Progress and challenges in the understanding of chronic urticaria

Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases

Disruption of the skin barrier and immunity has been associated with several skin diseases, namely atopic dermatitis (AD), psoriasis, and acne. Resident and non-resident immune cells and the barrier system of the skin are integral to innate immunity. Recent advances in understanding skin microbiota have opened the scope of further understanding the various communications between these microbiota and skin immune cells. Vitamins, being one of the important micronutrients, have been reported to exert antioxidant, anti-inflammatory, and anti-microbial effects. The immunomodulatory action of vitamins can halt the progression of skin diseases, and thus, understanding the immuno-pharmacology of these vitamins, especially for skin diseases can pave the way for their therapeutic potential. At the same time, molecular and cellular markers modulated with these vitamins and their derivatives need to be explored. The present review is focused on significant vitamins (vitamins A, B3, C, D, and E) consumed as nutritional supplements to discuss the outcomes and scope of studies related to skin immunity, health, and diseases.

Illuminating the Role of Vitamin A in Skin Innate Immunity and the Skin Microbiome: A Narrative Review

Vitamin A is a fat-soluble vitamin that plays an important role in skin immunity. Deficiencies in Vitamin A have been linked to impaired immune response and increased susceptibility to skin infections and inflammatory skin disease. This narrative review summarizes recent primary evidence that elucidates the role of vitamin A and its derivatives on innate immune regulators through mechanisms that promote skin immunity and sustain the skin microbiome.

Gulf War Illness: Unifying Hypothesis for a Continuing Health Problem

An estimated 25%⁻32% of veterans of the 1991 Gulf War continue to experience multiple unexplained health problems known as Gulf War Illness (GWI). GWI encompasses chronic pain, musculoskeletal weakness, headache, fatigue, cognitive deficits, alterations in mood, and numerous multi-system complaints. Most potential exposures implicated in GWI were not well documented but included varying levels of several neurotoxicants as well as the anticholinergic drug pyridostigmine bromide (PB), which was routinely taken as prophylaxis against the nerve agent soman. While some veterans also took chloroquine as an antimalarial agent, the literature suggests an association between receipt of multiple vaccinations prior to or during the conflict (perhaps combined with other exposures), and GWI. In-theater exposures may account for any single individual veteran's ill health but many veterans of the same era who were not deployed overseas also suffer the same or similar symptoms. The features of GWI also overlap with those of fibromyalgia, chronic fatigue syndrome and multiple chemical sensitivity, in all of which liver dysfunction has been documented, suggesting a unifying hypothesis. It is proposed that multiple vaccinations, with concurrent or subsequent exposure to PB or additional chemical insults of a liver-damaging nature, plausibly explain the pathogenesis and the observed chronicity of GWI. The suggested mechanism for GWI is thus a chemically-induced impaired liver function, with the spillage of stored vitamin A compounds ("retinoids") into the circulation in toxic concentrations, resulting in an endogenous chronic form of hypervitaminosis A. Implications of the hypothesis are briefly reviewed.

Pattern of chronic urticaria and value of autologous serum skin test in Sohag Province, Upper Egypt

Background

Chronic urticaria (CU) is a debilitating disorder with variable clinical course. It is characterized by hives occurring for at least 6 weeks, and is classified as spontaneous or inducible.

Objective

The aim of this study was to detect the pattern of CU, to study association between results of autologous serum skin test (ASST) and urticaria severity score (USS), and to detect serum levels of anti IgE receptors antibodies.

Methods

This study included all patients attending the Dermatology Outpatient Clinic, Sohag University Hospital, who were diagnosed as CU from April 2015 to March 2016. ASST and serum level of anti IgE receptor antibodies was assessed using ELISA. Data were analyzed by SPSS version 16, using descriptive statistics, Kruskal-Wallis and Mann-Whitney U test.

Results

A total of 108 patients with CU were included in the study. Females with mean age 33±12.4 years were more affected. A total of 58.3% complained of CSU, 6.5% physical urticaria and 35.2% mixed type of CU. According to USS, mild score represented 20.4%, moderate 46.3% and severe in 33.3%. ASST showed positive in 38% of patients. There was a statistically significant relation between ASST and USS and duration of CU. This indicates that more severe symptoms and prolonged duration of CU are observed in positive ASST (autoreactive type). In all, 91% of the anti IgE receptor antibodies positive patients had positive ASST.

Conclusion

In conclusion, chronic urticaria is not an uncommon disease in our locality which represented 1.13% of our patients. Urticaria severity score and duration of urticaria was higher in positive ASST patients and hence the autoreactive type.

Retinoic Acid Negatively Impacts Proliferation and MCTC Specific Attributes of Human Skin Derived Mast Cells, but Reinforces Allergic Stimulability

The Vitamin-A-metabolite retinoic acid (RA) acts as a master regulator of cellular programs. Mast cells (MCs) are primary effector cells of type-I-allergic reactions. We recently uncovered that human cutaneous MCs are enriched with RA network components over other skin cells. Yet, direct experimental evidence on the significance of the RA-MC axis is limited. Here, skin-derived cultured MCs were exposed to RA for seven days and investigated by flow-cytometry (BrdU incorporation, Annexin/PI, FcεRI), microscopy, RT-qPCR, histamine quantitation, protease activity, and degranulation assays. We found that while MC size and granularity remained unchanged, RA potently interfered with MC proliferation. Conversely, a modest survival-promoting effect from RA was noted. The granule constituents, histamine and tryptase, remained unaffected, while RA had a striking impact on MC chymase, whose expression dropped by gene and by peptidase activity. The newly uncovered MRGPRX2 performed similarly to chymase. Intriguingly, RA fostered allergic MC degranulation, in a way completely uncoupled from FcεRI expression, but it simultaneously restricted MRGPRX2-triggered histamine release in agreement with the reduced receptor expression. Vitamin-A-derived hormones thus re-shape skin-derived MCs numerically, phenotypically, and functionally. A general theme emerges, implying RA to skew MCs towards processes associated with (allergic) inflammation, while driving them away from the skin-imprinted MC_TC (“MCs containing tryptase and chymase”) signature (chymase, MRGPRX2). Collectively, MCs are substantial targets of the skin retinoid network.

IL-4 and human skin mast cells revisited: reinforcement of a pro-allergic phenotype upon prolonged exposure

Mast cells (MCs), unique cellular elements of the body, are commonly associated with IgE-mediated reactions and manifestations of Th2-type immunity. A key characteristic of the lineage is its heterogeneity, with subsets displaying significant variation depending on maturation stage, species, tissue, microenvironment and other. Heterogeneity also affects MC responses to extracellular cues. Indeed, IL-4, the signature cytokine of Th2-immunity, can affect MCs in opposing ways ranging from the induction of apoptosis to positive regulation of lineage characteristics. It is unknown, however, whether IL-4 alters the phenotype of terminally differentiated human cutaneous MCs. Using our well-established technique for homogeneous purification of human skin MCs, we now report that prolonged contact with IL-4 not only increases MC expansion, but also phenotypically and functionally re-shapes the cells. FcεRI cell surface expression, FcεRIα-specific mRNA and FcεRI-mediated histamine release are all augmented by IL-4, while histamine release elicited by the non-immunological stimulus, substance P, remains unaffected. IL-4's potential to mold MCs is broad and similarly detectable across donors. Intriguingly, IL-4 impacts granule-associated mediators, especially histamine whose synthesis is boosted in the presence of IL-4. To our knowledge, an increase in histamine production by IL-4 has not been described yet for any type of MCs, but may well contribute to its pro-allergic effect given the significance of this biogenic amine to allergic symptoms. Collectively, IL-4 alters human skin MCs after long-term exposure mimicking chronic disorders by strengthening MC numbers and intensifying processes associated with allergic inflammation.

Demonstrating measurement equivalence of the electronic and paper formats of the Urticaria Patient Daily Diary in patients with chronic idiopathic urticaria

BACKGROUND

The Urticaria Patient Daily Diary (UPDD), originally developed on paper, is a measure of key symptoms of chronic idiopathic urticaria (CIU). The development of the electronic version (eUPDD) involved moderate modifications to the appearance of the paper version.

OBJECTIVE

This study assessed the measurement equivalence of the electronic and paper versions of the UPDD in a sample of patients with CIU.

METHODS

This was a cross-over study of patients with moderate-severe CIU refractory to H1 antihistamines. Patients were randomized to either the eUPDD followed by the paper UPDD or vice versa. The UPDD includes morning and evening questions; both sets were administered together in this study. An hour-long filler task was given between paper and electronic administrations. Patients with stable symptoms between the two assessments were included in the analyses. Cohen's kappa coefficients and intraclass correlation coefficients (ICC) were computed as applicable to assess equivalence.

RESULTS

A total of 91 patients participated (mean age 43 years, 79.1 % female). Symptoms were stable between assessments for 67-74 (74-81 %) patients (varied by symptom). Kappa coefficients ranged from 0.82 to 1.00 for the individual UPDD items. For the Urticaria Activity Score (the sum of the 'itch severity' and 'number of hives' item scores) the ICC was 0.90 for the morning (Wilcoxon p = 0.331) and 0.95 for the evening (Wilcoxon p = 0.836).

CONCLUSIONS

All test-retest statistics in this study were well above the accepted threshold, indicating excellent agreement between the two administration methods. Findings support the measurement equivalence of the electronic and paper versions of the UPDD to measure CIU symptoms.

Avidity Studies in Anisakis simplex-Associated Allergic Diseases

Gastroallergic anisakiasis (GAA) and Anisakis-sensitization-associated chronic urticaria (CU+) differ with respect to specific IgE levels. We hypothesised different immunoglobulin avidities in both entities as well as their dependence on TI and fish consumption. 16 patients with GAA and 17 patients with CU+ were included, and immunoglobulin levels were analysed by CAP (Phadia). IgE and IgG avidity indexes (AvIgE and AvIgG, resp.) were also determined. IgG avidity was higher in GAA than in CU+ (P = 0.035), whereas there was a tendency to lower IgE avidity in GAA (P = 0.095). When analysing all patients, AvIgG was positively correlated with specific IgE, IgG, and IgG₄ as well as total IgE (Rho between 0.66 and 0.71; P < 0.002), but AvIgE was negatively correlated with specific IgE (Rho −0.57; P < 0.001), specific IgG₄ (Rho −0.38; P < 0.05), and total IgE (Rho 0.66; P < 0.001). In GAA, weekly fish consumption was positively associated with AvIgE (Rho 0.51; P = 0.05). A multivariate regression showed that time interval was the main explaining factor for AvIgE in GAA. We could show a differential behaviour of immunoglobulin isotype avidities in both entities and their dependence on fish-eating habits as well as on the time elapsed to the last parasitic episode.