技术资料

Pancreatic β cells derived from human induced pluripotent stem cells (hiPSCs) represent a promising therapeutic avenue in regenerative medicine for diabetes treatment. However,current differentiation protocols lack the specificity and efficiency required to reliably produce fully functional β cells,limiting their clinical applicability. Epigenetic barriers,such as histone modifications,may hinder proper differentiation and the acquisition of essential maturation markers in these cells. Methods: hiPSCs were cultured under feeder-free conditions and subjected to lentiviral transduction with shRNA constructs to silence KDM4A. Differentiation into pancreatic β-like cells was performed using stepwise protocols,with or without doxycycline supplementation,to evaluate the effect of KDM4A suppression. Gene expression was quantified by RT-qPCR,protein expression was assessed by western blotting and immunofluorescence,and functional insulin release was determined by glucose-stimulated insulin secretion (GSIS) assays. Statistical analysis was conducted using unpaired two-tailed Student’s t-tests,with significance set at p < 0.05. Results: A reduction in pancreatic development proteins was observed in the different differentiation states evaluated,after blocking KDM4A expression. Knockdown of KDM4A significantly reduced the expression of pancreatic β-cell genes,such as PDX1,Nkx6.1,and Ins,by 50% compared to WT iPSCs differentiated under the same conditions. Similarly,glucose-stimulated insulin secretion was reduced by approximately 80% in KDM4A-deficient β-like cells. Conclusions: These results emphasize the critical role of histone demethylation in hiPSC differentiation toward β cells. Our findings identify KDM4A as a key epigenetic regulator,suggesting that its modulation could enhance the generation of functional β cells for regenerative medicine in diabetes. View Publication

Different innate immune cell types are known to release extracellular traps (ETs) in response to invasive pathogens,including parasites. These ETs function to trap,immobilize,and eventually kill pathogens. In line with this,monocytes and macrophages have been shown to release ETs,known as monocyte/macrophage extracellular traps (METs). Toxoplasma gondii (T. gondii) is an apicomplexan zoonotic parasite that infects humans and homeothermic animals. While most studies have focused on prolonged exposure of immune cells to T. gondii,this study characterized the early innate immune reaction of mononuclear phagocytes to vital T. gondii tachyzoites. Methods: Primary human and bovine monocytes,monocytic THP-1 cells,and THP-1 cell-derived macrophages (M0-,M1-,and M2-like) were exposed to T. gondii tachyzoites for 4 h. Scanning electron microscopy (SEM),transmission electron microscopy (TEM),immunofluorescencemicroscopy,and confocal microscopy were used to visualize cell activation and the presence of METs. Additionally,the release of pro-inflammatory cytokines interleukin (IL)-1β and IL-6,and expression of Toll-like receptor (TLR) 2 and TLR4 were analyzed. Results and discussion: Microscopic analysis illustrated the activation of all cell types tested within 4 h of exposure to T. gondii tachyzoites. Numerous tachyzoites were found intracellularly in THP-1 cell-derived M1-like macrophages. Furthermore,the co-localization of extracellular DNA (extDNA) and histones in extracellular web-like fibers proved classical characteristics of extruded T. gondii-induced METs,although this was a rare event. In primary human monocytes,an increased release of IL-1β and IL-6 was observed following exposure to T. gondii tachyzoites. When co-stimulated with lipopolysaccharide (LPS),primary human monocytes showed an enhanced release of IL-1β and IL-6 in response to T. gondii. In contrast to monocytic THP-1 cells,THP-1 cell-derived M1-like macrophages released IL-1β in response to T. gondii tachyzoite exposure. When additionally stimulated by LPS,all THP-1 cell-derived macrophages showed an enhanced release of IL-1β,and monocytic THP-1 cells an increased release of IL-6 in response to T. gondii tachyzoites. This study provides insights into the early innate immune response of human and bovine mononuclear phagocytes to T. gondii. While cytokine secretion was prominent,MET formation was rare in the early response (i.e. < 4 h of exposure) to T. gondii tachyzoites. View Publication

Gastrointestinal (GI) dysfunction,characterized by severe diarrhea and dehydration,is a central contributor to morbidity and mortality in filovirus disease in patients,yet the role of the epithelium in this clinical outcome remains poorly defined. Here,we employ induced pluripotent stem cell (iPSC)-derived human intestinal (HIOs) and colonic organoids (HCOs) to model Ebola virus (EBOV) and Marburg virus (MARV) infection. These organoids are permissive to filovirus infection and support viral replication. Bulk RNA sequencing revealed distinct intestinal and colonic epithelial responses,including apical and junctional disruption and a delayed virus-specific induction of interferon-stimulated genes. Moreover,infection impaired adenylate cyclase signaling and CFTR-mediated ion transport,providing mechanistic insight into virus-induced secretory diarrhea. This platform recapitulates key features of human GI pathology in filoviral disease and serves as a powerful system to dissect host-pathogen interactions and identify therapeutic targets. Author summaryEbola virus (EBOV) and Marburg virus (MARV) are among the most lethal viruses known. Infection with these viruses leads to severe disease and death. One of their most harmful effects is damage to the gastrointestinal tract,causing intense diarrhea and life-threatening dehydration. Yet,how these viruses affect the gut remains poorly understood. In this study,we used human mini-guts—small,three-dimensional tissues grown from stem cells that mimic the human intestinal and colonic epithelium—to investigate how these viruses interact with gut epithelial cells. We found that both EBOV and MARV infect and replicate in these tissues,disrupt key barrier structures,and interfere with the cells’ ability to regulate fluid secretion. These effects mirror the severe symptoms seen in patients. Our study provides new insight into how EBOV and MARV damage the gut and identifies specific cellular pathways that may be targeted for treatment. This research not only improves our understanding of EBOV and MARV infections but also offers new infection platforms for testing therapies aimed at protecting the gastrointestinal system during filovirus outbreaks. View Publication

Influenza infection predisposes individuals to secondary pneumonia caused by a range of pathogens,including both bacterial and fungal organisms. Neutrophils are critical effector cells during infection. In this study,we analyzed the transcriptional pathways of lung neutrophils isolated from mouse models of influenza-associated pulmonary aspergillosis (IAPA) and post-influenza methicillin-resistant Staphylococcus aureus (MRSA) pneumonia to examine the immunopathological mechanisms underlying post-influenza super-infection. Pathways associated with neutrophil chemotaxis and degranulation were inhibited in IAPA compared to singular A. fumigatus infection and pathways associated with neutrophil recruitment and phagocytosis were inhibited in IAPA compared to singular influenza infection. Pathways associated with neutrophil recruitment and degranulation were inhibited in post-influenza MRSA pneumonia compared to singular MRSA infection and pathways associated with cytokine signaling were inhibited in post-influenza MRSA pneumonia compared to singular influenza infection. When the 2 types of super-infection were directly compared,pathways related to cytokine induction and neutrophil function were inhibited in IAPA neutrophils compared to post-influenza MRSA pneumonia. These data demonstrate that influenza causes neutrophil dysfunction,predisposing to secondary fungal and bacterial infections. View Publication