Improvement in the Diagnosis of Tuberculosis Combining Mycobacterium Tuberculosis Immunodominant Peptides and Serum Host Biomarkers.

BACKGROUND: Pulmonary tuberculosis (PTB) is a public health problem with 10.4 million new cases reported in 2017 (1). According to the World Health Organization (WHO), accurate diagnostic tests based in serum biomarkers to detect new cases of tuberculosis are necessary. AIM OF THE STUDY: To evaluate antibodies against Mycobacterium. tuberculosis (Mtb) peptides (Ab-Mtb) and three soluble host biomarkers by ELISA serial multiple test in sera from non-infected controls (NIC, n = 31), latent tuberculosis (LTB, n = 37) and PTB (n = 28) patients in a diagnosis tuberculosis assay. MATERIALS AND METHODS: Levels of four Ab-Mtb peptides derived from Mtb and three host response molecules in serum from NIC, LTB and PTB were evaluated by ELISA as tuberculosis biomarkers. Multiple comparisons tests, determination of diagnostic values and ROC curves were performed. Serial and parallel multiple tests were performed with the biomarkers with the highest discriminatory capacity to improve diagnostic values of the test. RESULTS: We found significant differences between biomarkers levels in PTB comparing LTB and NIC to all candidate biomarkers; peptides P12033, P12037, and serum biomarkers such as sCD14 and chemokine CXCL9 showed the best sensitivity and specificity, the highest discriminatory power, and the best area under the curve (AUC) individually. In serial multiple tests, P12037 and sCD14 together have 92% of sensitivity and 91% of specificity, with positive and negative likelihood ratios greater than 10. CONCLUSIONS: Ab-Mtb peptide P12037 and sCD14 could be applied in a diagnostic test for suspected PTB to improve accuracy and time to diagnosis and could be implemented in a POCT device which can be affordable.

Associated Risk Factors for Latent Tuberculosis Infection in Subjects with Diabetes.

BACKGROUND AND AIMS: Type 2 diabetes mellitus (DM2) confers a higher risk for active tuberculosis (TB). However, information on associated risk factors for latent tuberculosis infection (LTBI) inpatients with DM2 is limited. We conducted a cross-sectional study to elucidate the prevalence of LTBI and its associated factors on Mexican adults with DM2 receiving medical care at the Mexican Social Security Institute (IMSS). METHODS: Six hundred patients with DM2 without a prior history of TB from outpatient diabetes clinics were enrolled in the study. The tuberculin-skin-test (TST) was performed. The presence of LTBI was defined by a TST value of ≥ 5 mm. A standardized interview and physical examination were conducted to obtain clinical, demographic, and LTBI risk factor information; all subjects were laboratory tested to determine the presence of exclusion criteria. Microscopic examination of sputum samples and chest x-rays was performed to identify potential active TB. Subjects with any finding suggesting active TB or malignancy were excluded. A logistic regression model was used to identify variables associated with LTBI. RESULTS: LTBI prevalence among patients with DM2 was 51.3%. Risk factors for LTBI were living with a relative with TB, having been in prison, having hemoglobin values >14 g/dL, and glycosylated hemoglobin (HbA1c) values of > 7%. Blood pressure, economic income, or anthropometric measurements were not associated risk factors. CONCLUSIONS: Over one half of patients with DM harbor LTBI. Exposure to certain environmental conditions and poorly controlled DM2 (HbA1c > 7.0%) were risk factors for having LTBI in persons with DM2.

Vitamin D supplementation promotes macrophages' anti-mycobacterial activity in type 2 diabetes mellitus patients with low vitamin D receptor expression.

The increasing number of people with type 2 diabetes (DM2) is alarming and if it is taken into account that the relative odds of developing tuberculosis in diabetic patients ranges from 2.44 to 8.33 compared with non-diabetic patients, thus in developing countries where these two diseases are encountering face to face, there is a need for prophylaxis strategies. The role of vitamin D has been widely implicated in growth control of Mycobacterium tuberculosis (Mtb) during primary infection mainly through the induction of certain antimicrobial peptides (AMPs). In this study we evaluated the vitamin D serum levels, CYP27B1-hydroxylase enzyme, vitamin D receptor (VDR) and AMPs gene expression in Healthy donors, DM2 and TB patients. Results showed that DM2 group has lower VDR and AMPs expression levels. When Monocytes Derived Macrophages (MDM) from DM2 patients with low VDR expression were supplemented with vitamin D, MDMs eliminate efficiently M. tuberculosis. This preliminary study suggests the use of vitamin D as prophylaxis for tuberculosis in high DM2 endemic countries.

Differential expression of antimicrobial peptides in active and latent tuberculosis and its relationship with diabetes mellitus.

Tuberculosis (TB) is one of the most important infectious diseases, causing 1.8 million deaths annually worldwide. This problem has increased because of the association with human immmunodeficiency virus and diabetes mellitus type 2, mainly in developing countries. In the past few years it has been highlighted the significance of antimicrobial peptides in the immunopathogenesis of TB ex vivo and in experimental models studies. In this study we analyzed the expression of CAMP, DEFA1, DEFB4, and DEFB103A in patients with latent TB and progressive TB with and without comorbidity with diabetes mellitus type 2. Antimicrobial peptide gene expression increased during progressive TB, which could be used as a biomarker for reactivation. By contrast, patients with diabetes mellitus type 2 have lower antimicrobial peptides gene expression, suggesting that the lack of its proper production in these patients contribute to enhance the risk for TB reactivation.