Semaphorin 3E regulates apoptosis in the intestinal epithelium during the development of colitis

Sema-3E/PlexinD1 axis modulates dendritic cell phenotypes and functions: Current status and future implications

This comprehensive research review explores the complex interplay between the Sema-3E/PlexinD1 axis and dendritic cells (DCs), highlighting its critical role in immune modulation with implications for clinical application Critical regulators of immune responses Dendritic cells are central to adaptive immunity, and the Sema-3E /PlexinD1 axis emerges as a key modulator affecting their phenotypes and functions Review delineates the impact of this signaling axis on DC maturation, migration, antigen presentation, and cytokine production, unravels its multifaceted role in shaping the immune response. Recognizing the limitations and gaps in current knowledge, the study highlights the need for further studies to condition downstream signaling events and related information experienced by the Sema-3E/PlexinD1 axis emphasizes the clarity of the immune system. The review concludes by identifying opportunities for translation, focusing on therapeutic and diagnostic potential. It highlights the importance of collaborative, interdisciplinary efforts to address the challenges and harness the therapeutic and pathological potential of targeting the Sema-3E/PlexinD1 axis, thus opening the way for transformative advances in immunology and clinical medicine.

The significance of long non-coding RNAs in the pathogenesis, diagnosis and treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are a group of chronic relapsing gastrointestinal inflammatory diseases with significant global incidence. Although the pathomechanism of IBD has been extensively investigated, several aspects of its pathogenesis remain unclear. Long non-coding RNAs (lncRNAs) are transcripts with more than 200 nucleotides in length that have potential protein-coding functions. LncRNAs play important roles in biological processes such as epigenetic modification, transcriptional regulation and post-transcriptional regulation. In this review, we summarize recent advances in research on IBD-related lncRNAs from the perspective of the overall intestinal microenvironment, as well as their potential roles as immune regulators, diagnostic biomarkers and therapeutic targets or agents for IBD.

Semaphorins in immune cell function, inflammatory and infectious diseases

The Semaphorin family is a group of proteins studied broadly for their functions in nervous systems. They consist of eight subfamilies ubiquitously expressed in vertebrates, invertebrates, and viruses and exist in membrane-bound or secreted forms. Emerging evidence indicates the relevance of semaphorins outside the nervous system, including angiogenesis, cardiogenesis, osteoclastogenesis, tumour progression, and, more recently, the immune system. This review provides a broad overview of current knowledge on the role of semaphorins in the immune system, particularly its involvement in inflammatory and infectious diseases, including chlamydial infections.

Adult expression of Semaphorins and Plexins is essential for motor neuron survival

Axon guidance cues direct the growth and steering of neuronal growth cones, thus guiding the axons to their targets during development. Nonetheless, after axons have reached their targets and established functional circuits, many mature neurons continue to express these developmental cues. The role of axon guidance cues in the adult nervous system has not been fully elucidated. Using the expression pattern data available on FlyBase, we found that more than 96% of the guidance genes that are expressed in the Drosophila melanogaster embryo continue to be expressed in adults. We utilized the GeneSwitch and TARGET systems to spatiotemporally knockdown the expression of these guidance genes selectively in the adult neurons, once the development was completed. We performed an RNA interference (RNAi) screen against 44 guidance genes in the adult Drosophila nervous system and identified 14 genes that are required for adult survival and normal motility. Additionally, we show that adult expression of Semaphorins and Plexins in motor neurons is necessary for neuronal survival, indicating that guidance genes have critical functions in the mature nervous system.

Curcumin alleviates experimental colitis in mice by suppressing necroptosis of intestinal epithelial cells

Curcumin, the primary bioactive substance in turmeric, exhibits potential therapeutic effects on ulcerative colitis. However, its mechanism for regulating necroptosis in colitis has not been fully elucidated. In this study, the effect of curcumin on experimental colitis-induced necroptosis of intestinal epithelial cells was investigated, and its molecular mechanism was further explored. We found that curcumin blocked necroptosis in a dose-dependent manner by inhibiting the phosphorylation of RIP3 and MLKL instead of RIP1 in HT-29 cells. Co-Immunoprecipitation assay showed that curcumin weakened the interaction between RIP1 and RIP3, possibly due to the direct binding of curcumin to RIP3 as suggested by drug affinity responsive target stability analysis. In a classical in vivo model of TNF-α and pan-caspase inhibitor-induced necroptosis in C57BL/6 mice, curcumin potently inhibited systemic inflammatory responses initiated by the necroptosis signaling pathway. Then, using a dextran sodium sulfate-induced colitis model in C57BL/6 mice, we found that curcumin inhibited the expression of p-RIP3 in the intestinal epithelium, reduced intestinal epithelial cells loss, improved the function of the intestinal tight junction barrier, and reduced local intestinal inflammation. Collectively, our findings suggest that curcumin is a potent targeted RIP3 inhibitor with anti-necroptotic and anti-inflammatory effects, maintains intestinal barrier function, and effectively alleviates colitis injury.

Natural Products Modulate Cell Apoptosis: A Promising Way for the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease impacting patients’ quality of life and imposing heavy societal and economic burdens. Apoptosis of intestinal epithelial cells (IECs) has been considered an early event during the onset of UC and plays a crucial role in disease development. Thus, effectively inhibiting apoptosis of IECs is of critical significance for the clinical management of UC, presenting a potential direction for the research and development of pharmacotherapeutic agents. In recent years, research on the ameliorative effects of natural products on UC through inhibiting IECs apoptosis has attracted increasing attention and made remarkable achievements in ameliorating UC. In this review, we summarized the currently available research about the anti-apoptotic effects of natural products on UC and its mechanisms involving the death-receptor mediated pathway, mitochondrial-dependent pathway, ERS-mediated pathway, MAPK-mediated pathway, NF-κB mediated pathway, P13k/Akt pathway, JAK/STAT3 pathway, and NLRP3/ASC/Caspase-1 pathway. Hopefully, this review may yield useful information about the anti-apoptotic effects of natural products on UC and their potential molecular mechanisms and provide helpful insights for further investigations.

mRNA-engineered mesenchymal stromal cells expressing CXCR2 enhances cell migration and improves recovery in IBD

Mesenchymal stromal cells (MSCs) have shown significant heterogeneity in terms of therapeutic efficacy for inflammatory bowel disease (IBD) treatment, which may be due to an insufficient number of MSCs homing to the damaged tissue of the colon. Engineering MSCs with specific chemokine receptors can enhance the homing ability by lentiviral transduction. However, the unclear specific chemokine profile related to IBD and the safety concerns of viral-based gene delivery limit its application. Thus, a new strategy to modify MSCs to express specific chemokine receptors using mRNA engineering is developed to evaluate the homing ability of MSCs and its therapeutic effects for IBD. We found that CXCL2 and CXCL5 were highly expressed in the inflammatory colon, while MSCs minimally expressed the corresponding receptor CXCR2. Transient expression of CXCR2 in MSC was constructed and exhibited significantly enhanced migration to the inflamed colons, leading to a robust anti-inflammatory effect and high efficacy. Furthermore, the high expression of semaphorins7A on MSCs were found to induce the macrophages to produce IL-10, which may play a critical therapeutic role. This study demonstrated that the specific chemokine receptor CXCR2 mRNA-engineered MSCs not only improves the therapeutic efficacy of IBD but also provides an efficient and safe MSC modification strategy.

TKT maintains intestinal ATP production and inhibits apoptosis-induced colitis

Inflammatory bowel disease (IBD) has a close association with transketolase (TKT) that links glycolysis and the pentose phosphate pathway (PPP). However, how TKT functions in the intestinal epithelium remains to be elucidated. To address this question, we specifically delete TKT in intestinal epithelial cells (IECs). IEC TKT-deficient mice are growth retarded and suffer from spontaneous colitis. TKT ablation brings about striking alterations of the intestine, including extensive mucosal erosion, aberrant tight junctions, impaired barrier function, and increased inflammatory cell infiltration. Mechanistically, TKT deficiency significantly accumulates PPP metabolites and decreases glycolytic metabolites, thereby reducing ATP production, which results in excessive apoptosis and defective intestinal barrier. Therefore, our data demonstrate that TKT serves as an essential guardian of intestinal integrity and barrier function as well as a potential therapeutic target for intestinal disorders.

Pancreastatin Reduces Alternatively Activated Macrophages, Disrupts the Epithelial Homeostasis and Aggravates Colonic Inflammation. A Descriptive Analysis

Ulcerative colitis (UC) is characterized by modifying alternatively activated macrophages (AAM) and epithelial homeostasis. Chromogranin-A (CHGA), released by enterochromaffin cells, is elevated in UC and is implicated in inflammation progression. CHGA can be cleaved into several derived peptides, including pancreastatin (PST), which is involved in proinflammatory mechanisms. Previously, we showed that the deletion of Chga decreased the onset and severity of colitis correlated with an increase in AAM and epithelial cells’ functions. Here, we investigated PST activity in colonic biopsies of participants with active UC and investigated PST treatment in dextran sulfate sodium (DSS)-induced colitis using Chga^−/− mice, macrophages, and a human colonic epithelial cells line. We found that the colonic protein expression of PST correlated negatively with mRNA expression of AAM markers and tight junction (TJ) proteins and positively with mRNA expression of interleukin (IL)-8, IL18, and collagen in human. In a preclinical setting, intra-rectal administration of PST aggravated DSS-induced colitis by decreasing AAM’s functions, enhancing colonic collagen deposition and disrupting epithelial homeostasis in Chga^+/+ and Chga^−/− mice. This effect was associated with a significant reduction in AAM markers, increased colonic IL-18 release, and decreased TJ proteins’ gene expression. In vitro, PST reduced Chga^+/+ and Chga^−/− AAM polarization and decreased anti-inflammatory mediators’ production. Conditioned medium harvested from PST-treated Chga^+/+ and Chga^−/− AAM reduced Caco-2 cell migration, viability, proliferation, and mRNA levels of TJ proteins and increased oxidative stress-induced apoptosis and proinflammatory cytokines release. In conclusion, PST is a CHGA proinflammatory peptide that enhances the severity of colitis and the inflammatory process via decreasing AAM functions and disrupting epithelial homeostasis.

Neuronal innervation of the intestinal crypt

Mucosal damage is a key feature of inflammatory bowel diseases (IBD) and healing of the mucosa is an endpoint of IBD treatment that is often difficult to achieve. Autonomic neurons of the parasympathetic and sympathetic nervous system may influence intestinal epithelial cell growth and modulating epithelial innervation could for that reason serve as an interesting therapeutic option to improve mucosal healing. Understanding of the biological processes triggered by nonspecific and specific epithelial adrenergic and cholinergic receptor activation is of key importance. At present, with rising technological advances, bioelectronic neuromodulation as treatment modality has gained momentum. We discuss the current view on state-of-the-art innervation of the intestinal crypt and its impact on epithelial cell growth and differentiation. Furthermore, we outline bioelectronic technology and review its relevance to wound healing processes.

Semaphorin 3E Protects against Chlamydial Infection by Modulating Dendritic Cell Functions

Recent studies have identified semaphorin 3E (Sema3E) as a novel mediator of immune responses. However, its function in immunity to infection has yet to be investigated. Using a mouse model of chlamydial lung infection, we show that Sema3E plays a significant role in the host immune response to the infection. We found that Sema3E is induced in the lung after chlamydial infection, and Sema3E deficiency has a detrimental impact on disease course, dendritic cell (DC) function, and T cell responses. Specifically, we found that Sema3E knockout (KO) mice exhibited higher bacterial burden, severe body weight loss, and pathological changes after Chlamydia muridarum lung infection compared with wild-type (WT) mice. The severity of disease in Sema3E KO mice was correlated with reduced Th1/Th17 cytokine responses, increased Th2 response, altered Ab response, and a higher number of regulatory CD4 T cells. Moreover, DCs isolated from Sema3E KO mice showed lower surface expression of costimulatory molecules and production of IL-12, but higher expression of PD-L1, PD-L2, and IL-10 production. Functional DC-T cell coculture studies revealed that DCs from infected Sema3E KO mice failed to induce Th1 and Th17 cell responses compared with DCs from infected WT mice. Upon adoptive transfer, mice receiving DCs from Sema3E KO mice, unlike those receiving DCs from WT mice, were not protected against challenge infection. In conclusion, our data evidenced that Sema3E acts as a critical factor for protective immunity against intracellular bacterial infection by modulating DC functions and T cell subsets.

Interdependence between Chromogranin-A, Alternatively Activated Macrophages, Tight Junction Proteins and the Epithelial Functions. A Human and In-Vivo/In-Vitro Descriptive Study

Background: Ulcerative colitis (UC) is characterized by altered chromogranin-A (CHGA), alternatively activated macrophages (M2) and intestinal epithelial cells (IECs). We previously demonstrated that CHGA is implicated in colitis progression by regulating the macrophages. Here, we investigated the interplay between CHGA, M2, tight junctions (TJ) and IECs in an inflammatory environment. Methods: Correlations between CHGA mRNA expression of and TJ proteins mRNA expressions of (Occludin [OCLN], zonula occludens-1 [ZO1], Claudin-1 [CLDN1]), epithelial associated cytokines (interleukin [IL]-8, IL-18), and collagen (COL1A2) were determined in human colonic mucosal biopsies isolated from active UC and healthy patients. Acute UC-like colitis (5% dextran sulphate sodium [DSS], five days) was induced in Chga-C57BL/6-deficient (Chga^−/−) and wild type (Chga^+/+) mice. Col1a2 TJ proteins, Il-18 mRNA expression and collagen deposition were determined in whole colonic sections. Naïve Chga^−/− and Chga^+/+ peritoneal macrophages were isolated and exposed six hours to IL-4/IL-13 (20 ng/mL) to promote M2 and generate M2-conditioned supernatant. Caco-2 epithelial cells were cultured in the presence of Chga^−/− and Chga^+/+ non- or M2-conditioned supernatant for 24 h then exposed to 5% DSS for 24 h, and their functional properties were assessed. Results: In humans, CHGA mRNA correlated positively with COL1A2, IL-8 and IL-18, and negatively with TJ proteins mRNA markers. In the experimental model, the deletion of Chga reduced IL-18 mRNA and its release, COL1A2 mRNA and colonic collagen deposition, and maintained colonic TJ proteins. Chga^−/− M2-conditioned supernatant protected caco-2 cells from DSS and oxidative stress injuries by improving caco-2 cells functions (proliferation, viability, wound healing) and by decreasing the release of IL-8 and IL-18 and by maintaining the levels of TJ proteins, and when compared with Chga^+/+ M2-conditioned supernatant. Conclusions: CHGA contributes to the development of intestinal inflammation through the regulation of M2 and epithelial cells. Targeting CHGA may lead to novel biomarkers and therapeutic strategies in UC.

The Role of Semaphorins in Metabolic Disorders

Semaphorins are a family originally identified as axonal guidance molecules. They are also involved in tumor growth, angiogenesis, immune regulation, as well as other biological and pathological processes. Recent studies have shown that semaphorins play a role in metabolic diseases including obesity, adipose inflammation, and diabetic complications, including diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, diabetic wound healing, and diabetic osteoporosis. Evidence provides mechanistic insights regarding the role of semaphorins in metabolic diseases by regulating adipogenesis, hypothalamic melanocortin circuit, immune responses, and angiogenesis. In this review, we summarize recent progress regarding the role of semaphorins in obesity, adipose inflammation, and diabetic complications.

Denosumab Regulates Gut Microbiota Composition and Cytokines in Dinitrobenzene Sulfonic Acid (DNBS)-Experimental Colitis

The pro-inflammatory mediator receptor activator of nuclear factor-kappa B ligand (RANKL) plays a significant role in the development of rheumatoid arthritis; however, its role in inflammatory bowel disease is unknown. Genome-wide association meta-analysis for Crohn's disease (CD) identified a variant near the TNFSF11 gene that encodes RANKL and CD risk allele increased expression of RANKL in specific cell lines. This study aims to elucidate if the RANKL inhibitor denosumab can reduce the severity of experimental colitis and modify the gut microbiota composition using murine dinitrobenzenesulfonic acid (DNBS)-experimental model of colitis mimicking CD. In colitic conditions, denosumab treatment significantly decreased the pro-inflammatory cytokines IL-6, IL-1β, and TNF-α within the colonic mucosa. Moreover, colitis was accompanied by disruption of gut microbiota, and preventative treatment with denosumab modulated this disruption. Denosumab treatment also modified the alpha- and beta diversity of colonic mucosa and fecal microbiota. These results provide a rationale for considering denosumab as a future potential therapy in CD; however, more detailed experimental and clinical studies are warranted.

The immune-sleep crosstalk in inflammatory bowel disease

Sleep disorders are progressively common and sometimes are associated with aberrant regulation of the adaptive and innate immune responses. Sleep interruption can increase the inflammatory burden by enhancing the pro-inflammatory cytokines particularly in patients with chronic diseases such as inflammatory bowel disease (IBD). IBD is a chronic inflammatory disease characterized by immune dysregulation, dysbiosis of gut microbiome, and poor-quality life. Therefore, this review highlights the crosstalk between sleep and immune responses during the progression of IBD.

A kinome-wide screen identifies a CDKL5-SOX9 regulatory axis in epithelial cell death and kidney injury

Renal tubular epithelial cells (RTECs) perform the essential function of maintaining the constancy of body fluid composition and volume. Toxic, inflammatory, or hypoxic-insults to RTECs can cause systemic fluid imbalance, electrolyte abnormalities and metabolic waste accumulation- manifesting as acute kidney injury (AKI), a common disorder associated with adverse long-term sequelae and high mortality. Here we report the results of a kinome-wide RNAi screen for cellular pathways involved in AKI-associated RTEC-dysfunction and cell death. Our screen and validation studies reveal an essential role of Cdkl5-kinase in RTEC cell death. In mouse models, genetic or pharmacological Cdkl5 inhibition mitigates nephrotoxic and ischemia-associated AKI. We propose that Cdkl5 is a stress-responsive kinase that promotes renal injury in part through phosphorylation-dependent suppression of pro-survival transcription regulator Sox9. These findings reveal a surprising non-neuronal function of Cdkl5, identify a pathogenic Cdkl5-Sox9 axis in epithelial cell-death, and support CDKL5 antagonism as a therapeutic approach for AKI.

Protein kinases have emerged as critical regulators of disease pathogenesis. Here, the authors have utilized kinome-wide screening approaches to reveal a pathogenic role of CDKL5 kinase in acute kidney injury, which is dependent on suppression of a SOX9-associated transcriptional network.

A Gene Expression Analysis of M1 and M2 Polarized Macrophages

Macrophages are professional innate immune cells that are broadly disseminated throughout the body, shape various innate and adaptive immune responses, and play crucial roles in inflammation, homeostasis, wound healing, and tissue remodelling. According to their surrounding microenvironments, macrophages can differentiate themselves in different phenotypes. Over the last two decades, gene expression profiling has been used to decipher new transcripts associated with macrophage phenotypes. This chapter outlines protocols used to isolate and culture murine macrophages and how they can be "polarized" to obtain a specific phenotype. Furthermore, we describe a protocol for gene expression profiling using a quantitative real-time polymerase chain reaction (qPCR), a high-standard technology in the field of gene expression.