Time Course of Priming Effect of TF Inducers on Synergistic TF Expression and Intra-Cellular Gap Formation of Human Vascular Endothelial Cells via the Extrinsic Coagulation Cascade

Chronic spontaneous urticaria (CSU) is characterized by daily recurring wheal and flare with itch for more than 6 weeks. The extrinsic coagulation system has been shown to be activated in correlation with CSU severity. We have reported that tissue factor (TF), a trigger of the extrinsic coagulation cascade, is synergistically expressed on vascular endothelial cells by simultaneous stimulation with TF inducers (TFI), followed by activation of the extrinsic coagulation cascade and hyper permeability in vitro. However, vascular endothelial cells are not likely to be simultaneously stimulated by multiple TFIs under physiological conditions. Therefore, in order to know whether sequential, rather than simultaneous, stimuli with interval may induce synergistic activation of TF, we investigated the time course of the priming effects of each TFI for synergistic TF expression in vascular endothelial cells (HUVECs). We stimulated HUVECs with a TFI (first stimulation) and then stimulated cells with another TFI at indicated time points (second stimulation) and detected TF expression and activity. The TF expression induced by simultaneous stimulation diminished in a few hours. However, both synergistic enhancement of TF expression and activation level of the coagulation cascade were detected even when the second stimulation was added 18 or 22 h after the first stimulation. Thus, the priming effect of TFI for synergistic TF expression may persist for a half day or longer.

Basophil Characteristics as a Marker of the Pathogenesis of Chronic Spontaneous Urticaria in Relation to the Coagulation and Complement Systems

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by daily or almost daily recurring skin edema and flare with itch and pruritus anywhere on the body for more than 6 weeks. Although basophil- and mast cell-released inflammatory mediators, such as histamine, play important roles in the pathogenesis of CSU, the detailed underlying mechanism is not clear. Since several auto-antibodies, IgGs which recognize IgE or the high-affinity IgE receptor (FcεRI) and IgEs against other self-antigens, are detected in CSU patients, they are considered to activate both mast cells in the skin and basophils circulating in the blood. In addition, we and other groups demonstrated that the coagulation and complement system also contribute to the development of urticaria. Here, we summarized the behaviors, markers and targets of basophils in relation to the coagulation-complement system, and for the treatment of CSU.

Altered Gut Microbiota in H1-Antihistamine-Resistant Chronic Spontaneous Urticaria Associates With Systemic Inflammation

Background and Objective

Chronic spontaneous urticaria (CSU) is a histamine-mediated inflammatory skin disease, and second-generation non-sedating H1-antihistamines (nsAH) at licensed doses have long been the first-line therapy in CSU. However, about 50% of patients are resistant to nsAH, and the precise pathogenesis remains largely unknown but seems to be associated with low-level systemic or intestinal inflammation. We aim to determine the fecal microbial composition and clarify its correlation with the clinical profiles og CSU with nsAH resistance.

Methods

A total of 25 CSU patients with or 19 CSU patients without nsAH resistance and 19 healthy controls (HC) were enrolled in this study. The intestinal microbiome was detected by 16S rRNA sequencing. The data were analyzed using R language software.

Results

Significantly higher urticarial activity score for 7 days, stool calprotectin, erythrocyte sedimentation rate, serum C-reactive protein, and interleukin-6, but much lower alpha-diversity and evenness of fecal bacterial community were observed in CSU patients with nsAH resistance than in those without (P <0.05 for all variables). Compared to patients with nsAH-responsiveness, the abundance of fecal genera Prevotella, Megamonas, and Escherichia were significantly increased, while that of Blautia, Alistipes, Anaerostipes, and Lachnospira were remarkably reduced in nsAH-resistant patients (uncorrected P <0.05 for all variables). Finally, systemic not intestinal inflammation degree was positively correlated with genera Escherichia, while negatively with genera Blautia, Dorea, Lactobacillus, Eubacterium_hallii_group, and Roseburia. CSU without nsAH resistance and HC individuals showed almost unchanged genera bacterium.

Conclusions

Among CSU patients, pro-inflammation phenotype relating to enteric dysbacteriosis features nsAH resistance in CSU patients. The results provide clues for future microbial-based or anti-inflammatory therapies on nsAH resistant CSU.

What Basophil Testing Tells Us About CSU Patients - Results of the CORSA Study

Basophil testing is the most effective single approach for diagnosing type-IIb autoimmune chronic spontaneous urticaria (TIIbaiCSU). A positive basophil test has been linked to long disease duration, higher disease activity, a poor response to antihistamines and omalizumab, and a better response to cyclosporine and fenebrutinib. As of now it is unclear what other features are connected to a positive basophil test in chronic spontaneous urticaria (CSU). We aimed to identify features of basophil test-positive CSU patients. We performed a cross-sectional study of 85 CSU patients. Basophil testing was done with the basophil activation test (BAT) and the basophil histamine release assay (BHRA). Data were analysed using SPSS: Student's t-test, Chi-square test, Odds Ratio, Spearman's correlation test. Of 85 CSU patients, 44% and 28% tested positive with the BAT and BHRA, respectively. These patients showed higher disease activity and impact, lower levels of disease control and total serum IgE, as well as higher rates of having a positive autologous serum skin test (ASST), angioedema, nocturnal symptoms, symptoms for >5 days/week, and thyroid autoantibodies. The ASST, by itself, was not a good predictor of basophil test results, but it predicted a positive basophil test in up to 100% of cases when combined with angioedema, thyroid autoantibodies or low IgE. In conclusion, a positive basophil test is linked to known features of TIIbaiCSU and novel characteristics including nocturnal symptoms. Further studies on basophil test-positive and -negative CSU patients can help to better understand CSU endotypes and to develop better management approaches.

The Role of Coagulation and Complement Factors for Mast Cell Activation in the Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by an almost daily recurrence of wheal and flare with itch for more than 6 weeks, in association with the release of stored inflammatory mediators, such as histamine, from skin mast cells and/or peripheral basophils. The involvement of the extrinsic coagulation cascade triggered by tissue factor (TF) and complement factors, such as C3a and C5a, has been implied in the pathogenesis of CSU. However, it has been unclear how the TF-triggered coagulation pathway and complement factors induce the activation of skin mast cells and peripheral basophils in patients with CSU. In this review, we focus on the role of vascular endothelial cells, leukocytes, extrinsic coagulation factors and complement components on TF-induced activation of skin mast cells and peripheral basophils followed by the edema formation clinically recognized as urticaria. These findings suggest that medications targeting activated coagulation factors and/or complement components may represent new and effective treatments for patients with severe and refractory CSU.

Involvement of Neuro-Immune Interactions in Pruritus With Special Focus on Receptor Expressions

Pruritus is a common, but very challenging symptom with a wide diversity of underlying causes like dermatological, systemic, neurological and psychiatric diseases. In dermatology, pruritus is the most frequent symptom both in its acute and chronic form (over 6 weeks in duration). Treatment of chronic pruritus often remains challenging. Affected patients who suffer from moderate to severe pruritus have a significantly reduced quality of life. The underlying physiology of pruritus is very complex, involving a diverse network of components in the skin including resident cells such as keratinocytes and sensory neurons as well as transiently infiltrating cells such as certain immune cells. Previous research has established that there is a significant crosstalk among the stratum corneum, nerve fibers and various immune cells, such as keratinocytes, T cells, basophils, eosinophils and mast cells. In this regard, interactions between receptors on cutaneous and spinal neurons or on different immune cells play an important role in the processing of signals which are important for the transmission of pruritus. In this review, we discuss the role of various receptors involved in pruritus and inflammation, such as TRPV1 and TRPA1, IL-31RA and OSMR, TSLPR, PAR-2, NK1R, H1R and H4R, MRGPRs as well as TrkA, with a focus on interaction between nerve fibers and different immune cells. Emerging evidence shows that neuro-immune interactions play a pivotal role in mediating pruritus-associated inflammatory skin diseases such as atopic dermatitis, psoriasis or chronic spontaneous urticaria. Targeting these bidirectional neuro-immune interactions and the involved pruritus-specific receptors is likely to contribute to novel insights into the underlying pathogenesis and targeted treatment options of pruritus.

Gut Microbiome and Serum Metabolome Analyses Identify Unsaturated Fatty Acids and Butanoate Metabolism Induced by Gut Microbiota in Patients With Chronic Spontaneous Urticaria

Chronic urticaria (CU) is defined as the continuous or intermittent presence of urticaria for a period exceeding 6 weeks and sometimes occurring with angioedema. Between 66 and 93% of patients with CU have chronic spontaneous urticaria (CSU), the precise pathogenesis of which is largely unknown. The aim of this study was to determine the relationship between gut microbiota and serum metabolites and the possible pathogenesis underlying CSU. We collected feces and blood samples from CSU patients and healthy controls and the relationship between gut microbiota and serum metabolites was assessed using 16S rRNA gene sequencing and untargeted metabolomic analyses. The CSU group exhibited decreased alpha diversity of the microbial population compared to the control group. The abundance of unidentified Enterobacteriaceae was increased, while the abundance of Bacteroides, Faecalibacterium, Bifidobacterium, and unidentified Ruminococcaceae was significantly reduced in CSU patients. The serum metabolome analysis revealed altered levels of docosahexaenoic acid, arachidonic acid, glutamate, and succinic acid, suggesting changes in unsaturated fatty acids and the butanoate metabolism pathway. The combined serum metabolomics and gut microbiome datasets were correlated; specifically, docosahexaenoic acid, and arachidonic acid were positively correlated with Bacteroides. We speculate that alterations in gut microbes and metabolites may contribute to exacerbated inflammatory responses and dysregulated immune function with or without regulatory T cell dependence in the pathogenesis of CSU.

Comparative Study of Positive Versus Negative Autologous Serum Skin Test in Chronic Spontaneous Urticaria and its Treatment Outcome

Background:

Chronic urticaria (CU) is defined as urticaria persisting daily or almost daily for more than 6 weeks and affecting 0.1% of the population. Mast cell degranulation and histamine release are of central importance in the pathogenesis of CU. About 40-50% of the patients with chronic idiopathic urticaria (CIU) or chronic spontaneous urticaria (CSU) demonstrates an immediate wheal and flare response to intradermal injected autologous serum. This led to the concept of autoimmune urticaria (AIU).

Aims:

To determine the occurrence, clinical features, associated clinical conditions, comorbidities of AIU, and to compare this with CSU. This study aimed to find the frequency of autologous serum skin test (ASST)-positive patients among patients with CSU and to identify the clinical and laboratory parameters associated with positive ASST and to compare the treatment outcome.

Materials and Methods:

A prospective correlation study in 110 patients with CSU was conducted, after screening 200 CU patients attending the outpatient Department of Dermatology during from January 2012 to May 2013. Patients were subjected to ASST, complete blood counts, urine routine examination, liver function tests, renal function tests, thyroid function tests (T3, T4, and TSH), and urine analysis.

Results:

Out of 200 CU patients screened, 90 patients had excludable causes based on detailed history and skin prick test, and the remaining 110 patients were considered to have CSU. These 110 patients were further subjected to ASST, serum immunoglobulin E (IgE), and peripheral blood eosinophilia. ASST was positive in 48 patients and negative in 62 patients. Frequency of urticarial attacks and associated diseases such as abnormal thyroid function tests in both ASST-positive and ASST-negative patients did not show any statistical significance. Only attacks of angioedema in ASST-positive individuals were higher and were statistically significant. In the ASST-positive group, 31 (81.25%) patients showed improvement with first-line antihistamines, along with oral prednisolone and injection Histaglobulin and 10 (10.41%) patients did not show any improvement. Thirty-three (43.54%) patients in the ASST-negative group showed improvement while 13 (30.62%) patients did not show improvement.

Conclusion:

ASST is considered a screening test for AIU, which decreases the rate of diagnosis of idiopathic form of CU. ASST-positive patients in addition to antihistamines, were treated with short course of oral steroids and weekly Histaglobulin injections for 5 weeks followed by the 3^rd and 6^th months.