👤 Sonal Dalvi

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains the leading cause of death from a single infectious agent worldwide. Drug-resistant TB (DR-TB) poses a major challenge. Bedaquiline (BDQ) is central to multidrug resistant tuberculosis/extensively drug-resistant TB (MDR/XDR-TB) treatment, yet emerging resistance prompted this study to assess its prevalence. This prospective observational study was conducted in the TB culture and drug susceptibility testing (DST) laboratory of a tertiary care hospital over 9 months. Sputum samples from presumptive DR-TB cases were included, whereas extrapulmonary and nontuberculous mycobacteria samples were excluded from the study. A total of 1190 samples were subjected to the first-line probe assay (LPA) for drug resistance detection in MTB. MDR-TB was most common, followed by mono-isoniazid and monorifampicin resistance. Of 512 DR-TB samples tested by second-line probe assay (SL-LPA), 25 yielded invalid results. Fluoroquinolone (FQ) resistance was highest (47.7%), whereas second-line injectable drug (SLID) resistance was rare (1.4%); combined FQ + SLID resistance occurred in 10.7% samples, whereas 35.4% samples were sensitive. Among 380 isolates subjected to liquid culture DST, resistance was detected to moxifloxacin (7.4%), linezolid (2.1%), and BDQ (0.78%). BDQ resistance is low but emerging; routine DST, rational drug use, and robust surveillance are vital to preserve BDQ efficacy and ensure effective DR-TB management. Show less

Disruption of photoreceptor-retinal pigment epithelium (RPE) interface with loss of photoreceptor outer segments (POSs) in the retina is a pathological hallmark of several neurodegenerative and retinal diseases including lysosomal storage disorder's like CLN3 disease. However, the retina is a functional composite Acid ceramidase deficiency and consequently altered sphingolipid signaling promotes disease phenotype(s) in a lysosomal storage disorder, CLN3 disease. Show less

CLN3 Batten disease (also known as juvenile neuronal ceroid lipofuscinosis) is a lysosomal storage disorder that typically initiates with retinal degeneration but is followed by seizure onset, motor decline and premature death. Patient-derived CLN3 disease induced pluripotent stem cell-RPE cells show defective phagocytosis of photoreceptor outer segment (POS). Because modifier genes are implicated in CLN3 disease, our goal here was to investigate a direct link between CLN3 mutation and POS phagocytosis defect. Isogenic control and CLN3 mutant stem cell lines were generated by CRISPR-Cas9-mediated biallelic deletion of exons 7 and 8. A transgenic CLN3Δ7-8/Δ7-8 (CLN3) Yucatan miniswine was also used to study the impact of CLN3Δ7-8/Δ7-8 mutation on POS phagocytosis. POS phagocytosis by cultured RPE cells was analyzed by Western blotting and immunohistochemistry. Electroretinogram, optical coherence tomography and histological analysis of CLN3Δ7-8/Δ7-8 and wild-type miniswine eyes were carried out at 6, 36, or 48 months of age. CLN3Δ7-8/Δ7-8 RPE (CLN3 RPE) displayed decreased POS binding and consequently decreased uptake of POS compared with isogenic control RPE cells. Furthermore, wild-type miniswine RPE cells phagocytosed CLN3Δ7-8/Δ7-8 POS less efficiently than wild-type POS. Consistent with decreased POS phagocytosis, lipofuscin/autofluorescence was decreased in CLN3 miniswine RPE at 36 months of age and was followed by almost complete loss of photoreceptors at 48 months of age. CLN3Δ7-8/Δ7-8 mutation (which affects ≤85% of patients) affects both RPE and POS and leads to photoreceptor cell loss in CLN3 disease. Furthermore, both primary RPE dysfunction and mutant POS independently contribute to impaired POS phagocytosis in CLN3 disease. Show less

CLN3 Batten disease (also known as Juvenile Neuronal Ceroid Lipofuscinosis; JNCL) is a lysosomal storage disorder that typically initiates with retinal degeneration but is followed by seizure onset, motor decline and premature death. Patient-derived CLN3 disease iPSC-RPE cells show defective phagocytosis of photoreceptor outer segments (POSs). Because modifier genes are implicated in CLN3 disease, our goal here was to investigate a direct link between Isogenic control and Show less

Mutations in CLN3 lead to photoreceptor cell loss in CLN3 disease, a lysosomal storage disorder characterized by childhood-onset vision loss, neurological impairment, and premature death. However, how CLN3 mutations cause photoreceptor cell death is not known. Here, we show that CLN3 is required for phagocytosis of photoreceptor outer segment (POS) by retinal pigment epithelium (RPE) cells, a cellular process essential for photoreceptor survival. Specifically, a proportion of CLN3 in human, mouse, and iPSC-RPE cells localized to RPE microvilli, the site of POS phagocytosis. Furthermore, patient-derived CLN3 disease iPSC-RPE cells showed decreased RPE microvilli density and reduced POS binding and ingestion. Notably, POS phagocytosis defect in CLN3 disease iPSC-RPE cells could be rescued by wild-type CLN3 gene supplementation. Altogether, these results illustrate a novel role of CLN3 in regulating POS phagocytosis and suggest a contribution of primary RPE dysfunction for photoreceptor cell loss in CLN3 disease that can be targeted by gene therapy. Show less