The Joint Vasculitis Registry in German-speaking countries (GeVas): subgroup analysis of 195 GCA patients.

OBJECTIVES: Giant cell arteritis (GCA) is one of the most common forms of vasculitis. There is an abundance of studies which are conducted in a randomised controlled trial setting but limited with respect to cohort size and follow-up time. GeVas is the first large-scale registry for vasculitides in German-speaking countries that enables to evaluate this rare disease. Herein we focus on the subgroup of GCA patients including follow-up data up to one year. METHODS: GeVas is a prospective, web-based, multicentre registry for the documentation of organ manifestations, outcomes, and therapy regimens in vasculitides. Recruitment started in June 2019. By April 2023, 15 centres were initiated and have started to enrol patients. RESULTS: After 4 years, 195 GCA-patients were included in the registry, of which 64% were female and 36% were male. The average age was 76 years at the time of recruitment (IQR=69-82). Seventy-nine percent were included in the registry because of a newly diagnosed GCA and 21% because of a relapse. At the first assessment most of the patients (89%) described general symptoms. Thirty-one percent stated ocular symptoms. Cranial symptoms were documented in 78% of the cases. All patients were documented with immunosuppressive treatment at start, of whom 95% received prednisolone, 16% cyclophosphamide, 20% methotrexate, and 48% tocilizumab. After three months 62% and after one year 91% of the patients achieved remission. CONCLUSIONS: Regarding demographics, clinical manifestations and diagnostics, our study showed a similar composition compared to other studies. However, our data differed in terms of treatment regimens.

The Joint Vasculitis Registry in German-speaking countries (GeVas): subgroup analysis of 266 AAV patients.

OBJECTIVES: Prospective long-term observational data on the disease course of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) were missing in Germany to date. Therefore, the Joint Vasculitis Registry in German-speaking countries (GeVas) has been established to follow the course of patients with AAV. The aim of this study is to present baseline data of patients with newly diagnosed and relapsing AAV enrolled in the GeVas registry. METHODS: GeVas is a prospective, web-based, multicentre, clinician-driven registry for the documentation of organ manifestations, damage, long-term outcomes, and therapy regimens in various types of vasculitis. Recruitment started in June 2019. RESULTS: Between June 2019 and October 2022, 266 patients with AAV were included in the GeVas registry: 173 (65%) with new-onset and 93 (35%) with relapsing AAV. One hundred and sixty-two (61%) patients were classified as granulomatosis with polyangiitis (GPA), 66 (25%) as microscopic polyangiitis (MPA), 36 (13%) as eosinophilic granulomatosis with polyangiitis (EGPA), and 2 (1%) as renal limited AAV. The median age was 59 years (51-70 years, IQR), 130 (51%) patients were female. Most patients were ANCA positive (177; 67%) and affected by general symptoms, pulmonary, ear nose throat (ENT), renal and neurological involvement. For induction of remission, the majority of patients received glucocorticoids (247, 93%) in combination with either rituximab (118, 45%) or cyclophosphamide (112, 42%). CONCLUSIONS: Demographic characteristics are comparable to those in other European countries. Differences were found regarding ANCA status, frequencies of organ manifestations, and therapeutic regimens. The GeVas registry will allow longitudinal observations and prospective outcome measures in AAV.

Efficient integration of transmembrane domains depends on the folding properties of the upstream sequences.

The topology of most membrane proteins is defined by the successive integration of α-helical transmembrane domains at the Sec61 translocon. The translocon provides a pore for the transfer of polypeptide segments across the membrane while giving them lateral access to the lipid. For each polypeptide segment of ∼20 residues, the combined hydrophobicities of its constituent amino acids were previously shown to define the extent of membrane integration. Here, we discovered that different sequences preceding a potential transmembrane domain substantially affect its hydrophobicity requirement for integration. Rapidly folding domains, sequences that are intrinsically disordered or very short or capable of binding chaperones with high affinity, allow for efficient transmembrane integration with low-hydrophobicity thresholds for both orientations in the membrane. In contrast, long protein fragments, folding-deficient mutant domains, and artificial sequences not binding chaperones interfered with membrane integration, requiring higher hydrophobicity. We propose that the latter sequences, as they compact on their hydrophobic residues, partially folded but unable to reach a native state, expose hydrophobic surfaces that compete with the translocon for the emerging transmembrane segment, reducing integration efficiency. The results suggest that rapid folding or strong chaperone binding is required for efficient transmembrane integration.

Membrane Protein Integration and Topogenesis at the ER.

Most membrane proteins are composed of hydrophobic α-helical transmembrane segments and are integrated into the lipid bilayer of the endoplasmic reticulum by the highly conserved Sec61 translocon. With respect to the integration mechanism, three types of transmembrane segments can be distinguished-the signal, the stop-transfer sequence, and the re-integration sequence-which in linear succession can account for all kinds of membrane protein topologies. The transmembrane orientation of the initial signal and to a weaker extent also of downstream transmembrane segments is affected by charged flanking residues according to the so-called positive-inside rule. The main driving force for transmembrane integration is hydrophobicity. Systematic analysis suggested thermodynamic equilibration of each peptide segment in the translocon with the membrane as the underlying mechanism. However, there is evidence that integration is not entirely sequence-autonomous, but depends also on the sequence context, from very closely spaced transmembrane segments to the folding state and properties of neighboring sequences. Topogenesis is even influenced by accessory proteins that appear to act as intramembrane chaperones.

The Natural Product Cavinafungin Selectively Interferes with Zika and Dengue Virus Replication by Inhibition of the Host Signal Peptidase.

Flavivirus infections by Zika and dengue virus impose a significant global healthcare threat with no US Food and Drug Administration (FDA)-approved vaccination or specific antiviral treatment available. Here, we present the discovery of an anti-flaviviral natural product named cavinafungin. Cavinafungin is a potent and selectively active compound against Zika and all four dengue virus serotypes. Unbiased, genome-wide genomic profiling in human cells using a novel CRISPR/Cas9 protocol identified the endoplasmic-reticulum-localized signal peptidase as the efficacy target of cavinafungin. Orthogonal profiling in S. cerevisiae followed by the selection of resistant mutants pinpointed the catalytic subunit of the signal peptidase SEC11 as the evolutionary conserved target. Biochemical analysis confirmed a rapid block of signal sequence cleavage of both host and viral proteins by cavinafungin. This study provides an effective compound against the eukaryotic signal peptidase and independent confirmation of the recently identified critical role of the signal peptidase in the replicative cycle of flaviviruses.

Asp563 of the horizontal helix of subunit NuoL is involved in proton translocation by the respiratory complex I.

The NADH:ubiquinone oxidoreductase couples the electron transfer from NADH to ubiquinone with the translocation of protons across the membrane. It contains a 110Å long helix running parallel to the membrane part of the complex. Deletion of the helix resulted in a reduced H(+)/e(-) stoichiometry indicating its direct involvement in proton translocation. Here, we show that the mutation of the conserved amino acid D563(L), which is part of the horizontal helix of the Escherichia coli complex I, leads to a reduced H(+)/e(-) stoichiometry. It is discussed that this residue is involved in transferring protons to the membranous proton translocation site.