SARS-CoV-2-reactive T-cell receptors isolated from convalescent COVID-19 patients confer potent T-cell effector function

Both B cells and T cells are involved in an effective immune response to SARS-CoV-2, the disease-causing virus of COVID-19. While B cells—with the indispensable help of CD4⁺ T cells—are essential to generate neutralizing antibodies, T cells on their own have been recognized as another major player in effective anti-SARS-CoV-2 immunity. In this report, we provide insights into the characteristics of individual HLA-A*02:01- and HLA-A*24:02-restricted SARS-CoV-2-reactive TCRs, isolated from convalescent COVID-19 patients. We observed that SARS-CoV-2-reactive T-cell populations were clearly detectable in convalescent samples and that TCRs isolated from these T cell clones were highly functional upon ectopic re-expression. The SARS-CoV-2-reactive TCRs described in this report mediated potent TCR signaling in reporter assays with low nanomolar EC50 values. We further demonstrate that these SARS-CoV-2-reactive TCRs conferred powerful T-cell effector function to primary CD8⁺ T cells as evident by a robust anti-SARS-CoV-2 IFN-γ response and in vitro cytotoxicity. We also provide an example of a long-lasting anti-SARS-CoV-2 memory response by reisolation of one of the retrieved TCRs 5 months after initial sampling. Taken together, these findings contribute to a better understanding of anti-SARS-CoV-2 T-cell immunity and may contribute to paving the way toward immunotherapeutics approaches targeting SARS-CoV-2.     

Yersinia enterocolitica and Photorhabdus asymbiotica β-lactamases BlaA are exported by the twin-arginine translocation pathway

In general, β-lactamases of medically important Gram-negative bacteria are Sec-dependently translocated into the periplasm. In contrast, β-lactamases of Mycobacteria spp. (BlaC, BlaS) and the Gram-negative environmental bacteria Stenotrophomonas maltophilia (L2) and Xanthomonas campestris (Bla_XCC-1) have been reported to be secreted by the twin-arginine translocation (Tat) system. Yersinia enterocolitica carries 2 distinct β-lactamase genes (blaA and blaB) encoding BlaA_Ye and the AmpC-like β-lactamase BlaB, respectively. By using the software PRED-TAT for prediction and discrimination of Sec from Tat signal peptides, we identified a functional Tat signal sequence for Yersinia BlaA_Ye. The Tat-dependent translocation of BlaA_Ye could be clearly demonstrated by using a Y. enterocolitica tatC-mutant and cell fractionation. Moreover, we could demonstrate a unique unusual temperature-dependent activity profile of BlaA_Ye ranging from 15 to 60 °C and a high ‘melting temperature’ (T_M = 44.3°) in comparison to the related Sec-dependent β-lactamase TEM-1 (20–50 °C, T_M = 34.9 °C). Strikingly, the blaA gene of Y. enterocolitica is present in diverse environmental Yersinia spp. and a blaA homolog gene could be identified in the closely related Photorhabdus asymbiotica (BlaA_Pa; 69% identity to BlaA_Ye). For BlaA_Pa of P. asymbiotica, we could also demonstrate Tat-dependent secretion. These results suggest that Yersinia BlaA-related β-lactamases may be the prototype of a large Tat-dependent β-lactamase family, which originated from environmental bacteria.     

Performance of Antinuclear Antibodies for Classifying Systemic Lupus Erythematosus: A Systematic Literature Review and Meta‐Regression of Diagnostic Data

Objective

To review the published literature on the performance of indirect immunofluorescence (IIF)–HEp‐2 antinuclear antibody (ANA) testing for classification of systemic lupus erythematosus (SLE).

Methods

A systematic literature search was conducted in the Medline, Embase, and Cochrane databases for articles published between January 1990 and October 2015. The research question was structured according to Population, Intervention, Comparator, Outcome (PICO) format rules, and Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) recommendations were followed where appropriate. Meta‐regression analysis for diagnostic tests was performed, using the ANA titer as independent variable, while sensitivity and specificity were dependent variables.

Results

Of 4,483 publications screened, 62 matched the eligibility criteria, and another 2 articles were identified through reference analysis. The included studies comprised 13,080 SLE patients in total, of whom 12,542 (95.9%) were reported to be IIF‐ANA positive at various titers. For ANA at titers of 1:40, 1:80, 1:160, and 1:320, meta‐regression gave sensitivity values of 98.4% (95% confidence interval [95% CI] 97.6–99.0%), 97.8% (95% CI 96.8–98.5%), 95.8% (95% CI 94.1–97.1%), and 86.0% (95% CI 77.0–91.9%), respectively. The corresponding specificities were 66.9% (95% CI 57.8–74.9%), 74.7% (95% CI 66.7–81.3%), 86.2% (95% CI 80.4–90.5%), and 96.6% (95% CI 93.9–98.1%), respectively.

Conclusion

The results of this systematic literature review and meta‐regression confirm that IIF‐ANAs have high sensitivity for SLE. ANAs at a titer of 1:80 have sufficiently high sensitivity to be considered as an entry criterion for SLE classification criteria, i.e., formally test other classification criteria for SLE only if ANAs of at least 1:80 have been found.

     

Prediction,identification and progression of histopathological liver disease activity in children with intestinal failure

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Trefoil factor 3 in perinatal pancreas is increased by gestational low protein diet and associated with accelerated β-cell maturation

The endocrine pancreas expands markedly in the first postnatal days and the insulin producing β-cells initiate a functional maturation preceded by a morphological change of the islets of Langerhans. Trefoil factor 3 (TFF3) is a secreted peptide expressed in intestinal epithelia, where it promotes migration, but its role in the pancreas is not characterized. The aim of this study was to examine the expression and function of TFF3 in perinatal rat pancreas, ex vivo cultured fetal rat pancreas and in the rat β-cell line INS-1E.

Control or gestational low-protein diet perinatal rat pancreas was harvested at embryonic day 20 (E20), day of birth (P0) and postnatal day 2 (P2). TFF3 mRNA was upregulated 4.5-fold at P0 vs. E20 and downregulated again at P2. In protein-undernourished pups induction of TFF3 at P0 was further increased to 9.7-fold and was increased at P2. TFF3 caused tyrosine phosphorylation of EGFR in INS-1E β-cells, and purified recombinant TFF3 increased both attachment and spreading of INS-1E β-cells. In ex vivo cultures of collagenase digested fetal rat pancreas, a model of perinatal β-cell maturation, TFF3 increased cellular spreading as well as insulin mRNA levels. TFF3 also increased the expression of Pref1/Dlk1 that shares similarities in expression and regulation with TFF3.

These results suggest that TFF3 may promote adhesion and spreading of cells to accelerate β-cell maturation. This study indicates a functional role for TFF3 in pancreatic β-cell maturation in the perinatal period, which is altered by low protein diet during gestation.     

Gallbladder disease in patients with primary sclerosing cholangitis

BACKGROUND/AIMS: Gallbladder abnormalities may be part of the spectrum in primary sclerosing cholangitis (PSC). The aim of the present study was to evaluate the occurrence and prognostic importance of gallbladder abnormalities in patients with PSC. METHODS: Presence of gallbladder abnormalities was assessed in 286 patients with PSC treated at the Liver Unit, Karolinska University Hospital, Huddinge, between 1970 and 2005. RESULTS: One or more gallbladder abnormalities were found in 41% of the patients. Gallstones were found in 25% and cholecystitis in 25%. Cholecystitis among patients with extrahepatic involvement of PSC (30% (65/214)) was significantly higher than among those with intrahepatic involvement (9% (6/70)) (P<0.0001). A gallbladder mass lesion with a mean size of 21 (+/-9) mm (S.D.) was found in 18 (6%) patients, in 56% (10/18) of whom it constituted gallbladder carcinoma. In 9 patients without a gallbladder mass lesion, histological re-evaluation disclosed epithelial dysplasia of the gallbladder. CONCLUSIONS: Gallbladder disease is common in patients with PSC. Dysplasia and carcinoma are commonly found in gallbladder epithelium, suggesting that regular examination of the gallbladder in PSC patients could be of value for early detection of a gallbladder mass lesion. Cholecystectomy is recommended when such a lesion is detected, regardless of its size.