17-Beta-Hydroxysteroid Dehydrogenase 13 Loss of Function Does Not Confer Protection to Nonalcoholic Fatty Liver Disease in Indian Population.

Background: A splice variant in HSD17B13 gene is demonstrated to protect against nonalcoholic fatty liver disease (NAFLD), and mitigate the effect of Patatin-like phospholipase domain-containing 3 (PNPLA3-I148M). It is being explored as a putative drug target and in polygenic risk scores. Based on whole exome sequencing (WES) in our cohort of biopsy proven NAFLD and limited data on the variant in our ethnicity, we sought to explore its role. Methods: This is a cross-sectional study that recruited 1,020 individuals with ultrasound/biopsy-confirmed NAFLD and matched controls. Liver enzymes and lipid profiles were estimated (Beckman coulter LX750/DXH800); WES was performed in NAFLD patients and controls (Illumina; HiSeqX); HSD17B13-A-INS/I148M-PNPLA3 variants were genotyped (sequencing/qR T-PCR); HSD17B13 protein expression was estimated (immunohistochemistry); the Student's t-test/Mann-Whitney U/Chi-square test and odds ratio (95% confidence interval) were used. Results: There was no significant difference (Odds ratio = 0.76; 95% CI -0.57 to 1.03; P = 0.76) in the frequency of the rs72613567-A-INS between controls and patients (17.8% vs. 14.4%). No difference in the ALT (Alanine transaminase; 72.24 ± 65.13 vs. 73.70 ± 60.06; P = 0.51) and AST levels (Aspartate aminotransferase; 60.72 ± 55.59 vs. 61.63 ± 60.33; P = 0.91) between HSD17B13-wild and variant carriers were noted. Significantly elevated liver enzymes were seen in PNPLA3-148-variant/HSD17B13-wild compared with PNPLA3-148-variant/HSD17B13-variant (90.44 ± 59.0 vs. 112.32 ± 61.78; P = 0.02). No difference in steatosis (P = 0.51) between HSD17B13-wild and variant carriers was noted. No other variants in the intron-exon boundaries were identified. Although, protein expression differences were noted between wild and variant carriers, no difference in the extent of steatosis was seen. Conclusion: Our study reports lack of association of the splice variant with reduced risk of NAFLD, and mitigating the effect of PNPLA3 variant. Ethnicity-based validation must be carried out before including it in assessing protection against NAFLD.

Integration of metabolites from meta-analysis with transcriptome reveals enhanced SPHK1 in PDAC with a background of pancreatitis.

BACKGROUND: Pathophysiology of transformation of inflammatory lesions in chronic pancreatitis (CP) to pancreatic ductal adenocarcinoma (PDAC) is not clear. METHODS: We conducted a systematic review, meta-analysis of circulating metabolites, integrated this data with transcriptome analysis of human pancreatic tissues and validated using immunohistochemistry. Our aim was to establish biomarker signatures for early malignant transformation in patients with underlying CP and identify therapeutic targets. RESULTS: Analysis of 19 studies revealed AUC of 0.86 (95% CI 0.81-0.91, P < 0.0001) for all the altered metabolites (n = 88). Among them, lipids showed higher differentiating efficacy between PDAC and CP; P-value (< 0.0001). Pathway enrichment analysis identified sphingomyelin metabolism (impact value-0.29, FDR of 0.45) and TCA cycle (impact value-0.18, FDR of 0.06) to be prominent pathways in differentiating PDAC from CP. Mapping circulating metabolites to corresponding genes revealed 517 altered genes. Integration of these genes with transcriptome data of CP and PDAC with a background of CP (PDAC-CP) identified three upregulated genes; PIGC, PPIB, PKM and three downregulated genes; AZGP1, EGLN1, GNMT. Comparison of CP to PDAC-CP and PDAC-CP to PDAC identified upregulation of SPHK1, a known oncogene. CONCLUSIONS: Our analysis suggests plausible role for SPHK1 in development of pancreatic adenocarcinoma in long standing CP patients. SPHK1 could be further explored as diagnostic and potential therapeutic target.

A variant in TMPRSS2 is associated with decreased disease severity in COVID-19.

BACKGROUND: Mortality due to COVID-19 caused by SARS-CoV-2 infection varies among populations. Functional relevance of genetic variations in Angiotensin-converting enzyme 2 (ACE2) and Transmembrane serine protease 2 (TMPRSS2), two crucial host factors for viral entry, might explain some of this variation. METHODS: In this comparative study in Indian subjects, we recruited 510 COVID-19 patients and retrieved DNA from 520 controls from a repository. Associations between variants in ACE2 and TMPRSS2 with disease severity were identified by whole exome sequencing (WES, n = 20) and targeted genotyping (n = 1010). Molecular dynamic simulations (MDS) were performed to explore functional relevance of the variants. Cleavage of spike glycoprotein by wild and variant TMPRSS2 was determined in HEK293T cells. Potential effects of confounders on the association between genotype and disease severity were tested (Mantel-Haenszel test). RESULTS: WES identified deleterious variant in TMPRSS2 (rs12329760, G > A, p. V160M). The minor allele frequency (MAF) was 0·27 in controls, 0·31 in asymptomatic, 0·21 in mild-to-moderately affected and 0·19 in severely affected COVID-19 patients. Risk of severity increased with decreasing MAF: Asymptomatic: Odds ratio-0·69 (95% CI-0·52-0·93; p = 0·01); mild-to-moderate: Odds ratio-1·89 (95% CI-1·22-2.92;p = 0·004) and severe: Odds ratio-1·79 (95% CI-1·11-2.88;p = 0·01). No confounding effect of diabetes and hypertension were observed on the risk of developing severe COVID-19 disease with respect to genotype. MDS revealed decreased stability of TMPRSS2 with 160 M variant. Spike glycoprotein cleavage by TMPRSS2 reduced ~2·4-fold in cells expressing 160 M variant. CONCLUSION: We demonstrate association of TMPRSS2 variant rs12329760 with decreased disease severity in COVID-19 patients from India.

Immunological memory and neutralizing activity to a single dose of COVID-19 vaccine in previously infected individuals.

BACKGROUND: The efficacy of COVID-19 vaccines to generate immunological memory post-vaccination has not previously been studied. OBJECTIVE: To assess immunological memory in previously SARS-CoV-2 infected individuals after a single dose of mRNA vaccine. PATIENTS AND METHODS: Healthcare workers (n = 280) were enrolled after obtaining written informed consent and grouped under previously infected and no prior exposure (reverse transcription-polymerase chain reaction positive and negative, respectively). Blood was drawn at baseline and post-vaccination (single dose of COVISHIELD) for enumerating neutralizing antibodies by chemiluminescence and memory T- and B-cells by flow cytometry. RESULTS: Post vaccination, compared with the no prior exposure group, the previously infected group had higher levels of: antibody response (1124.73 ± 869.13 vs 94.23 ± 140.06 AU/ml, p = 0.0001); CD4 memory T-cells: central memory CCR7+CD45RA- (p = 0.0001), effector memory CCR7-/CD45RA- (p = 0.01); total CD8+ T-cells (p = 0.004); CD8+ naïve T-cells CCR7+CD45RA+ (p = 0.01); and memory B-cells CD20+CD27+ (p = 0.0001). DISCUSSION: Single-dose vaccination elicited higher neutralizing antibody response and protective immunity in individuals who had recovered from SARS-CoV-2 infection compared with those with no prior exposure.

NUDT15 C415T variant compared with TPMT genotyping in predicting azathioprine-induced leucopenia: prospective analysis of 1014 inflammatory bowel disease patients in India.

BACKGROUND: Recent studies reported that Nudix Hydrolase 15(NUDT 15) gene variant (C415T) can better predict thiopurine induced leucopenia in Asian patients with inflammatory bowel disease (IBD) than thiopurine S-methyl transferase (TPMT). AIM: To evaluate the role of the NUDT variant compared with TPMT in predicting azathioprine induced leucopenia in Indian IBD patients. METHODS: Prospectively collected data of consecutive patients treated with azathioprine from a large IBD registry were analysed for side effects, discontinuation time, and initial and maximum dose tolerated. Genotyping of NUDT15 C415T (rs116855232; p.R139C) was carried out retrieving blood samples from bio-repository employing real time polymerase chain reaction with age and sex-matched healthy volunteers. The association of NUDT15 C415T with leucopenia (<3 × 109 /L) and neutropenia (<1.5 × 109 /L) was evaluated. TPMT genotyping was done in patients who developed leucopenia. RESULTS: Among 1014 patients (mean age 35.84 ± 12.74 years; 61% males; 54% ulcerative colitis, 44% Crohn's disease and 2% IBD-unclassified), 79 were excluded due to inadequate blood samples. Of the remaining 935, 81 (9%) developed leucopenia and 70 (7.5%) developed neutropenia. The variant "T" allele [heterozygous (CT) and homozygous (TT) versus wild type (CC)] was associated with a 19-fold higher odds (OR19.35, 95% CI11.55-32.42; P < 0.0001) of leucopenia and 21-fold higher odds of neutropenia (OR21.41, 95% CI12.25-37.41). There was significant difference in median dose tolerated between CC, CT and TT (1.35, 1.38 and 0.92 mg/kg body weight, respectively) (P = 0.037) and median duration of therapy (18, 15 and 10 months for CC/CT/TT) (P = 0.003). NUDT15 genotype was an independent risk factor for leucopenia (hazard ratio (HR): CT 11.31, 95% CI6.85-18.03, P < 0.0001 and TT 31.283, 95% CI14.76-66.30 compared to CC) and neutropenia (HR: CT 13.04, 95% CI7.65-22.22, P < 0.0001 and TT 43.39, 95% CI20.21-92.68 compared to CC). The sensitivities for predicting leucopenia and neutropenia by number of mutant NUDT 15 alleles based on additive predictive model were 66.67% and 70% with a receptor operator characteristic curve area under curve value of 0.791 and 0.807, respectively. Among patients with leucopenia, only 6.2% were heterozygous and none were homozygous for TPMT variants. CONCLUSION: NUDT15 variant genotyping appears to be a better predictor for azathioprine-induced leucopenia in an Indian population than TPMT with high accuracy and can be useful in optimizing azathioprine dosage.

Genetic variants in TMPRSS2 and Structure of SARS-CoV-2 spike glycoprotein and TMPRSS2 complex

SARS-CoV-2, a highly transmittable pathogen has infected over 3.8 million people around the globe. The spike glycoprotein of SARS-CoV-2 engages host ACE2 for adhesion, TMPRSS2 for activation and entry. With the aid of whole-exome sequencing, we report a variant rs12329760 in TMPRSS2 gene and its mutant V160M, which might impede viral entry. Furthermore, we identified TMPRSS2 cleavage sites in S2 domain of spike glycoprotein and report the structure of TMPRSS2 in complex with spike glycoprotein. We also report the structures of protease inhibitors in complex with TMPRSS2, which could hamper the interaction with spike protein. These findings advance our understanding on the role of TMPRSS2 and in the development of potential therapeutics.Competing Interest StatementThe authors have declared no competing interest.View Full Text

Polymorphisms in UGT1A1 Gene Predispose South Indians to Pigmentous Gallstones.

BACKGROUND/OBJECTIVES: Pigmentous gallstones occur in South Indians despite significant higher levels of circulating cholesterol. This study was conducted to identify the biochemical and/or genetic causes for the formation of pigmentous gallstones in this ethnic group. METHODS: Plasma lipid profile, bile cholesterol, acids, and phospholipid levels were estimated in patients with gall stone disease and age, sex matched controls using standard protocols. Twenty-seven SNPs related to cholesterol and bilirubin metabolism pathway genes were genotyped in the study population using the Sequenom platform. An equilibrium phase diagram involving bile salt-phospholipid-cholesterol was generated to relate phenotype with the genotype. RESULTS: There were no significant differences in the lipid profiles between the patients (n = 305) and controls (n = 177). Biliary cholesterol, acids, and phospholipids were significantly different between patients and controls. Single locus analysis revealed association of variants in ABCG6, ABCG8, and UGT1A1 genes with the disease; however when correction was applied as multiple testing was done, only one variant (rs6742078) in UGT1A1 gene was found to be associated with gall stone disease. Equilibrium phase diagram suggested that few samples were in the crystal formation zone. The mutant, but not wild type or heterozygous genotype of SNPs (rs6742078 and rs887829) in UGT1A1 gene, was associated with significantly higher levels of bilirubin. CONCLUSIONS: Higher incidence of pigment stones in South Indians could be due to raised serum bilirubin levels that may be ascribed to variant in the UGT1A1 gene involved in glucuronidation of free bilirubin.