Biology subjects

John, P.

Publications and source records attributed to John, P..

4 recordsLinked to original sources

bioRxiv2025

Diabetes mellitus affects urinary tissue tropism of group B streptococci in a sex-dependent manner

Diabetes mellitus (DM) increases susceptibility to Streptococcus agalactiae (group B Streptococcus or GBS) urinary tract infections (UTI) and their exacerbations such as ascending pyelonephritis and sepsis, although underlying molecular mechanisms have not been fully deciphered. To address our hypothesis that DM mediated alterations in the host urinary immune defenses increase susceptibility to GBS-UTI, we inoculated, via transurethral route, GBS strain 10/84 into the urinary bladders of 8 weeks old, male and female, diabetic (obese, hyperglycemic mice denoted as D) and non-diabetic (ND) mouse littermates. At 24 h post-infection (hpi), compared to their ND littermates, the D-mice showed significantly higher GBS CFUs in the bladder, the kidneys, and the spleen. This was accompanied by a significantly reduced recruitment of CD45+ leukocytes to and suppression of pro-inflammatory cytokine production in GBS-infected D-bladder and D-kidneys compared to their ND counterparts. We also noted sex-dependent differences in GBS urinary tissue tropism. For example, D-females exhibited significantly higher bladder burden compared to ND-females, D-males, and to ND-males, while the bladder burden in ND-females was not significantly different from that in ND-males. In contrast, ND-males showed significantly higher kidney CFUs than ND-females and DM further increased kidney CFU burden in males. GBS-induced recruitment of CD45+ leukocytes was not different between male and female mice within either D or ND cohorts. GBS-UTI induced significantly higher CXCL1 production in male bladders in both D and ND cohorts compared to their female counterparts. These results indicate that DM increases susceptibility to GBS-UTI and the dissemination to spleen by affecting leukocyte recruitment and pro-inflammatory cytokine production in a sex-dependent manner. ImportanceIn this study we sought to understand why diabetic individuals are more susceptible to urinary tract infections (UTI) by Gram positive Streptococcus agalactiae (group B Streptococcus or GBS). We induced UTI by inoculating GBS into the bladders of diabetic (obese, hyperglycemic) and non-diabetic, male and female mice. At 24 hours after infection, compared to the non-diabetic mice, the diabetic mouse urinary tracts showed higher GBS counts and reduced immune defenses. Diabetes also promoted dissemination of GBS to the spleen. Furthermore, female diabetic mice were more susceptible to bladder infection while diabetes worsened the increased overall susceptibility of males to kidney infection, a difficult-to-treat, potentially life threatening exacerbation of GBS-UTI. Overall, our results suggest that both diabetes and sex are important determinants of susceptibility to GBS-UTI and resulting severe outcomes.

microbiology↗

bioRxiv2025

Obesity promotes urinary tract infection by disrupting urothelial immune defenses

Obesity is a significant public health concern that is associated with numerous health risks. Infections are a major complication of obesity, but the mechanisms responsible for increased infection risk are poorly defined. Here, we use a diet induced obesity mouse model and investigate how obesity impacts urinary tract infection (UTI) susceptibility and bladder immune defenses. Our results show that high-fat diet fed female and male mice exhibit increased susceptibility to uropathogenic E. coli (UPEC) following experimental UTI. Transcriptomic analysis of bladder urothelial cells shows that obesity alters gene expression in a sex-specific manner, with distinct differentially expressed genes in male and female mice, but shared activation of focal adhesion and extracellular matrix signaling. Western blot and immunostaining confirm activation of focal adhesion kinase, a central component of the focal adhesion pathway, in the bladders of obese female and male mice. Mechanistically, experiments using primary human urothelial cells demonstrate that focal adhesion kinase overexpression promotes UPEC invasion. These findings demonstrate that obesity enhances UTI susceptibility by activating focal adhesion kinase and promoting bacterial invasion of the urothelium. Together, they explain how obesity promotes UTI vulnerability and identify modifiable targets for managing obesity-associated UTI.

cell biology↗

bioRxiv2021

Reovirus sensitizes microsatellite stable colorectal cancer to anti-PD-1 treatment via cross-talk in innate and adaptive immune systems

BackgroundMicrosatellite stable (MSS) colorectal cancer (CRC) represents ~85% of all CRCs. These tumors are poorly immunogenic and largely resistant to immunotherapy, necessitating a need to develop new immune enhancing strategies. Oncolytic reovirus has a high propensity to replicate in KRAS mutant tumors which account for ~50% of MSS CRCs. Current study explores the ability of reovirus to potentiate the effect of immune checkpoint inhibition in MSS CRC. MethodsEffectiveness of reovirus infection was quantified through MTT assay for cell viability, and expression of immune-response genes by flow cytometry, RT-qPCR, and microarray. Computational analysis of differentially expressed genes was performed by TAC, DAVID and STRING. Combinatorial approach using anti-PD-1 monoclonal antibody was assessed in ex vivo and in vivo models. Live-cell imaging, tumor volume and survival were measured for quantification of anti-tumor activity. Expression of pattern recognition receptors (PRRs), cell surface and activation markers of immune cells, and PD-1/PD-L1 axis were studied using multi-color flow cytometry, immunoblotting, immunohistochemistry, and immunofluorescence. ResultsReovirus infection exerted growth arrest and expression of immune-response genes in CRCs cell lines in a KRAS-dependent manner. However, microsatellite instability, rather than KRAS status determined immune-repose pathways, functionalities and biological processes post-reovirus infection. Furthermore, reovirus significantly enhanced the anti-tumor activity of anti-human PD-1 [nivolumab] treatment in MSS CRC cell lines ex vivo. Similarly, reovirus increased the activity of anti-mouse PD-1 treatment in the CT26 [MSS, KRASMut], but not the MC38 [MSI, KRASWt] syngeneic mouse model of CRC. Combinatorial treatment has reduced the proliferative index, increased apoptosis and differentially altered PD-L1/PD-1 signaling among CT26 and MC38 tumors. Activation of innate immune system and expression of PRRs and antigen presentation markers were observed under reovirus and anti-PD-1 treatment that additionally reduced immunosuppressive macrophages. This led to an increase in T cell subsets, increase in effector T cell activation, and decrease in exhaustion markers specifically within CT26 microenvironment. ConclusionThe current study systematically evaluates immune characteristics and immune microenvironment of CRC under reovirus/anti-PD-1 combination treatment that proves increased effectiveness among MSS compared to MSI CRCs. This is a promising regimen warranting translation into clinical trials. One Sentence SummaryOncolytic reovirus alters innate and adaptive immune system and potentiates MSS type colorectal cancer to checkpoint inhibition therapy.

cancer biology↗

bioRxiv2016

Mapping Autosomal Recessive Intellectual Disability: Combined Microarray and Exome Sequencing Identifies 26 Novel Candidate Genes in 192 Consanguineous Families

Approximately 1% of the global population is affected by intellectual disability (ID), and the majority receive no molecular diagnosis. Previous studies have indicated high levels of genetic heterogeneity, with estimates of more than 2500 autosomal ID genes, the majority of which are autosomal recessive (AR). Here, we combined microarray genotyping, homozygosity-by-descent (HBD) mapping, copy number variation (CNV) analysis, and whole exome sequencing (WES) to identify disease genes/mutations in 192 multiplex Pakistani and Iranian consanguineous families with non-syndromic ID. We identified definite or candidate mutations (or CNVs) in 51% of families in 72 different genes, including 26 not previously reported for ARID. The new ARID genes include nine with loss-of-function mutations (ABI2, MAPK8, MPDZ, PIDD1, SLAIN1, TBC1D23, TRAPPC6B, UBA7, and USP44), and missense mutations include the first reports of variants in BDNF or TET1 associated with ID. The genes identified also showed overlap with de novo gene sets for other neuropsychiatric disorders. Transcriptional studies showed prominent expression in the prenatal brain. The high yield of AR mutations for ID indicated that this approach has excellent clinical potential and should inform clinical diagnostics, including clinical whole exome and genome sequencing, for populations in which consanguinity is common. As with other AR disorders, the relevance will also apply to outbred populations.

genetics↗