Serum cholesterol and diseases in Nigerians

Effects of Bacillus Calmette-Guérin on immunometabolism, microbiome and liver diseases⋆

Metabolic diseases have overtaken infectious diseases as the most serious public health issue and economic burden in most countries. Moreover, metabolic diseases increase the risk of having infectious diseases. The treatment of metabolic disease may require a long-term strategy of taking multiple medications, which can be costly and have side effects. Attempts to expand the therapeutic use of vaccination to prevent or treat metabolic diseases have attracted significant interest. A growing body of evidence indicates that Bacillus Calmette-Guérin (BCG) offers protection against non-infectious diseases. The non-specific effects of BCG occur likely due to the induction of trained immunity. In this regard, understanding how BCG influences the development of chronic metabolic health including liver diseases would be important. This review focuses on research on BCG, the constellation of disorders associated with metabolic health issues including liver diseases and diabetes as well as how BCG affects the gut microbiome, immunity, and metabolism.

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.

Relationship between total cholesterol level and tuberculosis risk in a nationwide longitudinal cohort

The association between the total cholesterol level and tuberculosis (TB) risk has been controversial. Our study aimed to evaluate whether total cholesterol level can predict the risk of TB. Data from 5,000,566 subjects who participated in a health screening exam in 2009 were investigated using the Korean National Health Insurance Service database (2009–2018). Cox hazard regression analyses were used to evaluate TB risk according to the quartile of total cholesterol levels. During an average of 8.2 years of follow-up, 32,078 cases of TB occurred. There was a significant inverse association between the total cholesterol level and TB risk. Compared with subjects in the highest quartile, those in the lowest quartile had a 1.35-fold increased TB risk (95% confidence interval = 1.31–1.39). The association between total cholesterol level and TB risk was more apparent in young subjects (age < 65 years), those without diabetes mellitus (DM), and those without obesity (p for interaction < 0.001 for age group, DM, and body mass index). Although there was a significant inverse association between total cholesterol level and TB risk in subjects who did not use a statin, no significant association was observed between the total cholesterol level and TB risk in subjects who used a statin. A low total cholesterol level was significantly associated with an increased risk of TB, even after adjusting for confounders, especially in patients younger than 65 years, those without DM or obesity, and those who did not use a statin.

The Echo of Pulmonary Tuberculosis: Mechanisms of Clinical Symptoms and Other Disease-Induced Systemic Complications

Clinical symptoms of active tuberculosis (TB) can range from a simple cough to more severe reactions, such as irreversible lung damage and, eventually, death, depending on disease progression. In addition to its clinical presentation, TB has been associated with several other disease-induced systemic complications, such as hyponatremia and glucose intolerance. Here, we provide an overview of the known, although ill-described, underlying biochemical mechanisms responsible for the clinical and systemic presentations associated with this disease and discuss novel hypotheses recently generated by various omics technologies. This summative update can assist clinicians to improve the tentative diagnosis of TB based on a patient's clinical presentation and aid in the development of improved treatment protocols specifically aimed at restoring the disease-induced imbalance for overall homeostasis while simultaneously eradicating the pathogen. Furthermore, future applications of this knowledge could be applied to personalized diagnostic and therapeutic options, bettering the treatment outcome and quality of life of TB patients.

BCG lowers plasma cholesterol levels and delays atherosclerotic lesion progression in mice

BACKGROUND AND AIMS

Bacille-Calmette-Guérin (BCG), prepared from attenuated live Mycobacterium bovis, modulates atherosclerosis development as currently explained by immunomodulatory mechanisms. However, whether BCG is pro- or anti-atherogenic remains inconclusive as the effect of BCG on cholesterol metabolism, the main driver of atherosclerosis development, has remained underexposed in previous studies. Therefore, we aimed to elucidate the effect of BCG on cholesterol metabolism in addition to inflammation and atherosclerosis development in APOE*3-Leiden.CETP mice, a well-established model of human-like lipoprotein metabolism.

METHODS

Hyperlipidemic APOE*3-Leiden.CETP mice were fed a Western-type diet containing 0.1% cholesterol and were terminated 6 weeks after a single intravenous injection with BCG (0.75 mg; 5 × 10(6) CFU).

RESULTS

BCG-treated mice exhibited hepatic mycobacterial infection and hepatomegaly. The enlarged liver (+53%, p = 0.001) coincided with severe immune cell infiltration and a higher cholesterol content (+31%, p = 0.03). Moreover, BCG reduced plasma total cholesterol levels (-34%, p = 0.003), which was confined to reduced nonHDL-cholesterol levels (-36%, p = 0.002). This was due to accelerated plasma clearance of cholesterol from intravenously injected [(14)C]cholesteryl oleate-labelled VLDL-like particles (t½ -41%, p = 0.002) as a result of elevated hepatic uptake (+25%, p = 0.05) as well as reduced intestinal cholestanol and plant sterol absorption (up to -37%, p = 0.003). Ultimately, BCG decreased foam cell formation of peritoneal macrophages (-18%, p = 0.02) and delayed atherosclerotic lesion progression in the aortic root of the heart. BCG tended to decrease atherosclerotic lesion area (-59%, p = 0.08) and reduced lesion severity.

CONCLUSIONS

BCG reduces plasma nonHDL-cholesterol levels and delays atherosclerotic lesion formation in hyperlipidemic mice.

Dietary Cholesterol Increases the Risk whereas PUFAs Reduce the Risk of Active Tuberculosis in Singapore Chinese

BACKGROUND

Experimental studies suggest that cholesterol enhances the intracellular survival of Mycobacterium tuberculosis, whereas marine ω-3 (n-3) and ω-6 (n-6) fatty acids (FAs) may modulate responses to M. tuberculosis in macrophage and animal models. However, there are no epidemiologic data from prospective studies of the relation between dietary cholesterol and FAs and the risk of developing active tuberculosis.

OBJECTIVE

We aimed to investigate the relation between dietary intake of cholesterol and FAs and the risk of active tuberculosis in a prospective cohort in Singapore.

METHODS

We analyzed data from the Singapore Chinese Health Study, a cohort of 63,257 Chinese men and women aged 45-74 y recruited between 1993 and 1998. Dietary intake of cholesterol and FAs was determined with the use of a validated food-frequency questionnaire. Incident cases of active tuberculosis were identified via linkage with the nationwide tuberculosis registry. Analysis was performed with the use of Cox proportional hazards models.

RESULTS

As of 31 December 2013, 1136 incident cases of active tuberculosis were identified. Dietary cholesterol was positively associated with an increased risk of active tuberculosis in a dose-dependent manner. Compared with the lowest intake quartile, the HR was 1.22 (95% CI: 1.00, 1.47) for the highest quartile (P-trend = 0.04). Conversely, dietary marine n-3 and n-6 FAs were associated with a reduced risk of active tuberculosis in a dose-dependent manner. Compared with the lowest quartile, the HR for the highest intake quartile was 0.77 (95% CI: 0.62, 0.95) for marine n-3 FAs (P-trend = 0.01) and 0.82 (95% CI: 0.68, 0.98) for n-6 FAs (P-trend = 0.03). There was no association with saturated, monounsaturated, or plant-based n-3 FA intake.

CONCLUSION

Dietary intake of cholesterol may increase the risk of active tuberculosis, whereas marine n-3 and n-6 FAs may reduce the risk of active tuberculosis in the Chinese population.

Analysis of serum metabolic profile by ultra-performance liquid chromatography-mass spectrometry for biomarkers discovery: application in a pilot study to discriminate patients with tuberculosis

BACKGROUND

Tuberculosis (TB) is a chronic wasting inflammatory disease characterized by multisystem involvement, which can cause metabolic derangements in afflicted patients. Metabolic signatures have been exploited in the study of several diseases. However, the serum that is successfully used in TB diagnosis on the basis of metabolic profiling is not by much.

METHODS

Orthogonal partial least-squares discriminant analysis was capable of distinguishing TB patients from both healthy subjects and patients with conditions other than TB. Therefore, TB-specific metabolic profiling was established. Clusters of potential biomarkers for differentiating TB active from non-TB diseases were identified using Mann-Whitney U-test. Multiple logistic regression analysis of metabolites was calculated to determine the suitable biomarker group that allows the efficient differentiation of patients with TB active from the control subjects.

RESULTS

From among 271 participants, 12 metabolites were found to contribute to the distinction between the TB active group and the control groups. These metabolites were mainly involved in the metabolic pathways of the following three biomolecules: Fatty acids, amino acids, and lipids. The receiver operating characteristic curves of 3D, 7D, and 11D-phytanic acid, behenic acid, and threoninyl-γ-glutamate exhibited excellent efficiency with area under the curve (AUC) values of 0.904 (95% confidence interval [CI]: 0863-0.944), 0.93 (95% CI: 0.893-0.966), and 0.964 (95% CI: 00.941-0.988), respectively. The largest and smallest resulting AUCs were 0.964 and 0.720, indicating that these biomarkers may be involved in the disease mechanisms. The combination of lysophosphatidylcholine (18:0), behenic acid, threoninyl-γ-glutamate, and presqualene diphosphate was used to represent the most suitable biomarker group for the differentiation of patients with TB active from the control subjects, with an AUC value of 0.991.

CONCLUSION

The metabolic analysis results identified new serum biomarkers that can distinguish TB from non-TB diseases. The metabolomics-based analysis provides specific insights into the biology of TB and may offer new avenues for TB diagnosis.

Caseation of human tuberculosis granulomas correlates with elevated host lipid metabolism

The progression of human tuberculosis (TB) to active disease and transmission involves the development of a caseous granuloma that cavitates and releases infectious Mycobacterium tuberculosis bacilli. In the current study, we exploited genome-wide microarray analysis to determine that genes for lipid sequestration and metabolism were highly expressed in caseous TB granulomas. Immunohistological analysis of these granulomas confirmed the disproportionate abundance of the proteins involved in lipid metabolism in cells surrounding the caseum; namely, adipophilin, acyl-CoA synthetase long-chain family member 1 and saposin C. Biochemical analysis of the lipid species within the caseum identified cholesterol, cholesteryl esters, triacylglycerols and lactosylceramide, which implicated low-density lipoprotein-derived lipids as the most likely source. M. tuberculosis infection in vitro induced lipid droplet formation in murine and human macrophages. Furthermore, the M. tuberculosis cell wall lipid, trehalose dimycolate, induced a strong granulomatous response in mice, which was accompanied by foam cell formation. These results provide molecular and biochemical evidence that the development of the human TB granuloma to caseation correlates with pathogen-mediated dysregulation of host lipid metabolism.

Hypocholesterolemia: A major risk factor for developing pulmonary tuberculosis?

Although one-third of the world's population is infected by Mycobacterium tuberculosis, only approximately 10% will develop the overt clinical disease due to a yet undefined risk factor. We hypothesize that hypocholesterolemia might constitute such a factor, because: (a) cholesterol is an important molecule for the good functioning of an immune system, and is necessary for macrophages to uptake and engulf mycobacteria, (b) tuberculous patients often have hypocholesterolemia, in comparison with the general population and household contacts, (c) cholesterol has a beneficial effect against pulmonary tuberculosis, since a cholesterol-rich diet accelerates the bacteriological sterilization of sputum, and (d) many conditions traditionally considered major risk factors for tuberculosis are accompanied by hypocholesterolemia. If this hypothesis proves to be true, cholesterol might be given to hypocholesterolemic subjects who are at high risk for developing pulmonary tuberculosis.

A cholesterol-rich diet accelerates bacteriologic sterilization in pulmonary tuberculosis

BACKGROUND

Hypocholesterolemia is common among tuberculous patients and is associated with mortality in miliary cases. Some in vitro studies have shown that cholesterol is necessary for the good functioning of macrophages and lymphocytes.

STUDY OBJECTIVES

To determine whether a cholesterol-rich diet could accelerate sputum sterilization in patients with pulmonary tuberculosis.

DESIGN

An 8-week follow-up, randomized, controlled trial carried out from March 2001 to January 2002.

SETTING

A third-level hospital for respiratory diseases in Mexico City.

PATIENTS AND INTERVENTIONS

Adult patients with newly diagnosed pulmonary tuberculosis were hospitalized for 8 weeks and randomly assigned to receive a cholesterol-rich diet (800 mg/d cholesterol [experimental group]) or a normal diet (250 mg/d cholesterol [control group]). All patients received the same four-drug antitubercular regimen (ie, isoniazid, rifampin, pyrazinamide, and ethambutol).

MEASUREMENTS AND RESULTS

Every week, a quantitative sputum culture and laboratory tests were done and respiratory symptoms were recorded. Patients in the experimental group (10 patients) and the control group (11 subjects) were HIV-negative and harbored Mycobacterium tuberculosis that was fully sensitive to antitubercular drugs. Sterilization of the sputum culture was achieved faster in the experimental group, as demonstrated either by the percentage of negative culture findings in week 2 (80%; control group, 9%; p = 0.0019) or by the Gehan-Breslow test for Kaplan-Meier curves (p = 0.0037). Likewise, the bacillary population decreased faster (p = 0.0002) in the experimental group. Respiratory symptoms improved in both groups, but sputum production decreased faster in the experimental group (p < 0.05). Laboratory test results did not differ between the groups.

CONCLUSIONS

A cholesterol-rich diet accelerated the sterilization rate of sputum cultures in pulmonary tuberculosis patients, suggesting that cholesterol should be used as a complementary measure in antitubercular treatment.

Awareness of atherosclerosis risk factors in Nigeria

Non-communicable diseases, which include hypertension and diabetes mellitus, have become an important cause of morbidity and mortality in Nigeria. The determination of serum lipid levels is used routinely to assess the risk of atherosclerosis. This study was performed in order to determine the frequency of serum lipid requests in the community. Information on both lipid and total chemical pathology requests for the study period (May 1998 to April 2000) was obtained from the Department of Chemical Pathology, University of Ilorin Teaching Hospital, whilst data on the total hospital attendance was obtained from the hospital's Record Department. The number of serum lipid requests increased from year to year (May 1998 to April 1999 = 780; May 1999 to April 2000 = 1,357; May 2000 to April 2001 = 1,382). The percentages of total requests for serum Lipids when compared with the total laboratory requests for the period of study were 12.0%, 13.3% and 14.0% for the first, second and third year respectively. More men than women had their serum lipid levels determined; 31.3% of the patients had hyper-cholesterolaemia (> 5.2 mmol/L), while 9.9% had values > or = 6.2 mmol/L. Industrial disputes (strikes) affected our results. For the three-year period there was no remarkable increase in the use of the lipid profile facilities available in the centre. This reflects the inadequate awareness of lipid disorders as a risk factor for atherosclerosis.

Correlates of serum lipids in a lean black population

Exposure to an urban, sedentary work environment and higher socioeconomic status (SES) may stimulate adoption of Westernized lifestyles by populations in developing countries reversing the historically low risk for coronary heart disease. In a study of serum lipids in 1407 Nigerian civil servants, aged 25-54 years, we found a more atherogenic lipid profile among higher SES males and females compared with lower SES (LDL-cholesterol, 113 vs. 97 mg/dl, males, 125 vs. 114 mg/dl, females). Mean body mass index (BMI, kg/m2) in higher and lower SES was 22.6 and 21.3, respectively, males, and 24.7 and 24.4, respectively females. A strong relationship was observed between BMI and lipids although this relationship was absent among the leanest half of the population (BMI < 21.8). In multiple regression, SES and BMI were both strong and independent predictors of cholesterol. Both high and low SES consumed a typical Nigerian low fat, high carbohydrate diet, but somewhat higher meat, milk and egg intake suggested that some Westernization of the diet had occurred among the higher SES. Physical activity was lower among the higher SES. We conclude that SES related changes in lifestyle contribute to substantially higher total and LDL-cholesterol even in a generally lean population consuming a low fat diet.

Changes in plasma high density lipoprotein cholesterol and phospholipid in acute viral hepatitis and cholestatic jaundice

Forty-four male and female subjects aged 22-57 years were studied. Thirteen patients had acute viral hepatitis, and eleven patients had cholestatic jaundice due to carcinoma of the head of the pancreas. Twenty healthy volunteers who served as controls were also included. In hepatitis patients, the mean plasma levels of total cholesterol (TC) and the high density lipoprotein (HDL)-phospholipid/phospholipid (HDLPL/PL) ratio were reduced, and HDL-cholesterol (HDLC), HDL-phospholipid (HDLPL) and the phospholipid/total cholesterol (PL/TC) ratio were normal, while total phospholipid (PL) levels and the HDLC/TC ratio were significantly increased compared to the control values. In patients with cholestatic jaundice the mean plasma total cholesterol, phospholipid and HDLC levels were elevated, and HDLPL/PL, HDLPL, HDLC/TC and PL/TC remained normal compared to the control values. A comparison within the patient groups showed that plasma TC, PL and HDLC levels were significantly increased in cholestatic jaundice when compared with the corresponding levels in hepatitis patients. The mean plasma levels of HDLPL, HDLC/TC and PL/TC did not show any significant variation within the patient groups. Alkaline phosphatase (ALP) correlated positively with TC, and total protein correlated negatively with TC and HDLPL, while albumin correlated negatively with TC, HDLC and HDLPL in cholestatic jaundice. Alanine amino-transferase (ALAT) also correlated positively with PL in cholestatic jaundice, while albumin correlated positively with TC in hepatitis. The results suggest that lipoproteins might be metabolized differently in these two forms of cholestasis.

Blood pressure and other cardiovascular disease risk factors in black adults with sickle cell trait or glucose-6-phosphate dehydrogenase deficiency

In this study, we examined the relationship of two common genetic markers in black populations, sickle cell trait and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, to cardiovascular risk factors. The subjects were Nigerian civil servants in Benin City, Nigeria. We measured blood pressure, height, weight, sickle cell hemoglobin, G-6-PD, proteinuria, microalbuminuria and fasting serum cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides, apoprotein (APO) AI, and APO B. Data were collected on age, alcohol consumption, cigarette smoking, job status, and years lived in an urban area. There were 257 males (3 SS hemoglobin, 73 AS, 181 AA) and 69 females (23 AS, 46 AA). In comparing cardiovascular risk factors, males differed only in percent of smokers (31.5 in AS vs. 17.8 in AA, P less than 0.01). Among females, only high-density lipoprotein (HDL) cholesterol differed (61.5 mg/dl in AS vs. 52.4 in AA, P less than 0.01). We hypothesize that females with sickle cell trait are more likely to use oral contraceptives than nontrait females. If so, the high-estrogen oral contraceptives available in Nigeria could elevate HDL. G-6-PD deficiency status among males (52 deficient, 207 nondeficient) and females (1 deficient, 5 carriers, 65 nondeficient) was not related to any of the cardiovascular risk factors. We conclude that sickle cell hemoglobin trait and G-6-PD deficiency are not useful genetic markers for risk factors for cardiovascular disease.