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Background: Dying tumor cells release intracellular potassium (K+), raising extracellular K+ ([K+]e) in the tumor microenvironment (TME) to 40-50 mM (high-[K+]e). Here, we investigated the effect of high-[K+]e on T cell functions. Materials and Methods: Functional impacts of high-[K+]e on human T cells were determined by cellular, molecular, and imaging assays. Results: Exposure to high-[K+]e suppressed the proliferation of central memory and effector memory T cells, while T memory stem cells were unaffected. High-[K+]e inhibited T cell cytokine production and dampened antitumor cytotoxicity, by modulating the Akt signaling pathway. High-[K+]e caused significant upregulation of the immune checkpoint protein PD-1 in activated T cells. Although the number of KCa3.1 calcium-activated potassium channels expressed in T cells remained unaffected under high-[K+]e, a novel KCa3.1 activator, SKA-346, rescued T cells from high-[K+]e-mediated suppression. Conclusion: High-[K+]e represents a so far overlooked secondary checkpoint in cancer. KCa3.1 activators could overcome such "ionic-checkpoint"-mediated immunosuppression in the TME, and be administered together with known PD-1 inhibitors and other cancer therapeutics to improve outcomes.

The article discusses a study on the molecular portrait of recombinant NSO cells. The study utilized DNA microarray, two-dimensional gel electrophoresis (2DE) and iTRAQ as tools to survey the transcriptome and proteome profiles of 11 lines of NSO cells that produce same antibody molecule. It is revealed that there is a high degree of consistency between the transcriptomic annd proteomic analysis.

Candida albicans , the most frequently isolated fungal pathogen in humans, forms biofilms that enhance resistance to antifungal drugs and host immunity, leading to frequent treatment failure. Understanding the molecular mechanisms governing biofilm formation is crucial for developing anti-biofilm therapies. In this study, we conducted a genetic screen to identify novel genes that regulate biofilm formation in C. albicans . One identified gene is ORF19.6693 , a homolog of the Saccharomyces cerevisiae SDD3 gene. The sdd3 ∆/∆ mutant exhibited severe defects in biofilm formation and significantly reduced chitin content in the cell wall. Overexpression of the constitutively active version of the Rho1 GTPase Rho1 G18V , an upstream activator of the protein kinase C (PKC)-mitogen-activated protein kinase (MAPK) cell-wall integrity pathway, rescued these defects. Affinity purification, mass spectrometry, and co-immunoprecipitation revealed Sdd3's physical interaction with Bem2, the GTPase-activating protein of Rho1. Deletion of SDD3 significantly reduced the amount of the active GTP-bound form of Rho1, thereby diminishing PKC-MAPK signaling and downregulating chitin synthase genes CHS2 and CHS8 . Taken together, our studies identify a new biofilm regulator, Sdd3, in C. albicans that modulates Rho1 activity through its inhibitory interaction with Bem2, thereby regulating the PKC-MAPK pathway to control chitin biosynthesis, which is critical for biofilm formation. As an upstream component of the pathway and lacking a homolog in mammals, Sdd3 has the potential to serve as an antifungal target for biofilm infections.IMPORTANCEThe human fungal pathogen Candida albicans is categorized as a critical priority pathogen on the World Health Organization's Fungal Priority Pathogens List. A key virulence attribute of this pathogen is its ability to form biofilms on the surfaces of indwelling medical devices. Fungal cells in biofilms are highly resistant to antifungal drugs and host immunity, leading to treatment failure. This study conducted a genetic screen to discover novel genes that regulate biofilm formation. We found that deletion of the SDD3 gene caused severe biofilm defects. Sdd3 negatively regulates the Rho1 GTPase, an upstream activator of the protein kinase C-mitogen-activated protein kinase pathway, through direct interaction with Bem2, the GTPase-activating protein of Rho1, resulting in a significant decrease in chitin content in the fungal cell wall. This chitin synthesis defect leads to biofilm formation failure. Given its essential role in biofilm formation, Sdd3 could serve as an antifungal target for biofilm infections.

Background: The compromised gut microbiome that results from C-section birth has been hypothesized as a risk factor for the development of non-communicable diseases (NCD). In a double-blind randomized controlled study, 153 infants born by elective C-section received an infant formula supplemented with either synbiotic, prebiotics, or unsupplemented from birth until 4 months old. Vaginally born infants were included as a reference group. Stool samples were collected from day 3 till week 22. Multi-omics were deployed to investigate the impact of mode of delivery and nutrition on the development of the infant gut microbiome, and uncover putative biological mechanisms underlying the role of a compromised microbiome as a risk factor for NCD., Results: As early as day 3, infants born vaginally presented a hypoxic and acidic gut environment characterized by an enrichment of strict anaerobes (Bifidobacteriaceae). Infants born by C-section presented the hallmark of a compromised microbiome driven by an enrichment of Enterobacteriaceae. This was associated with meta-omics signatures characteristic of a microbiome adapted to a more oxygen-rich gut environment, enriched with genes associated with reactive oxygen species metabolism and lipopolysaccharide biosynthesis, and depleted in genes involved in the metabolism of milk carbohydrates. The synbiotic formula modulated expression of microbial genes involved in (oligo)saccharide metabolism, which emulates the eco-physiological gut environment observed in vaginally born infants. The resulting hypoxic and acidic milieu prevented the establishment of a compromised microbiome., Conclusions: This study deciphers the putative functional hallmarks of a compromised microbiome acquired during C-section birth, and the impact of nutrition that may counteract disturbed microbiome development., Trial Registration: The study was registered in the Dutch Trial Register (Number: 2838 ) on 4th April 2011.

Background: Dying tumor cells release intracellular potassium (K + ), raising extracellular K + ([K + ] e ) in the tumor microenvironment (TME) to 40-50 mM (high-[K + ] e ). Here, we investigated the effect of high-[K + ] e on T cell functions. Materials and Methods: Functional impacts of high-[K + ] e on human T cells were determined by cellular, molecular, and imaging assays. Results: Exposure to high-[K + ] e suppressed the proliferation of central memory and effector memory T cells, while T memory stem cells were unaffected. High-[K + ] e inhibited T cell cytokine production and dampened antitumor cytotoxicity, by modulating the Akt signaling pathway. High-[K + ] e caused significant upregulation of the immune checkpoint protein PD-1 in activated T cells. Although the number of K Ca 3.1 calcium-activated potassium channels expressed in T cells remained unaffected under high-[K + ] e , a novel K Ca 3.1 activator, SKA-346, rescued T cells from high-[K + ] e -mediated suppression. Conclusion: High-[K + ] e represents a so far overlooked secondary checkpoint in cancer. K Ca 3.1 activators could overcome such "ionic-checkpoint"-mediated immunosuppression in the TME, and be administered together with known PD-1 inhibitors and other cancer therapeutics to improve outcomes., Competing Interests: No competing financial interests exist., (Copyright 2019, Mary Ann Liebert, Inc., publishers.)