Antigen-specific CD8 T cells can eliminate antigen-bearing keratinocytes with clonogenic potential via an IFN-γ-dependent mechanism

The immune system surveys the skin for keratinocytes (KCs) infected by viruses or with acquired genetic damage. The mechanism by which T cells mediate KC elimination is however undefined. In this study we show that antigen-specific CD8 T cells can eliminate antigen-bearing KCs in vivo and inhibit their clonogenic potential in vitro, independently of the effector molecules perforin and Fas-ligand (Fas-L). In contrast, IFN-gamma receptor expression on KCs and T cells producing IFN-gamma are each necessary and sufficient for in vitro inhibition of KC clonogenic potential. Thus, antigen-specific cytotoxic T lymphocytes (CTLs) may mediate destruction of epithelium expressing non-self antigen by eliminating KCs with potential for self-renewal through an IFN-gamma-dependent mechanism

IdeS, a Highly Specific Immunoglobulin G (IgG)-Cleaving Enzyme from Streptococcus pyogenes, Is Inhibited by Specific IgG Antibodies Generated during Infection

IdeS, a recently discovered cysteine proteinase secreted by the important human pathogen Streptococcus pyogenes, interferes with phagocytic killing by specifically cleaving the heavy chain of immunoglobulin G. The fact that the enzyme targets one of the key molecules of the adapted immune response raised the question of whether an antibody response against IdeS could inhibit, i.e., neutralize, enzyme activity. Paired acute- and convalescent-phase serum samples from patients with pharyngotonsillitis (n = 10), bacteremia (n = 7), and erysipelas (n = 4) were analyzed. Antibodies with the ability to neutralize IdeS enzymatic activity were already found in two-thirds of acute-phase sera. However, patients who seroconverted to IdeS, in particular patients with pharyngotonsillitis and erysipelas, developed specific antibodies during convalescence with an increased capability to efficiently neutralize the enzymatic activity of IdeS. Also, the presence of neutralizing antibodies decreased the ability of IdeS to mediate bacterial survival in human immune blood. In patients with bacteremia, several acute-phase sera contained neutralizing antibodies, but no correlation was found to severity or outcome of invasive infections. Still, the fact that the human immune response targets the enzymatic activity of IdeS supports the view that the enzyme plays an important role during streptococcal infection

Dipeptidyl peptidase-4 is increased in the abdominal aortic aneurysm vessel wall and is associated with aneurysm disease processes.

BACKGROUND:Abdominal aortic aneurysm (AAA) is a potentially life-threatening disease, and until today there is no other treatment available than surgical intervention. Dipeptidyl peptidase-4 (DPP4)-inhibitors, used clinically to treat type 2 diabetes, have in murine models been shown to attenuate aneurysm formation and decrease aortic wall matrix degradation, inflammation and apoptosis. Our aim was to investigate if DPP4 is present, active and differentially expressed in human AAA. METHODS AND RESULTS:DPP4 gene expression was elevated in both media and adventitia of AAA tissue compared with control tissue, as measured by microarrays and qPCR, with consistent findings in external data. The plasma activity of DPP4 was however lower in male patients with AAA compared with age- and gender-matched controls, independently of comorbidity or medication. Immunohistochemical double staining revealed co-localization of DPP4 with cells positive for CD68, CD4 and -8, CD20, and SMA. Gene set enrichment analysis demonstrated that expression of DPP4 in AAA tissue correlated with expression of biological processes related to B- and T-cells, extracellular matrix turnover, peptidase activity, oxidative stress and angiogenesis whereas it correlated negatively with muscle-/actin-related processes. CONCLUSION:DPP4 is upregulated in both media and adventitia of human AAA and correlates with aneurysm pathophysiological processes. These results support previous murine mechanistic studies and implicate DPP4 as a target in AAA disease

Elevated high-sensitivity troponin T levels at 1-year follow-up are associated with increased long-term mortality after TAVR

Background!#!Elevated pre-procedural high-sensitivity troponin T (hs-TnT) levels predict adverse outcomes in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR). It is unknown whether elevated troponin levels still provide prognostic information during follow-up after successful TAVR. We evaluated the long-term implications of elevated hs-TnT levels found at 1-year post-TAVR.!##!Methods and results!#!The study included 349 patients who underwent TAVR for severe AS from 2010-2019 and for whom 1-year hs-TnT levels were available. Any required percutaneous coronary interventions were performed > 1 week before TAVR. The primary endpoint was survival time starting at 1-year post-TAVR. Optimal hs-TnT cutoff for stratifying risk, identified by ROC analysis, was 39.4 pg/mL. 292 patients had hs-TnT < 39.4 pg/mL (median 18.3 pg/mL) and 57 had hs-TnT ≥ 39.4 pg/mL (median 51.2 pg/mL). The high hs-TnT group had a higher median N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, greater left ventricular (LV) mass, higher prevalence of severe diastolic dysfunction, LV ejection fraction < 35%, severe renal dysfunction, and more men compared with the low hs-TnT group. All-cause mortality during follow-up after TAVR was significantly higher among patients who had hs-TnT ≥ 39.4 pg/mL compared with those who did not (mortality rate at 2 years post-TAVR: 12.3% vs. 4.1%, p = 0.010). Multivariate analysis identified 1-year hs-TnT ≥ 39.4 pg/mL (hazard ratio 2.93, 95% CI 1.91-4.49, p < 0.001), NT-proBNP level > 300 pg/mL, male sex, an eGFR < 60 mL/min/1.73 m!##!Conclusions!#!Elevated hs-TnT concentrations at 1-year after TAVR were associated with a higher long-term mortality