Phenotypical analysis of ectoenzymes CD39/CD73 and adenosine receptor 2A in CD4+ CD25high Foxp3+ regulatory T-cells in psoriasis

Current treatment of Psoriasis triggered by Cytokine Storm and future immunomodulation strategies

Psoriasis is a chronic condition caused by an inflammation mediated mainly by cytokines and T cells. In COVID-19, the same type of imbalance is common, generating the Cytokine Storm and promoting a worsening in the skin conditions of patients with autoimmune disorders, such as Psoriasis. In this context, one of the main mediators of immune responses presented by SARS-CoV-2 infected patients is the Purinergic System. This immunological resource is capable of stimulating the hyperinflammatory state presented by infected individuals, mainly by the activity of the P2X7 receptor, culminating in the Cytokine Storm and consequently in the Psoriasis crisis. Currently, different drugs are used for patients with Psoriasis, such as immunosuppressants and small molecules; however, the safety of these drugs in infected patients has not been analyzed yet. In this context, studies are being developed to evaluate the possible administration of these traditional drugs to COVID-19 patients with Psoriasis crisis. Along with that, researchers must evaluate the potential of administrating P2X7 antagonists to these patients as well, improving both the systemic and the dermatological prognostics of patients, by reducing the Cytokine Storm and its general effects, but also avoiding the provocation of Psoriasis crisis.

MicroRNA-125a-5p regulates the effect of Tregs on Th1 and Th17 through targeting ETS-1/STAT3 in psoriasis

BACKGROUND

Psoriasis is an inflammatory disease mediated by helper T (Th)17 and Th1 cells. MicroRNA-125a (miR-125a) is reduced in the lesional skin of psoriatic patients. However, the mechanism by which miR-125a participates in psoriasis remains unclear.

METHODS

The levels of miR-125a-5p and its downstream targets (ETS-1, IFN-γ, and STAT3) were detected in CD4+ T cells of healthy controls and psoriatic patients by quantitative real-time PCR (qRT-PCR). In vitro, transfection of miR-125a-5p mimics was used to analyze the effect of miR-125a-5p on the differentiation of Th17 cells by flow cytometry. Imiquimod (IMQ)-induced mouse model was used to evaluate the role of upregulating miR-125a-5p by intradermal injection of agomir-125a-5p in vivo.

RESULTS

miR-125a-5p was downregulated in peripheral blood CD4+ T cells of psoriatic patients, which was positively associated with the proportion of regulatory T cells (Tregs) and negatively correlated with the Psoriasis Area and Severity Index (PASI) score. Moreover, the miR-125a-5p mimics promoted the differentiation of Tregs and downregulated the messenger RNA (mRNA) levels of ETS-1, IFN-γ, and STAT3 in murine CD4+ T cells. Furthermore, agomir-125a-5p alleviated psoriasis-like inflammation in an IMQ-induced mouse model by downregulating the proportion of Th17 cells.

CONCLUSIONS

miR-125a-5p may have therapeutic potential in psoriasis by restoring the suppressive function of Tregs on Th17 cells through targeting STAT3, and on Th1 cells indirectly through targeting ETS-1 and IFN-γ.

The role of platelets in immune-mediated inflammatory diseases

Immune-mediated inflammatory diseases (IMIDs) are characterized by excessive and uncontrolled inflammation and thrombosis, both of which are responsible for organ damage, morbidity and death. Platelets have long been known for their role in primary haemostasis, but they are now also considered to be components of the immune system and to have a central role in the pathogenesis of IMIDs. In patients with IMIDs, platelets are activated by disease-specific factors, and their activation often reflects disease activity. Here we summarize the evidence showing that activated platelets have an active role in the pathogenesis and the progression of IMIDs. Activated platelets produce soluble factors and directly interact with immune cells, thereby promoting an inflammatory phenotype. Furthermore, platelets participate in tissue injury and promote abnormal tissue healing, leading to fibrosis. Targeting platelet activation and targeting the interaction of platelets with the immune system are novel and promising therapeutic strategies in IMIDs.

Regulatory T cells in psoriatic arthritis: an IL-17A-producing, Foxp3intCD161 + RORγt + ICOS + phenotype, that associates with the presence of ADAMTSL5 autoantibodies

In psoriatic arthritis (PsA), predisposing class I HLA alleles, the presence of synovial clonally proliferated CD8 + T cells and autoantibodies all point towards the loss of immune tolerance. However, the key mechanisms that lead to immune dysregulation are not fully understood. In other types of inflammatory arthritis, T regulatory cell (Treg) dysfunction and plasticity at sites of inflammation were suggested to negatively affect peripheral tolerance. We here addressed if Treg variances associate with psoriatic disease. We collected clinical data, sera and peripheral blood mononuclear cells from 13 healthy controls, 21 psoriasis and 21 PsA patients. In addition, we obtained synovial fluid mononuclear cells from 6 PsA patients. We studied characteristics of CD4 + CD25 + CD127^loFoxp3 + Tregs by flow cytometry and used ELISA to quantify antibodies against ADAMTSL5, a recently discovered autoantigen in psoriatic disease. In comparison with their circulating counterparts, Tregs from inflamed joints express increased levels of ICOS, CTLA-4 and TIGIT. Furthermore, synovial fluid-derived Tregs have a distinct phenotype, characterized by IL-17A production and upregulation of CD161 and RORγt. We identified a subset of Tregs with intermediate Foxp3 expression as the major cytokine producer. Furthermore, ICOS + Tregs associate with PsA disease activity as measured by PASDAS. Lastly, we observed that presence of the Foxp3^int Tregs associates with an increased abundance of anti-ADAMTSL5 autoantibodies. Tregs derived from the inflammatory environment of inflamed PsA joints exhibit a distinct phenotype, which associates with loss of peripheral immune tolerance in psoriatic disease.

Regulatory T cells and immunoglobulin E: A new therapeutic link for autoimmunity?

Autoimmune diseases have a prevalence of approximately 7 to 9% and are classified as either organ-specific diseases, including type I diabetes, multiple sclerosis, inflammatory bowel disease and myasthenia gravis, or systemic diseases, including systemic lupus erythematosus, rheumatoid arthritis and Sjögren's syndrome. While many advancements have been made in understanding of the mechanisms of autoimmune disease, including the nature of self-tolerance and its breakdown, there remain unmet needs in terms of effective and highly targeted treatments. T regulatory cells (Tregs) are key mediators of peripheral tolerance and are implicated in many autoimmune diseases, either as a result of reduced numbers or altered function. Tregs may be broadly divided into those generated in the thymus (tTregs) and those generated in the periphery (pTregs). Tregs target many different immune cell subsets and tissues to suppress excessive inflammation and to support tissue repair and homeostasis: there is a fine balance between Treg cell stability and the plasticity that is required to adjust Tregs' regulatory purposes to particular immune responses. The central role of immunoglobulin E (IgE) in allergic disease is well recognized, and it is becoming increasingly apparent that this immunoglobulin also has a wider role encompassing other diseases including autoimmune disease. Anti-IgE treatment restores the capacity of plasmacytoid dendritic cells (pDCs) impaired by IgE- high-affinity IgE receptor (FcεR1) cross-linking to induce Tregs in vitro in atopic patients. The finding that anti-IgE therapy restores Treg cell homeostasis, and that this mechanism is associated with clinical improvement in asthma and chronic spontaneous urticaria suggests that anti-IgE therapy may also have a potential role in the treatment of autoimmune diseases in which Tregs are involved.

Regulatory T cell niche in the bone marrow, a new player in Haematopoietic stem cell transplantation

Challenges in haematopoietic stem cell transplantation such as low bone marrow (BM) engraftment, graft versus host disease (GvHD) and the need for long-term immunosuppression could be addressed using T regulatory cells (Tregs) resident in the tissue of interest, in this case, BM Tregs. Controlling the adverse immune response in haematopoietic stem cell transplantation (HSCT) and minimising the associated risks such as infection and secondary cancers due to long-term immunosuppression is a crucial aspect of clinical practice in this field. While systemic immunosuppressive therapy could achieve reasonable GvHD control in most patients, related side effects remain the main limiting factor. Developing more targeted immunosuppressive strategies is an unmet clinical need and is the focus of several ongoing research projects. Tregs are a non-redundant sub-population of CD4⁺ T cells essential for controlling the immune homeostasis. Tregs are known to be reduced in number and function in autoimmune conditions. There is considerable interest in these cells as cell therapy products since they can be expanded in vitro and infused into patients. These trials have found Treg therapy to be safe, well-tolerated, and with some early signs of efficacy. However, Tregs are a heterogeneous subpopulation of T cells, and several novel subpopulations have been identified in recent years beyond the conventional thymic (tTregs) and peripheral (pTregs). There is increasing evidence for the presence of resident and tissue-specific Tregs. Bone marrow (BM) Tregs are one example of tissue-resident Tregs. BM Tregs are enriched within the marrow, serving a dual function of immunosuppression and maintenance of haematopoietic stem cells (HSCs). HSCs maintenance is achieved through direct suppression of HSCs differentiation, maintaining a proliferating pool of HSCs, and promoting the development of functional stromal cells that support HSCs. In this review, we will touch upon the biology of Tregs, focusing on their development and heterogeneity. We will focus on the BM Tregs from their biology to their therapeutic potential, focusing on their use in HSCT.

T-cell trans-synaptic vesicles are distinct and carry greater effector content than constitutive extracellular vesicles

The immunological synapse is a molecular hub that facilitates the delivery of three activation signals, namely antigen, costimulation/corepression and cytokines, from antigen-presenting cells (APC) to T cells. T cells release a fourth class of signaling entities, trans-synaptic vesicles (tSV), to mediate bidirectional communication. Here we present bead-supported lipid bilayers (BSLB) as versatile synthetic APCs to capture, characterize and advance the understanding of tSV biogenesis. Specifically, the integration of juxtacrine signals, such as CD40 and antigen, results in the adaptive tailoring and release of tSV, which differ in size, yields and immune receptor cargo compared with steadily released extracellular vesicles (EVs). Focusing on CD40L+ tSV as model effectors, we show that PD-L1 trans-presentation together with TSG101, ADAM10 and CD81 are key in determining CD40L vesicular release. Lastly, we find greater RNA-binding protein and microRNA content in tSV compared with EVs, supporting the specialized role of tSV as intercellular messengers.

Expression Profiles of Immune Cells after Propofol or Sevoflurane Anesthesia for Colorectal Cancer Surgery: A Prospective Double-blind Randomized Trial

BACKGROUND

The antitumor effects of natural killer cells, helper T cells, and cytotoxic T cells after cancer surgery were reported previously. This study hypothesized that propofol-based anesthesia would have fewer harmful effects on immune cells than volatile anesthetics-based anesthesia during colorectal cancer surgery.

METHODS

In total, 153 patients undergoing colorectal cancer surgery were randomized and included in the analysis. The primary outcome was the fraction of circulating natural killer cells over time in the propofol and sevoflurane groups. The fractions of circulating natural killer, type 1, type 17 helper T cells, and cytotoxic T cells were investigated. The fractions of CD39 and CD73 expressions on circulating regulatory T cells were investigated, along with the proportions of circulating neutrophils, lymphocytes, and monocytes.

RESULTS

The fraction of circulating natural killer cells was not significantly different between the propofol and sevoflurane groups until 24 h postoperatively (20.4 ± 13.4% vs. 20.8 ± 11.3%, 17.9 ± 12.7% vs. 20.7 ± 11.9%, and 18.6 ± 11.6% vs. 21.3 ± 10.8% before anesthesia and after 1 and 24 h after anesthesia, respectively; difference [95% CI], -0.3 [-4.3 to 3.6], -2.8 [-6.8 to 1.1], and -2.6 [-6.2 to 1.0]; P = 0.863, P = 0.136, and P = 0.151 before anesthesia and after 1 and 24 h, respectively). The fractions of circulating type 1 and type 17 helper T cells, cytotoxic T cells, and CD39+ and CD73+ circulating regulatory T cells were not significantly different between the two groups. The neutrophil to lymphocyte ratio in both groups remained within the normal range and was not different between the groups.

CONCLUSIONS

Propofol-based anesthesia was not superior to sevoflurane-based anesthesia in terms of alleviating suppression of immune cells including natural killer cells and T lymphocytes during colorectal cancer surgery.

EDITOR’S PERSPECTIVE

Regulation of IL-17A-Producing Cells in Skin Inflammatory Disorders

This review focuses on the IL-17A family of cytokines produced by T lymphocytes and other immune cells and how they are involved in cutaneous pathogenic responses. It will also discuss cutaneous dysbiosis and FOXP3⁺ regulatory T cells in the context of inflammatory conditions linked to IL-17 responses in the skin. Specifically, it will review key literature on chronic mucocutaneous candidiasis and psoriasis.

New Frontiers in Psoriatic Disease Research, Part I: Genetics, Environmental Triggers, Immunology, Pathophysiology, and Precision Medicine

Psoriasis is a chronic inflammatory condition characterized by systemic immune dysregulation. Over the past several years, advances in genetics, microbiology, immunology, and mouse models have revealed the complex interplay between the heritable and microenvironmental factors that drive the development of psoriatic inflammation. In the first of this two-part review series, the authors will discuss the newest insights into the pathogenesis of psoriatic disease and highlight how the evolution of these scientific fields has paved the way for a more personalized approach to psoriatic disease treatment.

Ectonucleotidase Modulation of Lymphocyte Function in Gut and Liver

Imbalance between regulatory and effector T lymphocytes contributes to loss of immunotolerance and plays a permissive role in the initiation, perpetuation, and progression of chronic inflammatory diseases and autoimmune disorders. Regulatory/effector cell balance is governed by the CD39 ectonucleotidase, the prototype member of the NTPDase family that hydrolyzes ATP and ADP into AMP, subsequently converted into adenosine by CD73. Generation of adenosine impacts T-cell function as it contributes to the mechanism of suppression of Tregs and confers regulatory properties to pathogenic Th17-cells. CD39 cell distribution, mechanism of regulation and impact on inflammatory and regulatory signaling pathways are also discussed here. Innovative therapeutic strategies to boost CD39 levels and activity by either administering soluble ADPases or interfering with CD39 inhibitory signals are reviewed. Restoration of CD39 levels and function has enormous translational and clinical implications and should be regarded as an additional form of treatment to be deployed in the chronic inflammatory setting. The key role of CD39 in immunoregulation in the context of Crohn's disease, one of the most frequent manifestations of inflammatory bowel disease, and autoimmune hepatitis, an autoimmune disorder of the liver, is reviewed and discussed here.

Adenosine Signaling in Autoimmune Disorders

The molecular components of the purinergic system (i.e., receptors, metabolizing enzymes and membrane transporters) are widely expressed in the cells of the immune system. Additionally, high concentrations of adenosine are generated from the hydrolysis of ATP in any "danger" condition, when oxygen and energy availability dramatically drops. Therefore, adenosine acts as a retaliatory metabolite to counteract the nucleotide-mediated boost of the immune reaction. Based on this observation, it can be foreseen that the recruitment with selective agonists of the receptors involved in the immunomodulatory effect of adenosine might represent an innovative anti-inflammatory approach with potential exploitation in autoimmune disorders. Quite surprisingly, pro-inflammatory activity exerted by some adenosine receptors has been also identified, thus paving the way for the hypothesis that at least some autoimmune disorders may be caused by a derailment of adenosine signaling. In this review article, we provide a general overview of the roles played by adenosine on immune cells with a specific focus on the development of adenosine-based therapies for autoimmune disorders, as demonstrated by the exciting data from concluded and ongoing clinical trials.

Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin

Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.

Salp15, a Multifunctional Protein From Tick Saliva With Potential Pharmaceutical Effects

Ixodes ticks are the main vectors for a number of zoonotic diseases, including Lyme disease. Ticks secrete saliva directly into a mammalian host while feeding on the host's blood. This action serves to modulate host immunity and coagulation, thus allowing ticks to attach and feed upon their host. One of the most extensively studied components of tick saliva is Salp15. Research has shown that this protein binds specifically to CD4 molecules on the surface of T lymphocytes, interferes with TCR-mediated signaling transduction, inhibits CD4+ T cell activation and proliferation, and impedes the secretion of interleukin 2 (IL-2). Salp15 also binds specifically to dendritic cell dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) to up-regulate the expression of CD73 in regulatory T cells. Collectively, these findings render this salivary protein a potential candidate for a range of therapeutic applications. Here, we discuss our current understanding of Salp15 and the mechanisms that might be used to treat disease.

The Purinergic System as a Pharmacological Target for the Treatment of Immune-Mediated Inflammatory Diseases

Immune-mediated inflammatory diseases (IMIDs) encompass a wide range of seemingly unrelated conditions, such as multiple sclerosis, rheumatoid arthritis, psoriasis, inflammatory bowel diseases, asthma, chronic obstructive pulmonary disease, and systemic lupus erythematosus. Despite differing etiologies, these diseases share common inflammatory pathways, which lead to damage in primary target organs and frequently to a plethora of systemic effects as well. The purinergic signaling complex comprising extracellular nucleotides and nucleosides and their receptors, the P2 and P1 purinergic receptors, respectively, as well as catabolic enzymes and nucleoside transporters is a major regulatory system in the body. The purinergic signaling complex can regulate the development and course of IMIDs. Here we provide a comprehensive review on the role of purinergic signaling in controlling immunity, inflammation, and organ function in IMIDs. In addition, we discuss the possible therapeutic applications of drugs acting on purinergic pathways, which have been entering clinical development, to manage patients suffering from IMIDs.

ATP as a Pathophysiologic Mediator of Bacteria-Host Crosstalk in the Gastrointestinal Tract

Extracellular nucleotides, such as adenosine triphosphate (ATP), are released from host cells including nerve termini, immune cells, injured or dead cells, and the commensal bacteria that reside in the gut lumen. Extracellular ATP interacts with the host through purinergic receptors, and promotes intercellular and bacteria-host communication to maintain the tissue homeostasis. However, the release of massive concentrations of ATP into extracellular compartments initiates acute and chronic inflammatory responses through the activation of immunocompetent cells (e.g., T cells, macrophages, and mast cells). In this review, we focus on the functions of ATP as a pathophysiologic mediator that is required for the induction and resolution of inflammation and inter-species communication.

Methotrexate restores the function of peripheral blood regulatory T cells in psoriasis vulgaris via the CD73/AMPK/mTOR pathway

BACKGROUND

Methotrexate (MTX) is used to treat psoriasis, a chronic inflammatory skin disease.

OBJECTIVES

To investigate the molecular mechanism of MTX in the treatment of psoriasis.

METHODS

Regulatory T cells (Tregs) and effector T (Teff) cells were isolated from the blood of patients with psoriasis and healthy controls. The proliferation of Teff cells was detected by carboxyfluorescein succinimidyl ester assay. The interferon (IFN)-γ and interleukin (IL)-17 levels were analysed by enzyme-linked immunosorbent assay. The expression of CD73 and FoxP3 were determined by flow cytometry. The expression of proteins in the AMPK/mTOR pathway were detected by Western blot analysis.

RESULTS

The data suggested that patients with psoriasis have Tregs with decreased immune suppression function and reduced expression of CD73 compared with healthy controls. Moreover, MTX could significantly restore the immunosuppressive function of IL-17-secreting Tregs. This, in turn, inhibits aberrant proliferation of Teff cells in patients with psoriasis, reverses downregulation of CD73, upregulates phosphorylated AMPK and inhibits phosphorylated mTOR, and downregulates IL-17 and IFN-γ levels.

CONCLUSIONS

We speculate that MTX can restore the immunosuppressive function of Tregs through upregulating CD73, activating AMPK and inactivating the mTOR pathway. These findings may partly explain the mechanism by which MTX treats psoriasis.