C1R Mutations Trigger Constitutive Complement 1 Activation in Periodontal Ehlers-Danlos Syndrome.

Heterozygous missense or in-frame insertion/deletion mutations in complement 1 subunits C1r and C1s cause periodontal Ehlers-Danlos Syndrome (pEDS), a specific EDS subtype characterized by early severe periodontal destruction and connective tissue abnormalities like easy bruising, pretibial haemosiderotic plaques, and joint hypermobility. We report extensive functional studies of 16 C1R variants associated with pEDS by in-vitro overexpression studies in HEK293T cells followed by western blot, size exclusion chromatography and surface plasmon resonance analyses. Patient-derived skin fibroblasts were analyzed by western blot and Enzyme-linked Immunosorbent Assay (ELISA). Overexpression of C1R variants in HEK293T cells revealed that none of the pEDS variants was integrated into the C1 complex but cause extracellular presence of catalytic C1r/C1s activities. Variants showed domain-specific abnormalities of intracellular processing and secretion with preservation of serine protease function in the supernatant. In contrast to C1r wild type, and with the exception of a C1R missense variant disabling a C1q binding site, pEDS variants had different impact on the cell: retention of C1r fragments inside the cell, secretion of aggregates, or a new C1r cleavage site. Overexpression of C1R variants in HEK293T as well as western blot analyses of patient fibroblasts showed decreased levels of secreted C1r. Importantly, all available patient fibroblasts exhibited activated C1s and activation of externally added C4 in the supernatant while control cell lines secreted proenzyme C1s and showed no increase in C4 activation. The central elements in the pathogenesis of pEDS seem to be the intracellular activation of C1r and/or C1s, and extracellular presence of activated C1s that independently of microbial triggers can activate the classical complement cascade.

A Review of the Dermatologic Symptoms of Idiopathic Mast Cell Activation Syndrome

Since the first reported cases in 2007, idiopathic mast cell activation syndrome has been increasingly recognized. Understanding of the cutaneous manifestations of this condition is imperative for dermatologists given the substantial clinical heterogeneity in its presentation and high estimated prevalence. A review of PubMed® and SCOPUS® databases was performed in order to investigate the most common dermatologic manifestations of idiopathic mast cell activation syndrome. Evidence to date suggests that flushing, pruritus, and clotting dysfunction or bleeding disorder are the most frequently observed dermatologic symptoms in idiopathic mast cell activation syndrome, while dermatographism has been identified as a common finding in patients as well. Mast cell activation syndromes have also been linked to connective tissue disorders, including an Ehlers-Danlos Syndrome-like phenotype possibly mediated by matrix metalloproteinases and tryptase released by mast cells. Current literature regarding dermatologic manifestations of idiopathic mast cell activation syndrome is limited by the heterogeneity of studies including clinical descriptions, inconsistency of diagnostic criteria implemented, and a paucity of literature available. This work provides a guide for dermatologists to strengthen diagnostic acuity for idiopathic mast cell activation syndrome, therefore contributing toward a goal of helping patients to receive timely, effective, and targeted therapy. J Drugs Dermatol. 2019;18(2):162-168.

Two Different Missense C1S Mutations, Associated to Periodontal Ehlers-Danlos Syndrome, Lead to Identical Molecular Outcomes.

Ehlers-Danlos syndromes (EDS) are clinically and genetically heterogeneous disorders characterized by soft connective tissue alteration like joint hypermobility and skin hyper-extensibility. We previously identified heterozygous missense mutations in the C1R and C1S genes, coding for the complement C1 proteases, in patients affected by periodontal EDS, a specific EDS subtype hallmarked by early severe periodontitis leading to premature loss of teeth and connective tissue alterations. Up to now, there is no clear molecular link relating the nominal role of the C1r and C1s proteases, which is to activate the classical complement pathway, to these heterogeneous symptoms of periodontal EDS syndrome. We aim therefore to elucidate the functional effect of these mutations, at the molecular and enzymatic levels. To explore the molecular consequences, a set of cell transfection experiments, recombinant protein purification, mass spectroscopy and N-terminal analyses have been performed. Focusing on the results obtained on two different C1S variants, namely p.Val316del and p.Cys294Arg, we show that HEK293-F cells stably transfected with the corresponding C1s variant plasmids, unexpectedly, do not secrete the full-length mutated C1s, but only a truncated Fg40 fragment of 40 kDa, produced at very low levels. Detailed analyses of the Fg40 fragments purified for the two C1s variants show that they are identical, which was also unexpected. This suggests that local misfolding of the CCP1 module containing the patient mutation exposes a novel cleavage site, between Lys353 and Cys354, which is not normally accessible. The mutation-induced Fg40 fragment contains the intact C-terminal serine protease domain but not the N-terminal domain mediating C1s interaction with the other C1 subunits, C1r, and C1q. Thus, Fg40 enzymatic activity escapes the normal physiological control of C1s activity within C1, potentially providing a loss-of-control. Comparative enzymatic analyses show that Fg40 retains the native esterolytic activity of C1s, as well as its cleavage efficiency toward the ancillary alarmin HMGB1 substrate, for example, whereas the nominal complement C4 activation cleavage is impaired. These new results open the way to further molecular explorations possibly involving subsidiary C1s targets.

Pathophysiology of Eosinophilic Esophagitis.

Eosinophilic esophagitis is an emerging disease that is distinguished from gastroesophageal reflux disease by the expression of a unique esophageal transcriptome and the interplay of early life environmental factors with distinct genetic susceptibility elements at 5q22 (TSLP) and 2p23 (CAPN14). Rare genetic syndromes have uncovered the contribution of barrier disruption, mediated in part by defective desmosomes and dysregulated transforming growth factor beta production and signaling, to eosinophilic esophagitis pathophysiology. Experimental modeling has defined a cooperative role of activated eosinophils, mast cells, and the cytokines IL-5 and IL-13, mediated by allergic sensitization to multiple foods. Understanding these processes is opening the way to better treatment based on disrupting allergic inflammatory and type 2 cytokine-mediated responses, including anti-cytokine therapeutics and dietary therapy.

Generalized acquired cutis laxa associated with coeliac disease: evidence of immunoglobulin A deposits on the dermal elastic fibres.

Acquired cutis laxa (ACL) is an uncommon elastolytic disorder of unknown aetiology. In rare instances, ACL has been reported in association with autoimmune diseases and dermal deposit of immunoglobulins, suggesting that destruction of elastic tissue may be immunologically mediated. We report a 35-year-old man with generalized acquired cutis laxa (GACL) associated with a persistent papular erythematous eruption that histopathologically showed some resemblance to dermatitis herpetiformis. A marked reduction and degeneration of dermal elastic fibres was noted in biopsies from loose-hanging skin. Direct immunofluorescence from non-inflammatory loose skin revealed granular immunoglobulin A (IgA) deposits at the basement membrane zone and fibrillar IgA deposits in the dermal papillae. IgA deposits were also observed on the elastic fibres of the reticular dermis. Electron microscopy of skin from the submammary fold revealed fragmented elastic fibres, partial absence of peripheral microfibrils and abundant neutrophils, some of which were degranulated and adjacent to elastic fibres. Immunoelectron microscopy of an erythematous papule revealed IgA deposits around dermal elastic fibres. Antigliadin, antireticulin and antiendomysium antibodies were present. Jejunal biopsies showed a gluten-sensitive enteropathy. A possible IgA-mediated immune mechanism for the development of GACL in our patient is suggested.

Intractable vasculitis, resorptive osteolysis, and immunity to type I collagen in type VIII Ehlers-Danlos syndrome.

A unique patient with type VIII Ehlers-Danlos syndrome and cutaneous vasculitis, resorptive osteolysis, and cardiac valvular disease is described. Collagen analyses identified morphologic and physical abnormalities of type I collagen. The patient's T lymphocytes could be propagated in vitro with type I collagen and produced a 60-kd lymphokine that bound this protein. Cellular autoimmunity to type I collagen may be responsible for this patient's intractable clinical condition.

[Immunologic disorders in children with developmental thoracic defects]. / Immunologicheskie narusheniia u detei s defektami razvitiia grudnoi kletki.

As the result of immunological examination of 21 children with developmental defects of the chest and analysis of the course of the postoperative period in 136 children, among which 36 had hereditary syndromes of systemic connective-tissue dyshistogenesis, it was found that suppurative complications of thoracoplasty, which are encountered in 15% of children with isolated developmental chest defects and in 33.3% of those with the above mentioned syndromes, were caused to a great measure by disorders of the immune status. The most serious immunological deviations were encountered in the Marfan syndrome due to impaired phagocytic activity of neutrophils and monocytes, decreased number of T, T active, and B lymphocytes, and diminished function of T helpers. In unclassified complexes of developmental defects with Marfaneic ++ phenotypes, the immunological disorders were similar, but less deep. In the Ehlers-Danlos syndrome, a decrease of the number of immunocompetent cells, function of T helpers, and neutrophils was mainly revealed. In isolated forms of funnel chest the function of monocytes and the number of immunoglobulins are mainly decreased.

Biochemical and immunological studies of fibroblasts derived from a patient with Ehlers-Danlos syndrome type IV. Demonstrate reduced type III collagen synthesis.

Fibroblasts derived from a skin biopsy of a patient with the Ehlers-Danlos syndrome (EDS) type IV were cultured in monolayer. The amount of collagen synthesized during a 24-h pulse was not different from that found with normal fibroblasts. Chromatographic procedures and immunofluorescence staining showed a normal synthesis of type I procollagen and collagen but a deficiency in synthesis of type III procollagen and collagen. This could be corroborated by radioimmuno assays showing a reduction in type III procollagen by about 90%. The secretion and degradation of collagens was not altered. The results demonstrate that the molecular defect in this particular patient is due to an impairment of the mechanism controlling the gene expression for type III procollagen.