Rho family GTPases and their regulators in lymphocytes

Hem1 inborn errors of immunity: waving goodbye to coordinated immunity in mice and humans

Inborn errors of immunity (IEI) are a group of diseases in humans that typically present as increased susceptibility to infections, autoimmunity, hyperinflammation, allergy, and in some cases malignancy. Among newly identified genes linked to IEIs include 3 independent reports of 9 individuals from 7 independent kindreds with severe primary immunodeficiency disease (PID) and autoimmunity due to loss-of-function mutations in the NCKAP1L gene encoding Hematopoietic protein 1 (HEM1). HEM1 is a hematopoietic cell specific component of the WASp family verprolin homologous (WAVE) regulatory complex (WRC), which acts downstream of multiple immune receptors to stimulate actin nucleation and polymerization of filamentous actin (F-actin). The polymerization and branching of F-actin is critical for creating force-generating cytoskeletal structures which drive most active cellular processes including migration, adhesion, immune synapse formation, and phagocytosis. Branched actin networks at the cell cortex have also been implicated in acting as a barrier to regulate inappropriate vesicle (e.g. cytokine) secretion and spontaneous antigen receptor crosslinking. Given the importance of the actin cytoskeleton in most or all hematopoietic cells, it is not surprising that HEM1 deficient children present with a complex clinical picture that involves overlapping features of immunodeficiency and autoimmunity. In this review, we will provide an overview of what is known about the molecular and cellular functions of HEM1 and the WRC in immune and other cells. We will describe the common clinicopathological features and immunophenotypes of HEM1 deficiency in humans and provide detailed comparative descriptions of what has been learned about Hem1 disruption using constitutive and immune cell-specific mouse knockout models. Finally, we discuss future perspectives and important areas for investigation regarding HEM1 and the WRC.

Harnessing the cytotoxic granule exocytosis to augment the efficacy of T-cell-engaging bispecific antibody therapy

T-cell-engaging bispecific antibody (T-BsAb, also known as BiTE) therapy has emerged as a powerful therapeutic modality against multiple myeloma. Given that T-BsAb therapy redirects endogenous T cells to eliminate tumor cells, reinvigorating dysfunctional T cells may be a potential approach to improve the efficacy of T-BsAb. While various immunostimulatory cytokines can potentiate effector T-cell functions, the optimal cytokine treatment for T-BsAb therapy is yet to be established, partly due to a concern of cytokine release syndrome driven by aberrant interferon (IFN)-γ production. Here, we functionally screen immunostimulatory cytokines to determine an ideal combination partner for T-BsAb therapy. This approach reveals interleukin (IL)-21 as a potential immunostimulatory cytokine with the ability to augment T-BsAb-mediated release of granzyme B and perforin, without increasing IFN-γ release. Transcriptome profiling and functional characterization strongly support that IL-21 selectively targets the cytotoxic granule exocytosis pathway, but not pro-inflammatory responses. Notably, IL-21 modulates multiple steps of cytotoxic effector functions including upregulation of co-activating CD226 receptor, increasing cytotoxic granules, and promoting cytotoxic granule delivery at the immunological synapse. Indeed, T-BsAb-mediated myeloma killing is cytotoxic granule-dependent, and IL-21 priming significantly augments cytotoxic activities. Furthermore, in vivo IL-21 treatment induces cytotoxic effector reprogramming in bone marrow T cells, showing synergistic anti-myeloma effects in combination with T-BsAb therapy. Together, harnessing the cytotoxic granule exocytosis pathway by IL-21 may be a potential approach to achieve better responses by T-BsAb therapy.

Two-Part Phase 1 Study to Evaluate the Taste Profile of Novel Belumosudil Oral Suspensions and Assess the Relative Bioavailability and Food Effect of the Selected Belumosudil Oral Suspension Compared With Oral Tablet Reference in Healthy Male Participants

Belumosudil is a selective rho-associated coiled-coil-containing protein kinase 2 inhibitor in clinical use for the treatment of chronic graft-versus-host disease. The current tablet formulation may be inappropriate for children or adults with dysphagia and/or upper gastrointestinal manifestations of chronic graft-versus-host disease. This study (NCT04735822) assessed the taste and palatability of oral suspensions of belumosudil, evaluated the relative bioavailability of an oral suspension versus the tablet formulation, and characterized the effect of food on the pharmacokinetics of an oral suspension. Addition of sweetener and/or flavor vehicle improved the taste. Relative bioavailability of 200-mg doses of the oral suspension and tablet in the fed state was similar for belumosudil and its metabolites (KD025m1 and KD025m2), but absorption was faster with the oral suspension (median time to maximum concentration: 2 vs 3 hours). Administration of the oral suspension with food increased exposure compared with fasted administration, with maximum observed concentration being increased by 16% and area under the concentration-time curve from time 0 to the last measurable concentration (AUC0-last) by 19%. Safety and tolerability were consistent with the known safety profile of belumosudil. These results may support administration of a 200-mg belumosudil oral suspension with or without food.

Spatially Exploring RNA Biology in Archival Formalin-Fixed Paraffin-Embedded Tissues

Spatial transcriptomics has emerged as a powerful tool for dissecting spatial cellular heterogeneity but as of today is largely limited to gene expression analysis. Yet, the life of RNA molecules is multifaceted and dynamic, requiring spatial profiling of different RNA species throughout the life cycle to delve into the intricate RNA biology in complex tissues. Human disease-relevant tissues are commonly preserved as formalin-fixed and paraffin-embedded (FFPE) blocks, representing an important resource for human tissue specimens. The capability to spatially explore RNA biology in FFPE tissues holds transformative potential for human biology research and clinical histopathology. Here, we present Patho-DBiT combining in situ polyadenylation and deterministic barcoding for spatial full coverage transcriptome sequencing, tailored for probing the diverse landscape of RNA species even in clinically archived FFPE samples. It permits spatial co-profiling of gene expression and RNA processing, unveiling region-specific splicing isoforms, and high-sensitivity transcriptomic mapping of clinical tumor FFPE tissues stored for five years. Furthermore, genome-wide single nucleotide RNA variants can be captured to distinguish different malignant clones from non-malignant cells in human lymphomas. Patho-DBiT also maps microRNA-mRNA regulatory networks and RNA splicing dynamics, decoding their roles in spatial tumorigenesis trajectory. High resolution Patho-DBiT at the cellular level reveals a spatial neighborhood and traces the spatiotemporal kinetics driving tumor progression. Patho-DBiT stands poised as a valuable platform to unravel rich RNA biology in FFPE tissues to study human tissue biology and aid in clinical pathology evaluation.

ROCK1/2 signaling contributes to corticosteroid-refractory acute graft-versus-host disease

Patients with corticosteroid-refractory acute graft-versus-host disease (aGVHD) have a low one-year survival rate. Identification and validation of novel targetable kinases in patients who experience corticosteroid-refractory-aGVHD may help improve outcomes. Kinase-specific proteomics of leukocytes from patients with corticosteroid-refractory-GVHD identified rho kinase type 1 (ROCK1) as the most significantly upregulated kinase. ROCK1/2 inhibition improved survival and histological GVHD severity in mice and was synergistic with JAK1/2 inhibition, without compromising graft-versus-leukemia-effects. ROCK1/2-inhibition in macrophages or dendritic cells prior to transfer reduced GVHD severity. Mechanistically, ROCK1/2 inhibition or ROCK1 knockdown interfered with CD80, CD86, MHC-II expression and IL-6, IL-1β, iNOS and TNF production in myeloid cells. This was accompanied by impaired T cell activation by dendritic cells and inhibition of cytoskeletal rearrangements, thereby reducing macrophage and DC migration. NF-κB signaling was reduced in myeloid cells following ROCK1/2 inhibition. In conclusion, ROCK1/2 inhibition interferes with immune activation at multiple levels and reduces acute GVHD while maintaining GVL-effects, including in corticosteroid-refractory settings.

Biology of Tenascin C and its Role in Physiology and Pathology

Tenascin-C (TNC) is a multimodular extracellular matrix (ECM) protein hexameric with several molecular forms (180-250 kDa) produced by alternative splicing at the pre-mRNA level and protein modifications. The molecular phylogeny indicates that the amino acid sequence of TNC is a well-conserved protein among vertebrates. TNC has binding partners, including fibronectin, collagen, fibrillin-2, periostin, proteoglycans, and pathogens. Various transcription factors and intracellular regulators tightly regulate TNC expression. TNC plays an essential role in cell proliferation and migration. Unlike embryonic tissues, TNC protein is distributed over a few tissues in adults. However, higher TNC expression is observed in inflammation, wound healing, cancer, and other pathological conditions. It is widely expressed in a variety of human malignancies and is recognized as a pivotal factor in cancer progression and metastasis. Moreover, TNC increases both pro-and anti-inflammatory signaling pathways. It has been identified as an essential factor in tissue injuries such as damaged skeletal muscle, heart disease, and kidney fibrosis. This multimodular hexameric glycoprotein modulates both innate and adaptive immune responses regulating the expression of numerous cytokines. Moreover, TNC is an important regulatory molecule that affects the onset and progression of neuronal disorders through many signaling pathways. We provide a comprehensive overview of the structural and expression properties of TNC and its potential functions in physiological and pathological conditions.

Vasospastic angina: Past, present, and future

Vasospastic angina (VSA) is characterized by episodes of rest angina that are responsive to short-acting nitrates and are attributable to coronary artery vasospasm. The condition is underdiagnosed as the provocation test is rarely performed. VSA, the most important component of non-obstructive coronary artery disease, can present with angina, be asymptomatic, or can even present with fatal arrhythmias and cardiac arrest. Although most patients with VSA respond well to vasodilating medications, prognosis does not improve as expected in most patients, suggesting the existence elusive prognostic factors and pathogenesis that warrant further exploration. Moreover, patients with either severe or refractory VSA barely respond to conventional treatment and may develop life-threatening arrhythmias or suffer sudden cardiac death during ischemic attacks, which are associated with immune-inflammatory responses and have been shown to achieve remission following glucocorticoid and immunoglobulin treatments. Our recent work revealed that inflammation plays a key role in the initiation and development of coronary spasms, and that inflammatory cytokines have predictive value for diagnosis. In contrast to the existing literature, this review both summarizes the theoretical and clinical aspects of VSA, and also discusses the relationship between inflammation, especially myocarditis and VSA, in order to provide novel insights into the etiology, diagnosis, and treatment of VSA.

Chronic graft-versus-host disease in pediatric patients: Differences and challenges

Despite the use of high-resolution molecular techniques for tissue typing, chronic graft-versus-host disease (cGVHD) remains a major complication following allogeneic hematopoietic stem cell transplant. cGVHD adversely affects the life-expectancy and quality of life. The latter is particularly important and functionally relevant in pediatric patients who have a longer life-expectancy than adults. Current laboratory evidence suggests that there is not any difference in the pathophysiology of cGVHD between adults and pediatric patients. However, there are some clinical features and complications of the disease that are different in pediatric patients. There are also challenges in the development of new therapeutics for this group of patients. In this review, we will discuss the epidemiology, pathophysiology, clinical features and consequences of the disease, and highlight the differences between pediatric and adult patients. We will examine the current treatment options for pediatric patients with moderate to severe cGVHD and discuss the challenges facing therapeutic development for cGVHD in the pediatric population.

Tape stripped stratum corneum samples are suitable for diagnosis and comprehensive proteomic investigation in mycosis fungoides

BACKGROUND

Mycosis Fungoides (MF) is a common cutaneous T-cell lymphoma. It can sometimes be challenging to diagnose MF using current clinico-histopathological criteria. Non-invasive molecular profiling analysis has the potential to aid the diagnosis and understanding of MF.

METHOD

Lesional and body site matched normal stratum corneum samples were obtained from the same MF patients (n = 28) using adhesive discs, followed by proteomic analyses using data-independent acquisition mass spectrometry (DIA-MS). Differential abundance analyses and bioinformatic analyses were performed to identify differentially abundant proteins and altered biofunctions between the MF and normal stratum corneum samples.

RESULTS

In total, 1303 proteins were identified, of which 290 proteins were significantly changed in the MF cohort compared to the normal stratum corneum. Ingenuity pathway analysis (IPA) predicted the significant inhibition of cell death of cancer cells and significant activation of immune-related activities and viral infection in the MF lesions. MF lesions were also associated with upstream regulators relating to immuno-oncologic dysfunctions. The top-250 variating proteins efficiently separated normal stratum corneum from matched MF samples.

CONCLUSION

Non-invasive proteomic analysis could transform the diagnosis of MF by reducing the need for invasive biopsy. The identification of altered biological functions may serve as useful biomarkers to predict MF progression.

Role of Rho GTPases in inflammatory bowel disease

Rat sarcoma virus homolog (Rho) guanosine triphosphatases (GTPases) function as "molecular switch" in cellular signaling regulation processes and are associated with the pathogenesis of inflammatory bowel disease (IBD). This chronic intestinal tract inflammation primarily encompasses two diseases: Crohn's disease and ulcerative colitis. The pathogenesis of IBD is complex and considered to include four main factors and their interactions: genetics, intestinal microbiota, immune system, and environment. Recently, several novel pathogenic components have been identified. In addition, potential therapies for IBD targeting Rho GTPases have emerged and proven to be clinically effective. This review mainly focuses on Rho GTPases and their possible mechanisms in IBD pathogenesis. The therapeutic possibility of Rho GTPases is also discussed.

The phosphatidylinositol-transfer protein Nir3 promotes PI(4,5)P2 replenishment in response to TCR signaling during T cell development and survival

Hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP₂) by phospholipase C-γ (PLCγ1) represents a critical step in T cell antigen receptor (TCR) signaling and subsequent thymocyte and T cell responses. PIP₂ replenishment following its depletion in the plasma membrane (PM) is dependent on delivery of its precursor phosphatidylinositol (PI) from the endoplasmic reticulum (ER) to the PM. We show that a PI transfer protein (PITP), Nir3 (Pitpnm2), promotes PIP₂ replenishment following TCR stimulation and is important for T cell development. In Nir3^-/- T lineage cells, the PIP₂ replenishment following TCR stimulation is slower. Nir3 deficiency attenuates calcium mobilization in double-positive (DP) thymocytes in response to weak TCR stimulation. This impaired TCR signaling leads to attenuated thymocyte development at TCRβ selection and positive selection as well as diminished mature T cell fitness in Nir3^-/- mice. This study highlights the importance of PIP₂ replenishment mediated by PITPs at ER-PM junctions during TCR signaling.

Pattern recognition receptor mediated innate immune response requires a Rif-dependent pathway

Small GTPases play critical roles in cell morphology, movement, and adhesion by dynamic regulation of actin cytoskeleton. The small Rho GTPase Rif/RhoF (Rho in filopodia) regulates the formation of filopodia and stress fibers in cells. Rif is highly expressed in a number of cell types in the immune system; however, it's role in immune system function is unclear. In this research, we found that Rif expression is necessary for NF-κB activation in primary immune cells, and mature dendritic cell (mature DCs) induced from Bone Marrow-Derived Dendritic Cells (BMDCs) isolated from Rif knock out (Rif KO) mice displayed impaired degradation of I-κBα, as well as reduced TNF-α secretion and p38 MAPK phosphorylation under LPS stimulation. Interestingly, we revealed that TLR agonists, such as LPS and poly (I:C), as well as bacterial virulence factor SopE could induce a transient increase in Rif activation in monocytes THP-1 cells. Furthermore, Rif was found to be an integral part of the TLR4, TLR3 and nodosome signaling complex. We further identified Src tyrosine kinases as upstream activator of Rif in both bacterial and viral induced immune responses. Moreover, activated Rif induces activation of transcription factors, such as NF-κB, AP-1 and IRF-3, and mediates inflammation through secretion of IL-6, IL-8 or TNFα. Rif activation by PRRs contributes in a variety of ways to protective host responses against invading microbes. Taken together, this study reveals that Rif is indispensable for both extracellular and intracellular pattern-recognition receptor-mediated innate immune responses. Rif possess broad anti-pathogenic effect and understanding of the molecular mechanisms by which this small Rho GTPase interferes with innate immune system will be beneficial to develop therapies against infectious agents.

A meta-analysis indicates that the regulation of cell motility is a non-intrinsic function of chemoattractant receptors that is governed independently of directional sensing

Chemoattraction, defined as the migration of a cell toward a source of a chemical gradient, is controlled by chemoattractant receptors. Chemoattraction involves two basic activities, namely, directional sensing, a molecular mechanism that detects the direction of a source of chemoattractant, and actin-based motility, which allows the migration of a cell towards it. Current models assume first, that chemoattractant receptors govern both directional sensing and motility (most commonly inducing an increase in the migratory speed of the cells, i.e. chemokinesis), and, second, that the signaling pathways controlling both activities are intertwined. We performed a meta-analysis to reassess these two points. From this study emerge two main findings. First, although many chemoattractant receptors govern directional sensing, there are also receptors that do not regulate cell motility, suggesting that is the ability to control directional sensing, not motility, that best defines a chemoattractant receptor. Second, multiple experimental data suggest that receptor-controlled directional sensing and motility can be controlled independently. We hypothesize that this independence may be based on the existence of separated signalling modules that selectively govern directional sensing and motility in chemotactic cells. Together, the information gathered can be useful to update current models representing the signalling from chemoattractant receptors. The new models may facilitate the development of strategies for a more effective pharmacological modulation of chemoattractant receptor-controlled chemoattraction in health and disease.

Transcriptome-Wide lncRNA and mRNA Profiling of Spleens from Meishan Pigs at Different Development Stages

Simple Summary

Meishan pig is a local pig breed in China, which has higher immunity than commercial pig breeds for some diseases. The spleen has hematopoietic and immune response functions, making it a good organ model for studying immunity. We depicted the expression profiles of lncRNA-mRNA in the spleen of Meishan pigs at different developmental time points (7 d, 21 d, 35 d, 120 d and 180 d). In addition, we found that AKT3, CBL and PTK2B may be involved in immune regulation in Meishan pigs through a competing endogenous RNA network. This result provides valuable genomic resources for studying immune regulation in animals and finds potential molecular markers for pig disease resistance breeding.

Abstract

Meishan is a well-established local Chinese breed known for its high fecundity, strong immune response and high meat quality. However, the molecular mechanism of immune regulation during the development of Meishan pigs still remains unclear. Here, we performed the transcriptional sequencing of spleen tissues from Meishan pigs at different development stages. In total, 10,268 lncRNAs were identified, including 1254 novel lncRNAs and 9014 known lncRNAs. Time series analysis revealed that genes of the up-regulated module were enriched in pathways associated with transport, immunity, and histone acetylation modifications, while genes of the down-regulated module were enriched in DNA metabolic process and cell cycle. Weighted gene co-expression network analysis (WGCNA) showed the functional linkage between mRNAs and lncRNAs, indicating that lncRNAs are important regulatory elements of mRNAs. Notably, a lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) network that contained 3 mRNAs (AKT3, CBL and PTK2B), 17 lncRNAs and 67 miRNAs were screened out, which probably plays a critical role in immune regulation of Meishan pigs. Our findings not only revealed the transcriptome profile of spleen development, but also provide novel insights into the mechanism of lncRNA-miRNA-mRNA axis in the immune response in Meishan pigs.

Sex-based comparison of CD4+ T cell DNA methylation in lupus reveals proinflammatory epigenetic changes in men

Systemic lupus erythematosus (SLE) is more common in women than men, but the disease is more severe when it affects men. Lupus CD4+ T cells demonstrate dysregulated DNA methylation patterns. The purpose of this study was to investigate genome-wide CD4+ T cell differential DNA methylation between men (n = 12) and women (n = 10) with SLE. DNA methylation was evaluated using the Infinium MethylationEPIC array, and differences between male versus female SLE patients were calculated with probe-wise linear regressions with adjustment for age and disease activity. We identified 198 hypomethylated and 108 hypermethylated CpG sites in CD4+ T cells isolated from male compared to female SLE patients, annotated to 201 and 102 genes, respectively. A great proportion of these genes were related to apoptosis and immune functions. Among differentially methylated genes, CASP10, which is involved in the extrinsic apoptotic pathway, and multiple genes involved in T cell function and differentiation such as ELAVL1, UHRF1, and SMAD2, were hypomethylated in men compared to women with SLE. Importantly, network analysis of differentially methylated genes revealed a pattern consistent with increased activation of ROCK, PP2A, PI3K, and ERK1/ERK2 in men compared to women with SLE. These data provide epigenetic evidence suggesting activation of key T cell pathways in men compared to women with SLE and shed new light into possible mechanisms underlying increased SLE disease severity in men.

A MZB Cell Activation Profile Present in the Lacrimal Glands of Sjögren's Syndrome-Susceptible C57BL/6.NOD-Aec1Aec2 Mice Defined by Global RNA Transcriptomic Analyses

The C57BL/6.NOD-Aec1Aec2 mouse has been extensively studied to define the underlying cellular and molecular basis for the onset and development of Sjögren's syndrome (SS), a human systemic autoimmune disease characterized clinically as the loss of normal lacrimal and salivary gland functions leading respectively to dry eye and dry mouth pathologies. While an overwhelming majority of SS studies in both humans and rodent models have long focused primarily on pathophysiological events and the potential role of T lymphocytes in these events, recent studies in our murine models have indicated that marginal zone B (MZB) lymphocytes are critical for both development and onset of SS disease. Although migration and function of MZB cells are difficult to study in vivo and in vitro, we have carried out ex vivo investigations that use temporal global RNA transcriptomic analyses to track early cellular and molecular events in these exocrine glands of C57BL/6.NOD-Aec1Aec2 mice. In the present report, genome-wide transcriptome analyses of lacrimal glands indicate that genes and gene-sets temporally upregulated during early onset of disease define the Notch2/NF-kβ14 and Type1 interferon signal transduction pathways, as well as identify chemokines, especially Cxcl13, and Rho-GTPases, including DOCK molecules, in the cellular migration of immune cells to the lacrimal glands. We discuss how the current results compare with our recently published salivary gland data obtained from similar studies carried out in our C57BL/6.NOD-Aec1Aec2 mice, pointing out both similarities and differences in the etiopathogeneses underlying the autoimmune response within the two glands. Overall, this study uses the power of transcriptomic analyses to identify temporal molecular bioprocesses activated during the preclinical covert pathogenic stage(s) of SS disease and how these findings may impact future intervention therapies as the disease within the two exocrine glands may not be identical.

Hem-1 regulates protective humoral immunity and limits autoantibody production in a B cell-specific manner

Hematopoietic protein-1 (Hem-1) is a member of the actin-regulatory WASp family verprolin homolog (WAVE) complex. Loss-of-function variants in the NCKAP1L gene encoding Hem-1 were recently discovered to result in primary immunodeficiency disease (PID) in children, characterized by poor specific Ab responses, increased autoantibodies, and high mortality. However, the mechanisms of how Hem-1 deficiency results in PID are unclear. In this study, we utilized constitutive and B cell-specific Nckap1l-KO mice to dissect the importance of Hem-1 in B cell development and functions. B cell-specific disruption of Hem-1 resulted in reduced numbers of recirculating follicular (FO), marginal zone (MZ), and B1 B cells. B cell migration in response to CXCL12 and -13 were reduced. T-independent Ab responses were nearly abolished, resulting in failed protective immunity to Streptococcus pneumoniae challenge. In contrast, T-dependent IgM and IgG2c, memory B cell, and plasma cell responses were more robust relative to WT control mice. B cell-specific Hem-1-deficient mice had increased autoantibodies against multiple autoantigens, and this correlated with hyperresponsive BCR signaling and increased representation of CD11c+T-bet+ age-associated B cell (ABC cells) - alterations associated with autoimmune diseases. These results suggest that dysfunctional B cells may be part of a mechanism explaining why loss-of-function Hem-1 variants result in recurring infections and autoimmunity.

The Small GTPase RHOA Links SLP65 Activation to PTEN Function in Pre B Cells and Is Essential for the Generation and Survival of Normal and Malignant B Cells

The generation, differentiation, survival and activation of B cells are coordinated by signals emerging from the B cell antigen receptor (BCR) or its precursor, the pre-BCR. The adaptor protein SLP65 (also known as BLNK) is an important signaling factor that controls pre-B cell differentiation by down-regulation of PI3K signaling. Here, we investigated the mechanism by which SLP65 interferes with PI3K signaling. We found that SLP65 induces the activity of the small GTPase RHOA, which activates PTEN, a negative regulator of PI3K signaling, by enabling its translocation to the plasma membrane. The essential role of RHOA is confirmed by the complete block in early B cell development in conditional RhoA-deficient mice. The RhoA-deficient progenitor B cells showed defects in activation of immunoglobulin gene rearrangement and fail to survive both in vitro and in vivo. Reconstituting the RhoA-deficient cells with RhoA or Foxo1, a transcription factor repressed by PI3K signaling and activated by PTEN, completely restores the survival defect. However, the defect in differentiation can only be restored by RhoA suggesting a unique role for RHOA in B cell generation and selection. In full agreement, conditional RhoA-deficient mice develop increased amounts of autoreactive antibodies with age. RHOA function is also required at later stage, as inactivation of RhoA in peripheral B cells or in a transformed mature B cell line resulted in cell loss. Together, these data show that RHOA is the key signaling factor for B cell development and function by providing a crucial SLP65-activated link between BCR signaling and activation of PTEN. Moreover, the identified essential role of RHOA for the survival of transformed B cells offers the opportunity for targeting B cell malignancies by blocking RHOA function.

Thyroid Hormone Disruption by Organophosphate Esters Is Mediated by Nuclear/Membrane Thyroid Hormone Receptors: In Vitro, In Vivo, and In Silico Studies

Earlier mechanistic studies of many prohibited flame retardants (FRs) highlighted their thyroid hormone-disrupting activity through nuclear thyroid hormone receptors (nTRs), whereas some alternative FRs such as organophosphate esters (OPEs) exerted weak nTR-disrupting effects. However, an increasing number of studies have revealed that OPEs also exert thyroid hormone-disrupting effects, and the underlying mechanism is unclear. Herein, the thyroid hormone-disrupting effects and mechanisms of 8 typical OPEs were investigated using integrated in vitro, in vivo, and in silico assays. All tested chemicals competitively bound to the membrane thyroid hormone receptor (mTR) [the 20% relative inhibitory concentration (RIC20): (3.5 ± 0.2) × 10¹ to (4.9 ± 1.0) × 10⁷ nM], and Cl-OPEs and alkyl-OPEs had lower RIC20 values. In contrast, only 4 OPEs showed nTR antagonistic activities at higher concentrations [≥ (4.8 ± 0.8) × 10³ nM]. Cl-OPEs and alkyl-OPEs preferentially interacted with mTR. Molecular docking illustrated that OPEs docked into mTRs, consistent with the competitive binding assay. In vivo analyses of zebrafish embryonic development confirmed that tris(1,3-dichloro-2-propyl) phosphate induced inappropriate expression of proteins, and these protein interactions might be associated with mTR according to the quantitative proteomic analysis. Based on the results, mTR might play a critical role in mediating the thyroid hormone-disrupting effects of OPEs.

RSV-induced changes in a 3-dimensional organoid model of human fetal lungs

We have shown that respiratory syncytial virus (RSV) can spread hematogenously from infected airways of a pregnant woman to the developing fetal lungs in utero. This study sought to measure RSV replication, cytopathic effects, and protein expression in human lung organoids (HLOs) reproducing architecture and transcriptional profiles of human fetal lungs during the 1st trimester of gestation. HLOs derived from human pluripotent stem cells were microinjected after 50 or 100 days in culture with medium or recombinant RSV-A2 expressing the red fluorescent protein gene (rrRSV). Infection was monitored by fluorescent microscopy and PCR. Immunohistochemistry and proteomic analysis were performed. RSV infected HLOs in a dose- and time-dependent manner. RSV-infected HLOs increased expression of CC10 (Club cells), but had sparse FOXJ1 (ciliated cells). Disruption of F-actin cytoskeleton was consistent with proteomic data showing a significant increase in Rho GTPases proteins. RSV upregulated the transient receptor potential vanilloid 1 (TRPV1) channel and, while β2 adrenergic receptor (β2AR) expression was decreased overall, its phosphorylated form increased. Our data suggest that prenatal RSV infection produces profound changes in fetal lungs' architecture and expression profiles and maybe an essential precursor of chronic airway dysfunction. expression profiles, and possibly be an important precursor of chronic airway dysfunction.

Phase 1 Studies to Evaluate the Food Effect and Relative Bioavailability of Tablet and Capsule Formulations of Belumosudil in Healthy Adult Subjects

Belumosudil is a selective Rho-associated coiled-coil containing protein kinase 2 inhibitor. A capsule formulation was used during early clinical development of belumosudil; it was later replaced by a tablet formulation, which mimicked the capsule's release properties and facilitated manufacturing scalability. To assess belumosudil's pharmacokinetics, including potential food effects, and evaluate the relative bioavailability of the 2 formulations, 2 phase 1 clinical trials were conducted. Administration of both belumosudil tablets and capsules with food increased exposure ≈2× as compared to the fasted state and delayed time to maximum concentration by 0.5 hour, indicating a decrease in the rate but increase in the extent of absorption with fed administration. Relative bioavailability was slightly higher when belumosudil was administered as tablets vs capsules, although the difference was not clinically meaningful. Safety and tolerability were generally consistent with the known safety profile of belumosudil. The results of these studies support administration of belumosudil with food.

A Phase 1 Pharmacokinetic Drug Interaction Study of Belumosudil Coadministered With CYP3A4 Inhibitors and Inducers and Proton Pump Inhibitors

Belumosudil is a selective Rho-associated protein kinase 2 inhibitor. Inhibition of Rho-associated protein kinase 2 has emerged as a promising treatment for chronic graft-versus-host disease by restoring immune homeostasis and reducing fibrosis. In vitro assessments have suggested that metabolism of belumosudil is primarily dependent on cytochrome P450 (CYP) 3A4 activity and that the solubility of belumosudil is pH dependent. As such, this 2-part clinical drug-drug interaction study was conducted to assess the effect of itraconazole (a strong CYP3A4 inhibitor), rifampicin (a strong CYP3A4 inducer), rabeprazole, and omeprazole (both proton pump inhibitors) on the pharmacokinetics of belumosudil. No clinically relevant change in belumosudil exposure was observed following a 200-mg single oral dose of belumosudil with itraconazole; however, exposure of main metabolite, KD025m2, was decreased. Consistent with the proposed metabolic pathway of belumosudil, the strong CYP3A4 inducer rifampicin significantly decreased exposure of belumosudil and KD025m2 and increased KD025m1 exposure. When a 200-mg single oral dose of belumosudil was coadministered with both rabeprazole and omeprazole, parent and metabolite exposures were largely reduced, suggesting that belumosudil dosage should be increased when given with PPIs. Administration of belumosudil with and without perpetrator drugs was safe, and no notable adverse events were reported.

Absolute Bioavailability, Mass Balance, and Metabolic Profiling Assessment of [14 C]-Belumosudil in Healthy Men: A Phase 1, Open-Label, 2-Part Study

Belumosudil is a selective Rho-associated coiled-coil containing protein kinase 2 (ROCK2) inhibitor. ROCK2 has been shown to drive proinflammatory response and fibrosis that occurs with chronic graft-versus-host disease; therefore, inhibition of ROCK2 has emerged as a therapeutic target for chronic graft-versus-host disease. In this phase 1 two-part study, the pharmacokinetics, mass balance, and metabolic profile of belumosudil were evaluated after single doses of unlabeled belumosudil oral tablets (200 mg), radiolabeled belumosudil intravenous (IV) microtracer infusions (100 μg), and radiolabeled oral capsules (200 mg). Absolute bioavailability based on area under the plasma concentration-time curve from time 0 to infinity for the oral dose/area under the plasma concentration-time curve from time 0 to infinity for the IV dose was calculated as 63.7%. Radiolabeled IV microtracer dosing demonstrated a low extraction ratio and distribution of belumosudil into tissues. The majority of total radioactivity was recovered in feces, with minimal amounts recovered in urine, suggesting minimal renal elimination of belumosudil. In addition to parent and main metabolite KD025m2, metabolites identified in plasma included the phase 2 metabolites O-dealkylated belumosudil sulfate and belumosudil glucuronide. These metabolites (with the exception of the glucuronide) in addition to monohydroxy-belumosudil, and belumosudil diol were identified in feces. No metabolites in urine accounted for >10% of the radioactive dose.

The Molecular Interaction of Collagen with Cell Receptors for Biological Function

Collagen, an extracellular protein, covers the entire human body and has several important biological functions in normal physiology. Recently, collagen from non-human sources has attracted attention for therapeutic management and biomedical applications. In this regard, both land-based animals such as cow, pig, chicken, camel, and sheep, and marine-based resources such as fish, octopus, starfish, sea-cucumber, and jellyfish are widely used for collagen extraction. The extracted collagen is transformed into collagen peptides, hydrolysates, films, hydrogels, scaffolds, sponges and 3D matrix for food and biomedical applications. In addition, many strategic ideas are continuously emerging to develop innovative advanced collagen biomaterials. For this purpose, it is important to understand the fundamental perception of how collagen communicates with receptors of biological cells to trigger cell signaling pathways. Therefore, this review discloses the molecular interaction of collagen with cell receptor molecules to carry out cellular signaling in biological pathways. By understanding the actual mechanism, this review opens up several new concepts to carry out next level research in collagen biomaterials.

Potential Role of CXCL13/CXCR5 Signaling in Immune Checkpoint Inhibitor Treatment in Cancer

Simple Summary

Immunotherapy is currently the backbone of new drug treatments for many cancer patients. CXC chemokine ligand 13 (CXCL13) is an important factor involved in recruiting immune cells that express CXC chemokine receptor type 5 (CXCR5) in the tumor microenvironment and serves as a key molecular determinant of tertiary lymphoid structure (TLS) formation. An increasing number of studies have identified the influence of CXCL13 on prognosis in patients with cancer, regardless of the use of immunotherapy treatment. However, no comprehensive reviews of the role of CXCL13 in cancer immunotherapy have been published to date. This review aims to provide an overview of the CXCL13/CXCR5 signaling axis to summarize its mechanisms of action in cancer cells and lymphocytes, in addition to effects on immunity and cancer pathobiology, and its potential as a biomarker for the response to cancer immunotherapy.

Abstract

Immune checkpoint inhibitors (ICIs), including antibodies that target programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), or cytotoxic T lymphocyte antigen 4 (CTLA4), represent some of the most important breakthroughs in new drug development for oncology therapy from the past decade. CXC chemokine ligand 13 (CXCL13) exclusively binds CXC chemokine receptor type 5 (CXCR5), which plays a critical role in immune cell recruitment and activation and the regulation of the adaptive immune response. CXCL13 is a key molecular determinant of the formation of tertiary lymphoid structures (TLSs), which are organized aggregates of T, B, and dendritic cells that participate in the adaptive antitumor immune response. CXCL13 may also serve as a prognostic and predictive factor, and the role played by CXCL13 in some ICI-responsive tumor types has gained intense interest. This review discusses how CXCL13/CXCR5 signaling modulates cancer and immune cells to promote lymphocyte infiltration, activation by tumor antigens, and differentiation to increase the antitumor immune response. We also summarize recent preclinical and clinical evidence regarding the ICI-therapeutic implications of targeting the CXCL13/CXCR5 axis and discuss the potential role of this signaling pathway in cancer immunotherapy.

Kinase Inhibition as Treatment for Acute and Chronic Graft-Versus-Host Disease

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potentially curative therapy for patients suffering from hematological malignancies via the donor immune system driven graft-versus-leukemia effect. However, the therapy is mainly limited by severe acute and chronic graft-versus-host disease (GvHD), both being life-threatening complications after allo-HCT. GvHD develops when donor T cells do not only recognize remaining tumor cells as foreign, but also the recipient’s tissue, leading to a severe inflammatory disease. Typical GvHD target organs include the skin, liver and intestinal tract. Currently all approved strategies for GvHD treatment are immunosuppressive therapies, with the first-line therapy being glucocorticoids. However, therapeutic options for glucocorticoid-refractory patients are still limited. Novel therapeutic approaches, which reduce GvHD severity while preserving GvL activity, are urgently needed. Targeting kinase activity with small molecule inhibitors has shown promising results in preclinical animal models and clinical trials. Well-studied kinase targets in GvHD include Rho-associated coiled-coil-containing kinase 2 (ROCK2), spleen tyrosine kinase (SYK), Bruton’s tyrosine kinase (BTK) and interleukin-2-inducible T-cell kinase (ITK) to control B- and T-cell activation in acute and chronic GvHD. Janus Kinase 1 (JAK1) and 2 (JAK2) are among the most intensively studied kinases in GvHD due to their importance in cytokine production and inflammatory cell activation and migration. Here, we discuss the role of kinase inhibition as novel treatment strategies for acute and chronic GvHD after allo-HCT.

IL-1β in atherosclerotic vascular calcification: From bench to bedside

Atherosclerotic vascular calcification contributes to increased risk of death in patients with cardiovascular diseases. Assessing the type and severity of inflammation is crucial in the treatment of numerous cardiovascular conditions. IL-1β, a potent proinflammatory cytokine, plays diverse roles in the pathogenesis of atherosclerotic vascular calcification. Several large-scale, population cohort trials have shown that the incidence of cardiovascular events is clinically reduced by the administration of anti-IL-1β therapy. Anti-IL-1β therapy might reduce the incidence of cardiovascular events by affecting atherosclerotic vascular calcification, but the mechanism underlying this effect remains unclear. In this review, we summarize current knowledge on the role of IL-1β in atherosclerotic vascular calcification, and describe the latest results reported in clinical trials evaluating anti-IL-1β therapies for the treatment of cardiovascular diseases. This review will aid in improving current understanding of the pathophysiological roles of IL-1β and mechanisms underlying its activity.

MicroRNA regulation of B cell receptor signaling

B lymphocytes play a central role in host immune defense. B cell receptor (BCR) signaling regulates survival, proliferation, and differentiation of B lymphocytes. Signaling through the BCR signalosome is a multi-component cascade that is tightly regulated and is important in the coordination of B cell differentiation and function. At different stages of development, B cells that have BCRs recognizing self are eliminated to prevent autoimmunity. microRNAs (miRNAs) are small single-stranded non-coding RNAs that contribute to post-transcriptional regulation of gene expression and have been shown to orchestrate cell fate decisions through the regulation of lineage-specific transcriptional profiles. Studies have identified miRNAs to be crucial for B cell development in the bone marrow and their subsequent population of the peripheral immune system. In this review, we focus on the role of miRNAs in the regulation of BCR signaling as it pertains to B lymphocyte development and function. In particular, we discuss the most recent studies describing the role of miRNAs in the regulation of both early B cell development and peripheral B cell responses and examine the ways by which miRNAs regulate signal downstream of B cell antigen receptor to prevent aberrant activation and autoimmunity.

Exploring the therapeutic promise of targeting Rho kinase in rheumatoid arthritis

Rheumatoid arthritis (RA) is a prevalent systemic autoimmune disease caused by dysregulated inflammatory reactions, T lymphocyte invasion into the joints, and articular thickening. Immune cells, primarily tumor necrosis factor-alpha (TNF-α) and chemokines (interleukin or IL-1), which are predominantly generated by activated macrophages cells, have also been involved with the pathogenesis of rheumatoid arthritis. Rho GTPases are integral factors of biochemical cascades utilized by antigens, and also by cellular receptors, cytokines, and chemokines, to modulate inflammatory reactions, according to growing data. The Rho family is a group of G proteins that govern a variety of biological and physiological activities such as mobility, actin stress fiber production, growth, and polarity. Research suggests that the Rho A and Rho-associated coiled-coil kinase (ROCK) regulatory cascade could be essential in several autoimmune conditions, including RA. ROCK is activated in the synovial of rheumatoid arthritis patients, while the blocking of ROCK with fasudil could also decrease IL-6, TNF-α, and IL-1. This review covers current developments in understanding the overactivation of Rho enzyme activity in RA suppressed by ROCK inhibitors which can be utilized for the treatment of autoimmune disease. We offer an outline of the function of ROCK inhibitors in immune cells and discuss findings which emphasize the rising participation of this category of kinases within the pathological process of autoimmune disorders. Assuming the potential ability of ROCK as a therapeutic, we define approaches that might be used to inhibit Rho kinase activity in rheumatoid disorders.

MiRNA expression profiling in HIV pathogenesis, disease progression and response to treatment: a systematic review

Aim: A systematic review was conducted to identify the association of miRNA expression with HIV pathogenesis, progression and treatment. Methods: A search of articles was conducted in MEDLINE^®, Cochrane Central Register of Controlled Trials and Global Health. Results: 35 articles were included. Due to the heterogeneity of HIV phenotypes, a harmonization based on key progression parameters was proposed. The hsa-miR-29 family, hsa-miR-146b-5p and hsa-miR-150-5p, are the most frequently differentially expressed in HIV. Direct comparison of studies was not possible due to heterogeneity in biological samples and miRNA analysis techniques. Conclusion: This is the first attempt to systematically identify miRNA's different expression in well-defined patient phenotypes and could represent a helpful way to increase general knowledge in this field.

Circular RNA CircHIPK3 Promotes Homeostasis of the Intestinal Epithelium by Reducing MicroRNA 29b Function

BACKGROUND & AIMS

Circular RNAs (circRNAs) are a class of endogenous noncoding RNAs that form covalently closed circles. Although circRNAs influence many biological processes, little is known about their role in intestinal epithelium homeostasis. We surveyed circRNAs required to maintain intestinal epithelial integrity and identified circular homeodomain-interacting protein kinase 3 (circHIPK3) as a major regulator of intestinal epithelial repair after acute injury.

METHODS

Intestinal mucosal tissues were collected from mice exposed to cecal ligation and puncture for 48 hours and patients with inflammatory bowel diseases and sepsis. We isolated primary enterocytes from the small intestine of mice and derived intestinal organoids. The levels of circHIPK3 were silenced in intestinal epithelial cells (IECs) by transfection with small interfering RNAs targeting the circularization junction of circHIPK3 or elevated using a plasmid vector that overexpressed circHIPK3. Intestinal epithelial repair was examined in an in vitro injury model by removing part of the monolayer. The association of circHIPK3 with microRNA 29b (miR-29b) was determined by biotinylated RNA pull-down assays.

RESULTS

Genome-wide profile analyses identified ∼300 circRNAs, including circHIPK3, differentially expressed in the intestinal mucosa of mice after cecal ligation and puncture relative to sham mice. Intestinal mucosa from patients with inflammatory bowel diseases and sepsis had reduced levels of circHIPK3. Increasing the levels of circHIPK3 enhanced intestinal epithelium repair after wounding, whereas circHIPK3 silencing repressed epithelial recovery. CircHIPK3 silencing also inhibited growth of IECs and intestinal organoids, and circHIPK3 overexpression promoted intestinal epithelium renewal in mice. Mechanistic studies revealed that circHIPK3 directly bound to miR-29b and inhibited miR-29 activity, thus increasing expression of Rac1, Cdc42, and cyclin B1 in IECs after wounding.

CONCLUSIONS

In studies of mice, IECs, and human tissues, our results indicate that circHIPK3 improves repair of the intestinal epithelium at least in part by reducing miR-29b availability.

HGAL inhibits lymphoma dissemination by interacting with multiple Cytoskeletal proteins

In vivo experiments demonstrate that HGAL expression in lymphoma decreases tumor dissemination and prolongs animal survival.

HGAL inhibits cell motility by interacting with multiple cytoskeletal proteins, thereby affecting cell motility by multiple mechanisms.

Human germinal center–associated lymphoma (HGAL) is an adaptor protein specifically expressed in germinal center lymphocytes. High expression of HGAL is a predictor of prolonged survival of diffuse large B-cell lymphoma (DLBCL) and classic Hodgkin lymphoma. Furthermore, HGAL expression is associated with early-stage DLBCL, thus potentially limiting lymphoma dissemination. In our previous studies, we demonstrated that HGAL regulates B-cell receptor signaling and cell motility in vitro and deciphered some molecular mechanisms underlying these effects. By using novel animal models for in vivo DLBCL dispersion, we demonstrate here that HGAL decreases lymphoma dissemination and prolongs survival. Furthermore, by using an unbiased proteomic approach, we demonstrate that HGAL may interact with multiple cytoskeletal proteins thereby implicating a multiplicity of effects in regulating lymphoma motility and spread. Specifically, we show that HGAL interacts with tubulin, and this interaction may also contribute to HGAL effects on cell motility. These findings recapitulate previous observations in humans, establish the role of HGAL in dissemination of lymphoma in vivo, and explain improved survival of patients with HGAL-expressing lymphomas.

ROCK2, a critical regulator of immune modulation and fibrosis has emerged as a therapeutic target in chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is an immune-mediated disorder characterized by chronic inflammation and fibrosis. Rho-associated coiled-coil-containing protein kinases (ROCKs) are key coordinators of tissue response to injury, regulating multiple functions, such as gene expression and cell migration, proliferation and survival. Relevant to cGVHD and autoimmunity, only the ROCK2 isoform drives a pro-inflammatory type 17 helper T (Th17) cell response. Moreover, ROCK2 inhibition shifts the Th17/regulatory T (Treg) cell balance toward Treg cells and restores immune homeostasis in animal models of autoimmunity and cGVHD. Furthermore, the selective inhibition of ROCK2 by belumosudil reduces fibrosis by downregulating both transforming growth factor-β signaling and profibrotic gene expression, thereby impeding the creation of focal adhesions. Consistent with its anti-inflammatory and antifibrotic activities, belumosudil has demonstrated efficacy in clinical studies, resulting in an overall response rate of >70% in patients with cGVHD who failed 2 to 5 prior lines of systemic therapy. In summary, selective ROCK2 inhibition has emerged as a promising novel therapeutic approach for treating cGVHD and other immunologic diseases with unique mechanisms of action, targeting both immune imbalance and detrimental fibrotic responses.

HIV-1 Hijacking of Host ATPases and GTPases That Control Protein Trafficking

The human immunodeficiency virus (HIV-1) modifies the host cell environment to ensure efficient and sustained viral replication. Key to these processes is the capacity of the virus to hijack ATPases, GTPases and the associated proteins that control intracellular protein trafficking. The functions of these energy-harnessing enzymes can be seized by HIV-1 to allow the intracellular transport of viral components within the host cell or to change the subcellular distribution of antiviral factors, leading to immune evasion. Here, we summarize how energy-related proteins deviate from their normal functions in host protein trafficking to aid the virus in different phases of its replicative cycle. Recent discoveries regarding the interplay among HIV-1 and host ATPases and GTPases may shed light on potential targets for pharmacological intervention.

Upregulated Chemokine and Rho-GTPase Genes Define Immune Cell Emigration into Salivary Glands of Sjögren's Syndrome-Susceptible C57BL/6.NOD-Aec1Aec2 Mice

The C57BL/6.NOD-Aec1Aec2 mouse is considered a highly appropriate model of Sjögren's Syndrome (SS), a human systemic autoimmune disease characterized primarily as the loss of lacrimal and salivary gland functions. This mouse model, as well as other mouse models of SS, have shown that B lymphocytes are essential for the development and onset of observed clinical manifestations. More recently, studies carried out in the C57BL/6.IL14α transgenic mouse have indicated that the marginal zone B (MZB) cell population is responsible for development of SS disease, reflecting recent observations that MZB cells are present in the salivary glands of SS patients and most likely initiate the subsequent loss of exocrine functions. Although MZB cells are difficult to study in vivo and in vitro, we have carried out an ex vivo investigation that uses temporal global RNA transcriptomic analyses to profile differentially expressed genes known to be associated with cell migration. Results indicate a temporal upregulation of specific chemokine, chemokine receptor, and Rho-GTPase genes in the salivary glands of C57BL/6.NOD-Aec1Aec2 mice that correlate with the early appearance of periductal lymphocyte infiltrations. Using the power of transcriptomic analyses to better define the genetic profile of lymphocytic emigration into the salivary glands of SS mice, new insights into the underlying mechanisms of SS disease development and onset begin to come into focus, thereby establishing a foundation for further in-depth and novel investigations of the covert and early overt phases of SS disease at the cellular level.

Microtubule destabilization is a critical checkpoint of chemotaxis and transendothelial migration in melanoma cells but not in T cells

Microtubules (MTs) control cell shape and intracellular cargo transport. The role of MT turnover in the migration of slow-moving cells through endothelial barriers remains unclear. To irreversibly interfere with MT disassembly, we have used the MT-stabilizing agent zampanolide (ZMP) in Β16F10 melanoma as amodel of slow-moving cells. ZMP-treated B16 cells failed to follow chemotactic gradients across rigid confinements and could not generate stable sub-endothelial pseudopodia under endothelial monolayers. In vivo, ZMP-treated Β16 cells failed to extravasate though lung capillaries. In contrast to melanoma cells, the chemotaxis and transendothelial migration of ZMP-treated Tcells were largely conserved. This is afirst demonstration that MT disassembly is akey checkpoint in the directional migration of cancer cells but not of lymphocytes.

RSV attenuates epithelial cell restitution by inhibiting actin cytoskeleton-dependent cell migration

The airway epithelium's ability to repair itself after injury, known as epithelial restitution, is an essential mechanism enabling the respiratory tract's normal functions. Respiratory Syncytial Virus (RSV) is the leading cause of lower respiratory tract infections worldwide. We sought to determine whether RSV delays the airway epithelium wound repair process both in vitro and in vivo. We found that RSV infection attenuated epithelial cell migration, a step in wound repair, promoted stress fiber formation, and mediated assembly of large focal adhesions (FA). Inhibition of Rho kinase (ROCK), a master regulator of actin function, reversed these effects. There was increased RhoA and phospho-myosin light chain (pMLC2) following RSV infection. In vivo, mice were intraperitoneally inoculated with naphthalene to induce lung injury, followed by RSV infection. RSV infection delayed re-epithelialization. There were increased concentrations of pMLC2 in day 7 naphthalene plus RSV animals which normalized by day 14. This study suggests a key mechanism by which RSV infection delays wound healing.

Transcriptomic Analysis of Inbred Chicken Lines Reveals Infectious Bursal Disease Severity Is Associated with Greater Bursal Inflammation In Vivo and More Rapid Induction of Pro-Inflammatory Responses in Primary Bursal Cells Stimulated Ex Vivo

In order to better understand differences in the outcome of infectious bursal disease virus (IBDV) infection, we inoculated a very virulent (vv) strain into White Leghorn chickens of inbred line W that was previously reported to experience over 24% flock mortality, and three inbred lines (15I, C.B4 and 0) that were previously reported to display no mortality. Within each experimental group, some individuals experienced more severe disease than others but line 15I birds experienced milder disease based on average clinical scores, percentage of birds with gross pathology, average bursal lesion scores and average peak bursal virus titre. RNA-Seq analysis revealed that more severe disease in line W was associated with significant up-regulation of pathways involved in inflammation, cytoskeletal regulation by Rho GTPases, nicotinic acetylcholine receptor signaling, and Wnt signaling in the bursa compared to line 15I. Primary bursal cell populations isolated from uninfected line W birds contained a significantly greater percentage of KUL01+ macrophages than cells isolated from line 15I birds (p < 0.01) and, when stimulated ex vivo with LPS, showed more rapid up-regulation of pro-inflammatory gene expression than those from line 15I birds. We hypothesize that a more rapid induction of pro-inflammatory cytokine responses in bursal cells following IBDV infection leads to more severe disease in line W birds than in line 15I.

WASP and Mst1 coregulate B-cell development and B-cell receptor signaling

Mst1 is a serine/threonine kinase involved in cell survival, proliferation, apoptosis, and tumorigenesis. In mice, Mst1 regulates actin dynamics required for T-cell adhesion and migration, which correlate with thymic egress and entry into lymphatic tissue. The role of Mst1 in B cells and how it may control actin-dependent processes has not been well characterized. Wiskott-Aldrich syndrome protein (WASP) deficiency only moderately affects development and B-cell receptor (BCR) signaling, suggesting WASP likely associates with other molecules. We investigated whether Mst1 associates with WASP to regulate B-cell development and activation. Experimenting on Mst1/WASP double knockout (DKO) mice, we found a severe defect in the bone marrow B-cell development, and BCR signaling in the DKO mice was severely reduced. Even though WASP or Mst1 could influence the early B-cell activation, we found that the early activation events such as B-cell spreading, BCR clustering, and BCR signaling were much more impaired in the B cells from DKO mice. Furthermore, reciprocal regulation between Mst1 and WASP was observed in WASP and Mst1 KO mice, whereby the localization and function of phosphorylated WASP were affected in Mst1 KO mice. Most importantly, Mst1 inhibits the expression of WASP by decreasing the expression of WASP-interacting protein. Interestingly, we also found that WASP deficiency in patients and mice interferes with phosphorylated Mst1 localization and therefore function in B cells. Overall, our study provides a partner for WASP to regulate B-cell development and BCR signaling, as well as the reciprocal regulating molecular mechanism of one another.

DOCK8-related Immunodeficiency Syndrome (DIDS): Report of Novel Mutations in Iranian Patients

DOCK8 immunodeficiency syndrome (DIDS) is a rare autosomal recessive (AR) disorder characterized by elevated serum IgE levels, eosinophilia, recurrent cutaneous infections, severe eczema, and sinopulmonary and gastrointestinal infections. This syndrome is a multisystem disease that is associated with both immune deficiency and neurological complications. In this study, we describe the clinical characteristics of two Iranian patients with DOCK8 deficiency and propose possible mechanisms for this condition. By using whole exome sequencing (WES), we identified two novel mutations, namely c.3233_3234del AG (p.Q1078fs) in exon 6 and a large deletion with 94 kb (c.405-3231 deletion, p.K135fs), in these two patients. These variations are confirmed with Sanger sequencing and CGH array. Subsequent co-segregation analysis is performed to identify inheritance patterns. Both patients were homozygote and their parents were heterozygote for the variations. For further investigation, prediction tools were applied to identify the pathogenicity of the variations and also for modeling the truncated proteins. The patients did not show neurological abnormalities associated with a deficiency of the N terminal region of DOCK8. The absence of neurological complications in the first patient is justifiable due to the maintenance of the proline-rich region in DOCK8, but for the second patient with expanded deletion which is almost like null DOCK8 protein, it is not presumable, pointing to the fact that the C terminal region of the protein might have functions in the proliferation and migration neurons in the peripheral nervous system. Alternatively, it is possible that neurological abnormalities follow an age-dependent pattern, leading to the appearance of related symptoms later in life. Further multiple functional studies are needed to model different identified variants in animal models to confirm our results and suggest possible mechanisms associated with DOCK8 deficiency in this study.

The Role of RhoH in TCR Signalling and Its Involvement in Diseases

As an atypical member of the Rho family small GTPases, RhoH shares less than 50% sequence similarity with other members, and its expression is commonly observed in the haematopoietic lineage. To date, RhoH function was observed in regulating T cell receptor signalling, and less is known in other haematopoietic cells. Its activation may not rely on the standard GDP/GTP cycling of small G proteins and is thought to be constitutively active because critical amino acids involved in GTP hydrolysis are absent. Alternatively, its activation can be regulated by other types of regulation, including lysosomal degradation, somatic mutation and transcriptional repressor, which also results in an altered protein expression. Aberrant protein expression of RhoH has been implicated not only in B cell malignancies but also in immune-related diseases, such as primary immunodeficiencies, systemic lupus erythematosus and psoriasis, wherein its involvement may provide the link between immune-related diseases and cancer. RhoH association with these diseases involves several other players, including its interacting partner, ZAP-70; activation regulators, Vav1 and RhoGDI and other small GTPases, such as RhoA, Rac1 and Cdc42. As such, RhoH and its associated proteins are potential attack points, especially in the treatment of cancer and immune-related diseases.

The Regulatory Subunit PPP2R2A of PP2A Enhances Th1 and Th17 Differentiation through Activation of the GEF-H1/RhoA/ROCK Signaling Pathway

Protein phosphatase 2A (PP2A) composed of a scaffold subunit, a catalytic subunit, and multiple regulatory subunits is a ubiquitously expressed serine/threonine phosphatase. We have previously shown that the PP2A catalytic subunit is increased in T cells from patients with systemic lupus erythematosus and promotes IL-17 production by enhancing the activity of Rho-associated kinase (ROCK) in T cells. However, the molecular mechanism whereby PP2A regulates ROCK activity is unknown. In this study, we show that the PP2A regulatory subunit PPP2R2A is increased in T cells from people with systemic lupus erythematosus and binds to, dephosphorylates, and activates the guanine nucleotide exchange factor GEF-H1 at Ser⁸⁸⁵, which in turn increases the levels of RhoA-GTP and the activity of ROCK in T cells. Genetic PPP2R2A deficiency in murine T cells reduced Th1 and Th17, but not regulatory T cell differentiation and mice with T cell-specific PPP2R2A deficiency displayed less autoimmunity when immunized with myelin oligodendrocyte glycoprotein peptide. Our studies indicate that PPP2R2A is the regulatory subunit that dictates the PP2A-directed enhanced Th1 and Th17 differentiation, and therefore, it represents a therapeutic target for pathologies linked to Th1 and Th17 cell expansion.

GTPases, genome, actin: A hidden story in DNA damage response and repair mechanisms

The classical small Rho GTPase (Rho, Rac, and Cdc42) protein family is mainly responsible for regulating cell motility and polarity, membrane trafficking, cell cycle control, and gene transcription. Cumulative recent evidence supports important roles for these proteins in the maintenance of genomic stability. Indeed, DNA damage response (DDR) and repair mechanisms are some of the prime biological processes that underlie several disease phenotypes, including genetic disorders, cancer, senescence, and premature aging. Many reports guided by different experimental approaches and molecular hypotheses have demonstrated that, to some extent, direct modulation of Rho GTPase activity, their downstream effectors, or actin cytoskeleton regulation contribute to these cellular events. Although much attention has been paid to this family in the context of canonical actin cytoskeleton remodeling, here we provide a contextualized review of the interplay between Rho GTPase signaling pathways and the DDR and DNA repair signaling components. Interesting questions yet to be addressed relate to the spatiotemporal dynamics of this collective response and whether it correlates with different subcellular pools of Rho GTPases. We highlight the direct and indirect targets, some of which still lack experimental validation data, likely associated with Rho GTPase activation that provides compelling evidence for further investigation in DNA damage-associated events and with potential therapeutic applications in translational medicine.

A conserved PI(4,5)P2-binding domain is critical for immune regulatory function of DOCK8

This study uncovers a critical role of DOCK8 in coupling PI(4,5)P2 signaling with Cdc42 activation through its DHR-1 domain during interstitial leukocyte migration.

DOCK8 is a Cdc42-specific guanine-nucleotide exchange factor that is essential for development and functions of various subsets of leukocytes in innate and acquired immune responses. Although DOCK8 plays a critical role in spatial control of Cdc42 activity during interstitial leukocyte migration, the mechanism remains unclear. We show that the DOCK homology region (DHR)-1 domain of DOCK8 binds specifically to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and is required for its recruitment to the plasma membrane. Structural and biochemical analyses reveal that DOCK8 DHR-1 domain consists of a C2 domain-like core with loops creating the upper surface pocket, where three basic residues are located for stereospecific recognition of phosphoinositides. Substitution of the two basic residues, K576 and R581, with alanine abolished PI(4,5)P2 binding in vitro, ablated the ability of DOCK8 to activate Cdc42 and support leukocyte migration in three-dimensional collagen gels. Dendritic cells carrying the mutation exhibited defective interstitial migration in vivo. Thus, our study uncovers a critical role of DOCK8 in coupling PI(4,5)P2 signaling with Cdc42 activation for immune regulation.

The Adhesome Network: Key Components Shaping the Tumour Stroma

Beyond the conventional perception of solid tumours as mere masses of cancer cells, advanced cancer research focuses on the complex contributions of tumour-associated host cells that are known as "tumour microenvironment" (TME). It has been long appreciated that the tumour stroma, composed mainly of blood vessels, cancer-associated fibroblasts and immune cells, together with the extracellular matrix (ECM), define the tumour architecture and influence cancer cell properties. Besides soluble cues, that mediate the crosstalk between tumour and stroma cells, cell adhesion to ECM arises as a crucial determinant in cancer progression. In this review, we discuss how adhesome, the intracellular protein network formed at cell adhesions, regulate the TME and control malignancy. The role of adhesome extends beyond the physical attachment of cells to ECM and the regulation of cytoskeletal remodelling and acts as a signalling and mechanosensing hub, orchestrating cellular responses that shape the tumour milieu.

Downregulation of Rac1/PAK1/LIMK1/cofilin signaling pathway in colon cancer SW620 cells treated with Chlorin e6 photodynamic therapy

BACKGROUND

Colorectal cancer is one of the most common gastrointestinal malignancies. Photodynamic therapy (PDT) is a novel and non-invasive treatment for tumors as PDT features small trauma, good applicability, andaccurate targeting. PDT may also be a potential treatment for colon cancer as itmay may induce suppressive effects on metastatic potential.. However, the molecular mechanism of the Chlorin e6 Photodynamic therapy (Ce6-PDT) inhibiting the migration of human colon cancer SW620 cells remains unclear.

METHODS

Scratch wound healing assay, scanning electron microscope, MTT, immunofluorescence and laser confocal technique were used to investigate the suppressive effects of Ce6-PDT on the SW620 cells migration, pseudopodia, viability and the actin cytoskeleton. The effect of Ce6-PDT on actin-Filaments and signaling molecules of the Rac1/PAK1/LIMK1/cofilin signaling pathway in SW620 cells were examined by western blot analysis. RNA interference (RNAi) technology was used to establish siRNA-Rac1/SW620 cells. The combined effects of Ce6-PDT and RNAi on colon cancer SW620 cells was investigated by the same technology and methods mentioned above to clarify the signal transduction effect of Rac1/PAK1/LIMK1/cofilin signaling pathway in Ce6-PDT caused inhibition of SW620 cell migration.

RESULTS

The healing and migration rate of the SW620 cells was significantly reduced and the cell pseudopodia were reduced or disappeared by Ce6-PDT. The Immunofluorescence and western blot analysis results showed that Ce6-PDT destroy microfilament's original structure and significantly downregulated F-actin protein expression. The Rac1/PAK1/LIMK1/cofilin signaling pathway was downregulated by Ce6-PDT. Furthermore, the RNAi significantly strengthened the effect of Ce6-PDT on colon cancer SW620 cells migration.

CONCLUSIONS

Actin cytoskeleton and protrusions of SW620 cells correlate with its migration ability. Ce6-PDT suppresses SW620 cells migration by downregulating the Rac1/PAK1/LIMK1/cofilin signaling pathway, and its suppressive effect was enhanced by knocking down Rac1 gene expression.

Transcriptome Analysis Reveals Inhibitory Effects of Lentogenic Newcastle Disease Virus on Cell Survival and Immune Function in Spleen of Commercial Layer Chicks

As a major infectious disease in chickens, Newcastle disease virus (NDV) causes considerable economic losses in the poultry industry, especially in developing countries where there is limited access to effective vaccination. Therefore, enhancing resistance to the virus in commercial chickens through breeding is a promising way to promote poultry production. In this study, we investigated gene expression changes at 2 and 6 days post inoculation (dpi) at day 21 with a lentogenic NDV in a commercial egg-laying chicken hybrid using RNA sequencing analysis. By comparing NDV-challenged and non-challenged groups, 526 differentially expressed genes (DEGs) (false discovery rate (FDR) < 0.05) were identified at 2 dpi, and only 36 at 6 dpi. For the DEGs at 2 dpi, Ingenuity Pathway Analysis predicted inhibition of multiple signaling pathways in response to NDV that regulate immune cell development and activity, neurogenesis, and angiogenesis. Up-regulation of interferon induced protein with tetratricopeptide repeats 5 (IFIT5) in response to NDV was consistent between the current and most previous studies. Sprouty RTK signaling antagonist 1 (SPRY1), a DEG in the current study, is in a significant quantitative trait locus associated with virus load at 6 dpi in the same population. These identified pathways and DEGs provide potential targets to further study breeding strategy to enhance NDV resistance in chickens.

Molecular cloning and characterization of DjRac1, a novel small G protein gene from planarian Dugesia japonica

Rac proteins are classified as a subfamily of the Rho family of small G proteins. They are important molecular switches which act as key signal transducers regulating a wide variety of processes in the cell. DjRac1, a novel Rac gene from planarian Dugesia japonica was cloned by RACE method and characterized. This cDNA contains 851 bp with a putative open reading frame of 190 amino acids. It has a predicted molecular mass of 21.12 kDa and an isoelectric point of 8.42. Whole-mount in situ hybridization and relative quantitative real-time PCR were used to study the spatial and temporal expression pattern of DjRac1 from 1 to 7 days in the regenerating planarians. Results showed that the expression of DjRac1 was concentrated in the blastema and the transcription level of DjRac1 was significantly upregulated after amputation within three days, suggesting DjRac1 might participate in the process of regeneration in planarian.

The diagnostic and prognostic role of RhoA in hepatocellular carcinoma

The aim of this study was to investigate the expression level of Ras homolog gene family, member A (RhoA) in patients with hepatocellular carcinoma (HCC) and to investigate the prognostic and diagnostic value of RhoA. Data mining from various data bases and wet experiments on samples from Peking Union Medical College Hospital showed that RhoA mRNA and protein expression were significantly higher in the HCC tissues than in the normal tissues. Higher expression at both the mRNA and protein levels was associated with a poorer prognosis. High sensitivity (92.5%) and specificity (90.0%) were observed in the diagnostic model based on protein level rather than mRNA level. RhoA expression was modulated by genetic amplification. The lysosome, pathogenic Escherichia coli infection, purine metabolism and pyrimidine metabolism pathways were mainly enriched in the high RhoA level group, while the hedgehog signaling, linoleic acid metabolism, olfactory transduction and taste transduction pathways were enriched in the low RhoA level group. RhoA is commonly upregulated in HCC tissues, and its expression at both the mRNA and protein levels is associated with poor prognosis. Notably, RhoA protein levels serve as a diagnostic biomarker for HCC.