Impact of Transient and Persistent Donor-Specific Antibodies in Lung Transplantation.

Lung transplantation (LuTx) is an established treatment for patients with end-stage lung diseases, however, outcomes are limited by acute and chronic rejection. One aspect that has received increasing attention is the role of the host's humoral alloresponse, particularly the formation of de novo donor-specific antibodies (dnDSAs). The aim of this study was to investigate the clinical significance of transient and persistent dnDSAs and to understand their impact on outcomes after LuTx. A retrospective analysis was conducted using DSA screening data from LuTx recipients obtained at the Medical University of Vienna between February 2016 and March 2021. Of the 405 LuTx recipients analyzed, 205 patients developed dnDSA during the follow-up period. Among these, 167 (81%) had transient dnDSA and 38 (19%) persistent dnDSA. Persistent but not transient dnDSAs were associated with chronic lung allograft dysfunction (CLAD) and antibody-mediated rejection (AMR) (p < 0.001 and p = 0.006, respectively). CLAD-free survival rates for persistent dnDSAs at 1-, 3-, and 5-year post-transplantation were significantly lower than for transient dnDSAs (89%, 59%, 56% vs. 91%, 79%, 77%; p = 0.004). Temporal dynamics of dnDSAs after LuTx have a substantial effect on patient outcomes. This study underlines that the persistence of dnDSAs poses a significant risk to graft and patient survival.

2-Hydroxyisonicotinate dehydrogenase isolated from Mycobacterium sp. INA1.

2-Hydroxyisonicotinate dehydrogenase from Mycobacterium sp. INA1 was purified 26-fold to apparent homogeneity. The enzyme is involved in isonicotinate degradation by Mycobacterium sp. INA1 and catalyzes the conversion of 2-hydroxyisonicotinate to 2,6-dihydroxypyridine-4-carboxylate. The purified protein exhibited a native molecular mass of 300 kDa and subunits of 97, 31 and 17 kDa, respectively, indicating an alpha 2 beta 2 gamma 2 structure. The absorption spectrum of the homogeneous enzyme was characteristic for an iron/sulfur flavoprotein, 3.8 mol of iron, 3.7 mol of acid labile sulfur, 0.94 mol of FAD and 0.75 mol of molybdenum were determined per mol of protomer. The molybdenum cofactor was identified as molybdopterin cytosine dinucleotide. 2-Hydroxyisonicotinate dehydrogenase was inactivated in the presence of cyanide. According to these basic properties the protein seems to belong to the class of molybdo-iron/sulfur flavoproteins of the xanthine oxidase family.