Immunoglobulin E-Mediated Autoimmunity

Bullous Pemphigoid IgG Induces Cell Dysfunction and Enhances the Motility of Epidermal Keratinocytes via Rac1/Proteasome Activation

Bullous pemphigoid (BP) is an autoimmune disease characterized by the formation of blisters, in which autoantibodies mainly target type XVII collagen (ColXVII) expressed in basal keratinocytes. BP IgG is known to induce the internalization of ColXVII from the plasma membrane of keratinocytes through macropinocytosis. However, the cellular dynamics following ColXVII internalization have not been completely elucidated. BP IgG exerts a precise effect on cultured keratinocytes, and the morphological/functional changes in BP IgG-stimulated cells lead to the subepidermal blistering associated with BP pathogenesis. Based on the electron microscopy examination, BP IgG-stimulated cells exhibit alterations in the cell membrane structure and the accumulation of intracellular vesicles. These morphological changes in the BP IgG-stimulated cells are accompanied by dysfunctional mitochondria, increased production of reactive oxygen species, increased motility, and detachment. BP IgG triggers the cascade leading to metabolic impairments and stimulates cell migration in the treated keratinocytes. These cellular alterations are reversed by pharmacological inhibitors of Rac1 or the proteasome pathway, suggesting that Rac1 and proteasome activation are involved in the effects of BP IgG on cultured keratinocytes. Our study highlights the role of keratinocyte kinetics in the direct functions of IgG in patients with BP.

Treatment of urticarial vasculitis: A systematic review

Urticarial vasculitis (UV) is a difficult-to-treat condition characterized by long-lasting urticarial rashes and histopathologic findings of leukocytoclastic vasculitis. Treatment is dictated by the severity of skin and systemic involvement and the underlying systemic disease. This is a comprehensive systematic review of the efficacy of current UV treatment options. We searched for relevant studies in 7 databases, including MEDLINE, Scopus, and Web of Science. In total, 261 eligible studies and 789 unique patients with UV were included in the systematic review. Most patients with UV are adult women with chronic (≥6 weeks) and systemic disease. UV is mostly idiopathic but can be associated with drugs, malignancy, autoimmunity, and infections. It usually resolves with their withdrawal or cure. Corticosteroids are effective for the treatment of skin symptoms in more than 80% of patients with UV. However, their long-term administration can lead to potentially serious adverse effects. The addition of immunomodulatory or immunosuppressive agents often allows corticosteroid tapering and improves the efficacy of therapy. Biologicals, including omalizumab, as well as corticosteroids, cyclophosphamide, dapsone, mycophenolate mofetil, plasmapheresis, colchicine, hydroxychloroquine, intravenous immunoglobulin, nonsteroidal anti-inflammatory drugs, and cyclosporine, can be effective for both skin and systemic symptoms in patients with UV. H₁-antihistamines, montelukast, danazol, H₂-antihistamines, pentoxifylline, doxepin, and tranexamic acid are not effective in most patients with UV. As of yet, no drugs have been approved for UV, and management recommendations are based mostly on case reports and retrospective studies. Prospective studies investigating the effects of treatment on the signs and symptoms of UV are needed.

On the Lipophilic Nature of Autoreactive IgE in Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is a skin disease related to autoreactive IgE in at least a subgroup of patients. However, the nature of this autoreactive IgE remains poorly characterized. This investigation had three objectives: first, to quantity CSU autoreactive IgE; second, to recognize the patterns of CSU autoreactive IgE compared with healthy control IgE; and third, to investigate the physiochemical nature of CSU autoreactive IgE.

Methods: IgE autoreactivity was assessed in sera from 7 CSU and 7 healthy individuals. Autoantigen recognition patterns were assessed using principal component analysis (PCA) and heatmap visualization. Lipophilicity was assessed using NanoOrange reagent.

Results: First, although total IgE levels did not differ significantly, the autoreactive proportion of IgE of CSU patients was 62% ± 37%, 1000-fold higher than that of healthy controls 0.03% ± 0.008% (P = 0.0006). Second, CSU autoreactive IgE differed from healthy control IgE by recognizing more and different autoantigens (226 vs. 34; P = 0.01). Third, the median (with 10-90% percentiles) serum level of lipophilic IgE was 39% (38-40%) in 232 CSU patients, 1.4-fold higher than the 28% (26-29%) of 173 healthy controls (P < 0.0001). Furthermore, lipophilicity correlated with autoreactivity (r = 0.8; P < 0.0001), connecting these two observed features.

Conclusion: We believe that these novel observations about CSU autoreactive IgE, particularly the finding that it is more lipophilic than that of IgE from healthy individuals, will lead to the development of new diagnostic tests and therapies for autoreactive IgE-mediated diseases.

Cutting Edge: Biomarkers for Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined by the appearance of wheals and a variable presence of angioedema which persists for at least 6 weeks. It represents the most common subtype of chronic urticaria and is gaining importance in civil society because of its association with impaired quality of life. Moreover, CSU has a growing impact on national health systems representing a great burden due to its variable rate of response to the approved therapies. In this scenario, the identification of clinical and molecular biomarkers is of pivotal importance. Some groups are trying to detect molecules which would be able to help clinicians in reaching a proper diagnosis; additionally, the opportunity to describe disease severity which leads to cluster patients in different groups could fill the gap in the numerous unmet clinical needs. Several biomarkers are currently being studied with the purpose to predict the response to a defined therapy; unfortunately, none of them are ready to be translated from bench to bedside.