.08 [0.54–6.34] ng/mL; p = 0.028).

Conclusions

We identified lower sRAGE levels and higher leptin levels in patients with TB who died as compared with patients who survive. In addition, an inverse and significant correlation between serum leptin and sRAGE levels was demonstrated. Future studies, with a larger sample size and in different settings, including not only hospitalized patients, are needed to confirm these findings.

Leptin Functions in Infectious Diseases

Leptin, a pleiotropic protein has long been recognized to play an important role in the regulation of energy homeostasis, metabolism, neuroendocrine function, and other physiological functions through its effects on the central nervous system (CNS) and peripheral tissues. Leptin is secreted by adipose tissue and encoded by the obese (ob) gene. Leptin acts as a central mediator which regulates immunity as well as nutrition. Importantly, leptin can modulate both innate and adaptive immune responses. Leptin deficiency/resistance is associated with dysregulation of cytokine production, increased susceptibility toward infectious diseases, autoimmune disorders, malnutrition and inflammatory responses. Malnutrition induces a state of immunodeficiency and an inclination to death from communicable diseases. Infectious diseases are the disease of poor who invariably suffer from malnutrition that could result from reduced serum leptin levels. Thus, leptin has been placed at the center of many interrelated functions in various pathogenic conditions, such as bacterial, viruses and parasitic infections. We review herein, the recent advances on the role of leptin in malnutrition in pathogenesis of infectious diseases with a particular emphasis on parasitic diseases such as Leishmaniasis, Trypanosomiasis, Amoebiasis, and Malaria.

The relation between leptin and inflammatory markers with respiratory and peripheral muscle strength in tuberculosis: A case-control study

BACKGROUND

Muscle weakness is a part of the wasting syndrome associated with TB. Cytokines are candidates as the initial causative agents of the metabolic changes in TB. The objective of this study is to assess the peripheral and respiratory muscle strength in patients with TB and controls and relate these findings with leptin, IL-6 and TNF-α serum levels.

METHODS

Case-control study. Hospitalized patients with pulmonary TB and controls were included. Maximal voluntary handgrip strength (HS), maximal inspiratory pressure (MIP) and maximum expiratory pressure (MEP) were measured. Leptin, IL-6 and TNF-α dosage were performed.

RESULTS

We included 35 cases and 35 controls. Leptin was lower and TNF-α levels were higher in TB patients than in controls (P < .0001 for both). Body mass index (BMI), HS, MIP and MEP were all significantly lower in cases than in controls (P < .0001). Lower leptin and higher TNF-α levels are associated with malnutrition and reduced MIP, MEP and HS. Patients who reported fever and those with positive culture for Mycobacterium tuberculosis had higher serum levels of IL-6.

CONCLUSION

Peripheral and respiratory muscle strength and leptin levels were reduced in patients with active TB. Lower levels of leptin and higher levels of TNF-α were associated with malnutrition and with reduced MIP, MEP and HS.

Malnutrition and Associated Disorders in Tuberculosis and Its Therapy

Tuberculosis (TB) has become the most important infectious disease to see resurgence worldwide. In 2014, there were 9.6 million documented cases worldwide with a mortality of almost 1.5 million (Global Tuberculosis Report 2014). One of the Millennium Development Goals set by the United Nations was the reversal of the TB epidemic, which has been achieved worldwide with an 18% lower incidence of TB globally compared to the incidence in the year 2000. Though efficient intervention has brought down the relative incidence and mortality of TB globally, the fact remains that one third of the world population has latent TB infection, and 10% of people with latent TB infection develop active TB at some point in their life (The Facts about Tuberculosis 1995). Risk factors that prompt the reactivation of latent TB into active TB are a compromised immune system, HIV, malnutrition, and use of tobacco. In developing and underdeveloped economies, malnutrition and undernutrition play a major role in subverting the immune system and reactivating the latent TB infection. Undernutrition is one of the major factors in India and Southeast Asia leading to an increase in TB infections. Once tuberculosis sets in, it leads to an increase in metabolism and a decrease in appetite that compounds the already present malnutrition. Drawing on previous studies, we have aimed at understanding the relationship between malnutrition and TB infection and making minimal recommendations for corrective action.

Nutrition Status Among HIV-Positive and HIV-Negative Inpatients with Pulmonary Tuberculosis

BACKGROUND

The association between tuberculosis (TB) and malnutrition is well recognized. Considering the risk of mortality due to malnutrition in patients with TB, it is necessary to conduct a thorough nutrition assessment to identify individuals at nutrition risk. The study objective was to assess the nutrition status of hospitalized patients with TB, co-infected or not by human immunodeficiency virus (HIV).

METHODS

Patients with confirmed diagnosis of TB were included using a cross-sectional design. Nutrition assessment parameters included: body mass index (BMI), triceps skin-fold thickness (TSF), bioelectrical impedance analysis (BIA), mid-upper-arm circumference (MUAC), mid-arm muscle circumference (MAMC), food frequency questionnaire, Malnutrition Screening Tool (MST), Subjective Global Assessment (SGA), and serum levels of hemoglobin.

RESULTS

A total 108 patients completed the study. Forty-four patients (40.7%) were HIV positive. Considering the BMI, 36.1% of the patients met the criteria for nutrition deficiency. Body fat percentage was low in 27.8% of patients. In addition, more than half of the participants met criteria for malnutrition according to MUAC, MAMC, TSF, SGA, or MST. Malnutrition measured by MAMC was more frequent in HIV-positive patients (n=33, 75.0%) than in HIV-negative patients (n=31, 48.4%) (P = 0.010). Regarding the components of diet, selenium and vitamin C intake among HIV-positive patients was significantly lower than in HIV-negative patients.

CONCLUSIONS

We identified a high prevalence of malnutrition in hospitalized patients with pulmonary TB, regardless of the method used to assess nutrition status. In HIV-positive patients, malnutrition measured by MAMC was more frequent than in HIV-negative patients.

The association between tuberculosis and the development of insulin resistance in adults with pulmonary tuberculosis in the Western sub-district of the Cape Metropole region, South Africa: a combined cross-sectional, cohort study

BACKGROUND

The existence of a bi-directional relationship between tuberculosis (TB) and insulin resistance (IR)/diabetes has been alluded to in literature. Although diabetes has been linked to increased tuberculosis risk, the relationship between tuberculosis as a causative factor for IR remains unclear. The study aimed to determine if an association existed between tuberculosis and IR development in adults with newly diagnosed pulmonary tuberculosis at baseline. It was additionally aimed to document changes in IR status during TB follow-up periods.

METHODS

This cross-sectional study evaluated ambulatory participants at baseline for IR prevalence via anthropometry, biochemistry and diagnostic IR tests [homeostasis model assessment-IR (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI)]. A prospective cohort sub-section study was additionally performed on approximately half of the baseline study population, who were followed-up at two and five months whilst on tuberculosis treatment. Summary statistics, correlation co-efficients and appropriate analysis of variance were used to describe and analyse data. Participants were excluded if they presented with other forms of tuberculosis, were HIV-positive, obese or had any pre-disposing IR conditions such as diabetes or metabolic syndrome.

RESULTS

Fifty-nine participants were included from August 2013 until December 2014 (33.95 ± 12.02 years old; 81.4% male). IR prevalence was 25.4% at baseline, determined by a calculated HOMA-IR cut-off point of 2.477. Patients with IR were younger (p = 0.04). Although the difference between IR levels in participants between baseline and follow-up was not significant, a decrease was observed over time. The majority of participants (61.0%) presented with a normal BMI at baseline. Mean baseline values of fasting glucose were within normal ranges (4.82 ± 0.80 mmol/L), whereas increased mean CRP levels (60.18 ± 50.92 mg/L) and decreased mean HDL-cholesterol levels (males: 0.94 ± 0.88 mmol/L; females: 1.14 ± 0.88 mmol/L) were found.

CONCLUSIONS

The study found an association between tuberculosis and IR development in newly diagnosed pulmonary tuberculosis patients. Although not significant, IR levels decreased over time, which could be indicative of a clinical improvement. A high prevalence of IR amongst young tuberculosis patients therefore highlights the need for early identification in order to facilitate a reversal of IR and prevent possible IR-related complications.

Changes in Host Immune-Endocrine Relationships during Tuberculosis Treatment in Patients with Cured and Failed Treatment Outcomes

A bidirectional communication between the immune and endocrine systems exists and facilitates optimum responses in the host during infections. This is in part achieved through changes in secretion patterns of hypothalamic hormones induced by inflammatory cytokines. The aim of this study was to elucidate the immune–endocrine alterations during tuberculosis (TB) treatment in patients with cured and failed TB treatment outcomes. Blood samples were collected from 27 cured and 10 failed patients and hormone as well as cytokine concentrations quantified at baseline, week 4, and month 6 of TB treatment. Hormone profiles of the two treatment outcome groups were different from each other prior to as well as during TB treatment. Treatment response effects were observed for cortisol, estradiol, T3, T4 ghrelin, leptin, amylin, adiponectin, and dehydroepiandrosterone (DHEA). Trends suggest that T4, amylin, and DHEA concentrations were different between treatment outcomes, although these did not reach statistical significance. Relationships between endocrine and inflammatory markers and the biological pathways involved differed between cured and failed treatment patients. These results highlight the complex interaction between the endocrine and immune system during active TB disease and throughout treatment and suggest that endocrine markers in conjunction with inflammatory markers may be useful in predicting unfavorable treatment outcomes.

Effect of tuberculosis treatment on leptin levels, weight gain, and percentage body fat in Indonesian children

PURPOSE

Tuberculosis (TB) remains a problem in the community. TB patients usually experience malnutrition, which is characterized by both decreased body weight (BW) and body fat percentage (BFP). Leptin, an important regulator of BW, also plays an important role in cellular immunity, which is integral to defense against Mycobacterium tuberculosis infection. We analyzed the effect of an anti-TB treatment regimen on the leptin level, BW, and BFP of children with TB.

METHODS

The design of this study was a group interrupted time series. The subjects were children with probable TB according to clinical criteria based on an Indonesian scoring system adopted from the Consensus of Expert Panel. BW; BFP; energy intake; fat and protein intake; and leptin levels before, 2 months after (intensive phase), and 6 months after (continuation phase) anti-TB treatment, were measured. About 40 children, aged 5-14 years, participated in this study.

RESULTS

The BW, BFP and leptin level increased from before treatment to after completion of the intensive phase and still showed an increased during the continuation phase: BW 18.65 kg, 19.75 kg, and 20.85 kg; BFP 18.3%, 19.5%, and 20.2%; and leptin level 1.9 mg/dL, 3.07 mg/dL, and 3.4 mg/dL, respectively (P<0.01).

CONCLUSION

Leptin level, BW, and BFP increased throughout the course of anti-TB treatment, compared with pretreatment values. Further research is needed to compare the results with data for healthy children.

Microarray expression profile analysis of mRNAs and long non-coding RNAs in pulmonary tuberculosis with different traditional Chinese medicine syndromes

Background

Combination chemotherapy with Western anti-tuberculosis (TB) drugs is the mainstay of TB treatment. Chinese herbal medicines with either heat clearing and detoxifying effects or nourishing Yin and reducing fire effects have been used to treat TB based on the Traditional Chinese Medicine (TCM) syndromes of TB patients. This study analyzed the expression profiles of long non-coding RNAs (lncRNAs) and mRNAs in TB patients with different TCM syndromes.

Methods

TB patients were classified as pulmonary Yin deficiency (PYD) syndrome, hyperactivity of fire due to Yin deficiency (HFYD) syndrome, and deficiency of Qi and Yin (DQY) syndrome. Total RNA from 44 TB patients and healthy controls was extracted and hybridized with a human lncRNA microarray containing 30586 lncRNAs and 26109 mRNAs probes. Bioinformatics analyses, including gene ontology (GO) and pathways, were performed. Related clinical data were also analyzed.

Results

Differentially expressed mRNAs and lncRNAs were identified (fold change >2, and P < 0.05) in PYD (634 mRNAs and 566 lncRNAs), HFYD (47 mRNAs and 55 lncRNAs), and DQY (63 mRNAs and 60 lncRNAs) patients. The most enriched pathways were the hippo signaling pathway (P = 0.000164) and the protein digestion and absorption pathway (P = 5.89017E-05). Clinical analyses revealed that the lipid indexes of TB patients were abnormal and that the triglyceride concentration was significantly higher in DQY patients (P = 0.0252). Our study is the first to acquire the microarray expression profiles of lncRNAs and mRNAs and analyze pathway enrichment in PYD, HFYD, and DQY patients with TB.

Conclusions

Our analyses of the expression profiles of lncRNAs and mRNAs may represent a novel method to explore the biological essence of TCM syndromes of TB.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1436-y) contains supplementary material, which is available to authorized users.

Relation of leptin, ghrelin and inflammatory cytokines with body mass index in pulmonary tuberculosis patients with and without type 2 diabetes mellitus

BACKGROUND

Pulmonary tuberculosis (TB) patients often suffer from anorexia and poor nutrition, causing weight loss. The peptide hormones leptin and its counterpart ghrelin, acting in the regulation of food intake and fat utilization, play an important role in nutritional balance. This study aimed to investigate the association of blood concentrations of leptin, ghrelin and inflammatory cytokines with body mass index (BMI) in TB patients with and without type 2 diabetes mellitus (T2DM).

METHODS

BMI, biochemical parameters and plasma levels of leptin, ghrelin and inflammatory cytokines were measured before the start of treatment in 27 incident TB patients with T2DM, 21 TB patients and 23 healthy subjects enrolled in this study.

RESULTS

The levels of leptin were significantly higher in TB patients (35.2 ± 19.1 ng/ml) than TB+T2DM (12.6 ± 6.1 ng/ml) and control (16.1 ± 11.1 ng/ml) groups. The level of ghrelin was significantly lower in TB (119.9 ± 46.1 pg/ml) and non-significantly lower in TB+T2DM (127.7 ± 38.6 pg/ml) groups than control (191.6 ± 86.5 pg/ml) group. The levels of TNF-α were higher, while IFN-γ and IL-6 levels were lower in patients than in the control group. Leptin showed a negative correlation with BMI in TB (r=-0.622, p<0.05) and TB+T2DM (r= -0.654, p<0.05) groups, but a positive correlation with BMI in the control group (r=0.521, p<0.05). Contrary ghrelin showed a positive correlation with BMI in TB (r=0.695, p<0.05) and TB+T2DM (r= 0.199, p>0.05) groups, but negative correlation with BMI in the control (r=-0.693, p<0.05) group. Inflammatory cytokines were poorly correlated with BMI in this study. Only IFN-γ showed a significant negative correlation with BMI in the control group (r=-0.545, p<0.05).

CONCLUSIONS

This study may suggest that possible abnormalities in ghrelin and leptin regulation (high levels of leptin and low levels of ghrelin) may be associated with low BMI and may account for the poor nutrition associated with TB and TB+T2DM.

The prognostic significance of nutritional status using malnutrition universal screening tool in patients with pulmonary tuberculosis

Background

Malnutrition is frequently observed in patients with pulmonary tuberculosis (TB). The present study aimed to examine the relationship between nutritional status using Malnutrition Universal Screening Tool (MUST) and the mortality of patients with pulmonary TB.

Methods

Fifty-seven patients with pulmonary TB were analyzed. Nutrition assessment was carried out using MUST. The Cox proportional hazard model was applied to assess the ability of MUST to predict prognosis. Receiver operating characteristic curve analysis was used to assess MUST score as a prognostic indicator in pulmonary TB patients. To obtain optimal cut-off values for MUST score for prognostic assessment in TB patients, we used the maximum Youden Index.

Results

For predicting the risk of mortality, the optimal cut-off value for MUST score was 3.5. Univariate and multivariate analyses identified age and MUST score ≥ 4 as significant independent prognostic factors for survival. The patients with MUST score ≤ 3 had a median survival of 481 days (95% CI: 453 to 510) and that for the patients with MUST score ≥ 4 was 304 days (95% CI: 214 to 394); the difference was statistically significant (P = 0.001).

Conclusion

MUST appears to be a reliable tool for nutritional risk assessment of patients with pulmonary TB. In addition, MUST may be a useful prognostic indicator of survival in patients with pulmonary TB.

Gut hormones, appetite suppression and cachexia in patients with pulmonary TB

Background

Cachexia is a hallmark of pulmonary tuberculosis and is associated with poor prognosis. A better understanding of the mechanisms behind such weight loss could reveal targets for therapeutic intervention. The role of appetite-regulatory hormones in tuberculosis is unknown.

Methods and Findings

41 subjects with newly-diagnosed pulmonary TB (cases) were compared to 82 healthy controls. We measured appetite, body mass index (BMI), % body fat (BF), plasma peptide YY (PYY), leptin, ghrelin, and resistin for all subjects. Measurements were taken at baseline for controls and at treatment days 0, 30, and 60 for cases. Baseline appetite, BMI, and BF were lower in cases than in controls and improved during treatment. PYY, ghrelin, and resistin were significantly elevated in cases and fell during treatment. Leptin was lower in cases and rose with treatment. Appetite was inversely related to PYY in cases. High pre-treatment PYY predicted reduced gains in appetite and BF. PYY was the strongest independent predictor of appetite in cases across all time points.

Conclusions

Appetite-regulatory hormones are altered in TB patients. As hormones normalize during treatment, appetite is restored and nutritional status improves. High baseline PYY is an indicator of poor prognosis for improvement in appetite and nutrition during treatment. Wasting in TB patients may partly be mediated by upregulation of PYY with resulting appetite suppression.

The role of feed regulating peptides on weight loss in patients with pulmonary tuberculosis

PURPOSE

Malnutrition is a prominent feature of tuberculosis (TB). The aim of our study was to explore the function of plasma regulatory proteins in pulmonary TB and to investigate the relationship between these parameters and loss of body weight.

METHODS

Plasma levels of fasting insulin, leptin, ghrelin, adiponectin and orexin-A were measured in 23 pulmonary TB patients, 39 patients with pulmonary sarcoidosis, 22 patients with different diffuse interstitial lung diseases and 21 healthy patients serving as controls.

RESULT

Plasma leptin (p<0.001) and orexin-A (p<0.01) levels were significantly decreased in TB patients compared with those of the other study subjects. TB patients also had higher levels of plasma ghrelin compared with those of the other study subjects, while sarcoidosis patients had higher plasma adiponectin levels than the other study subjects. Glucose levels were similar in all groups, yet, insulin and Homeostasis Model of Assessment-Insulin Resistance (HOMA-IR) levels were significantly higher in the TB group compared to the other study groups. There was no correlation between leptin, ghrelin, adiponectin and orexin-A and other parameters.

CONCLUSIONS

These data suggest that leptin and orexin-A levels have effects on weight loss in patients with pulmonary tuberculosis. Particularly, leptin may play a role in the early immune response to pulmonary TB and prolonged inflammation may further suppress leptin production. Measurement of HOMA-IR can indeed be used as a marker for the risk of activated TB. Further clinical studies are needed to better understand the role of feed regulating proteins in pulmonary tuberculosis.

Circulating levels of adiponectin, leptin, fetuin-A and retinol-binding protein in patients with tuberculosis: markers of metabolism and inflammation

BACKGROUND

Wasting is known as a prominent feature of tuberculosis (TB). To monitor the disease state, markers of metabolism and inflammation are potentially useful. We thus analyzed two major adipokines, adiponectin and leptin, and two other metabolic markers, fetuin-A and retinol-binding protein 4 (RBP4).

METHODS

The plasma levels of these markers were measured using enzyme-linked immunosorbent assays in 84 apparently healthy individuals (=no-symptom group) and 46 patients with active pulmonary TB around the time of treatment, including at the midpoint evaluation (=active-disease group) and compared them with body mass index (BMI), C-reactive protein (CRP), chest radiographs and TB-antigen specific response by interferon-γ release assay (IGRA).

RESULTS

In the no-symptom group, adiponectin and leptin showed negative and positive correlation with BMI respectively. In the active-disease group, at the time of diagnosis, leptin, fetuin-A and RBP4 levels were lower than in the no-symptom group [adjusted means 2.01 versus 4.50 ng/ml, P<0.0001; 185.58 versus 252.27 µg/ml, P<0.0001; 23.88 versus 43.79 µg/ml, P<0.0001, respectively]. High adiponectin and low leptin levels were associated with large infiltrates on chest radiographs even after adjustment for BMI and other covariates (P=0.0033 and P=0.0020). During treatment, adiponectin levels increased further and then decreased. Leptin levels remained low. Initial low levels of fetuin-A and RBP4 almost returned to the normal reference range in concert with reduced CRP.

CONCLUSIONS

Our data and recent literature suggest that low fat store and underlying inflammation may regulate these metabolic markers in TB in a different way. Decreased leptin, increased adiponectin, or this ratio may be a promising marker for severity of the disease independent of BMI. We should further investigate pathological roles of the balance between these adipokines.

Energy expenditure in HIV infection

Energy intake recommendations for adults should be based preferably on direct measurements of total daily energy expenditure (TDEE) in corresponding populations who are maintaining healthy body weight and satisfactory physical activity levels. During adolescence, pregnancy, and lactation, energy requirements should be based on TDEE plus the additional energy required to advance these physiologic states. With illness, energy expenditure and energy intake change, but nutritional intervention is not necessarily beneficial. This article reviews data on energy expenditure in HIV infection with a focus on adults, adolescents aged ≥14 y, and pregnant and lactating women. Resting energy expenditure (REE) in adults with untreated asymptomatic HIV is ~ 10% higher than in healthy control subjects. In asymptomatic adults receiving antiretroviral therapy, REE may be similarly increased. HIV wasting and secondary infections are also associated with increased REE. In contrast, TDEE is typically normal in asymptomatic HIV and decreased in HIV wasting and secondary infection. No direct measurements of REE or TDEE are available in adolescents or in pregnant or lactating women with HIV. On the basis of current data, energy intake may need to increase by ~ 10% in adults with asymptomatic HIV to maintain body weight. In adolescents and in pregnant and lactating women with asymptomatic HIV, energy requirements should approximate recommendations for their uninfected counterparts until further data are available. In the resource-rich world, the energy expenditure changes associated with HIV are unlikely to contribute to significant weight loss. More data are needed on energy expenditure in HIV-infected populations from developing nations, where concurrent malnutrition and coinfections are common.

A multifaceted analysis of immune-endocrine-metabolic alterations in patients with pulmonary tuberculosis

Our study investigated the circulating levels of factors involved in immune-inflammatory-endocrine-metabolic responses in patients with tuberculosis with the aim of uncovering a relation between certain immune and hormonal patterns, their clinical status and in vitro immune response. The concentration of leptin, adiponectin, IL-6, IL-1β, ghrelin, C-reactive protein (CRP), cortisol and dehydroepiandrosterone (DHEA), and the in vitro immune response (lymphoproliferation and IFN-γ production) was evaluated in 53 patients with active untreated tuberculosis, 27 household contacts and 25 healthy controls, without significant age- or sex-related differences. Patients had a lower body mass index (BMI), reduced levels of leptin and DHEA, and increased concentrations of CRP, IL-6, cortisol, IL-1β and nearly significant adiponectin values than household contacts and controls. Within tuberculosis patients the BMI and leptin levels were positively correlated and decreased with increasing disease severity, whereas higher concentrations of IL-6, CRP, IL-1β, cortisol, and ghrelin were seen in cases with moderate to severe tuberculosis. Household contacts had lower DHEA and higher IL-6 levels than controls. Group classification by means of discriminant analysis and the k-nearest neighbor method showed that tuberculosis patients were clearly different from the other groups, having higher levels of CRP and lower DHEA concentration and BMI. Furthermore, plasma leptin levels were positively associated with the basal in vitro IFN-γ production and the ConA-driven proliferation of cells from tuberculosis patients. Present alterations in the communication between the neuro-endocrine and immune systems in tuberculosis may contribute to disease worsening.

Subjective global assessment in patients with pulmonary tuberculosis

BACKGROUND

Malnutrition is observed frequently in patients with pulmonary tuberculosis (TB). Subjective global assessment (SGA) is a subjective method of measuring nutrition status. Few studies have investigated the prognostic role of SGA in patients with pulmonary TB.

METHODS

The authors evaluated 39 patients with pulmonary TB. The SGA classification technique was performed; patients were classified as well nourished (A), moderately malnourished (B), or severely malnourished (C).

RESULTS

The mean patient age was 67.7 ± 19.0 years, and the majority of patients were male (64.1% ). Twelve patients (30.1% ) were categorized as SGA class A, 14 patients (35.9% ) as class B, and 13 patients (33.3% ) as class C. The SGA-A group had a median survival of 438 days (95% confidence interval, 366-509), the median survival of the SGA-B group was 344 days (251-436), and the median survival of the SGA-C group was 118 days (37-198); these survival rates were significantly different (P < .001).

CONCLUSION

SGA appears to be a useful tool for nutrition assessment of patients with pulmonary TB. In addition, SGA may be a prognostic indicator of survival in patients with pulmonary TB.

The role of leptin in the respiratory system: an overview

Since its cloning in 1994, leptin has emerged in the literature as a pleiotropic hormone whose actions extend from immune system homeostasis to reproduction and angiogenesis. Recent investigations have identified the lung as a leptin responsive and producing organ, while extensive research has been published concerning the role of leptin in the respiratory system. Animal studies have provided evidence indicating that leptin is a stimulant of ventilation, whereas researchers have proposed an important role for leptin in lung maturation and development. Studies further suggest a significant impact of leptin on specific respiratory diseases, including obstructive sleep apnoea-hypopnoea syndrome, asthma, COPD and lung cancer. However, as new investigations are under way, the picture is becoming more complex. The scope of this review is to decode the existing data concerning the actions of leptin in the lung and provide a detailed description of leptin's involvement in the most common disorders of the respiratory system.

Slender, older women appear to be more susceptible to nontuberculous mycobacterial lung disease

BACKGROUND

Nontuberculous mycobacteria (NTM) are environmental microbes that are associated with a variety of human diseases, particularly chronic lung infections. Over the past several decades, NTM lung disease has been increasingly seen in postmenopausal women with slender body habitus.

OBJECTIVE

This article reviewed the clinical and experimental evidence that supports the observation that thin older women (aged 50-80 years) are predisposed to NTM lung disease. We posited 3 potential pathways for this predisposition: relative estrogen deficiency, abnormal levels of adipokines that alter immune responses, and abnormal expression of transforming growth factor-beta (TGF-beta) related to fibrillin anomalies similar to Marfan syndrome (MFS).

METHODS

Using the PubMed database, a literature search was performed (all publications up to July 2009) by pairing the key phrase nontuberculous mycobacteria with weight, malnutrition, female gender, body habitus, leptin, adipokines, estrogen, menopause, postmenopausal, or body mass index. Non-English-language articles were included if their abstracts were in English. Relevant articles were also identified from the abstracts.

RESULTS

Published case reports and series indicate that in the past 20 years, NTM lung disease has been recognized in disproportionately increased numbers in postmenopausal women. Among these patients, slender body habitus and thoracic cage abnormalities, such as pectus excavatum and scoliosis, are commonly described. Notably, no long-term prospective clinical studies exist to corroborate that low weight is an independent risk factor for NTM lung disease. However, based on the findings of a limited number of experimental studies, we hypothesize that decreased leptin, increased adiponectin, and/or decreased estrogen in older women with slender body habitus may account for their increased susceptibility to NTM infections. We further speculate that in some patients with features mindful of MPS (slender, scoliosis, pectus excavatum, or mitral valve prolapse), there may be anomalies of fibrillin, similar to MFS, that lead to the expression of the immunosuppressive cytokine TGP-beta further increasing their susceptibility to NTM.

CONCLUSIONS

It is likely that both sufficient environmental exposure and host susceptibility are required for the establishment of NTM lung disease. The observation that NTM lung infections are more common in slender, older women without any overt immune defects suggests that abnormal expression of adipokines, sex hormones, and/or TGF-beta may play an important role in their susceptibility.

Relation of ghrelin, leptin and inflammatory markers to nutritional status in active pulmonary tuberculosis

BACKGROUNDS & AIMS

Malnutrition is a prominent feature of tuberculosis. Little is known about the role of the appetite-related hormones, ghrelin and leptin, in malnutrition in tuberculosis. This study was undertaken to determine whether ghrelin and leptin contribute to malnutrition in active pulmonary tuberculosis.

METHODS

Nutritional parameters and plasma levels of ghrelin, leptin, and inflammatory cytokines were measured before treatment and after clinical improvement following anti-tuberculosis chemotherapy in 23 tuberculosis subjects and 23 healthy controls prospectively. Patients were divided into well-nourished (n=15) and malnourished (n=8) groups.

RESULTS

Ghrelin but not leptin levels were significantly lower in the malnourished tuberculosis group than in the well-nourished tuberculosis group [44.0 (43.0-54.0) vs. 122 (108-158)pg/mL; p<0.05]. Malnutrition score was negatively correlated to ghrelin (rho=-0.76, p<0.01) but not to leptin levels. TNF-alpha and IL-6 levels were significantly higher in the malnourished tuberculosis group than in the well-nourished tuberculosis group and controls. Plasma levels of ghrelin tended to decrease as inflammatory cytokines increased before treatment.

CONCLUSIONS

Decreased plasma ghrelin levels, in addition to increased plasma inflammatory cytokine levels, may be associated with malnutrition in active pulmonary tuberculosis.

Visceral adipose tissue specific persistence of Mycobacterium tuberculosis may be reason for the metabolic syndrome

Mycobacterium tuberculosis (Mtb) is highly successful intracellular pathogen. Infection is maintained in spite of acquired immunity and resists eradication by antimicrobials. Following bacillaemia, small numbers of bacteria are disseminated to the extrapulmonary organs most likely including visceral adipose tissue by a mechanism that may involve the migration of M. tuberculosis within dendritic cells. In this lipid rich environment, Mtb can metabolize the fatty acids in a glyoxylate cycle dependent manner, and a state of chronic persistence may ensue. The persistent bacilli primarily use fatty acids as their carbon source. Expression of isocitrate lyase (ICL), gating enzyme of glyoxylate cycle, is upregulated during infection. ICL is important for survival during the persistent phase of infection. Expression of adipokines, particularly monocyte chemoattractant protein-1 (MCP-1), which is a potent proinflammatory cytokine, may be increased. MCP-1 contributes both to the recruitment of macrophages to adipose tissue and to the development of insulin resistance in humans. In addition, prolonged low level immune stimulation induces local adipolipogenesis, increasing visceral fat. Increased delivery of free fatty acid to the liver may stimulate the glyoxylate cycle-induced gluconeogenesis, raising hepatic glucose output. Hence, inhibition of the triggering enzyme ICL, which initiates all the pathologies related to persistent Mtb infection, may block the growth of the bacteria and may resolve the systemic metabolic complications.

Serum leptin concentrations and fat redistribution in HIV-1-infected children on highly active antiretroviral therapy

OBJECTIVES

HIV-related lipodystrophy is a syndrome of adipose tissue redistribution, dyslipidaemia and insulin resistance. Combination antiretroviral therapy (CART) is a key risk factor. We hypothesized that fat redistribution in HIV-infected children is related to altered endocrine function of adipose tissue, namely leptin secretion.

METHODS

Serum leptin and fat redistribution were measured in 104 HIV-infected children in a prospective observational study from 2003 to 2004. Fat redistribution was defined by clinical observation. Body fatness was estimated using body mass index and four skinfold measurements. Serum leptin was determined using an enzyme-linked immunosorbent assay (Quantikine; R&D Systems, Abingdon, UK). Linear analogue models were used to adjust the leptin concentration for body fatness.

RESULTS

There was no significant difference in serum leptin among children treated with protease inhibitors (PIs), children on non-PI CART and children not treated with CART (P>0.05). When leptin concentrations were adjusted for body fatness, there was again no difference among PI-treated, non-PI-treated and untreated children. Categorization of CART exposure as never, current or past did not change these results.

CONCLUSIONS

There is no evidence that leptin plays any role in lipodystrophy other than reflecting body fatness.

Malnutrition and infection: complex mechanisms and global impacts

The authors discuss current concepts and controversies surrounding the complex influences of malnutrition on infection and immunity, and point to practical consequences of countermeasures in acute malnutrition.

Leptin levels in various manifestations of pulmonary tuberculosis

BACKGROUND

Proinflammatory cytokines are prime candidates as causative agents of the metabolic changes that eventually result in tuberculosis-associated weight loss. Microbial products and cytokines such as TNF and IL-1 increase leptin expression dose dependently in adipose tissue. Leptin plays an important role in cellular immunity.

OBJECTIVES

In this study, we investigated serum leptin and TNF-alpha levels before and after antituberculosis therapy in patients with active pulmonary tuberculosis (TB).

METHODS

Twenty five in patients with active pulmonary TB and 18 healthy controls participated in the study. Leptin and TNF-alpha levels were measured before treatment and six months after the treatment and they were compared with the control group. Body mass index (BMI) and chest X-rays before and after the treatment were also evaluated.

RESULTS

The leptin levels before and after the treatment were 1.66+/-1.68 ng/mL and 3.26+/-3.81 ng/mL, respectively. The leptin levels of tuberculous patients were significant than in healthy patients (P < .05). The BMI was 19.36+/-2.55 kg/m2 before the treatment and 22.87+/-3.13 kg/m2 after the treatment. The TNF-alpha level was 23.19+/-12.78 pg/mL before the treatment and 15.95+/-6.58 pg/mL after the treatment. There was no correlation between leptin and TNF-alpha levels. Leptin levels were low in patients who had sequela lesion on chest radiographs.

CONCLUSION

Leptin levels are suppressed in tuberculous patients and low leptin levels may contribute to increased susceptibility to infection and recovery with sequela lesions.

Diagnostic value of leptin in tuberculous pleural effusions

It is suggested that leptin may be involved in inflammation. Although relation between leptin levels and active pulmonary tuberculosis has been studied, there is no information about relation between leptin levels and tuberculous pleural effusions (TPE). We evaluated the diagnostic value of pleural fluid and serum leptin levels in TPE and compared them with adenosine deaminase (ADA). Forty-five patients, 17 tuberculous effusion and 28 nontuberculous effusion, with exudative pleural effusions were included. Leptin and ADA levels were measured from serum and pleural fluid in all patients. There were no statistically significant differences between tuberculous and nontuberculous groups with respect to the serum ADA activity and pleural fluid/serum leptin ratio. On the contrary, pleural fluid leptin level, pleural fluid ADA activity, serum leptin level and pleural fluid/serum ADA activity ratio were statistically different between tuberculous and nontuberculous groups. When leptin levels were corrected for body mass index, serum leptin levels did not reach statistical significance. Cut-off points to predict tuberculosis were calculated as 9.85 ng/ml and 35.55 U/l for pleural fluid leptin level and pleural fluid ADA activity, respectively. Sensitivity, specificity and area under the curve +/- standard error were 82.4%, 82.1%, 0.83 +/- 0.07 for pleural fluid leptin levels and 100%, 100%, 1.00 +/- 0.00 for pleural fluid ADA activity, respectively; the difference between these curves was significant (p = 0.01). Pleural fluid leptin levels were lower in tuberculous effusions than in other exudates. Pleural fluid leptin has a diagnostic value for TPE but not as good as that of ADA.

Population variation and differences in serum leptin independent of adiposity: a comparison of Ache Amerindian men of Paraguay and lean American male distance runners

Background

Serum leptin variation is commonly associated with fat percentage (%), body mass index (BMI), and activity. In this investigation, we report population differences in mean leptin levels in healthy men as well as associations with fat % and BMI that are independent of these factors and reflect likely variation resulting from chronic environmental conditions.

Methods

Serum leptin levels, fat %, and BMI were compared between lean American distance runners and healthy Ache Native Americans of Paraguay. Mean levels were compared as were the regressions between fat %, BMI, and leptin. Comparisons were performed between male American distance runners (n = 13, mean age 32.2 ± 9.2 SD) and highly active male New World indigenous population (Ache of Paraguay, n = 20, mean age 32.8 ± 9.2) in order to determine whether significant population variation in leptin is evident in physically active populations living under different ecological circumstances independent of adiposity and BMI.

Results

While the Ache were hypothesized to exhibit higher leptin due to significantly greater adiposity (fat %, Ache 17.9 ± 1.8 SD; runners 9.7 ± 3.2, p < 0.0001), leptin levels were nonetheless significantly higher in American runners (Ache 1.13 ng/ml ± 0.38 SD; runners 2.19 ± 1.15; p < 0.007). Significant differences in the association between leptin and fat % was also evident between Ache and runner men. Although fat % was significantly related with leptin in runners (r = 0.90, p < 0.0001) fat % was negatively related in Ache men (r = -0.50, p < 0.03).

Conclusion

These results illustrate that chronic ecological conditions in addition to activity are likely factors that contribute to population variation in leptin levels and physiology. Population variation independent of adiposity should be considered to be an important source of variation, especially in light of ethnic and population differences in the incidence and etiology of obesity, diabetes, and other metabolic conditions.

ESPEN Guidelines on Enteral Nutrition: Wasting in HIV and other chronic infectious diseases

Undernutrition (wasting) is still frequent in patients infected with the human immunodeficiency virus (HIV), despite recent decreases in the prevalence of undernutrition in western countries (as opposed to developing countries) due to the use of highly active antiretroviral treatment. Undernutrition has been shown to have a negative prognostic effect independently of immunodeficiency and viral load. These guidelines are intended to give evidence-based recommendations for the use of enteral nutrition (EN) by means of oral nutritional supplements (ONS) and tube feeding (TF) in HIV-infected patients. They were developed by an interdisciplinary expert group in accordance with officially accepted standards and is based on all relevant publications since 1985. Nutritional therapy is indicated when significant weight loss (>5% in 3 months) or a significant loss of body cell mass (>5% in 3 months) has occurred, and should be considered when the body mass index (BMI) is <18.5 kg/m(2). If normal food intake including nutritional counselling and optimal use of ONS cannot achieve an adequate nutrient intake, TF with standard formulae is indicated. Due to conflicting results from studies investigating the impact of immune-modulating formulae, these are not generally recommended. The results obtained in HIV patients may be extrapolated to other chronic infectious diseases, in the absence of available data.

Pulmonary Mycobacterium tuberculosis infection in leptin-deficient ob/ob mice

The development of active tuberculosis after infection with Mycobacterium tuberculosis is almost invariably caused by a persistent or transient state of relative immunodeficiency. Leptin, the product of the obese (ob) gene, is a pleiotropic protein produced mainly by adipocytes and is down-regulated during malnutrition and starvation, conditions closely connected with active tuberculosis. To investigate the role of leptin in tuberculosis, we intranasally infected wild-type (Wt) and leptin-deficient ob/ob mice with live virulent M. tuberculosis. Ob/ob mice displayed higher mycobacterial loads in the lungs after 5 and 10 weeks of infection, although the difference with Wt mice remained 1 log of M. tuberculosis colony forming unit. Nevertheless, ob/ob mice were less able to form well-shaped granuloma and lung lymphocyte numbers were reduced compared with Wt mice early during infection. In addition, ob/ob mice had a reduced capacity to produce the protective cytokine IFNgamma at the site of the infection early during infection and upon antigen-specific recall stimulation, and showed reduced delayed-type hypersensitivity reaction to intra-dermal tuberculin purified protein derivative. Leptin replacement restored the reduced IFNgamma response observed in ob/ob mice. Mortality did not differ between ob/ob and Wt mice. These data suggest that leptin plays a role in the early immune response to pulmonary tuberculosis.

Impact of tuberculosis on serum leptin levels in patients with HIV infection

AIM

Tuberculosis (TB) and human immunodeficiency virus (HIV) are classical wasting diseases accompanied by immunosuppression. As leptin is involved in the weight regulation and cellular immunity, we investigated the role of leptin levels in the co-infection of HIV and TB (HIV-TB).

METHODS

The study group consists of the patients with asymptomatic HIV infection (n = 20), patients with HIV-TB co-infection (n = 20) and healthy control subjects (n = 20). Serum leptin levels and the concentrations of IFN-gamma, TNF-alpha, IL-12 and IL-4 cytokines were measured by ELISA before the start of the treatment. CD4+ T-cell counts were determined in patients with HIV and HIV-TB by flow cytometry. Body mass index (BMI) of the study subjects was calculated.

RESULTS

Serum leptin levels and BMI were significantly lower in the patients with HIV-TB than control and HIV subjects. Multivariate regression analysis showed that serum leptin concentration was significantly dependent on BMI and sex but not on age and the disease groups. The leptin levels did not correlate either with CD4+ T-cell counts or with any of the serum cytokines in HIV and HIV-TB patients.

CONCLUSION

Thus our finding suggests that the leptin concentrations were strongly associated with BMI and gender but not with the disease state or with the circulating cytokine levels.

Nutrient partitioning during treatment of tuberculosis: gain in body fat mass but not in protein mass

BACKGROUND

Tuberculosis is an important cause of wasting. The functional consequences of wasting and recovery may depend on the distribution of lost and gained nutrient stores between protein and fat masses.

OBJECTIVE

The goal was to study nutrient partitioning, ie, the proportion of weight change attributable to changes in fat mass (FM) versus protein mass (PM), during antimycobacterial treatment.

DESIGN

Body-composition measures were made of 21 men and 9 women with pulmonary tuberculosis at baseline and after 1 and 6 mo of treatment. All subjects underwent dual-energy X-ray absorptiometry and deuterium bromide dilution tests, and a four-compartment model of FM, total body water (TBW), bone minerals (BM), and PM was derived. The ratio of PM to FM at any time was expressed as the energy content (p-ratio). Changes in the p-ratio were related to disease severity as measured by radiologic criteria.

RESULTS

Patients gained 10% in body weight (P < 0.001) from baseline to month 6. This was mainly due to a 44% gain in FM (P < 0.001); PM, BM, and TBW did not change significantly. Results were similar in men and women. The p-ratio decreased from baseline to month 1 and then fell further by month 6. Radiologic disease severity was not correlated with changes in the p-ratio.

CONCLUSIONS

Microbiological cure of tuberculosis does not restore PM within 6 mo, despite a strong anabolic response. Change in the p-ratio is a suitable parameter for use in studying the effect of disease on body composition because it allows transformation of such effects into a normal distribution across a wide range of baseline proportion between fat and protein mass.