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Responsabile: Dott.ssa Fabiana Ziberna
La Dermatite Erpetiforme è una malattia cutanea autoimmune associata alla celiachia, di cui in molti casi può essere la prima manifestazione. La diagnosi di Dermatite Erpetiforme è spesso difficile, poiché le tipiche lesioni cutanee possono non essere chiaramente riconoscibili, e richiede l’esecuzione della biopsia cutanea per la ricerca, mediante immunofluorescenza, dei depositi epidermici di anticorpi IgA. Questa metodica oltre ad essere invasiva, è operatore dipendente e può non essere conclusiva. Di recente nei soggetti affetti da Dermatite Erpetiforme è stata identificata la presenza nel sangue di specifici anticorpi anti-transglutaminasi epidermica (anti-TG3) che potrebbero rappresentare un marcatore utile per la diagnosi. La disponibilità di un test diagnostico accurato per la rilevazione di questi anticorpi potrebbe in futuro rappresentare una alternativa, meno invasiva e meno costosa, alla biopsia cutanea.
Background
Dermatitis Herpetiformis (DH) is an autoimmune gluten-dependent cutaneous disorder closely related to Coeliac Disease (CD). The diagnosis of DH is challenging because the primary lesions may be absent due to scratching, and gastrointestinal CD symptoms are usually absent. Direct immunofluorescence (DIF) on skin biopsy with the characteristic finding of IgA deposition, is still considered the gold standard to establish the final diagnosis. In recent years, serologic testing for IgA against epidermal transglutaminase (anti-TG3), a key autoantigen in DH, has attracted growing interest. This methodology offers the advantage of being less invasive, less expensive, personal-expertise independent and could ideally replace skin biopsy.
Aims
To develop and evaluate the diagnostic accuracy and reproducibility of a novel quantitative ELISA test, for the measurement of serum anti-TG3 antibodies (Abs), to be used for the diagnosis of DH in clinical practice.
Study design and methods
This was a multicentre retrospective study involving four University Hospitals, in Italy and Finland. Stored serum samples of 46 DH patients, 212 CD patients and 288 controls were analysed at IRCCS Burlo Garofolo, Trieste, Italy. After preliminary optimization of experimental conditions, an ELISA, based on the combined use of the activated form of TG3 together with a specific standard curve, created using a gut-derived monoclonal IgA antibody, was set-up to quantitatively measure the anti-TG3 Abs.
All serum samples were tested for anti-TG3 Abs using the novel ELISA assay (TG3-ELISA).
Main Results
The novel TG3-ELISA had a sensitivity of 93% and a specificity of 99% to distinguish DH patients from healthy controls. Using the novel TG3-ELISA we found that DH patients had significantly higher concentrations of anti-TG3 Abs compared to all the other groups (p<0.0001) and that anti-TG3 Abs concentrations significantly decreased with gluten free diet (p<0.0001).
Significance and Relevance for National Health System
Given its high diagnostic performance, this novel ELISA is suitable as a screening tool in patients in whom DH is clinically suspected and will be helpful in cases in which the diagnosis is uncertain.