Cell Polarity Regulators, Multifunctional Organizers of Lymphocyte Activation and Function

pH-regulated single cell migration

Over the last two decades, extra- and intracellular pH have emerged as fundamental regulators of cell motility. Fundamental physiological and pathological processes relying on appropriate cell migration, such as embryonic development, wound healing, and a proper immune defense on the one hand, and autoimmune diseases, metastatic cancer, and the progression of certain parasitic diseases on the other, depend on surrounding pH. In addition, migrating single cells create their own localized pH nanodomains at their surface and in the cytosol. By this means, the migrating cells locally modulate their adhesion to, and the re-arrangement and digestion of, the extracellular matrix. At the same time, the cytosolic nanodomains tune cytoskeletal dynamics along the direction of movement resulting in concerted lamellipodia protrusion and rear end retraction. Extracellular pH gradients as found in wounds, inflamed tissues, or the periphery of tumors stimulate directed cell migration, and long-term exposure to acidic conditions can engender a more migratory and invasive phenotype persisting for hours up to several generations of cells after they have left the acidic milieu. In the present review, the different variants of pH-dependent single cell migration are described. The underlying pH-dependent molecular mechanisms such as conformational changes of adhesion molecules, matrix protease activity, actin (de-)polymerization, and signaling events are explained, and molecular pH sensors stimulated by H+ signaling are presented.

Development of a prognostic model for lung adenocarcinoma polarity-related genes and analysis of immune landscape

Despite the progress made in the management of lung adenocarcinoma (LUAD), the overall prognosis for LUAD individuals remains suboptimal. While the role of cell polarity in tumor invasion and metastasis is well established, its prognostic significance in LUAD is still unknown. Differential analysis was performed on the Cancer Genome Atlas (TCGA)-LUAD and normal lung tissue, and candidate genes were identified by intersecting differentially expressed genes with polarity-related genes (PRGs). A prognostic model was constructed using univariate and multivariate Cox regression and LASSO regression. To enhance the robustness of the analysis, an independent prognostic analysis was conducted by incorporating relevant clinical information. The accuracy and sensitivity of the model were validated using survival analysis and ROC curves. Finally, immune landscape, immune therapy, tumor mutation burden, and drug sensitivity analysis were carried out on high- and low-risk patients. Ten prognostic genes were screened to divide LUAD patients into different risk groups. Survival analysis, ROC curves, and univariate/multivariate Cox regression analyses collectively demonstrated the favorable predictive performance of the model, which could be an independent prognostic factor. The nomogram, in conjunction with the calibration curve, demonstrated the model's compelling predictive capacity in prognosticating the overall survival of LUAD individuals. Low-risk LUAD patients exhibited heightened levels of immune cell infiltration, immune scores, and immune checkpoint expression compared to high-risk individuals. So, they may have a greater likelihood of benefiting from immune therapy. The high-risk group demonstrated a remarkably higher tumor mutation burden (TMB) in contrast with the low-risk group. XAV-939, Fulvestrant, and SR16157 may have potential value in the clinical use of LUAD. We revealed the potential linkage between PRGs and LUAD prognosis, and the application of these prognostic factors in risk stratification and prognosis prediction of LUAD patients may be of great significance.

Cell polarity changes in cancer initiation and progression

Cell polarity, which consists of the morphological, structural, and functional organization of cells along a defined axis, is a feature of healthy cells and tissues. In contrast, abnormal polarity is a hallmark of cancer cells. At the molecular level, key evolutionarily conserved proteins that control polarity establishment and maintenance in various contexts are frequently altered in cancer, but the relevance of these molecular alterations in the oncogenic processes is not always clear. Here, we summarize the recent findings, shedding new light on the involvement of polarity players in cancer development, and discuss the possibility of harnessing cell polarity changes to better predict, diagnose, and cure cancers.

Lymphocyte to C-Reactive Protein Ratio as an Early Biomarker to Distinguish Sepsis from Pneumonia in Neonates

Background

Neonatal sepsis is an acute and severe disease that seriously threatens the life and health of newborns. Neonates with pneumonia may also have unrecognized neonatal sepsis. Early diagnosis of neonatal sepsis is beneficial for early treatment. This study aimed to evaluate the clinical significance of the lymphocyte-to-C-reactive protein ratio (LCR) as an early biomarker to distinguish sepsis from pneumonia.

Methods

This retrospective study enrolled 1635 neonates with pneumonia from February 2016 to March 2022. Among them, 182 cases were diagnosed with sepsis based on the positive blood culture results. Clinical and laboratory data were extracted from the electronic medical records. LCR was calculated as the ratio of the total lymphocyte count (×109 cells/L) to the C-reactive protein level (mg/L). Binary logistic regression analysis was conducted to evaluate the clinical significance of LCR as an early biomarker in distinguishing sepsis from pneumonia. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic value of LPCR in sepsis cases. All statistical analyses were conducted using Statistical Product and Service Solutions, version 24.0.

Results

The neonates with pneumonia combined with sepsis had a lower LCR than that of the neonates with pneumonia. Further analysis showed that the prevalence of neonatal pneumonia combined with sepsis was significantly higher in the low-LCR group than in the high-LCR group (20.7% vs 5.5%, P < 001). Binary logistic regression revealed that LCR was an independent risk factor for identifying pneumonia combined with sepsis. The ROC curve analysis revealed that LCR had better power than the lymphocyte count and CRP level individually in diagnosing neonatal pneumonia combined with sepsis (0.72 vs 0.65 vs 0.66, P < 0.001), with 62% sensitivity and 72% specificity.

Conclusion

LCR can be a potential early biomarker in distinguishing neonates with sepsis from those with pneumonia.

T cell migration and effector function differences in familial adenomatous polyposis patients with APC gene mutations

Familial adenomatous polyposis (FAP) is an inherited disease characterized by the development of large number of colorectal adenomas with high risk of evolving into colorectal tumors. Mutations of the Adenomatous polyposis coli (APC) gene is often at the origin of this disease, as well as of a high percentage of spontaneous colorectal tumors. APC is therefore considered a tumor suppressor gene. While the role of APC in intestinal epithelium homeostasis is well characterized, its importance in immune responses remains ill defined. Our recent work indicates that the APC protein is involved in various phases of both CD4 and CD8 T cells responses. This prompted us to investigate an array of immune cell features in FAP subjects carrying APC mutations. A group of 12 FAP subjects and age and sex-matched healthy controls were studied. We characterized the immune cell repertoire in peripheral blood and the capacity of immune cells to respond ex vivo to different stimuli either in whole blood or in purified T cells. A variety of experimental approaches were used, including, pultiparamater flow cytometry, NanosString gene expression profiling, Multiplex and regular ELISA, confocal microscopy and computer-based image analyis methods. We found that the percentage of several T and natural killer (NK) cell populations, the expression of several genes induced upon innate or adaptive immune stimulation and the production of several cytokines and chemokines was different. Moreover, the capacity of T cells to migrate in response to chemokine was consistently altered. Finally, immunological synapses between FAP cytotoxic T cells and tumor target cells were more poorly structured. Our findings of this pilot study suggest that mild but multiple immune cell dysfunctions, together with intestinal epithelial dysplasia in FAP subjects, may facilitate the long-term polyposis and colorectal tumor development. Although at an initial discovery phase due to the limited sample size of this rare disease cohort, our findings open new perspectives to consider immune cell abnormalities into polyposis pathology.

Imaging polarized granule release at the cytotoxic T cell immunological synapse using TIRF microscopy: Control by polarity regulators

Immunological synapse formation results from a profound T cell polarization process that involves the coordinated action of the actin and microtubule cytoskeleton, and the intracellular traffic of several vesicular organelles. T cell polarization is key for both T cell activation leading to T cell proliferation and differentiation, and for T cell effector functions such as polarized secretion of cytokines by helper T cells, or polarized delivery of lytic granules by cytotoxic T cells. Efficient targeting of lytic granules by cytotoxic T cells is a crucial event for the control and elimination of infected or tumor cells. Understanding how lytic granule delivery is regulated and quantifying its efficiency under physiological and pathological conditions may help to improve immune responses against infection and cancer.

Expression, Prognostic Value, and Functional Mechanism of Polarity-Related Genes in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor with high mortality and poor prognoses around the world. Within-cell polarity is crucial to cell development and function maintenance, and some studies have found that it is closely related to cancer initiation, metastasis, and prognosis. The aim of our research was to find polarity-related biomarkers which improve the treatment and prognosis of HCC. For the knowledge-driven analysis, 189 polarity-related genes (PRGs) were retrieved and curated manually from the molecular signatures database and reviews. Meanwhile, in the data-driven part, genomic datasets and clinical records of HCC was obtained from the cancer genome atlas database. The potential candidates were considered in the respect to differential expression, mutation rate, and prognostic value. Sixty-one PRGs that passed the knowledge and data-driven screening were applied for function analysis and mechanism deduction. Elastic net model combing least absolute shrinkage and selection operator and ridge regression analysis refined the input into a 12-PRG risk model, and its pharmaceutical potency was evaluated. These findings demonstrated that the integration of multi-omics of PRGs can help us in untangling the liver cancer pathogenesis as well as illustrate the underlying mechanisms and therapeutic targets.

High-resolution imaging of protein secretion at the single-cell level using plasmon-enhanced FluoroDOT assay

Secreted proteins mediate essential physiological processes. With conventional assays, it is challenging to map the spatial distribution of proteins secreted by single cells, to study cell-to-cell heterogeneity in secretion, or to detect proteins of low abundance or incipient secretion. Here, we introduce the "FluoroDOT assay," which uses an ultrabright nanoparticle plasmonic-fluor that enables high-resolution imaging of protein secretion. We find that plasmonic-fluors are 16,000-fold brighter, with nearly 30-fold higher signal-to-noise compared with conventional fluorescence labels. We demonstrate high-resolution imaging of different secreted cytokines in the single-plexed and spectrally multiplexed FluoroDOT assay that revealed cellular heterogeneity in secretion of multiple proteins simultaneously. Using diverse biochemical stimuli, including Mycobacterium tuberculosis infection, and a variety of immune cells such as macrophages, dendritic cells (DCs), and DC-T cell co-culture, we demonstrate that the assay is versatile, facile, and widely adaptable for enhancing biological understanding of spatial and temporal dynamics of single-cell secretome.

Actin network architecture can ensure robust centering or sensitive decentering of the centrosome

The orientation of cell polarity depends on the position of the centrosome, the main microtubule-organizing center (MTOC). Microtubules (MTs) transmit pushing forces to the MTOC as they grow against the cell periphery. How the actin network regulates these forces remains unclear. Here, in a cell-free assay, we used purified proteins to reconstitute the interaction of a microtubule aster with actin networks of various architectures in cell-sized microwells. In the absence of actin filaments, MTOC positioning was highly sensitive to variations in microtubule length. The presence of a bulk actin network limited microtubule displacement, and MTOCs were held in place. In contrast, the assembly of a branched actin network along the well edges centered the MTOCs by maintaining an isotropic balance of pushing forces. An anisotropic peripheral actin network caused the MTOC to decenter by focusing the pushing forces. Overall, our results show that actin networks can limit the sensitivity of MTOC positioning to microtubule length and enforce robust MTOC centering or decentering depending on the isotropy of its architecture.

What makes tics tick? Insights into Tourette syndrome

This issue of Biomedical Journal provides the reader with articles concerning the latest understanding of Tourette syndrome (TS), the relation to genetic predisposition, defects in the dopaminergic system, and related comorbidities which further complications like sleep disruption. Treatment approaches for TS, attention deficit hyperactivity disorder and developmental coordination disorder are discussed. The second section of this issue offers insights into inside out integrin activation and its link to T cell activation, demonstrates how polarity in immune cells allows adoption to specialized functions, and describes the endosomal signaling of internalized T cell receptors (TCRs). The link between mutations in TCR signaling and immunodeficiencies is elucidated, as well as the interactions of thymocyte-expressed molecule involved in selection in T cell development. Additionally, we learn about a potential biomarker for colorectal cancer, screening tools for determining frailty in older adults, surgical approaches in spinal metastases, the influence of autophagy on mating behavior, and the effect of nitrite administration on SNARE proteins associated with insulin secretion. Finally, parameters for surgery in breast cancer are discussed, as well as gender and age dependent pain perception in a lysosomal storage disease, and the use of laser meridian massage in opioid use disorder. Three letters complement this issue, one concerning neuroimaging in pediatric COVID-19 patients, and two discussing the role of cancer antigen-125 and renal impairment in ovarian cancer patients.

The ins and outs of T cell signaling

This special edition summarizes major advances in our understanding of signaling by T lymphocytes. T cell interactions with antigen-presenting cells (APCs) and other immune cells are characterized by changes in T cell adhesion and major rearrangements of the actin cytoskeleton. This issue describes some of the mediators of these changes both within the T cells and on the T cell surface. The five articles focus on “inside-out integrin signaling” in T cells, components of the immunological synapse between lymphocyte and APCs, an unexpected role for T cell receptor (TCR) signaling from endosomes, transfer of membrane constituents from APCs to T cells via trogocytosis, immune deficiencies in these T cell signaling pathways, and the role of thymocyte-expressed molecule involved in selection (THEMIS) in thymocyte development and peripheral T cell function.