Autoimmune bullous dermatoses in the elderly: an update on pathophysiology, diagnosis and management

Epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita is a rare autoimmune disease, characterized by the synthesis of anti-collagen VII autoantibodies, the main component of hemidesmosome anchoring fibrils. The antigen-antibody binding elicits a complex inflammatory response, which culminates in the loss of dermo-epidermal adhesion of the skin and/or mucous membranes. Skin fragility with bullae, erosions, and milia in areas of trauma characterizes the mechanobullous form of the disease. In the inflammatory form of epidermolysis bullosa acquisita, urticarial inflammatory plaques with tense bullae, similar to bullous pemphigoid, or mucosal lesions can determine permanent scars and loss of functionality in the ocular, oral, esophageal, and urogenital regions. Due to the similarity of the clinical findings of epidermolysis bullosa acquisita with other diseases of the pemphigoid group and with porphyria cutanea tarda, the diagnosis is currently confirmed mainly based on the clinical correlation with histopathological findings (pauci-inflammatory subepidermal cleavage or with a neutrophilic infiltrate) and the demonstration of the presence of anti-collagen VII IgG in situ by direct immunofluorescence, or circulating anti-collagen VII IgG through indirect immunofluorescence and/or ELISA. There is no specific therapy for epidermolysis bullosa acquisita and the response to treatment is variable, usually with complete remission in children and a worse prognosis in adults with mucosal involvement. Systemic corticosteroids and immunomodulators (colchicine and dapsone) are alternatives for the treatment of mild forms of the disease, while severe forms require the use of corticosteroid therapy associated with immunosuppressants, intravenous immunoglobulin, and rituximab.

Current knowledge of immunomodulation strategies for chronic skin wound repair

In orchestrating the wound healing process, the immune system plays a critical role. Hence, controlling the immune system to repair skin defects is an attractive approach. The highly complex immune system includes the coordinated actions of several immune cells, which can produce various inflammatory and antiinflammatory cytokines and affect the healing of skin wounds. This process can be optimized using biomaterials, bioactive molecules, and cell delivery. The present review discusses various immunomodulation strategies for supporting the healing of chronic wounds. In this regard, following the evolution of the immune system and its role in the wound healing mechanism, the interaction between the extracellular mechanism and immune cells for acceleration wound healing will be firstly investigated. Consequently, the immune-based chronic wounds will be briefly examined and the mechanism of progression, and conventional methods of their treatment are evaluated. In the following, various biomaterials-based immunomodulation strategies are introduced to stimulate and control the immune system to treat and regenerate skin defects. Other effective methods of controlling the immune system in wound healing which is the release of bioactive agents (such as antiinflammatory, antigens, and immunomodulators) and stem cell therapy at the site of injury are reviewed.

Nicotinamide protects against skeletal muscle atrophy in streptozotocin-induced diabetic mice

Context: Skeletal muscle atrophy is a complication of diabetes, partially induced by nicotinamide adenine dinucleotide (NAD⁺) deficiency. Objective: This study investigates the potential of nicotinamide (NAM) supplementation, a precursor of NAD⁺, against muscle atrophy. Methods: Mice were separated into normal control group, normal control with NAM administration group, diabetic group, and diabetic mice with NAM administration group. Basic characteristics, muscle weight, maximal grip strength, and myofibers cross-sectional area were analysed. Markers reflecting muscle atrophy and hypertrophy, and transforming growth factor β1/Smad2 (TGF-β1/Smad2) pathway were examined. Results: NAM did not influence body weight and blood glucose. In diabetic mice, NAM increased NAD⁺ level, rescued muscle weight and strength loss, and increased myofibers cross-sectional area. NAM inhibited MuRF1 and Atrogin1, while elevated phosphorylation of Akt. Overactivation of TGF-β1/Smad2 pathway was repressed by NAM. Conclusion: NAM ameliorated diabetic muscle atrophy by rebalancing protein anabolism and catabolism, probably through de-activation of TGF-β1/Smad2 signaling.

Consensus on the treatment of autoimmune bullous dermatoses: bullous pemphigoid, mucous membrane pemphigoid and epidermolysis bullosa acquisita - Brazilian Society of Dermatology

Bullous pemphigoid, mucous membrane pemphigoid and epidermolysis bullosa acquisita are subepidermal autoimmune blistering diseases whose antigenic target is located at the basement membrane zone. Mucous membrane pemphigoid and epidermolysis bullosa acquisita can evolve with cicatricial mucosal involvement, leading to respiratory, ocular and/or digestive sequelae with important morbidity. For each of these dermatoses, a literature review covering all therapeutic options was performed. A flowchart, based on the experience and joint discussion among the authors of this consensus, was constructed to provide treatment orientation for these diseases in Brazil. In summary, in the localized, low-risk or non-severe forms, drugs that have immunomodulatory action such as dapsone, doxycycline among others may be a therapeutic option. Topical treatment with corticosteroids or immunomodulators may also be used. Systemic corticosteroid therapy continues to be the treatment of choice for severe forms, especially those involving ocular, laryngeal-pharyngeal and/or esophageal mucosal involvement, as may occur in mucous membrane pemphigoid and epidermolysis bullosa acquisita. Several immunosuppressants are used as adjuvant alternatives. In severe and recalcitrant cases, intravenous immunoglobulin is an alternative that, while expensive, may be used. Immunobiological drugs such as rituximab are promising drugs in this area. Omalizumab has been used in bullous pemphigoid.

Anti-collagen XVII single-chain Fv antibody blocks the autoimmune reaction mediated by pathogenic autoantibodies in bullous pemphigoid

BACKGROUND

Pathogenic autoantibodies in bullous pemphigoid (BP) recognize the non-collagenous 16A domain (NC16A) of collagen XVII (COL17), a hemidesmosomal component at the skin membrane. This immune inflammation involves activation of the complement cascade via the classical pathway. With similar antigen binding activity, Fab and single-chain variable fragments (scFv) of pathogenic anti-COL17 antibodies can interfere with COL17 binding of autoantibodies, blocking subsequent complement activation and granulocyte activation.

OBJECTIVE

To characterize the biological functions of human anti-COL17 scFv antibody.

METHODS

We constructed scFv antibodies against the corresponding antigen from parental Fab by expression in Escherichia coli. IgG autoantibodies against COL17 were purified by affinity chromatography from serum of BP patients. The inhibitory effects of anti-COL17 scFv on binding of BP autoantibodies to the NC16A domain of human COL17 antigen were observed by inhibition ELISA, immunofluorescence, and inhibition of complement activation. Reactive oxygen production assay and BP cryosection model were performed to assess the inhibitory effect of scFv on granulocyte activation and then the dermal-epidermal separation.

RESULTS

ELISA and Western blot showed specific binding of scFv to COL17. We found that anti-COL17 scFv can inhibit the binding of intact IgG purified from BP parents to the corresponding COL17 antigen and then subsequent C1q and C3 activation and granulocyte activation in vitro. Most importantly, we confirmed that recombinant scFv can inhibit BP-IgG induced dermal-epidermal separation by BP cryosection model.

CONCLUSION

The anti-COL17 scFv antibody can inhibit the binding of BP-IgG autoantibodies to COL17, thereby affecting subsequent complement activation and granulocyte activation in vitro. Our results suggest that blocking pathogenic epitopes using engineered scFv is an efficient BP therapy.

The Use of Methotrexate in Dermatology / Upotreba metotreksata u dermatologiji

Methotrexate is a cytotoxic antimetabolite agent and a folic acid antagonist. Except for its use in oncology and rheumatology, it is widely used in dermatology. The most important indications include severe forms of psoriasis, but also a wide range of autoimmune diseases and dermatoses with different etiology and pathophysiology such as: bullous pemphigoid, dermatomyositis, pityriasis rubra pilaris, sarcoidosis, T-cell lymphomas, Behcet’s disease, adult atopic eczema, scleroderma, Reiter’s syndrome and many others. For dermatological indications methotrexate is usually taken in low oral doses, 5-25 mg once a week. In certain diseases it can be applied to the lesion itself, or in the form of local preparations. Considering the fact that numerous drugs affect various metabolic phases of methotrexate and may increase its toxicity, it is of utmost importance to consider other prescribed drugs, especially certain antibiotics, nonsteroidal antiinflammatory drugs, antiepileptic drugs, retinoids, proton pump inhibitors and so on. If the selection of patients is correct, if drugs are taken regularly and laboratory monitoring is included, methotrexate is a truly efficient and safe drug that can be taken for months or years if necessary.

Thymoma and autoimmunity

The thymus is a central lymphatic organ that is responsible for many immunological functions, including the production of mature, functional T cells and the induction of self-tolerance. Benign or malignant tumors may originate from the thymus gland, with thymoma being the most common and accounting for 50% of anterior mediastinal tumors. Malignancies linked to thymoma include the loss of self-tolerance and the presence of autoimmunity. In this review, we compiled the current scientific evidence detailing the various interactions between thymoma and autoimmune diseases, including myasthenia gravis, systemic lupus erythematosus, inappropriate antidiuretic hormone secretion, pure red cell aplasia, pernicious anemia, pemphigus and autoimmune thyroid diseases. In recent years, several mechanisms have been proposed to explain these interactions. Most are based on the assumption that the 'sick' thymus, like the 'normal' thymus, can generate mature T cells; however, the T cells generated by the sick thymus are impaired and thus may exert cellular autoreactivity. Here, we present several theories that may shed light on the loss of self-tolerance associated with this epithelial tumor of the thymus.