Jeffrey Justin Margret

Background: Hydrogen sulfide (H₂S) is known for its significant anti-inflammatory, antioxidant, and vasculoprotective properties. In diabetic patients, blood levels of H₂S are observed to be lower. Type 1 diabetic patients (T1D) often experience both hyperketonemia and hyperglycemia. Cystathionine-γ-lyase (CSE), an enzyme encoded by the CTH gene, is responsible for the biosynthesis of H₂S. However, it remains uncertain whether the downregulation of CTH genes by ketones is linked to reduced levels of H₂S. Objective: This study aims to test the hypothesis that ketones decrease CTH gene expression in cultured hepatocytes and that hyperketonemia negatively correlates with H₂S levels in T1D. Methods: Fasting blood samples were collected from children with T1D (n = 36) and age-matched healthy controls (n = 35), following written informed consent. Plasma levels of H₂S, 25(OH)VD, ketones, and inflammatory biomarkers were analyzed. To assess the effects of hyperglycemia and hyperketonemia on CTH gene expression, cultured hepatocytes were exposed to high glucose, acetoacetate, or β-hydroxybutyrate. Results: Blood levels of H₂S and 25(OH)VD were significantly lower in T1D patients compared to healthy controls. Plasma H₂S concentrations showed an inverse association with total ketones, BHB, acetoacetate, and MMP-9, while they were positively associated with HDL-cholesterol and 25(OH)VD. In cultured hepatocytes, exposure to acetoacetate and high glucose was linked to reduced CTH mRNA expression. Conclusions: Lower circulating H₂S concentrations are associated with hyperketonemia and inflammatory/metabolic abnormalities in children and adolescents with T1D. The in vitro findings suggest that high glucose and acetoacetate may affect CTH transcription; however, further studies measuring CSE protein, enzymatic activity, and H₂S production are necessary to clarify the underlying mechanism and establish causality.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder marked by amyloid-β buildup, tau pathology, neuroinflammation, and declining cognition. Adiponectin, a hormone produced by adipose tissue with insulin-sensitizing, anti-inflammatory, and antioxidant effects, may link peripheral metabolic health to brain function. Studies show that adiponectin helps neurons survive, improves synaptic plasticity, maintains blood–brain barrier integrity, and reduces amyloid-β and tau damage via AdipoR1/R2 signaling. Clinical studies evaluating circulating adiponectin have yielded inconsistent findings, giving rise to the ‘adiponectin paradox’ whereby elevated adiponectin levels in older adults and patients with AD may reflect frailty, weight loss, systemic inflammation, or compensatory responses rather than direct neuroprotective effects. Studies indicate that vitamin D (VD) and L-cysteine (L-Cys), a precursor to glutathione, act synergistically to modulate oxidative stress, inflammation, and adiponectin levels. VD increases circulating adiponectin and benefits metabolism, while L-Cys boosts glutathione, restores redox balance, and promotes adiponectin secretion by affecting fat cell function. Emerging experimental evidence, together with clinical observations from metabolic disorders, suggests that VD and L-Cys may influence adiponectin-related pathways, oxidative stress, and inflammation, which are implicated in AD pathogenesis. However, direct clinical evidence demonstrating that combined VD and L-Cys supplementation modulates these pathways or alters AD progression in humans is currently lacking. This narrative review covers current knowledge of adiponectin and its links to obesity, metabolic issues, and AD, and it also explores the roles of VD and L-Cys as regulators of adiponectin signaling. Overall, the available evidence supports the proposed interaction among VD–L-Cys and adiponectin, which warrants further mechanistic investigation and well-designed clinical studies to determine its therapeutic relevance in AD.

In recent years, numerous genetic variants have been linked with prelingual hearing loss (HL). Variants in the LOXHD1 gene (lipoxygenase homology domain—1) associated with DFNB 77 are highly heterogeneous, with different auditory characteristics varying from stable to progressive and mild to profound. To date, 168 DFNB 77 cases have been recorded worldwide. Forty‐one hearing‐impaired (HI) probands, who were previously excluded for a set of four common deafness‐causing genes (viz. , GJB2, GJB6, SLC26A4 , and CDH23) from 33 HI families, were subjected to clinical exome sequencing (CES) involving 285 genes associated with HL. This was followed by a segregation analysis of the available members in the family. We identified two pathogenic LOXHD1 variants in two unrelated inbred families. One is a novel homozygous pathogenic nonsense variant (c.3999C > A; p.C1333X), whereas the other is a likely pathogenic missense variant (c.6046G > T; p.E2046K). In silico tools such as SIFT, PolyPhen‐2, Mutation Taster, CADD, and REVEL scores were used to predict variant pathogenicity. Furthermore, American College of Medical Genetics and Genomics guidelines specific to HL were applied to finally classify a variant as pathogenic or otherwise. The frequency of LOXHD1 variants identified in our study is 4.88% (2/41). This is the first LOXHD1 report associated with non‐syndromic HL in South Indian families.

Dairy products, such as whey proteins, have been effectively utilized to enhance the effectiveness of vitamin D fortification and optimize circulating 25(OH)VD levels. Whey protein is rich in L-cysteine (LC) which is the precursor of hydrogen sulfide (H₂S), enhances glutathione (GSH) biosynthesis, and promotes positive nitrogen balance. Zucker diabetic rats (ZDF) were used as a model in this study, to examine the hypothesis that LC supplementation enhances blood levels of H₂S and nitrite (NO₂) while reducing inflammation biomarkers. Rats were gavaged daily (orally) with either saline placebo or L-cysteine along with a high-calorie diet starting at 6 weeks of age. Fasting blood levels showed LC supplementation significantly increased circulatory levels of H₂S and NO₂ compared with placebo rats. LC supplementation increased plasma concentration of 25(OH)VD and vitamin C and lowered leptin and body weight gain in ZDF rats. Furthermore, to assess the impact of H₂S and NO₂ in raising 25(OH)VD levels, the in vitro effect of H₂S/NO₂ on vitamin D metabolism genes was examined using THP-1 monocytes. The exogenous H₂S and NO₂ treatment upregulated the relative expression of CYP2R1 and CYP27B1 genes in cultured monocytes. This study suggests a potential mechanism for the observed increase in circulating 25(OH)VD levels following L-cysteine supplementation.

B-type natriuretic peptide (BNP) is a neurohormone primarily secreted from cardiac ventricles in reaction to increased volume and pressure. The plasma level of BNP is used to measure the mechanical function of the heart and the risk of developing chronic obstructive pulmonary disease (COPD). Alpha-1 antitrypsin (AAT) is a glycoprotein that acts as an inhibitor of serine proteases and plays a crucial role in protecting the lungs against potential harm. AAT deficiency also causes COPD. The data on the prevalence of BNP and AAT in African Americans (AA) are limited and inconsistent. No previous studies have investigated whether any association exists between BNP and AAT. We collected fasting blood samples from 114 AA subjects who provided informed consent. The plasma levels of the biomarkers were measured using ELISA. Our findings revealed a significant negative correlation between AAT and BNP (r=-0.266, p = 0.01) as well as between AAT and TNF-α (r=-0.242, p = 0.01). Sex hormones (estrogen and testosterone) have a significant relationship with the levels of AAT and BNP. Increasing the AAT and reducing the levels of inflammation can lower the levels of BNP, which in turn could help lower the risk of heart disease in the AA population.

Background: Developmental stuttering, a multifactorial speech disorder with remarkable rate of spontaneous recovery pose challenges for gene discoveries. Exonic variants in GNPTAB, GNPTG, and NAGPA involved in lysosomal pathway and AP4E1, IFNAR1, and ARMC3‐signaling genes reported till date explain only ∼2.1% – 3.7% of persistent stuttering cases.Aim: We aimed to identify additional genetic determinants of stuttering in a multiplex family by exome sequencing (n = 27) and further validation on additional extended family members (n = 21).Materials & Methods: We employed hypothesis‐free and pathway‐based analyses.Results: A novel heterozygous exonic variant NM_016256.4:c.322G > A in NAGPA with reduced penetrance and predicted pathogenicity segregated with the phenotype in a large subset of the family. Reanalysis to identify additional disease‐causing variant(s) revealed exonic heterozygous variants each in RIMS2 and XYLT1 in severely affected members; and IGF2R variant in a small subset of the family. Furthermore, pathway‐based analysis uncovered NM_022089.4:c.3529G > A in ATP13A2 (PARK9) in affected members; and variants in GNPTAB and GNPTG of minor significance in a few affected members.Discussion: Genotype–phenotype correlation efforts suggest that the combined effect of gene variants at multiple loci or variants in a single gene in different subsets of the pedigree (genetic heterogeneity) may be contributing to stuttering in this family. More importantly, variants identified in ATP13A2, a Parkinson's disease gene also implicated in lysosomal dysfunction, and RIMS2 suggests for the first time a likely role of dopamine signaling in stuttering.Conclusion: Screening for these variants in independent stuttering cohorts would be astute.

Leydig cells are the primary source of testosterone or androgen production in male mammals. The blood–testis barrier (BTB) maintains structural integrity and safeguards germ cells from harmful substances by blocking their entry into the seminiferous tubules. L-cysteine is essential to the production of glutathione, a powerful antioxidant crucial to protecting against oxidative stress-induced damage. Animal studies have demonstrated the protective effect of L-cysteine in preventing testicular damage caused by chemicals or radiation. This study examines whether L-cysteine enhances the expression of testosterone biosynthesis and the BTB genes in human Leydig cells and THP-1 monocytes. The Leydig cells and THP-1 monocytes were treated with L-cysteine for 24 h. RNA was extracted following treatment, and the gene expression was analyzed using quantitative RT-PCR. Testosterone levels in the cell supernatant were measured using an ELISA kit. L-cysteine treatment in Leydig cells significantly upregulated the expression of CYP11A1 (p = 0.03) and the BTB genes CLDN1 (p = 0.03), CLDN11 (p = 0.02), and TJP1 (p = 0.02). Similarly, L-cysteine significantly upregulated the expression of CYP11A1 (p = 0.03) and CYP19A1 (p < 0.01), and the BTB genes CLDN1 (p = 0.04), CLDN2 (p < 0.01), CLDN4 (p < 0.01), CLDN11 (p < 0.01), and TJP1 (p = 0.03) in THP-1 monocytes. Further, L-cysteine supplementation increased the testosterone secretion levels in human Leydig cells. The findings suggest that L-cysteine supplementation could be used as an adjuvant therapy to promote the integrity of the BTB genes, testosterone biosynthesis and secretion, and the maintenance of testicular functions, which in turn mitigates the risk of male infertility.

Blood–testis barrier (BTB) genes are crucial for the cellular mechanisms of spermatogenesis as they protect against detrimental cytotoxic agents, chemicals, and pathogens, thereby maintaining a sterile environment necessary for sperm development. BTB proteins predominantly consist of extensive tight and gap junctions formed between Sertoli cells. These junctions form a crucial immunological barrier restricting the intercellular movement of substances and molecules within the adluminal compartment. Epithelial tight junctions are complex membrane structures composed of various integral membrane proteins, including claudins, zonula occludens-1, and occludin. Inter-testicular cell junction proteins undergo a constant process of degradation and renewal. In addition, the downregulation of genes crucial to the development and preservation of cell junctions could disrupt the functionality of the BTB, potentially leading to male infertility. Oxidative stress and inflammation may contribute to disrupted spermatogenesis, resulting in male infertility. L-cysteine is a precursor to glutathione, a crucial antioxidant that helps mitigate damage and inflammation resulting from oxidative stress. Preclinical research indicates that L-cysteine may offer protective benefits against testicular injury and promote the expression of BTB genes. This review emphasizes various BTB genes essential for preserving its structural integrity and facilitating spermatogenesis and male fertility. Furthermore, it consolidates various research findings suggesting that L-cysteine may promote the expression of BTB-associated genes, thereby aiding in the maintenance of testicular functions.

Background: Subjects with metabolic syndrome and obesity have higher levels of inflammation with depression of the vitamin D (VD) hydroxylase/metabolising genes ( CYP2R1/CYP27A1/CYP27B1/VDR ) required to convert VD consumed in the diet into 25(OH)VD. Compared with total 25(OH)VD levels, measurement of bioavailable 25(OH)VD is a better method to determine the beneficial effect of VD. Objective: This study investigates whether cosupplementation with VD and L-cysteine (LC), which downregulates inflammation and upregulates VD-regulating genes, provides a better therapeutic benefit than supplementation with VD-alone in African Americans (AA). Methods: AA participants (men/women, aged 18–65 years; n=165) were block randomised into one of four groups and received daily, oral supplementation for 6 months with placebo, LC (1000 mg/day), VD (2000 IU/day) or VD+LC. Fasting blood collected at the baseline and final visits was analysed for total, free and bioavailable 25(OH)VD along with insulin, VD-binding protein (VDBP), sex hormone-binding globulin (SHBG), free and total testosterone, and inflammatory marker levels. Studies were carried out in THP-1 monocytes to elucidate the direct effect of LC and testosterone on VD-regulating genes. Results: Baseline data showed no differences in age, body mass index, calcium, liver or kidney function among the groups. Compared with levels in the group that received VD-alone supplementation, levels of neutrophil-to-lymphocyte ratio, C reactive protein, HOMA-IR, VDBP and HbA1c were significantly lower in the VD+LC group while the VD+LC group showed a significant increase in bioavailable 25(OH)VD in both sexes, total 25(OH)VD levels were significantly elevated in men but not in women treated with VD+LC. Blood levels of SHBG and free/total testosterone were elevated in the VD+LC group but not in the VD-alone group. LC and testosterone treatment significantly upregulated VD-metabolising genes ( CYP2R1/CYP27A1/CYP27B1/VDR ) and SHBG in THP-1 monocytes. Conclusions: VD cosupplemented with LC upregulates circulating bioavailable 25(OH)VD and reduces inflammation. Total 25(OH)VD levels were higher in men but not in women in the VD+LC group. This pilot study suggests that compared with supplementation with VD-alone, VD+LC cosupplementation could be a better approach to raising the total 25(OH)VD in men and the bioavailable 25(OH)VD in both sexes and lowering the inflammatory risk in the AA population. Trial registration number: NCT04939792 .

Vitamin D receptors are expressed in many organs and tissues, which suggests that vitamin D (VD) affects physiological functions beyond its role in maintaining bone health. Deficiency or inadequacy of 25(OH)VD is widespread globally. Population studies demonstrate that a positive association exists between a high incidence of VD deficiency and a high incidence of chronic diseases, including dementia, diabetes, and heart disease. However, many subjects have difficulty achieving the required circulating levels of 25(OH)VD even after high-dose VD supplementation, and randomized controlled clinical trials have reported limited therapeutic success post-VD supplementation. Thus, there is a discordance between the benefits of VD supplementation and the prevention of chronic diseases in those with VD deficiency. Why this dissociation exists is currently under debate and is of significant public interest. This review discusses the downregulation of VD-metabolizing genes needed to convert consumed VD into 25(OH)VD to enable its metabolic action exhibited by subjects with metabolic syndrome, obesity, and other chronic diseases. Research findings indicate a positive correlation between the levels of 25(OH)VD and glutathione (GSH) in both healthy and diabetic individuals. Cell culture and animal experiments reveal a novel mechanism through which the status of GSH can positively impact the expression of VD metabolism genes. This review highlights that for better success, VD deficiency needs to be corrected at multiple levels: (i) VD supplements and/or VD-rich foods need to be consumed to provide adequate VD, and (ii) the body needs to be able to upregulate VD-metabolizing genes to convert VD into 25(OH)VD and then to 1,25(OH)2VD to enhance its metabolic action. This review outlines the association between 25(OH)VD deficiency/inadequacy and decreased GSH levels, highlighting the positive impact of combined VD+LC supplementation on upregulating GSH, VD-metabolizing genes, and VDR. These effects have the potential to enhance 25(OH)VD levels and its therapeutic efficacy.