Skeletal muscle constitutes more than 30% of total body mass using substrates such as glycogen, glucose, free fatty acids, and creatinine phosphate to generate energy. consequently, multinucleated myofibers and resident mononucleated stem cells (satellite cells) generate several metabolites, which enter into circulation affecting the function of other organs, especially during exercise and atrophy. The present study was aimed at building a comprehensive profile of metabolites in primary human skeletal muscle cells during myogenic progression in an untargeted metabolomics approach using a high resolution Orbitrap Fusion Tribrid Mass Spectrometer. Identification of metabolites with multivariate statistical analyses showed a global shift in metabolomic profiles between myoblasts undergoing proliferation and differentiation along with distinctly separable profiles between early and late differentiating cultures. Pathway analyses of 71 unique metabolites revealed that Pantothenate metabolism and coenzyme A biosynthesis and Arginine proline metabolism play dominant roles in proliferating myoblasts, while metabolites involved in vitamin B6, Glyoxylate and Dicarboxylate, Nitrogen, Glutathione, and Tryptophan metabolism were upregulated during differentiation. We found that early and late differentiating cultures displayed differences in Phenylalanine, tyrosine, Glycine, Serine and threonine metabolism. our results identify metabolites during maturation of muscle from progenitor myoblasts that have implications in muscle regeneration and pathophysiology. Skeletal muscle physiology is critically dependent on the functionality of a progenitor population called, "satellite cells" that proliferate and differentiate to form multinucleated myofibers, thereby contributing to muscle regeneration during injury or exercise 1-4. Conversely, defects in satellite cell function can result in loss of muscle mass and decline in performance that is frequently observed in chronic illnesses and aging 5. In this aspect, the field of metabolomics has emerged with the intention of providing a comprehensive profile of metabolites and low molecular weight molecules in specific organ tissues, thereby enabling precision medicine and biomarker discovery in various disease states 6. Thus, identification of metabolic pathways during myogenic progression may provide information on energy requirements of cells during various physiological states of the muscle tissue. Recent studies have characterised the skeletal muscle metabolome during strenuous exercise in humans, neuromuscular diseases such as Pompe disease and Duchenne's muscular dystrophy, daily variations in tissue metabolites vis-à-vis nutritional challenges, overexpression of metabolic regulators, and aging 7-12. Metabolic profiles of young, post-mortem, and aging murine satellite cells have also been evaluated using measurement of mitochondrial function and analysis of metabolic gene signatures associated with different myogenic cell cycle states 13,14. Thus, studies from murine myogenic cell...
Introduction Intense monocyte activation and infiltration into the target tissues are the main mechanisms of lung injury in severe acute respiratory syndrome coronavirus 2 infection. A reduction in the degree and nature of such cellular responses is expected following recovery. We aimed to investigate the immune responses in moderate coronavirus disease 2019 (COVID‐19) patients and recovered patients. Methods Moderate COVID‐19 patients ( n = 34) at Lok Nayak Hospital, New Delhi, and COVID‐19 recovered patients ( n = 15) from the mild disease who were considered for convalescent plasma (COPLA) donation at the Institute of Liver and Biliary Sciences, New Delhi and healthy individuals ( n = 10), were recruited. We have assessed 21 plasma cytokines using cytokine bead array, performed proteomics on serum proteins, and analyzed immune cells using a detailed multicolor flow cytometry. Results A significant increase in inflammatory markers such as macrophage inflammatory protein (MIP)1‐α, monocyte chemotactic protein‐1, macrophage migration inhibitory factor, vascular endothelial growth factor‐A, and Leptin was observed in the moderate patients. Nonsurvivors additionally showed increased interleukin (IL)‐6 levels. Consistently, the proteomics analysis showed the signatures of cytokine production and interferon‐γ response, and increased level of acute‐phase protein SAA1 in the serum of COVID‐19 patients. Despite the sustained expression of MIPs, the recovered COPLA donors showed a surge in MCSF and IL‐18 levels. Both the groups had increased CCR2, CX3CR1 positive monocytes, low CD8 + T cells, A proliferation‐inducing ligand, and B‐cell activating factor receptor + B cells compared with healthy subjects. Conclusions Patients who have recovered and considered for COPLA donations still have compromised immunity with sustained expression of inflammatory monocytes and activated T cells.
Differentiation of mesenchymal stem cells (MSCs) derived from two different sources of fetal tissues such as umbilical cord blood (UCB) and tissue (UCT) into skeletal muscle have remained underexplored. Here, we present a comparative analysis of UCB and UCT MSCs, in terms of surface markers, proliferation and senescence marker expression. We find that CD45−CD34− MSCs obtained from UCT and UCB of term births display differences in the combinatorial expression of key MSC markers CD105 and CD90. Importantly, UCT MSCs display greater yield, higher purity, shorter culture time, and lower rates of senescence in culture compared to UCB MSCs. Using a robust myogenic differentiation protocol, we show that UCT MSCs differentiate more robustly into muscle than UCB MSCs by transcriptomic sequencing and specific myogenic markers. Functional assays reveal that CD90, and not CD105 expression promotes myogenic differentiation in MSCs and could explain the enhanced myogenic potential of UCT MSCs. These results suggest that in comparison to large volumes of UCB that are routinely used to obtain MSCs and with limited success, UCT is a more reliable, robust, and convenient source of MSCs to derive cells of the myogenic lineage for both therapeutic purposes and increasing our understanding of developmental processes.
Summary Background Hepatitis B surface antigen (HBsAg) seroconversion is sometimes observed in hepatitis B reactivation (rHBV), probably due to immune resetting and differentiation. Aims To investigate sequential immune differentiation and abrogation of tolerance in patients with rHBV who achieved HBsAg seroconversion. Methods We included 19 patients with chronic hepatitis B (CHBV; HBV DNA log103‐8), 67 with rHBV (raised ALT [>5XULN], HBV DNAlog104‐8) and 10 healthy controls. Immune differentiation, tolerance and functional status of CD4, CD8, T regulatory cells (Tregs), B cells and follicular T helper (Tfh) cells were assessed at baseline and 24 weeks. Results At 24 weeks, 81% rHBV (n = 67) lost HBV DNA and HBeAg (41%), and 12 (19%) lost HBsAg and made anti‐HBs titers >10 IU/ml. rHBV patients had higher Th1/17, TEM, Tfh, Tfh1/17, plasma and ATM B cells, and lower Tregs, Th2, Th17 and TEMRA expression. rHBV showed lower PD1, TIM3, LAG3, SLAM and TOX compared to CHBV. There was a significant increase in CD8, CD8EM, Tfh, Tfh1/17 and plasma B cells in seroconverters than non‐seroconverters. At 24 weeks, we also observed increased plasma B cell frequency in seroconverters. While non‐seroconverters showed higher expression of PD1, TIM3, LAG3, SLAM and TOX on CD4/CD8 T cells, blockade of PD1, TIM3, LAG3 and CTLA4 significantly enhanced IFN‐γ, TNF‐α, IL‐4 and IL‐21 expression on CD4/CD8 and Tfh cells in non‐seroconverters. Conclusions Non‐seroconverters have increased inhibitory markers on CD4/CD8 T cells. There is a critical play of CD8, Tfh and B cells and subsets in seroclearance, along with checkpoint molecules as a potential therapy for non‐seroconverters in HBV infection.
Background: The stoppage of nucleoside analog (NA) can lead to immune flare and loss of HBsAg in a proportion of HBeAg-negative chronic hepatitis B (CHB) patients. HBsAg loss could be improved by instituting Peg-Interferon therapy in those who show an immune flare after the stoppage of NA. We investigated the immune drivers of HBsAg loss in NA-treated HBeAg-negative CHB patients after stopping NAs and administration of Peg-IFN-α2b therapy. Methods: Fifty-five NA-treated eAg-ve, HBV DNA not detected CHB patients were subjected to stopping NA therapy. Twenty-two (40%) patients relapsed (REL-CHBV) within 6 months (HBV DNA ≥2000 IU/mL, ALT ≥2XULN) and were started on Peg-IFN-α2b (1.5 mcg/kg) for 48 weeks (PEG-CHBV). Cytokine levels, immune responses, and T-cell functionality were assessed. Results: Only 22 (40%) of 55 patients clinically relapsed, of which 6 (27%) cleared HBsAg. None of the 33 (60%) nonrelapsers cleared HBsAg. REL-CHBV patients had significantly increased IL-6 (p=0.035), IFN-γ (p=0.049), Th1/17 (p=0.005), CD4 effector memory (EM) (p=0.01), Tfh1/17 (p=0.005), and mature B cells (p=0.04) compared with CHBV. Six months after Peg-IFN therapy, immune resetting with a significant increase in CXCL10 (p=0.042), CD8 (p=0.01), CD19 (p=0.001), and mature B cells (p=0.001) was observed. HBV-specific T-cell functionality showed increased Tfh-secreting IFN-γ (p=0.001), IL-21 (p=0.001), and TNF-α (p=0.005) in relapsers and IFN-γ–secreting CD4 T cell (p=0.03) in PEG-CHBV. Conclusions: Stopping NA therapy induces flare in about 40% of HBeAg-negative patients. Peg-IFN therapy given to such patients causes immune restoration with HBsAg loss in one fourth of them.
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