The role of semaphorins in immune responses and autoimmune rheumatic diseases

Sema4D Knockout Attenuates Choroidal Neovascularization by Inhibiting M2 Macrophage Polarization Via Regulation of the RhoA/ROCK Pathway

Purpose

The aim of this study was to elucidate the role of Sema4D in the pathogenesis of senescence-associated choroidal neovascularization (CNV) and to explore its underlying mechanisms.

Methods

In this study, we utilized a model of laser-induced CNV in both young (3 months old) and old (18 months old) mice, including those with or without Sema4D knockout. The expression and localization of Sema4D in CNV were assessed using PCR, Western blot, and immunostaining. Subsequently, the morphological and imaging examinations were used to evaluate the size of CNV and vascular leakage. Finally, the expression of M2 markers, senescence-related markers, and molecules involved in the RhoA/ROCK pathway was detected.

Results

We found that Sema4D was predominantly expressed in macrophages within CNV lesions, and both the mRNA and protein levels of Sema4D progressively increased following laser photocoagulation, a trend more pronounced in old mice. Moreover, Sema4D knockout markedly inhibited M2 polarization in senescent macrophages and reduced the size and leakage of CNV, particularly in aged mice. Mechanistically, aging was found to upregulate RhoA/ROCK signaling, and knockout of Sema4D effectively suppressed the activation of this pathway, with more significant effects observed in aged mice.

Conclusions

Our findings revealed that the deletion of Sema4D markedly inhibited M2 macrophage polarization through the suppression of the RhoA/ROCK pathway, ultimately leading to the attenuation of senescence-associated CNV. These data indicate that targeting Sema4D could offer a promising approach for gene editing therapy in patients with neovascular age-related macular degeneration.

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

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 role of Semaphorin 3A in oral diseases

Semaphorin 3A (SEMA3A), also referred to as H-Sema III, is a molecule with significant biological importance in regulating physiological and pathological processes. However, its role in oral diseases, particularly its association with inflammatory immunity and alveolar bone remodeling defects, remains poorly understood. This comprehensive review article aims to elucidate the recent advances in understanding SEMA3A in the oral system, encompassing nerve formation, periodontitis, pulpitis, apical periodontitis, and oral squamous cell carcinoma. Notably, we explore its novel function in inflammatory immunomodulation and alveolar bone formation during oral infectious diseases. By doing so, this review enhances our comprehension of SEMA3A's role in oral biology and opens up possibilities for modulatory approaches and potential treatments in oral diseases.

Longitudinal Transcriptomic Analysis of Human Cortical Spheroids Identifies Axonal Dysregulation in the Prenatal Brain as a Mediator of Genetic Risk for Schizophrenia

BACKGROUND

Schizophrenia (SCZ) has a known neurodevelopmental etiology, but limited access to human prenatal brain tissue hampers the investigation of basic disease mechanisms in early brain development. Here, we elucidate the molecular mechanisms contributing to SCZ risk in a disease-relevant model of the prenatal human brain.

METHODS

We generated induced pluripotent stem cell-derived organoids, termed human cortical spheroids (hCSs), from a large, genetically stratified sample of 14 SCZ cases and 14 age- and sex-matched controls. The hCSs were differentiated for 150 days, and comprehensive molecular characterization across 4 time points was carried out.

RESULTS

The transcriptional and cellular architecture of hCSs closely resembled that of fetal brain tissue at 10 to 24 postconception weeks, showing strongest spatial overlap with frontal regions of the cerebral cortex. A total of 3520 genes were differentially modulated between SCZ and control hCSs across organoid maturation, displaying a significant contribution of genetic loading, an overrepresentation of risk genes for autism spectrum disorder and SCZ, and the strongest enrichment for axonal processes in all hCS stages. The two axon guidance genes SEMA7A and SEMA5A, the first a promoter of synaptic functions and the second a repressor, were downregulated and upregulated, respectively, in SCZ hCSs. This expression pattern was confirmed at the protein level and replicated in a large postmortem sample.

CONCLUSIONS

Applying a disease-relevant model of the developing fetal brain, we identified consistent dysregulation of axonal genes as an early risk factor for SCZ, providing novel insights into the effects of genetic predisposition on the neurodevelopmental origins of the disorder.

Comparison of the efficacy of combined budesonide and fexofenadine versus combined fluticasone propionate and fexofenadine on the expression of class-4 semaphorins and their receptors in the peripheral blood cells of patients with allergic rhinitis

Background

Allergic rhinitis (AR) is a common immunoglobulin (Ig) E-mediated disease. This study aimed to evaluate the gene expression levels of class 4 semaphorins and their receptors in AR patients before and after treatment with budesonide and fexofenadine (B/F) compared to fluticasone propionate and fexofenadine (FP/F).

Methods

In this study, 29 AR patients (age 34.4 ± 1.2 years, 18 men and 11 women) were treated with B/F, and 24 AR patients (age 32.8 ± 1.9 years, 15 men and 9 women) were treated with FP/F for one month. Before and after treatment, peripheral blood samples were taken from patients. The expression levels of SEMA4A, SEMA4C, SEMA4D, Plexin-B2, and Plexin-D1 genes were measured using the qPCR method. In addition, the serum levels of IgE were measured using an enzyme-linked immunosorbent assay (ELISA).

Results

The expression levels of SEMA4A (P = 0.011), 4C (P = 0.017), Plexin-B2 (P = 0.0005), and Plexin-D1 (P = 0.008) remarkably increased in AR patients treated with B/F. Our results show a significant reduction in the gene expression levels of SEMA4A (P = 0.002), 4C (P = 0.014), 4D (P = 0.003), Plexin-B2 (P = 0.033), and Plexin-D1 (P = 0.035) after treatment with FP/F. The serum levels of IgE increased in FP/F treated group (P = 0.017) and conversely decreased in the treated group with B/F (P = 0.019). Moreover, the percentages of eosinophils were reduced in both FP/F and B/F groups (P = 0.015 and P = 0.0001, respectively).

Conclusion

In conclusion, concomitant use of fexofenadine and fluticasone propionate reduced SEMA4A, 4C, 4D, Plexin-B2, and Plexin-D1, while the SEMA4A, 4C, Plexin-B2, and Plexin-D1 gene expression levels were increased in the patient group treated with B/F.

New Promising Routes in Peptic Ulcers: Toll-like Receptors and Semaphorins

Peptic ulcers (PU) are one of the commonest yet problematic diseases found to be existing in the majority of the population. Today, drugs from a wide range of therapeutic classes are available for the management of the disease. Still, the complications of the condition are difficult to tackle and the side effect profile is quite a concern. The literature indicates that Toll-like receptors (TLRs) and Semaphorins (SEMAs) have been under study for their various pharmacological actions over the past few decades. Both these signalling pathways are found to regulate immunological and inflammatory responses. Moreover, receptors and signalling molecules from the family of TLRs and SEMAs are found to have bacterial recognition and antibacterial properties which are essential in eradicating Helicobacter pylori (H. pylori), one of the major causative agents of PU. Our understanding of SEMAs, a class of proteins involved in cell signalling, is relatively less developed compared to TLRs, another class of proteins involved in the immune response. SEMAs and TLRs play different roles in biological processes, with SEMAs primarily involved in guiding cell migration and axon guidance during development, while TLRs are responsible for recognizing pathogens and initiating an immune response. Here, in this review, we will discuss in detail the signalling cascade of TLRs and SEMAs and thereby understand its association with PU for future therapeutic targeting. The review also aims at providing an overview of the study that has been into exploring the role of these signalling pathways in the management of PU.

A fully human monoclonal antibody targeting Semaphorin 5A alleviates the progression of rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common chronic autoimmune disease worldwide. Although progress has been made in RA treatment in recent decades, remission cannot be effectively achieved for a considerable proportion of RA patients. Thus, novel potential targets for therapeutic strategies are needed. Semaphorin 5A (SEMA5A) plays a pivotal role in RA progression by facilitating pannus formation, and it is a promising therapeutic target. In this study, we sought to develop an antibody treatment strategy targeting SEMA5A and evaluate its therapeutic effect using a collagen-induced arthritis (CIA) model. We generated SYD12-12, a fully human SEMA5A blocking antibody, through phage display technology. SYD12-12 intervention effectively inhibited angiogenesis and aggressive phenotypes of RA synoviocytes in vitro and dose-dependently inhibited synovial hyperplasia, pannus formation, bone destruction in CIA mice. Notably, SYD12-12 also improved the Treg/Th17 imbalance in CIA mice. We confirmed through immunofluorescence and molecular docking that SYD12-12 integrated with the unique TSP-1 domain of SEMA5A. In conclusion, we developed and characterized a fully human SEMA5A-blocking antibody for the first time. SYD12-12 effectively alleviated disease progression in CIA mice by inhibiting pannus formation and improving the Treg/Th17 imbalance, demonstrating its potential for the RA treatment.

Single-cell communication patterns and their intracellular information flow in synovial fibroblastic osteoarthritis and rheumatoid arthritis

BACKGROUND

Synovial fibroblasts are critical for maintaining homeostasis in major autoimmune diseases involving joint inflammation, including osteoarthritis and rheumatoid arthritis. However, little is known about the interactions among different cell subtypes and the specific sets of signaling pathways and activities that they trigger.

METHODS

Using social network analysis, pattern recognition, and manifold learning approaches, we identified patterns of single-cell communication in OA (osteoarthritis) and RA (rheumatoid arthritis).

RESULTS

Our results suggest that OA and RA have distinct cellular communication patterns and signaling pathways. The LAMININ (Laminin) and COLLAGEN (Collagen) pathways predominate in osteoarthritis, while the EGF (Epidermal growth factor), NT (Neurotrophin) and CDH5 (Cadherin 5) pathways predominate in rheumatoid arthritis, with a central role for THY1 (Thy-1 cell surface antigen) +CDH11 (Cadherin 11) + cells. The OA opens the PDGF (Platelet-derived growth factors) pathway (driver of bone angiogenesis), the RA opens the EGF pathway (bone formation) and the SEMA3 (Semaphorin 3A) pathway (involved in immune regulation). Interestingly, we found that OA no longer has cell types involved in the MHC complex (Major histocompatibility complex) and their activity, whereas the MHC complex functions primarily in RA in the presentation of inflammatory antigens, and that the complement system in OA has the potential to displace the function of the MHC complex. The specific signaling patterns of THY1+CDH11+ cells and their secreted ligand receptors are more conducive to cell migration and lay the foundation for promoting osteoclastogenesis. This subpopulation may also be involved in the accumulation of lymphocytes, affecting the recruitment of immune cells. Members of the collagen family (COL1A1 (Collagen Type I Alpha 1 Chain), COL6A2 (Collagen Type VI Alpha 2 Chain) and COL6A1 (Collagen Type VI Alpha 1 Chain)) and transforming growth factor (TGFB3) maintain the extracellular matrix in osteoarthritis and mediate cell migration and adhesion in rheumatoid arthritis, including the PTN (Pleiotrophin) / THBS1 (Thrombospondin 1) interaction.

CONCLUSION

Increased understanding of the interaction networks between synovial fibroblast subtypes, particularly the shared and unique cellular communication features between osteoarthritis and rheumatoid arthritis and their hub cells, should help inform the design of therapeutic agents for inflammatory joint disease.

Association of Immune Semaphorins with COVID-19 Severity and Outcomes

Semaphorins have recently been recognized as crucial modulators of immune responses. In the pathogenesis of COVID-19, the activation of immune responses is the key factor in the development of severe disease. This study aimed to determine the association of serum semaphorin concentrations with COVID-19 severity and outcomes. Serum semaphorin concentrations (SEMA3A, -3C, -3F, -4D, -7A) were measured in 80 hospitalized adult patients with COVID-19 (moderate (n = 24), severe (n = 32), critical, (n = 24)) and 40 healthy controls. While SEMA3C, SEMA3F and SEMA7A serum concentrations were significantly higher in patients with COVID-19, SEMA3A was significantly lower. Furthermore, SEMA3A and SEMA3C decreased with COVID-19 severity, while SEMA3F and SEMA7A increased. SEMA4D showed no correlation with disease severity. Serum semaphorin levels show better predictive values than CRP, IL-6 and LDH for differentiating critical from moderate/severe COVID-19. SEMA3F and SEMA7A serum concentrations were associated with the time to recovery, requirement of invasive mechanical ventilation, development of pulmonary thrombosis and nosocomial infections, as well as with in-hospital mortality. In conclusion, we provide the first evidence that SEMA3A, SEMA3C, SEMA3F and SEMA7A can be considered as new biomarkers of COVID-19 severity.

Semaphorin 3A influences neuronal processes that are altered in patients with autism spectrum disorder: Potential diagnostic and therapeutic implications

Autism spectrum disorder (ASD) is a pervasive disorder that most frequently manifests in early childhood and lasts for their entire lifespan. Several behavioural traits characterise the phenotype of patients with ASD, including difficulties in reciprocal social communication as well as compulsive/repetitive stereotyped verbal and non-verbal behaviours. Although multiple hypotheses have been proposed to explain the aetiology of ASD and many resources have been used to improve our understanding of ASD, several aspects remain largely unexplored. Class 3 semaphorins (SEMA3) are secreted proteins involved in the organisation of structural and functional connectivity in the brain that regulate synaptic and dendritic development. Alterations in brain connectivity and aberrant neuronal development have been described in some patients with ASD. Mutations and polymorphisms in SEMA3A and alterations in its receptors and signalling have been associated with some neurological disorders such as schizophrenia and epilepsy, which are comorbidities in ASD, but also with ASD itself. In addition, SEMA3A is a key regulator of the immune response and neuroinflammatory processes, which have been found to be dysregulated in mothers of children who develop ASD and in affected patients. In this review, we highlight neurodevelopmental-related processes in which SEMA3A is involved, which are altered in ASD, and provide a viewpoint emphasising the development of strategies targeting changes in the SEMA3A signal to identify patterns of anomalies distinctive of ASD or to predict the prognosis of affected patients.

Genetic variation in environmental enteropathy and stunting in Zambian children: A pilot genome wide association study using the H3Africa chip

PURPOSE

Stunting is known to be heavily influenced by environmental factors, so the genetic contribution has received little attention. Here we report an exploration of genetic influences in stunted Zambian children with environmental enteropathy.

METHOD

Children with stunting (LAZ < -2) were enrolled and given nutritional therapy. Those that were non-responsive to therapy were designated as cases, and children with good growth (LAZ > -1) from the same community as controls. Blood and stool samples were taken to measure biomarkers of intestinal inflammation, epithelial damage, and microbial translocation. Single nucleotide polymorphism array genotyping was carried out on saliva samples using the H3Africa consortium array.

RESULTS

Genome wide associations were analysed in 117 cases and 41 controls. While no significant associations with stunting were observed at P<5x10-8, likely due to the small sample size, interesting associations were observed at lower thresholds. SNPs associated with stunting were in genomic regions known to modulate neuronal differentiation and fatty acid biosynthesis. SNPs associated with increased microbial translocation were associated with non-integrin membrane ECM interactions, tight junctions, hemostasis, and G-alpha signalling events. SNPs associated with increased inflammation were associated with, ECM interactions, purine metabolism, axon guidance, and cell motility. SNPs negatively associated with inflammation overlapped genes involved in semaphoring interactions. We explored the existing coeliac disease risk HLA genotypes and found present: DQ2.5 (7.5%), DQ8 (3.5%) and DQ2.2 (3.8%); however, no children were positive for coeliac antibodies. We detected HLA-DRB:1301 and HLA-C:1802 with high odds ratios and P<0.05 in stunted children compared to controls.

CONCLUSION

Genetic variations associated with stunting and the enteropathy underlying it, include variants associated with multiple pathways relating to gene expression, glycosylation, nerve signalling, and sensing of the nutritional and microbiological milieu.

HOXA5 is a key regulator of class 3 semaphorins expression in the synovium of rheumatoid arthritis patients

OBJECTIVE

Class 3 semaphorins are reduced in the synovial tissue of RA patients and these proteins are involved in the pathogenesis of the disease. The aim of this study was to identify the transcription factors involved in the expression of class 3 semaphorins in the synovium of RA patients.

METHODS

Protein and mRNA expression in synovial tissue from RA and individuals at risk (IAR) patients, human umbilical vein endothelial cells (HUVEC) and RA fibroblast-like synoviocytes (FLS) was determined by ELISA, immunoblotting and quantitative PCR. TCF-3, EBF-1 and HOXA5 expression was knocked down using siRNA. Cell viability, migration and invasion were determined using MTT, calcein, wound closure and invasion assays, respectively.

RESULTS

mRNA expression of all class 3 semaphorins was significantly lower in the synovium of RA compared with IAR patients. In silico analysis suggested TCF-3, EBF-1 and HOXA5 as transcription factors involved in the expression of these semaphorins. TCF-3, EBF-1 and HOXA5 silencing significantly reduced the expression of several class 3 semaphorin members in FLS and HUVEC. Importantly, HOXA5 expression was significantly reduced in the synovium of RA compared with IAR patients and was negatively correlated with clinical disease parameters. Additionally, TNF-α down-regulated the HOXA5 expression in FLS and HUVEC. Finally, HOXA5 silencing enhanced the migratory and invasive capacities of FLS and the viability of HUVEC.

CONCLUSION

HOXA5 expression is reduced during the progression of RA and could be a novel therapeutic strategy for modulating the hyperplasia of the synovium, through the regulation of class 3 semaphorins expression.

Pathophysiological functions of semaphorins in the sympathetic nervous system

Upon exposure to external stressors, the body senses them and activates the sympathetic nervous system (SNS) to maintain the homeostasis, which is known as the "fight-or-flight" response. Recent studies have revealed that the SNS also plays pivotal roles in regulating immune responses, such as hematopoiesis, leukocyte mobilization, and inflammation. Indeed, overactivation of the SNS causes many inflammatory diseases, including cardiovascular diseases, metabolic disorders, and autoimmune diseases. However, the molecular basis essential for SNS-mediated immune regulation is not completely understood. In this review, we focus on axon guidance cues, semaphorins, which play multifaceted roles in neural and immune systems. We summarize the functions of semaphorins in the crosstalk between the SNS and the immune system, exploring its pathophysiological roles.

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.

Low expression of SEMA4D as a potential predictive molecular marker of poor survival in patients with melanoma combined with liver cancer

This study explored the correlation between semaphorin 4D (SEMA4D) and the prognosis and survival time of patients with melanoma combined with liver cancer. A total of 272 patients were recruited, and clinical and follow-up data were recorded. The expression levels of SEMA4D and SEMA3B were determined. Pearson's χ² test and Spearman's rank correlation coefficient were used to analyze the relationship between prognosis and the assessed parameters of melanoma patients. Univariate and multivariate Logistic regression and Cox proportional risk regression analyses were used for further analysis. Additionally, receiver operating characteristic curve and survival curves of subjects were plotted. The Pearson's χ² test showed that the prognosis of melanoma patients was significantly correlated with age, tumor grade, and decreased SEMA4D expression. Additionally, Spearman's correlation coefficient analysis showed that age, tumor grade, and SEMA4D expression were significantly correlated with prognosis. Univariate logistic regression analysis showed that age and tumor grade, and SEMA4D expression, were significantly correlated with prognosis. Older patients, a higher tumor grade, and lower SEMA4D expression were associated with a poorer prognosis. Multivariate logistic regression analysis showed that older patients had a poorer prognosis, and patients with lower SEMA4D expression levels had a significantly worse prognosis than patients with higher SEMA4D expression levels. Kaplan-Meier analysis showed that the survival time of older patients was lower than that of the younger patients. The survival times of patients with lower SEMA4D expression levels were significantly lower than that of patients with higher SEMA4D expression levels. Multivariate Cox regression analysis showed that the survival time of older patients was lower than that of younger patients. The survival time of melanoma patients with low SEMA4D expression was significantly lower than that of patients with higher SEMA4D expression. SEMA4D was significantly associated with melanoma, and lower SEMA4D expression was associated with a poorer survival prognosis in melanoma patients.

Semaphorin 4A as a Potential Biomarker for Diagnosis of Systemic Lupus Erythematosus

BACKGROUND

Semaphorin 4A (Sema4A) is an immunoregulatory molecule that is closely related to the pathogenesis of some autoimmune diseases. However, the relationship between Sema4A and systemic lupus erythematosus (SLE) remains unknown. We therefore aimed to investigate the expression and clinical value of Sema4A in SLE patients.

METHODS

Patients with SLE, rheumatoid arthritis (RA), and healthy controls (HC) were enrolled. The whole blood samples were collected from SLE (83), RA (29) and HC (85), and the expression of Sema4A on several types of leukocytes in peripheral blood was detected by flow cytometry. The serum samples were collected from SLE(77), RA (23) and HC (63), and the concentrations of soluble Sema4A in plasma were detected by ELISA. The diagnostic value of membrane-bound and soluble Sema4A in SLE patients was evaluated using a receiver operating characteristic (ROC) curve.

RESULTS

The concentration of soluble Sema4A was significantly higher in plasma from SLE patients compared to that from HC and RA patients. In SLE patients, the ratio of CD4+CD11c+ myeloid dendritic cells (mDCs) expressing Sema4A increased significantly, and the levels of soluble Sema4A and membrane-bound Sema4A were negatively correlated with the levels of C3 and C4, respectively. The same result was observed for membrane-bound Sema4A on CD4+CD11c+ mDCs cells. In addition, the level of soluble Sema4A negatively correlated with the concentration of hemoglobin (Hb). Importantly, the expression ratio of membrane-bound Sema4A on CD4+CD11c+ mDCs was positively correlated with systemic lupus erythematosus disease activity index (SLEDAI). Finally, we revealed that soluble and membrane- bound Sema4A had high sensitivity and specificity for diagnosis of SLE, and had a greater ability to distinguish between SLE and RA.

CONCLUSION

Sema4A has potential as a new diagnostic biomarker for SLE, and is promising for distinguishing between SLE and RA.

CD72-semaphorin3A axis: A new regulatory pathway in systemic lupus erythematosus

CD72 is a regulatory co-receptor on B cells, with a role in the pathogenesis of systemic lupus erythematosus (SLE) in both human and animal models. Semaphorin3A (sema3A) is a secreted member of the semaphorin family that can reconstruct B cells' regulatory functions by upregulating IL-10 expression and inhibiting the pro-inflammatory activity of B and T cells in autoimmune diseases. The aim of our present study was to identify a new ligand for CD72, namely sema3A, and exploring the signal transduction pathways following its ligation in B cells. We established that CD72 functions as sema3A binding and signal-transducing receptor. These functions of CD72 are independent of neuropilin-1 (NRP-1) (the known sema3A receptor). We discovered that sema3A induces the phosphorylation of CD72 on tyrosine residues and the association of CD72 with SHP-1 and SHP-2. In addition, the binding of sema3A to CD72 on B cells inhibits the phosphorylation of STAT-4 and HDAC-1 and induces the phosphorylation of p38-MAPK and PKC-theta in B-cells derived B-lymphoblastoid (BLCL) cells, and in primary B-cells isolated from either healthy donors or SLE patients. We concluded that sema3A is a functional regulatory ligand for CD72 on B cells. The sema3A-CD72 axis is a crucial regulatory pathway in the pathogenesis of autoimmune and inflammatory diseases namely SLE, and modulation of this pathway may have a potential therapeutic value for autoimmune diseases.

Increased sIL-2Rα leads to obstruction of IL-2 biological function and Treg cells differentiation in SLE patients via binding to IL-2

Background

The decrease of IL-2 level is believed to play an important role in the disease occurrence and development of SLE, but the relevant mechanisms have not been fully clarified. Many studies have found that the level of soluble interleukin 2 receptor α (sIL-2Rα) in SLE patients is significantly increased. Considering the fact that sIL-2Rα has the ability to bind IL-2, we want to know whether the increased sIL-2Rα has some impact on the level and function of IL-2 in SLE patients.

Methods

New onset SLE patients, treated SLE patients and healthy volunteers were recruited. The levels of serum IL-2, IL-2 mRNA in CD3⁺ T cells and serum sIL-2Rα were detected and compared in these subjects. Two mixed solid-phase sandwich ELISA system were designed to measure exclusively the heterodimers complex of sIL-2Rα/IL-2. The sera from SLE patients were pretreated with or without immune complex dissociation solution and detected for IL-2 levels. IL-2 standard or serum from HCs were used to co-incubate with recombinant sIL-2Rα or serum samples with high levels of sIL-2Rα and detected for IL-2 levels by ELISA. The inhibitory effect of sIL-2Rα on IL-2 biological activity was investigated by CTLL-2 cell proliferation assay. The frequencies and absolute counts of Treg cells were detected by flow cytometry before and after the addition of recombinant sIL-2Rα.

Results

The levels of serum IL-2 in SLE patients were significantly decreased and negatively correlated with SLEDAI. However, there was no significant difference in IL-2 mRNA levels in CD3⁺ T cells between SLE patients and healthy controls. The levels of serum sIL-2Rα in SLE patients were significantly increased, positively correlated with the SLEDAI and negatively correlated with the levels of serum IL-2. sIL-2Rα was shown to bind to IL-2 to form immune complex, resulting in false reduction in the detection level of serum IL-2 and significant decrease in biological activity of IL-2. The increase of sIL-2Rα was demonstrated to be one of the important mechanisms for the obstruction of Treg cells differentiation in SLE patients.

Conclusion

Increased serum sIL-2Rα can bind to IL-2, leading to obstruction of IL-2 activity and Treg cells differentiation.

A semaphorin-plexin-Rasal1 signaling pathway inhibits gastrin expression and protects against peptic ulcers

Peptic ulcer disease is a frequent clinical problem with potentially serious complications such as bleeding or perforation. A decisive factor in the pathogenesis of peptic ulcers is gastric acid, the secretion of which is controlled by the hormone gastrin released from gastric G cells. However, the molecular mechanisms regulating gastrin plasma concentrations are poorly understood. Here, we identified a semaphorin-plexin signaling pathway that operates in gastric G cells to inhibit gastrin expression on a transcriptional level, thereby limiting food-stimulated gastrin release and gastric acid secretion. Using a systematic siRNA screening approach combined with biochemical, cell biology, and in vivo mouse experiments, we found that the RasGAP protein Rasal1 is a central mediator of plexin signal transduction, which suppresses gastrin expression through inactivation of the small GTPase R-Ras. Moreover, we show that Rasal1 is pathophysiologically relevant for the pathogenesis of peptic ulcers induced by nonsteroidal anti-inflammatory drugs (NSAIDs), a main risk factor of peptic ulcers in humans. Last, we show that application of recombinant semaphorin 4D alleviates peptic ulcer disease in mice in vivo, demonstrating that this signaling pathway can be harnessed pharmacologically. This study unravels a mode of G cell regulation that is functionally important in gastric homeostasis and disease.

An antagonistic monoclonal anti-Plexin-B1 antibody exerts therapeutic effects in mouse models of postmenopausal osteoporosis and multiple sclerosis

Osteoporosis and multiple sclerosis are highly prevalent diseases with limited treatment options. In light of these unmet medical needs, novel therapeutic approaches are urgently sought. Previously, the activation of the transmembrane receptor Plexin-B1 by its ligand semaphorin 4D (Sema4D) has been shown to suppress bone formation and promote neuroinflammation in mice. However, it is unclear whether inhibition of this receptor–ligand interaction by an anti–Plexin-B1 antibody could represent a viable strategy against diseases related to these processes. Here, we raised and systematically characterized a monoclonal antibody directed against the extracellular domain of human Plexin-B1, which specifically blocks the binding of Sema4D to Plexin-B1. In vitro, we show that this antibody inhibits the suppressive effects of Sema4D on human osteoblast differentiation and mineralization. To test the therapeutic potential of the antibody in vivo, we generated a humanized mouse line, which expresses transgenic human Plexin-B1 instead of endogenous murine Plexin-B1. Employing these mice, we demonstrate that the anti–Plexin-B1 antibody exhibits beneficial effects in mouse models of postmenopausal osteoporosis and multiple sclerosis in vivo. In summary, our data identify an anti–Plexin-B1 antibody as a potential therapeutic agent for the treatment of osteoporosis and multiple sclerosis.

Semaphorin 5A suppresses ferroptosis through activation of PI3K-AKT-mTOR signaling in rheumatoid arthritis

Abnormal activation of synovial fibroblasts (SFs) plays an important role in rheumatoid arthritis (RA), the mechanism of which remains unknown. The purpose of our study is to comprehensively and systematically explore the mechanism for Semaphorin 5A-mediated abnormal SF activation in RA. Here, we found that Semaphorin 5A levels were significantly higher in synovial fluid and synovial tissue from RA patients compared with osteoarthritis patients. We further found that the mRNA level and protein abundance of Plexin-A1 was elevated in RA SFs compared with OA SFs, while Plexin-B3 expression showed no significant difference. The increased Semaphorin 5A in RA synovial fluid was mainly derived from CD68⁺ synovial macrophages, and the elevation led to increased binding between Semaphorin 5A and its receptors, thereby promoting cytokine secretion, proliferation, and migration, and decreasing apoptosis. Moreover, the effect of Semaphorin 5A on enhancing activation (cytokine secretion, cell proliferation and migration) and reducing apoptosis of SFs was significantly abolished after knockdown of Plexin-A1 and Plexin-B3 by small interfering RNA. Transcriptome sequencing and protein array detection revealed that Semaphorin 5A activated the PI3K/AKT/mTOR signaling pathway and inhibited ferroptosis. Morphologically, transmission electron microscopy results showed that Semaphorin 5A could significantly eliminate the mitochondrial diminution, membrane density increased and crest ruptured of SFs induced by ferroptosis inducer RSL3. Mechanistically, Semaphorin 5A enhanced GPX4 expression and SREBP1/SCD-1 signaling by activating the PI3K/AKT/mTOR signaling pathway, thus suppressing ferroptosis of RA SFs. In conclusion, our study provided the first evidence that elevated Semaphorin 5A in RA synovial fluid promotes SF activation by suppressing ferroptosis through the PI3K/AKT/mTOR signaling pathway.

Circulating Neurovascular Guidance Molecules and Their Relationship with Peripheral Microvascular Impairment in Systemic Sclerosis

Systemic sclerosis (SSc, scleroderma) is a complex connective tissue disease whose earliest clinical manifestations are microvascular tone dysregulation and peripheral microcirculatory abnormalities. Following previous evidence of an association between circulating neurovascular guidance molecules and SSc disturbed angiogenesis, here, we measured the levels of soluble neuropilin 1 (sNRP1), semaphorin 3E (Sema3E), and Slit2 by enzyme-linked immunosorbent assay in serum samples from a large case series of 166 SSc patients vs. 110 healthy controls. We focused on their possible correlation with vascular disease clinical features and applied logistic regression analysis to determine which of them could better reflect disease activity and severity. Our results demonstrate that, in SSc: (i) sNRP1 is significantly decreased, with lower sNRP1 serum levels correlating with the severity of nailfold videocapillaroscopy (NVC) abnormalities and the presence of ischemic digital ulcers (DUs); (ii) both Sema3E and Slit2 are increased, with Sema3E better reflecting early NVC abnormalities; and (iii) higher Sema3E correlates with the absence of DUs, while augmented Slit2 associates with the presence of DUs. Receiver operator characteristics curve analysis revealed that both circulating sNRP1 and Sema3E show a moderate diagnostic accuracy. Moreover, logistic regression analysis allowed to identify sNRP1 and Sema3E as more suitable independent biomarkers reflecting the activity and severity of SSc-related peripheral microvasculopathy.

Muscone Can Improve Spinal Cord Injury by Activating the Angiogenin/Plexin-B2 Axis

Spinal cord injury (SCI) is a devastating neurological disorder that usually damages sensorimotor and autonomic functions. Signaling pathways can play a key role in the repair process of SCI. The plexin-B2 acts as a receptor for angiogenin and mediates ribosomal RNA transcription, influencing cell survival and proliferation. Protein kinase B serine/threonine kinase interacts with angiogenin to form a positive feedback effect. Brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor can induce angiogenin nuclear translocation. Moreover, the BDNF can promote the secretion of angiogenin. Interestingly, all of them can activate the angiogenin/plexin-B2 axis. Muscone has anti-inflammatory and proliferative features as it can inhibit nuclear transcription factor kappa-B (NF-κB) and activate the angiogenin/plexin-B2 axis, thus being significant agent in the SCI repair process. Herein, we review the potential mechanism of angiogenin/plexin-B2 axis activation and the role of muscone in SCI treatment. Muscone may attenuate inflammatory responses and promote neuronal regeneration after SCI.

Clinical Values of the Identified Hub Genes in Systemic Lupus Erythematosus

Objective

This study was conducted to identify the biomarkers and mechanisms associated with systemic lupus erythematosus(SLE) at a transcriptome level.

Methods

Microarray datasets were downloaded, and differentially expressed genes (DEGs) were identified. Enrichment and protein-protein interaction networks were analyzed, and hub genes were discovered. The levels of top 10 hub genes were validated by another dataset. The diagnostic accuracy of the hub genes was evaluated with the area under the curve of the receiver operating characteristic curve (ROC-AUC). The odds ratios (OR) and 95% confidence intervals (CI) of the relationship between clinical manifestations and hub genes were estimated with multivariable logistic regression. The relationships between the expression levels of the 10 identified hub genes and SLEDAI scores were subjected to linear correlation analysis. Changes in the expression levels of the hub genes during patient follow-up were examined through one-way repeated measures ANOVA.

Results

A total of 136 DEGs were identified. Enrichment analysis indicated that DEGs were primarily enriched in type I interferon-associated pathways. The identified hub genes were verified by the GSE65391 dataset. The 10 hub genes had good diagnostic performances. Seven (except IFI6, OAS1 and IFIT3) of the 10 hub genes were positively associated with SLEDAI. The combination models of IFIT3, ISG15, MX2, and IFIH1 were effective in diagnosing mucosal ulcers among patients with SLE. The expression levels of IRF7, IFI35, IFIT3, and ISG15 decreased compared with the baseline expression (not significantly).

Conclusions

In this work, the clinical values of the identified hub genes in SLE were demonstrated.

Effects and Molecular Regulation Mechanisms of Salinity Stress on the Health and Disease Resistance of Grass Carp

Though some freshwater fish have been successfully cultivated in saline-alkali water, the survival rates of freshwater fish are greatly affected by different saline-alkali conditions. The mechanisms of immune adaptation or immunosuppression of freshwater fish under different saline-alkali stress remain unclear. Here, grass carp were exposed to 3‰ and 6‰ salinity for 30 days. It was observed that salinity treatments had no obvious effects on survival rates, but significantly increased the percent of unhealthy fish. Salinity treatments also increased the susceptibility of grass carp against Flavobacterium columnare infection. The fatality rate (16.67%) of grass carp treated with 6‰ salinity was much lower than that treated with 3‰ salinity (40%). In the absence of infection, higher numbers of immune-related DEGs and signaling pathways were enriched in 6‰ salinity-treated asymptomatic fish than in 3‰ salinity-treated asymptomatic fish. Furthermore different from salinity-treated symptomatic fish, more DEGs involved in the upstream sensors of NOD-like receptor signaling pathway, such as NLRs, were induced in the gills of 6‰ salinity-treated asymptomatic fish. However in the case of F. columnare infection, more immune-related signaling pathways were impaired by salinity treatments. Among them, only NOD-like receptor signaling pathway was significantly enriched at early (1 and/or 2 dpi) and late (7 dpi) time points of infection both for 3‰ salinity-treated and 6‰ salinity-treated fish. Besides the innate immune responses, the adaptive immune responses such as the production of Ig levels were impaired by salinity treatments in the grass carp infected with F. columnare. The present study also characterized two novel NLRs regulated by salinity stress could inhibit bacterial proliferation and improve the survival rate of infected cells. Collectively, the present study provides the insights into the possible mechanisms why the percent of unhealthy fish in the absence of infection and mortality of grass carp in the case of F. columnare infection were much lower in the 6‰ salinity-treated grass carp than in 3‰ salinity-treated grass carp, and also offers a number of potential markers for sensing both environmental salinity stress and pathogen.

Semaphorin 3G exacerbates joint inflammation through the accumulation and proliferation of macrophages in the synovium

Objectives

Methotrexate (MTX) is an anchor drug for the treatment of rheumatoid arthritis (RA). However, the precise mechanisms by which MTX stalls RA progression and alleviates the ensuing disease effects remain unknown. The aim of the present study was to identify novel therapeutic target molecules, the expression patterns of which are affected by MTX in patients with RA.

Methods

CD4⁺ T cells from 28 treatment-naïve patients with RA before and 3 months after the initiation of MTX treatment were subjected to DNA microarray analyses. The expression levels of semaphorin 3G, a differentially expressed gene, and its receptor, neuropilin-2, were evaluated in the RA synovium and collagen-induced arthritis synovium. Collagen-induced arthritis and collagen antibody-induced arthritis were induced in semaphorin3G-deficient mice and control mice, and the clinical score, histological score, and serum cytokines were assessed. The migration and proliferation of semaphorin 3G-stimulated bone marrow-derived macrophages were analyzed in vitro. The effect of local semaphorin 3G administration on the clinical score and number of infiltrating macrophages during collagen antibody-induced arthritis was evaluated.

Results

Semaphorin 3G expression in CD4⁺ T cells was downregulated by MTX treatment in RA patients. It was determined that semaphorin 3G is expressed in RA but not in the osteoarthritis synovium; its receptor neuropilin-2 is primarily expressed on activated macrophages. Semaphorin3G deficiency ameliorated collagen-induced arthritis and collagen antibody-induced arthritis. Semaphorin 3G stimulation enhanced the migration and proliferation of bone marrow-derived macrophages. Local administration of semaphorin 3G deteriorated collagen antibody-induced arthritis and increased the number of infiltrating macrophages.

Conclusions

Upregulation of semaphorin 3G in the RA synovium is a novel mechanism that exacerbates joint inflammation, leading to further deterioration, through macrophage accumulation.

Identifying Function Determining Residues in Neuroimmune Semaphorin 4A

Semaphorin 4A (Sema4A) exerts a stabilizing effect on human Treg cells in PBMC and CD4+ T cell cultures by engaging Plexin B1. Sema4A deficient mice display enhanced allergic airway inflammation accompanied by fewer Treg cells, while Sema4D deficient mice displayed reduced inflammation and increased Treg cell numbers even though both Sema4 subfamily members engage Plexin B1. The main objectives of this study were: 1. To compare the in vitro effects of Sema4A and Sema4D proteins on human Treg cells; and 2. To identify function-determining residues in Sema4A critical for binding to Plexin B1 based on Sema4D homology modeling. We report here that Sema4A and Sema4D display opposite effects on human Treg cells in in vitro PBMC cultures; Sema4D inhibited the CD4+CD25+Foxp3+ cell numbers and CD25/Foxp3 expression. Sema4A and Sema4D competitively bind to Plexin B1 in vitro and hence may be doing so in vivo as well. Bayesian Partitioning with Pattern Selection (BPPS) partitioned 4505 Sema domains from diverse organisms into subgroups based on distinguishing sequence patterns that are likely responsible for functional differences. BPPS groups Sema3 and Sema4 into one family and further separates Sema4A and Sema4D into distinct subfamilies. Residues distinctive of the Sema3,4 family and of Sema4A (and by homology of Sema4D) tend to cluster around the Plexin B1 binding site. This suggests that the residues both common to and distinctive of Sema4A and Sema4D may mediate binding to Plexin B1, with subfamily residues mediating functional specificity. We mutated the Sema4A-specific residues M198 and F223 to alanine; notably, F223 in Sema4A corresponds to alanine in Sema4D. Mutant proteins were assayed for Plexin B1-binding and Treg stimulation activities. The F223A mutant was unable to stimulate Treg stability in in vitro PBMC cultures despite binding Plexin B1 with an affinity similar to the WT protein. This research is a first step in generating potent mutant Sema4A molecules with stimulatory function for Treg cells with a view to designing immunotherapeutics for asthma.

Semaphorin 7A accelerates the inflammatory osteolysis of periapical lesions

INTRODUCTION

Semaphorin 7A (SEMA7A), the only member of the class VII semaphorin, has been considered as a potent immunomodulatory regulator, whose function in periapical lesions remains unclear. In our previous study, we found that SEMA7A was upregulated in human periapical periodontitis and might be involved in the immune response and tissue destruction of periapical lesions. In this research, we aimed to further explore the specifical regulatory role of SEMA7A as well as its regulatory mechanisms in the inflammatory progression of periapical lesions.

METHODS

Human periodontal ligament cells (hPDLCs) were collected from intact, caries-free, and healthy third molars and stimulated with recombinant human SEMA7A (rhSEMA7A). Real-time quantitative polymerase chain reaction (RT-qPCR), western blot and enzyme-linked immunosorbent assay (ELISA) were used to detect the mRNA and protein levels of inflammatory cytokines and matrix metalloproteinases (MMPs) in hPDLCs. 20 C57BL/6 mice were randomly divided into 4 groups: healthy control group, pulp exposure group, pulp exposure and saline treatment group and pulp exposure and rhSEMA7A treatment group. 20 μL sterile saline or 20 μL 200 ng/μL rhSEMA7A were injected respectively into the buccal mucosa around the root apex at day 0, 7, and 14. Mandibular tissues were collected at day 21. Micro-CT and immunohistochemical (IHC) staining were used to identify the bone destruction and inflammatory infiltration in periapical areas. Finally, AKT inhibitor (LY294002) was used to pretreat hPDLCs before rhSEMA7A stimulation to determine the role of AKT signaling activation in this process.

RESULTS

After treatment with rhSEMA7A, the mRNA and protein levels of interleukin (IL)-1β, IL-18, COX-2, MMP-1, and MMP-3 were remarkably upregulated in hPDLCs. In in vivo experiments, compared with other three groups, the treatment of rhSEMA7A would aggravate the osteolysis of alveolar bone and promote the infiltration of immune cells into the apex area accompanying with the increasing expression level of IL-1β, IL-18, matrix metalloproteinase (MMP)-1 and MMP-3. Furthermore, we found that the pro-inflammatory role of SEMA7A could be inhibited by the application of AKT inhibitor (LY294002).

CONCLUSION

SEMA7A likely aggravates the inflammatory reaction and bone destruction of existing periapical lesions. The pro-inflammatory role of SEMA7A in hPDLCs could partially be mediated through the ATK signaling transduction pathway.

Semaphorins as Potential Immune Therapeutic Targets for Cancer

Semaphorins are a large class of secreted or membrane-bound molecules. It has been reported that semaphorins play important roles in regulating several hallmarks of cancer, including angiogenesis, metastasis, and immune evasion. Semaphorins and their receptors are widely expressed on tumor cells and immune cells. However, the biological role of semaphorins in tumor immune microenvironment is intricate. The dysregulation of semaphorins influences the recruitment and infiltration of immune cells, leading to abnormal anti-tumor effect. Although the underlying mechanisms of semaphorins on regulating tumor-infiltrating immune cell activation and functions are not fully understood, semaphorins can notably be promising immunotherapy targets for cancer.

Semaphorin-3A: a promising therapeutic tool in allergic rhinitis

Semaphorin-3A (Sema-3A), a secreted member of the semaphorin family, is well known for playing regulatory functions at all stages of the immune response. Sema-3A transduces signals by binding to its cognate receptors, namely, class A plexins (Plxns A1 to A4) and neuropilin-1 (Nrp-1). The downstream diverse signaling pathways induced by connecting Sema-3A to its receptors were found to be involved in the pathogenesis of different immunological disorders, ranging from cancer to autoimmunity and allergies. Recent studies have demonstrated that Sema-3A expression is diminished in the murine models and patients with allergic rhinitis (AR; a chronic inflammatory disorder of the nasal mucosa), suggesting the involvement of Sema-3A in AR pathogenesis. Investigations also revealed that treatment of these mice with exogenous Sema-3A protein alleviates the clinical symptom scores of AR, thereby compensating for the reduced expression of Sema-3A in AR. Indeed, Sema-3A treatment could suppress allergic responses in AR via inhibiting Th2/Th17 responses and boosting Th1/Treg responses. Also, Sema-3A could diminish dendritic cell (DC) maturation and T cell proliferation. Since it is implicated in the pathogenesis of AR; thus, Sema-3A turns to be a promising tool of therapy to be studied and utilized in this disease. This review intends to highlight the recent evidence on the role of Sema-3A in AR pathogenesis and summarizes the recent findings regarding the expression status of Sema-3A, as well as its therapeutic potential for treating this disease. HIGHLIGHTS: Sema-3A plays regulatory functions at all stages of the immune response. Sema-3A receptors are the class A plexins (A1-A4) and neuropilin-1 (Nrp-1). Sema-3A expression is reduced in murine models and patients with allergic rhinitis. Connecting Sema-3A to Nrp-1 increases Foxp3 expression in Treg cells. Injecting Sema-3A protein exerts therapeutic effects in mouse models of allergic diseases. Sema-3A shows promise as a therapeutic tool for the treatment of allergic rhinitis.

OUP accepted manuscript

Omics-based biomedical learning frequently relies on data of high-dimensions (up to thousands) and low-sample sizes (dozens to hundreds), which challenges efficient deep learning (DL) algorithms, particularly for low-sample omics investigations. Here, an unsupervised novel feature aggregation tool AggMap was developed to Aggregate and Map omics features into multi-channel 2D spatial-correlated image-like feature maps (Fmaps) based on their intrinsic correlations. AggMap exhibits strong feature reconstruction capabilities on a randomized benchmark dataset, outperforming existing methods. With AggMap multi-channel Fmaps as inputs, newly-developed multi-channel DL AggMapNet models outperformed the state-of-the-art machine learning models on 18 low-sample omics benchmark tasks. AggMapNet exhibited better robustness in learning noisy data and disease classification. The AggMapNet explainable module Simply-explainer identified key metabolites and proteins for COVID-19 detections and severity predictions. The unsupervised AggMap algorithm of good feature restructuring abilities combined with supervised explainable AggMapNet architecture establish a pipeline for enhanced learning and interpretability of low-sample omics data.

Evaluation of molecular apoptosis signaling pathways and its correlation with EBV viral load in SLE patients using systems biology approach

BACKGROUND

Considerable evidence supports that SLE could be related to apoptotic cells and EBV infection.

OBJECTIVE

The aim of this study was to identify the transcriptional signature of EBV infection in SLE patients for survey of the molecular apoptosis signaling pathways.

METHODS

The PBMCs gene expression profiles of healthy control and SLE patients were obtained from GEO. Functional annotation and signaling pathway enrichment were carried out using DAVID, KEGG. To validate bioinformatics analysis the changes in genes expression of some of obtained genes, Real time PCR was performed on PBMCs from 28 SLE patients and 18 controls.

RESULTS

We found that mean viral load was 6013 ± 390.1 copy/μg DNA from PBMCs in all patients. QRT-PCR results showed that the expression of the DUSP1 and LAMP3 genes which had most changes in the logFC among 4 candidate genes, increased significantly in comparison with control. The consistent expression of LMP2 as viral latency gene involve in apoptosis signaling pathways was detected in SLE patients with EBV viral load and some controls.

CONCLUSIONS

The study indicated that some cellular genes may have an important role in pathogenesis of SLE through apoptosis signaling pathways. Beside, EBV infection as an environmental risk factor for SLE may affect the dysfunction of apoptosis.

Semaphorin 3A Levels in Lupus With and Without Secondary Antiphospholipid Antibody Syndrome and Renal Involvement

OBJECTIVE

The aim of this study is to evaluate semaphorin 3A levels in patients with systemic lupus erythematosus (SLE) with and without renal involvement and secondary antiphospholipid antibody syndrome (APS).

METHODS

Patients with SLE were grouped according to the presence of secondary APS or renal involvement. The control group consisted of age-matched, nonsmoking, healthy volunteers. Semaphorin 3A levels were compared among groups. All patients with SLE were regrouped according to the presence of thrombotic events, miscarriages, and proteinuria, and semaphorin 3A levels were investigated. Finally, semaphorin 3A levels of all patients with SLE as a single group were compared to those of the control patients.

RESULTS

The mean semaphorin 3A values were 16.16 ± 2.84 ng/mL in the control group, 9.05 ± 5.65 ng/mL in patients with SLE without nephritis and APS, 11.28 ± 5.23 ng/mL in the SLE with APS group, and 8.53 ± 5.11 ng/mL in the lupus nephritis group. When all 3 patient groups were examined as a single group, the mean semaphorin 3A value was significantly lower than that of the control group. Semaphorin 3A was reduced in patients with SLE with thromboembolism and/or history of miscarriage.

CONCLUSION

Semaphorin 3A levels were lower in all patient groups compared to the control group. Moreover, the reduced semaphorin 3A levels in patients with a history of thromboembolism and/or miscarriage suggest that semaphorin 3A may play an important role in the pathogenesis of vasculopathy.

The development and physiological and pathophysiological functions of resident macrophages and glial cells

In the past, brain function and the onset and progression of neurological diseases have been studied in a neuron-centric manner. However, in recent years the focus of many neuroscientists has shifted to other cell types that promote neurodevelopment and contribute to the functionality of neuronal networks in health and disease. Particularly microglia and astrocytes have been implicated in actively contributing to and controlling neuronal development, neuroinflammation, and neurodegeneration. Here, we summarize the development of brain-resident macrophages and astrocytes and their core functions in the developing brain. We discuss their contribution and intercellular crosstalk during tissue homeostasis and pathophysiology. We argue that in-depth knowledge of non-neuronal cells in the brain could provide novel therapeutic targets to reverse or contain neurological diseases.

Low Urine Secretion of Semaphorin3A in Lupus Patients with Proteinuria

Immune semaphorins are important in controlling both innate and adaptive immune responses. The regulatory role of semaphorin3A (sema3A) in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and other autoimmune diseases is widely reported. Decreased levels of serum sema3A were shown to correlate with SLE disease activity. The aim was to assess urine concentrations of sema3A in SLE patients and its correlation with renal involvement and disease activity. Urine levels of sema3A were analyzed in 38 SLE patients, 13 with renal involvement, and were compared to 10 healthy volunteers and 8 RA patients (disease control group). The excretion of urine sema3A was found to be significantly lower in SLE patients compared to healthy volunteers and RA patients (4.9 ± 3.9 ng/ml, 8.5 ± 2.7 ng/ml, 9.85 ± 1.7 ng/ml, respectively, p = 0.0006). Urine sema3A was significantly lower in SLE patients with lupus nephritis than in patients without nephritis (4.0 ± 3.4 ng/ml vs. 6.5 ± 3.8 ng/ml, p = 0.03). Urine sema3A inversely correlated with proteinuria and SLE disease activity. Urine sema3A is decreased in lupus patients and should be further evaluated as a possible biomarker for disease activity and renal involvement.

IL-33 Induces Sema4A Expression in Dendritic Cells and Exerts Antitumor Immunity

Cancer immunotherapy has shown great promise as a new standard therapeutic strategy against cancer. However, the response rate and survival benefit remain unsatisfactory because most current approaches, such as the use of immune checkpoint inhibitors, depend on spontaneous antitumor immune responses. One possibility for improving the efficacy of immunotherapy is to promote antitumor immunity using adjuvants or specific cytokines actively. IL-33 has been a candidate for such cytokine therapies, but it remains unclear how and in which situations IL-33 exerts antitumor immune effects. In this study, we demonstrate the potent antitumor effects of IL-33 using syngeneic mouse models, which included marked inhibition of tumor growth and upregulation of IFN-γ production by tumor-infiltrating CD8⁺ T cells. Of note, IL-33 induced dendritic cells to express semaphorin 4A (Sema4A), and the absence of Sema4A abolished the antitumor activity of IL-33, indicating that Sema4A is intrinsically required for the antitumor effects of IL-33 in mice. Collectively, these results not only present IL-33 and Sema4A as potential therapeutic targets but also shed light on the potential use of Sema4A as a biomarker for dendritic cell activation status, which has great value in various fields of cancer research, including vaccine development.

The emerging roles of semaphorin4D/CD100 in immunological diseases

In vertebrates, the semaphorin family of proteins is composed of 21 members that are divided into five subfamilies, i.e. classes 3 to 7. Semaphorins play crucial roles in regulating multiple biological processes, such as neural remodeling, tissue regeneration, cancer progression, and, especially, in immunological regulation. Semaphorin 4D (SEMA4D), also known as CD100, is an important member of the semaphorin family and was first characterized as a lymphocyte-specific marker. SEMA4D has diverse effects on immunologic processes, including immune cell proliferation, differentiation, activation, and migration, through binding to its specific membrane receptors CD72, PLXNB1, and PLXNB2. Furthermore, SEMA4D and its underlying signaling have been increasingly linked with several immunological diseases. This review focuses on the significant immunoregulatory role of SEMA4D and the associated underlying mechanisms, as well as the potential application of SEMA4D as a diagnostic marker and therapeutic target for the treatment of immunological diseases.

Sema7A is crucial for resolution of severe inflammation

Nonresolving inflammation, a hallmark of sepsis and/or multi-organ failure, still poses a challenge in medicine. The mortality rate is enormous, and so far no adequate curative therapy is available. Here we identify a previously unrecognized role of the neuronal guidance protein semaphorin 7A in the transition to resolution processes in severe systematic inflammation such as sepsis.

Endogenous mediators regulating acute inflammatory responses in both the induction and resolution phases of inflammatory processes are pivotal in host defense and tissue homeostasis. Recent studies have identified neuronal guidance proteins characterized in axonal development that display immunomodulatory functions. Here, we identify the neuroimmune guidance cue Semaphorin 7A (Sema7A), which appears to link macrophage (MΦ) metabolic remodeling to inflammation resolution. Sema7A orchestrated MΦ chemotaxis and chemokinesis, activated MΦ differentiation and polarization toward the proresolving M2 phenotype, and promoted leukocyte clearance. Peritoneal MΦ^{Sema7A−/−} displayed metabolic reprogramming, characterized by reductions in fatty acid oxidation and oxidative phosphorylation, increases in glycolysis and the pentose phosphate pathway, and truncation of the tricarboxylic acid cycle, which resulted in increased levels of the intermediates succinate and fumarate. The low accumulation of citrate in MΦ^{Sema7A−/−} correlated with the decreased synthesis of prostaglandins, leading to a reduced impact on lipid-mediator class switching and the generation of specialized pro resolving lipid mediators. Signaling network analysis indicated that Sema7A induced the metabolic reprogramming of MΦ by activating the mTOR- and AKT2-signaling pathways. Administration of Sema7A^SL4cd orchestrated the resolution response to tissue homeostasis by shortening the resolution interval, promoting tissue protection in murine peritonitis, and enhancing survival in polymicrobial sepsis.

Roles and Mechanisms of Axon-Guidance Molecules in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by progressive memory decline and cognitive dysfunctions. Although the causes of AD have not yet been established, many mechanisms have been proposed. Axon-guidance molecules play the roles in the occurrence and development of AD by participating in different mechanisms. Therefore, what roles do axon-guidance molecules play in AD? This study aimed at elucidating how axon-guidance molecules Netrins, Slits, Semaphorins, and Ephrins regulate the levels of Aβ, hyperphosphorylation of tau protein, Reelin, and other ways through different signaling pathways, in order to show the roles of axon-guidance molecules in the occurrence and development of AD. And it is hoped that this study can provide a theoretical basis and new perspectives in the search for new therapeutic targets for AD.

New Angiogenic Regulators Produced by TAMs: Perspective for Targeting Tumor Angiogenesis

Simple Summary

Since the targeting of a single pro-angiogenic factor fails to improve oncological disease outcome, significant efforts have been made to identify new pro-angiogenic factors that could compensate for the deficiency of current therapy or act independently as single drugs. Our review aims to present the state-of-the art for well-known and recently described factors produced by macrophages that induce and regulate angiogenesis. A number of positive and negative regulators of angiogenesis in the tumor microenvironment are produced by tumor-associated macrophages (TAMs). Accumulating evidence has indicated that, apart from the well-known angiogenic factors, there are plenty of novel angiogenesis-regulating proteins that belong to different classes. We summarize the data regarding the direct or indirect mechanisms of the interaction of these factors with endothelial cells during angiogenesis. We highlight the recent findings that explain the limitations in the efficiency of current anti-angiogenic therapy approaches.

Abstract

Angiogenesis is crucial to the supply of a growing tumor with nutrition and oxygen. Inhibition of angiogenesis is one of the main treatment strategies for colorectal, lung, breast, renal, and other solid cancers. However, currently applied drugs that target VEGF or receptor tyrosine kinases have limited efficiency, which raises a question concerning the mechanism of patient resistance to the already developed drugs. Tumor-associated macrophages (TAMs) were identified in the animal tumor models as a key inducer of the angiogenic switch. TAMs represent a potent source not only for VEGF, but also for a number of other pro-angiogenic factors. Our review provides information about the activity of secreted regulators of angiogenesis produced by TAMs. They include members of SEMA and S100A families, chitinase-like proteins, osteopontin, and SPARC. The COX-2, Tie2, and other factors that control the pro-angiogenic activity of TAMs are also discussed. We highlight how these recent findings explain the limitations in the efficiency of current anti-angiogenic therapy. Additionally, we describe genetic and posttranscriptional mechanisms that control the expression of factors regulating angiogenesis. Finally, we present prospects for the complex targeting of the pro-angiogenic activity of TAMs.

Semaphorin 3E deficiency dysregulates dendritic cell functions: In vitro and in vivo evidence

Regulation of dendritic cell functions is a complex process in which several mediators play diverse roles as a network in a context-dependent manner. The precise mechanisms underlying dendritic cell functions have remained to be addressed. Semaphorins play crucial roles in regulation of various cell functions. We previously revealed that Semaphorin 3E (Sema3E) contributes to regulation of allergen-induced airway pathology partly mediated by controlling recruitment of conventional dendritic cell subsets in vivo, though the underlying mechanism remained elusive. In this study, we investigate the potential regulatory role of Sema3E in dendritic cells. We demonstrated that bone marrow-derived dendritic cells differentiated from Sema3e^-/- progenitors have an enhanced migration capacity both at the baseline and in response to CCL21. The enhanced migration ability of Sema3E dendritic cells was associated with an overexpression of the chemokine receptor (CCR7), elevated Rac1 GTPase activity and F-actin polymerization. Using a mouse model of allergic airway sensitization, we observed that genetic deletion of Sema3E leads to a time dependent upregulation of CCR7 on CD11b⁺ conventional dendritic cells in the lungs and mediastinal lymph nodes. Furthermore, aeroallergen sensitization of Sema3e^-/- mice lead to an enhanced expression of PD-L2 and IRF-4 as well as enhanced allergen uptake in pulmonary CD11b⁺ DC, compared to wild type littermates. Collectively, these data suggest that Sema3E implicates in regulation of dendritic cell functions which could be considered a basis for novel immunotherapeutic strategies for the diseases associated with defective dendritic cells in the future.

The Expression of Semaphorin 7A in Human Periapical Lesions

INTRODUCTION

Semaphorin 7A (SEMA7A) is a membrane-bound or secretory protein exerting multiple functions in the regulation of inflammation, neural degradation, and cancer progression. Human periapical lesions are chronic and infectious diseases mainly caused by bacteria. However, the involvement of SEMA7A in human periapical lesions is still unclear. This study aimed to explore the expression of SEMA7A in human periapical lesions accompanied by the potential association of SEMA7A with matrix metalloproteinase (MMP)-1 and MMP-3 during the progression of apical periodontitis.

METHODS

Samples of periapical lesions and healthy controls were collected. Total RNA and protein were extracted respectively for quantitative real-time polymerase chain reaction and Western blot analysis. Additionally, 6 healthy samples and 27 periapical lesion samples were fixed, dehydrated, and embedded for further histologic and immunochemical analysis. The expression of SEMA7A was quantified by average integrated optical density. Immunofluorescence analysis was conducted to explore the colocalization of SEMA7A/MMP-1 and SEMA7A/MMP-3.

RESULTS

Compared with healthy controls, the messenger RNA and protein expression of SEMA7A was markedly up-regulated in periapical lesions. A stronger expression of MMP-1, MMP-3, and inflammatory cytokines was exhibited in periapical lesions than in healthy groups. An increasing expression of SEMA7A can be observed in both the periapical granuloma group and the radicular cyst group compared with the normal group (P < .01). Immunofluorescence results showed the colocalization of SEMA7A with both MMP-1 and MMP-3 in vascular vessels and extracellular matrix.

CONCLUSIONS

SEMA7A was up-regulated in periapical periodontitis and might be involved in the tissue destruction and infiltration of immune cells in periapical lesions.

A putative structural mechanism underlying the antithetic effect of homologous RND1 and RhoD GTPases in mammalian plexin regulation

Plexins are semaphorin receptors that play essential roles in mammalian neuronal axon guidance and in many other important mammalian biological processes. Plexin signaling depends on a semaphorin-induced dimerization mechanism and is modulated by small GTPases of the Rho family, of which RND1 serves as a plexin activator yet its close homolog RhoD an inhibitor. Using molecular dynamics (MD) simulations, we showed that RND1 reinforces the plexin dimerization interface, whereas RhoD destabilizes it due to their differential interaction with the cell membrane. Upon binding plexin at the Rho-GTPase-binding domain (RBD), RND1 and RhoD interact differently with the inner leaflet of the cell membrane and exert opposite effects on the dimerization interface via an allosteric network involving the RBD, RBD linkers, and a buttress segment adjacent to the dimerization interface. The differential membrane interaction is attributed to the fact that, unlike RND1, RhoD features a short C-terminal tail and a positively charged membrane interface.

Barcoded viral tracing of single-cell interactions in central nervous system inflammation

Cell-cell interactions control the physiology and pathology of the central nervous system (CNS). To study astrocyte cell interactions in vivo, we developed rabies barcode interaction detection followed by sequencing (RABID-seq), which combines barcoded viral tracing and single-cell RNA sequencing (scRNA-seq). Using RABID-seq, we identified axon guidance molecules as candidate mediators of microglia-astrocyte interactions that promote CNS pathology in experimental autoimmune encephalomyelitis (EAE) and, potentially, multiple sclerosis (MS). In vivo cell-specific genetic perturbation EAE studies, in vitro systems, and the analysis of MS scRNA-seq datasets and CNS tissue established that Sema4D and Ephrin-B3 expressed in microglia control astrocyte responses via PlexinB2 and EphB3, respectively. Furthermore, a CNS-penetrant EphB3 inhibitor suppressed astrocyte and microglia proinflammatory responses and ameliorated EAE. In summary, RABID-seq identified microglia-astrocyte interactions and candidate therapeutic targets.

The Role of Semaphorins and Their Receptors in Innate Immune Responses and Clinical Diseases of Acute Inflammation

Semaphorins are a group of proteins that have been studied extensively for their critical function in neuronal development. They have been shown to regulate airway development, tumorigenesis, autoimmune diseases, and the adaptive immune response. Notably, emerging literature describes the role of immunoregulatory semaphorins and their receptors, plexins and neuropilins, as modulators of innate immunity and diseases defined by acute injury to the kidneys, abdomen, heart and lungs. In this review we discuss the pathogenic functions of semaphorins in clinical conditions of acute inflammation, including sepsis and acute lung injury, with a focus on regulation of the innate immune response as well as potential future therapeutic targeting.

SEMAPHORINS and their receptors: focus on the crosstalk between melanoma and hypoxia

Hypoxia, a condition of oxygen deprivation, is considered a hallmark of tumor microenvironment regulating several pathways and promoting cancer progression and resistance to therapy. Semaphorins, a family of about 20 secreted, transmembrane and GPI-linked glycoproteins, and their cognate receptors (plexins and neuropilins) play a pivotal role in the crosstalk between cancer and stromal cells present in the tumor microenvironment. Many studies reported that some semaphorins are involved in the development of a permissive tumor niche, guiding cell-cell communication and, consequently, the development and progression, as well as the response to therapy, of different cancer histotypes, including melanoma.

In this review we will summarize the state of art of semaphorins regulation by hypoxic condition in cancer with different origin. We will also describe evidence about the ability of semaphorins to affect the expression and activity of transcription factors activated by hypoxia, such as hypoxia-inducible factor-1. Finally, we will focus our attention on findings reporting the role of semaphorins in melanocytes transformation, melanoma progression and response to therapy. Further studies are necessary to understand the mechanisms through which semaphorins induce their effect and to shed light on the possibility to use semaphorins or their cognate receptors as prognostic markers and/or therapeutic targets in melanoma or other malignancies.

Signalling and putative therapeutic molecules on the regulation of synoviocyte signalling in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by symmetrical and chronic polyarthritis. Fibroblast-like synoviocytes are mainly involved in joint inflammation and cartilage and bone destruction by inflammatory cytokines and matrix-degrading enzymes in RA. Approaches that induce various cellular growth alterations of synoviocytes are considered as potential strategies for treating RA. However, since synoviocytes play a critical role in RA, the mechanism and hyperplastic modulation of synoviocytes and their motility need to be addressed. In this review, we focus on the alteration of synoviocyte signalling and cell fate provided by signalling proteins, various antioxidant molecules, enzymes, compounds, clinical candidates, to understand the pathology of the synoviocytes, and finally to achieve developed therapeutic strategies of RA.

Cite this article: Bone Joint Res 2021;10(4):285–297.

The role of immune semaphorins in the pathogenesis of multiple sclerosis: Potential therapeutic targets

The immune and nervous systems possess a highly intricate network of synaptic connections, shared messenger molecules, and exquisite communication ways, allowing intercellular signal transduction. The semaphorins (Semas) were initially identified as axonal guidance molecules in the development of the nervous system but later were found to be implicated also in regulating the immune system, known in this case as the "immune Semas" or "immunoregulatory Semas". Increasingly, these molecules are involved in multiple aspects of both physiological and pathological immune responses and were recently indicated to take part in various immunological disorders, encompassing allergy, cancer, and autoimmunity. Semas transduce signals by connecting to their cognate receptors, namely, plexins and neuropilins. Some of them, like Sema-3F, have been found to function as the inducer of the remyelination process whereas some others, like Sema-3A and Sema-4D, act to inhibit this process, either directly or indirectly. Besides, Sema-4A is crucial to the differentiation of T helper type 1 (Th1) and Th17 cells that are potentially involved in the pathogenesis of multiple sclerosis (MS), an autoimmune disease of the central nervous system. This review aims to reveal the role of immune Semas in the pathogenesis of MS and its animal model, experimental autoimmune encephalomyelitis, focusing on the therapeutic usages of these molecules to treat this neurodegenerative disease.

Mechanochemical control of epidermal stem cell divisions by B-plexins

The precise spatiotemporal control of cell proliferation is key to the morphogenesis of epithelial tissues. Epithelial cell divisions lead to tissue crowding and local changes in force distribution, which in turn suppress the rate of cell divisions. However, the molecular mechanisms underlying this mechanical feedback are largely unclear. Here, we identify a critical requirement of B-plexin transmembrane receptors in the response to crowding-induced mechanical forces during embryonic skin development. Epidermal stem cells lacking B-plexins fail to sense mechanical compression, resulting in disinhibition of the transcriptional coactivator YAP, hyperproliferation, and tissue overgrowth. Mechanistically, we show that B-plexins mediate mechanoresponses to crowding through stabilization of adhesive cell junctions and lowering of cortical stiffness. Finally, we provide evidence that the B-plexin-dependent mechanochemical feedback is also pathophysiologically relevant to limit tumor growth in basal cell carcinoma, the most common type of skin cancer. Our data define a central role of B-plexins in mechanosensation to couple cell density and cell division in development and disease.