Altered expression of regulatory molecules in the skin of psoriasis

The Involvement of Semaphorins in the Pathogenesis of Skin Diseases

Semaphorins belong to a group of membrane and secretory proteins that act as ligands for several receptor families and are involved in modulating cell signaling pathways. They bind multimeric receptor complexes on the cell membrane to exert their effects and initiate unique intracellular signal transduction cascades. These proteins can influence several processes that are very important for cell function, such as cell division and differentiation. Semaphorins are involved in cell migration, apoptosis, cell adhesion, aggregation, and numerous immune processes due to their immunoregulatory effects. Semaphorins are expressed in keratinocytes, which is why they have become a target for studies on the pathogenesis of skin diseases. Most studies to date on the role of semaphorins in the pathogenesis of skin diseases have been carried out in cellular or animal models, and there are few clinical studies evaluating the role of semaphorins in the pathogenesis and therapy of skin diseases. In this narrative review, we summarized the current state of knowledge on the role of semaphorins in the pathogenesis of skin diseases and their potential importance as targets for therapy. We also tried to present the key findings and weaknesses of previous research in this field. The novelty of this article lies in the comprehensive presentation of the role of semaphorins in the pathogenesis of skin diseases, including the results of studies on cell cultures and animal models, elucidating the mechanisms and signaling pathways through which semaphorins affect the development of skin diseases, as well as on the presentation of the results of existing clinical trials evaluating the role of semaphorins in the pathogenesis of skin diseases, and as potential therapeutic targets.

Is neuropilin-1 the neuroimmune initiator of multi-system hyperinflammation in COVID-19?

A major immunopathological feature of Coronavirus disease-2019 (COVID-19) is excessive inflammation in the form of "cytokine storm". The storm is characterized by injurious levels of cytokines which form a complicated network damaging different organs, including the lungs and the brain. The main starter of "cytokine network" hyperactivation in COVID-19 has not been discovered yet. Neuropilins (NRPs) are transmembrane proteins that act as neuronal guidance and angiogenesis modulators. The crucial function of NRPs in forming the nervous and vascular systems has been well-studied. NRP1 and NRP2 are the two identified homologs of NRP. NRP1 has been shown as a viral entry pathway for SARS-CoV2, which facilitates neuroinvasion by the virus within the central or peripheral nervous systems. These molecules directly interact with various COVID-19-related molecules, such as specific regions of the spike protein (major immune element of SARS-CoV2), vascular endothelial growth factor (VEGF) receptors, VEGFR1/2, and ANGPTL4 (regulator of vessel permeability and integrity). NRPs mainly play a role in hyperinflammatory injury of the CNS and lungs, and also the liver, kidney, pancreas, and heart in COVID-19 patients. New findings have suggested NRPs good candidates for pharmacotherapy of COVID-19. However, therapeutic targeting of NRP1 in COVID-19 is still in the preclinical phase. This review presents the implications of NRP1 in multi-organ inflammation-induced injury by SARS-CoV2 and provides insights for NRP1-targeting treatments for COVID-19 patients.

Role of Semaphorin 3A in Kidney Development and Diseases

Kidney diseases are worldwide public health problems affecting millions of people. However, there are still limited therapeutic options against kidney diseases. Semaphorin 3A (SEMA3A) is a secreted and membrane-associated protein, which regulates diverse functions, including immune regulation, cell survival, migration and angiogenesis, thus involving in the several pathogeneses of diseases, including eyes and neurons, as well as kidneys. SEMA3A is expressed in podocytes and tubular cells in the normal adult kidney, and recent evidence has revealed that excess SEMA3A expression and the subsequent signaling pathway aggravate kidney injury in a variety of kidney diseases, including nephrotic syndrome, diabetic nephropathy, acute kidney injury, and chronic kidney disease. In addition, several reports have demonstrated that the inhibition of SEMA3A ameliorated kidney injury via a reduction in cell apoptosis, fibrosis and inflammation; thus, SEMA3A may be a potential therapeutic target for kidney diseases. In this review article, we summarized the current knowledge regarding the role of SEMA3A in kidney pathophysiology and their potential use in kidney diseases.

Transcriptional Analysis-Based Alterations Affecting Neuritogenesis of the Peripheral Nervous System in Psoriasis

An increasing amount of evidence indicates the critical role of the cutaneous nervous system in the initiation and maintenance of psoriatic skin lesions by neurogenic inflammation. However, molecular mechanisms affecting cutaneous neurons are largely uncharacterized. Therefore, we reanalyzed a psoriatic RNA sequencing dataset from published transcriptome experiments of nearly 300 individuals. Using the Ingenuity Pathway Analysis software, we associated several hundreds of differentially expressed transcripts (DETs) to nervous system development and functions. Since neuronal projections were previously reported to be affected in psoriasis, we performed an in-depth analysis of neurite formation-related process. Our in silico analysis suggests that SEMA-PLXN and ROBO-DCC-UNC5 regulating axonal growth and repulsion are differentially affected in non-lesional and lesional skin samples. We identified opposing expressional alterations in secreted ligands for axonal guidance signaling (RTN4/NOGOA, NTNs, SEMAs, SLITs) and non-conventional axon guidance regulating ligands, including WNT5A and their receptors, modulating axon formation. These differences in neuritogenesis may explain the abnormal cutaneous nerve filament formation described in psoriatic skin. The processes also influence T-cell activation and infiltration, thus highlighting an additional angle of the crosstalk between the cutaneous nervous system and the immune responses in psoriasis pathogenesis, in addition to the known neurogenic pro-inflammatory mediators.

Cytokine alterations in psoriasis: an updated review

INTRODUCTION

Psoriasis is a chronic immune-mediated disease affecting 125 million people globally. It is characterized by erythematous plaques in the skin, covered by silvery scales. However, non-cutaneous manifestations (e.g., joint symptoms in psoriatic arthritis) and a high prevalence of other immune-mediated diseases such as inflammatory bowel diseases reflect its systemic nature. So far, research on psoriasis pathogenesis has improved our knowledge of the roles of the immune system, and cytokines play significant roles in immune responses.

AREAS COVERED

Herein, we review cytokine changes in psoriasis patients. Moreover, we will investigate the possible relationships between disease severity and cytokines alongside describing cytokine alterations in psoriasis patients with other comorbidities. Lastly, we will discuss the biologics and their effects on cytokines in psoriasis patients.

EXPERT OPINION

Psoriasis could develop various clinical types and clinical manifestations in people. It is an immune-mediated disease, and these manifestations are associated with different impaired cytokines. Imbalanced cytokines could lead to abnormal keratinocytes, neovascularization, and inflammation in psoriasis patients. So, a better understanding of the cytokine roles can help one choose a specific cytokine-targeting biologic to treat psoriasis. Moreover, these cytokines may be used as a severity marker for following up with these patients.

The histopathological landscape of the major psoriasiform dermatoses

Psoriasiform dermatoses represent a wide spectrum of inflammatory conditions, with several major forms represented by psoriasis, as the prototype of this category, followed by pustular psoriasis, Reiter's syndrome, pityriasis rubra pilaris, lichen simplex chronicus and large-plaques parapsoriasis. They create a diagnostic challenge, both clinical and histopathological, because of their complexity and frequent overlapping of the microscopical features. The characteristic histopathological features of psoriasiform reaction comprise extensive hyperkeratosis, with horizontally confluent but vertically intermittent parakeratosis, which alternate with orthokeratosis, thin granular layer, with relative frequent mitoses, uniform elongated and fused rete ridges, edematous superficial papillary dermis, with dilated capillaries, perivascular lymphocytic infiltrate, Munro's microabscesses, and spongiform pustules of Kogoj. Our paper aims to review the histopathology of major form of psoriasiform dermatoses and to emphasize the characteristic microscopical differences between them, for a better approach of the diagnosis as an important key for clinical and therapeutical management. Using the clinicopathological correlations, a thoroughly evaluation of the microscopical features and compartments distribution or special stainings and techniques, the range of differential diagnosis can be decreased and a more accurate diagnostic can be usually achieved. The insights into the pathogenic mechanisms can lead to new therapeutic opportunities targeted to the specific type of inflammatory lesion.

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.

Modulation of regulatory T cell function and stability by co-inhibitory receptors

Regulatory T (T_reg) cells constitute a dynamic population that is essential for controlling immune responses in health and disease. Defects in T_reg cell function and decreases in T_reg cell numbers have been observed in patients with autoimmunity and the opposite effects on T_reg cells occur in cancer settings. Current research on new therapies for these diseases is focused on modulating T_reg cell function to increase or decrease suppressive activity in autoimmunity and cancer, respectively. In this regard, several co-inhibitory receptors that are preferentially expressed by T_reg cells under homeostatic conditions have recently been shown to control T_reg cell function and stability in different disease settings. These receptors could be amenable to therapeutic targeting aimed at modulating T_reg cell function and plasticity. This Review summarizes recent data regarding the role of co-inhibitory molecules in the control of T_reg cell function and stability, with a focus on their roles and potential therapeutic use in autoimmunity and cancer.