Analysis of the unique structural and physicochemical properties of the DraD/AfaD invasin in the context of its belonging to the family of chaperone/usher type fimbrial subunits

<p>Abstract</p> <p>Background</p> <p>DraD invasin encoded by the dra operon possesses a classical structure characteristic to fimbrial subunits of the chaperone/usher type. The Ig-fold of the DraD possesses two major characteristics distinguishing it from the family of fimbrial subunits: 1) a distortion of the β-barrel structure in the region of the acceptor cleft, demonstrated by a disturbance of the main-chain hydrogen bonds network, and 2) an unusually located disulfide bond connecting B and F strands - the localization exclusively observed in the subfamily of DraD/AfaD-type subunits.</p> <p>Results</p> <p>To evaluate the influence of the DraD-sc specific structural features on its stability and mechanism of thermal denaturation, a series of DSC and FT-IR denaturation experiments were performed giving following conclusions. 1) The DraD-sc is characterized by a low stability (standard Gibbs free energy and enthalpy of unfolding of 18.4 ±1.4 kJ mol^-1and 131 ±25 kJ mol^-1, respectively) that contrasts strongly with almost infinite stability of the described previously DraE-sc fimbrial protein. 2) The DraD-sc unfolds thermally according to the two state equilibrium model, in contrast to the irreversible kinetically controlled transition of the DraE-sc. 3) The DraD specific disulfide bond is crucial at the folding stage and has little stability effect in the mature protein.</p> <p>Conclusions</p> <p>Data published so far emphasize unique biological properties of the DraD invasin as fimbrial subunit: a chaperone independent folding, an usher independent surface localization and the possibility to exist in two forms: as unbound subunits and as loosely bound at fimbrial tip.</p> <p>Presented calorimetric and FT-IR stability data combined with structural correlations has underlined that the DraD invasin is also characterized by unique physicochemical and structural attributes in the context of its belonging to the family of fimbrial subunits.</p

Clinical characteristics of Polish patients with ANCA-associated vasculitides-retrospective analysis of POLVAS registry

Objective Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are rare small to medium-size vessel systemic diseases. As their clinical picture, organ involvement, and factors influencing outcome may differ between countries and geographical areas, we decided to describe a large cohort of Polish AAV patients coming from several referral centers-members of the Scientific Consortium of the Polish Vasculitis Registry (POLVAS). Methods We conducted a systematic multicenter retrospective study of adult patients diagnosed with AAV between Jan 1990 and Dec 2016 to analyze their clinical picture, organ involvement, and factors influencing outcome. Patients were enrolled to the study by nine centers (14 clinical wards) from seven Voivodeships populated by 22.3 mln inhabitants (58.2% of the Polish population). Results Participating centers included 625 AAV patients into the registry. Their distribution was as follows: 417 patients (66.7%) with GPA, 106 (17.0%) with MPA, and 102 (16.3%) with EGPA. Male-to-female ratios were almost 1:1 for GPA (210/207) and MPA (54/52), but EGPA was twice more frequent among women (34/68). Clinical manifestations and organ involvement were analyzed by clinical phenotype. Their clinical manifestations seem very similar to other European countries, but interestingly, men with GPA appeared to follow a more severe course than the women. Fifty five patients died. In GPA, two variables were significantly associated with death: permanent renal replacement therapy (PRRT) and respiratory involvement (univariate analysis). In multivariate analysis, PRRT (OR = 5.3; 95% confidence interval (CI) = 2.3–12.2), respiratory involvement (OR = 3.2; 95% CI = 1.06–9.7), and, in addition, age > 65 (OR = 2.6; 95% CI = 1.05–6.6) were independently associated with death. In MPA, also three variables were observed to be independent predictors of death: PRRT (OR = 5.7; 95% CI = 1.3–25.5), skin involvement (OR = 4.4; 95% CI = 1.02– 19.6), and age > 65 (OR = 6.3; 95% CI = 1.18–33.7). Conclusions In this first multicenter retrospective study of the Polish AAV patients, we have shown that their demographic characteristics, disease manifestations, and predictors of fatal outcome follow the same pattern as those from other European countries, with men possibly suffering from more severe course of the disease

Association of antineutrophil cytoplasmic antibody (ANCA) specificity with the demographic and clinical characteristics of patients with ANCA-associated vasculitides

Introduction Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) is characterized by the presence of proteinase-3(PR3) or myeloperoxidase(MPO) ANCA. In over 90% of cases, PR3-ANCA are associated with GPA. However, they are also rarely found in MPA and EGPA. On the other hand, MPO-ANCA being characteristic for MPA (>90% of cases), are also found in about 40% of EGPA and 5% of GPA patients. On the ground of this overlap, clinical importance of ANCA specificity identification has been questioned. Patients and methods We conducted a multicenter study AAV patients (417–GPA, 106–MPA, 102-EGPA; diagnosed between 1990 and 2016), included in the POLVAS registry. Data were systematically collected according to a standardized protocol. Results In the ANCA positive group (anti-MPO, anti-PR3) male to female ratio was 1:1, whereas in ANCA negative subgroup - 1:2, regardless of the AAV diagnosis. Anti-MPO antibodies were present in a significantly older patients. Patients with MPO+ GPA and MPO+ EGPA were older than those with corresponding ANCA-negative GPA and EGPA as well as PR3+ AAV. Moreover, ANCA-negative AAV were characterized by a low risk of ESKD and death. Conclusions The presence and specificity of ANCA in AAV patients is related to sex and age, determines their organ involvement and influences mortality as previously shown. Patients with MPO-ANCA-positive AAV constitute a clinically homogeneous group, whereas PR3-ANCA-positive patients are much more clinically heterogeneous. ANCA negative AAV patients are characterized by better prognosis. Thus, ANCA identification is an indispensable element and should not be omitted in establishing AAV diagnosis