Differential Upregulation and Functional Activity of S1PR1 in Human Peripheral Blood Basophils of Atopic Patients

TRPV1 Channel in Human Eosinophils: Functional Expression and Inflammatory Modulation

The transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel expressed on sensory neurons and immune cells. We hypothesize that TRPV1 plays a role in human eosinophil function and is modulated by inflammatory conditions. TRPV1 expression on human eosinophils was examined by qPCR, flow cytometry, and immunohistochemistry, respectively. TRPV1 functionality was analyzed by investigating calcium flux, apoptosis, modulation by cytokines and acidic pH, and CD69 externalization using flow cytometry. Activation of TRPV1 induced calcium influx and prolonged survival. Although eosinophils were not directly activated by TRPV1 agonists, activation by IL-3 or GM-CSF was mainly restricted to TRPV1-positive eosinophils. TRPV1 surface content was increased by acidic pH, IL-3, IL-31, IL-33, TSLP, TNF-α, BDNF, and NGF-β. Interestingly, TRPV1 was also expressed by eosinophils located in proximity to peripheral nerves in atopic dermatitis (AD) skin. In conclusion, eosinophils express functional TRPV1 channels which are increased by extracellular acidification and AD-related cytokines. Since eosinophils also express TRPV1 in AD skin, our results indicate an important role of TRPV1 for neuroimmune interaction mechanisms in itchy, inflammatory skin diseases, like AD.

Density Gradient Centrifugation-Independent Purification of Human Basophils

Basophils represent the rarest type of granulocyte in human peripheral blood. Thus, researching basophils has historically been challenging and has often been reliant on enrichment protocols using density gradient centrifugation. This article describes a novel, fast, and cost-effective method to purify highly viable human basophils from peripheral blood through negative immunomagnetic selection, foregoing the density centrifugation step in the Basic Protocol. The technique is easy to use and consistently produces purities >96%. Furthermore, the Support Protocols describe procedures to determine basophil yield, purity, and viability, and how to investigate functional activity of the purified basophils through flow cytometry and visualize the basophils through microscopy. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Gradient centrifugation-independent basophil isolation Support Protocol 1: Flow cytometry staining to assess basophil yield, purity, and viability Support Protocol 2: Giemsa staining Support Protocol 3: Calcium flux analysis Support Protocol 4: Basophil activation test.

The Role of Sphingolipids and Sphingosine-1-phosphate-Sphingosine-1-phosphate-receptor Signaling in Psoriasis

Psoriasis is a long-lasting skin condition characterized by redness and thick silver scales on the skin's surface. It involves various skin cells, including keratinocytes, dendritic cells, T lymphocytes, and neutrophils. The treatments for psoriasis range from topical to systemic therapies, but they only alleviate the symptoms and do not provide a fundamental cure. Moreover, systemic treatments have the disadvantage of suppressing the entire body's immune system. Therefore, a new treatment strategy with minimal impact on the immune system is required. Recent studies have shown that sphingolipid metabolites, particularly ceramide and sphingosine-1-phosphate (S1P), play a significant role in psoriasis. Specific S1P-S1P-receptor (S1PR) signaling pathways have been identified as crucial to psoriasis inflammation. Based on these findings, S1PR modulators have been investigated and have been found to improve psoriasis inflammation. This review will discuss the metabolic pathways of sphingolipids, the individual functions of these metabolites, and their potential as a new therapeutic approach to psoriasis.

S. epidermidis Rescues Allergic Contact Dermatitis in Sphingosine 1-Phosphate Receptor 2-Deficient Skin

Recent studies have identified a subtype of the S1P-receptor family called sphingosine-1-phosphate receptor 2 (S1PR2), which plays a crucial role in maintaining the skin barrier. It has been observed that S1PR2 and Staphylococcus epidermidis (S. epidermidis) work together to regulate the skin barrier. However, the interaction between these two factors is still unclear. To investigate this, a study was conducted on healthy skin and allergic contact dermatitis (ACD) using 3,4-Dibutoxy-3-cyclobutene-1,2-dione (SADBE) on the ears of S1pr2fl/fl and S1pr2fl/flK14-Cre mice and using 1 × 106 CFU of S. epidermidis to examine its effects on the skin. The results showed that in S. epidermidis-conditioned ACD, the ear thickness of S1pr2fl/flK14-Cre mice was lower than that of S1pr2fl/fl mice, and mRNA expressions of Il-1β and Cxcl2 of S1pr2fl/flK14-Cre mice were lower than that of S1pr2fl/fl mice in ACD with S. epidermidis. Furthermore, the gene expression of Claudin-1 and Occludin in S1pr2fl/flK14-Cre mice was higher than that of S1pr2fl/fl mice in ACD with S. epidermidis. The study concludes that S. epidermidis colonization improves the skin barrier and prevents ACD even when S1P signaling malfunctions.

Basophils in pruritic skin diseases

Basophils are rare cells in the peripheral blood which have the capability to infiltrate into the skin. Invasion of basophils has been detected in pruritic skin diseases, including atopic dermatitis, bullous pemphigoid, chronic spontaneous urticaria and contact dermatitis. In the skin, basophils are important players of the inflammatory immune response, as they release Th2 cytokines, including interleukin (IL)-4 and IL-13, subsequently inducing the early activation of T-cells. Further, basophils release a multitude of mediators, such as histamine and IL-31, which both play an important role in the initiation of the pruritic response via activation of sensory nerves. Chronic pruritus significantly affects the quality of life and the working capability of patients, though its mechanisms are not fully elucidated yet. Since basophils and neurons share many receptors and channels, bidirectional interaction mechanisms, which drive the sensation of itch, are highlighted in this review.