Maturation signatures of conventional dendritic cell subtypes in COVID‐19 suggest direct viral sensing

Growing evidence suggests that conventional dendritic cells (cDCs) undergo aberrant maturation in COVID-19, which negatively affects T-cell activation. The presence of effector T cells in patients with mild disease and dysfunctional T cells in severely ill patients suggests that adequate T-cell responses limit disease severity. Understanding how cDCs cope with SARS-CoV-2 can help elucidate how protective immune responses are generated. Here, we report that cDC2 subtypes exhibit similar infection-induced gene signatures, with the upregulation of interferon-stimulated genes and interleukin (IL)-6 signaling pathways. Furthermore, comparison of cDCs between patients with severe and mild disease showed severely ill patients to exhibit profound downregulation of genes encoding molecules involved in antigen presentation, such as MHCII, TAP, and costimulatory proteins, whereas we observed the opposite for proinflammatory molecules, such as complement and coagulation factors. Thus, as disease severity increases, cDC2s exhibit enhanced inflammatory properties and lose antigen presentation capacity. Moreover, DC3s showed upregulation of anti-apoptotic genes and accumulated during infection. Direct exposure of cDC2s to the virus in vitro recapitulated the activation profile observed in vivo. Our findings suggest that SARS-CoV-2 interacts directly with cDC2s and implements an efficient immune escape mechanism that correlates with disease severity by downregulating crucial molecules required for T-cell activation

Independent prognostic impact of CD15 on complete remission achievement in patients with acute myeloid leukemia

The prognostic role of CD15 in acute myeloid leukemia (AML) has been tested in different studies with conflicting results. To address this issue, we retrospectively evaluated a cohort of 460 AML patients of all ages with the exclusion of acute promyelocytic leukemia (M/F 243/217, median age 50.6 years [range 0.9-81.2]) intensively treated at our institute between January 1999 and December 2010. CD15 positivity was found in 171 of 406 evaluable patients (42.1%). Complete remission (CR) was achieved by 334 patients (72.6%), while 82 (17.8%) were resistant and 44 (9.6%) died during induction: the median CR duration was 15.5 months (range 0.6-176.0), with 2-year disease-free survival rate of 45.1% (95% confidence interval 39.6-50.6). The median overall survival was 14.4 months (range 0.3-177.0), with 2-year overall survival rate of 42.2% (95% confidence interval 37.5-46.9). At univariate analysis for CR achievement, age  8 g/dL (P = .020), and white blood cell < 50 × 10(9) /L (P = .034) had a favorable impact. At a multivariate logistic regression model, CD15 positivity (P = .002), age < 60 years (P = .008), white blood cell < 50 × 10(9) /L (P = .017), and low-risk/no high-risk karyotype (P = .026/P = .025) retained an independent prognostic role on CR achievement. The baseline assessment of CD15 positivity appears to have a role in the risk evaluation for CR achievement in AML patients undergoing intensive chemotherapy and should be assessed in prospective studies together with other clinical and biologic features already reported

Monocyte–macrophage polarization and recruitment pathways in the tumour microenvironment of B‐cell acute lymphoblastic leukaemia

Summary B‐cell acute lymphoblastic leukaemia (B‐ALL) reprograms the surrounding bone marrow (BM) stroma to create a leukaemia‐supportive niche. To elucidate the contribution of immune cells to the leukaemic microenvironment, we investigated the involvement of monocyte/macrophage compartments, as well as several recruitment pathways in B‐ALL development. Immunohistochemistry analyses showed that CD68‐expressing macrophages were increased in leukaemic BM biopsies, compared to controls and predominantly expressed the M2‐like markers CD163 and CD206. Furthermore, the "non‐classical" CD14 CD16 monocyte subset, expressing high CX3CR1 levels, was significantly increased in B‐ALL patients' peripheral blood. CX3CL1 was shown to be significantly upregulated in leukaemic BM plasma, thus providing an altered migratory pathway possibly guiding NC monocyte recruitment into the BM. Additionally, the monocyte/macrophage chemoattractant chemokine ligand 2 (CCL2) strongly increased in leukaemic BM plasma, possibly because of the interaction of leukaemic cells with mesenchymal stromal cells and vascular cells and due to a stimulatory effect of leukaemia‐related inflammatory mediators. C5a, a macrophage chemoattractant and M2‐polarizing factor, further appeared to be upregulated in the leukaemic BM, possibly as an effect of PTX3 decrease, that could unleash complement cascade activation. Overall, deregulated monocyte/macrophage compartments are part of the extensive BM microenvironment remodelling at B‐ALL diagnosis and could represent valuable targets for novel treatments to be coupled with classical chemotherapy

The ABO blood group locus and a chromosome 3 gene cluster associate with SARS-CoV-2 respiratory failure in an Italian-Spanish genome-wide association analysis

[Background] Respiratory failure is a key feature of severe Covid-19 and a critical driver of mortality, but for reasons poorly defined affects less than 10% of SARS-CoV-2 infected patients.[Methods] We included 1,980 patients with Covid-19 respiratory failure at seven centers in the Italian and Spanish epicenters of the SARS-CoV-2 pandemic in Europe (Milan, Monza, Madrid, San Sebastian and Barcelona) for a genome-wide association analysis. After quality control and exclusion of population outliers, 835 patients and 1,255 population-derived controls from Italy, and 775 patients and 950 controls from Spain were included in the final analysis. In total we analyzed 8,582,968 single-nucleotide polymorphisms (SNPs) and conducted a metaanalysis of both case-control panels.[Results] We detected cross-replicating associations with rs11385942 at chromosome 3p21.31 and rs657152 at 9q34, which were genome-wide significant (P<5×10-8) in the meta-analysis of both study panels, odds ratio [OR], 1.77; 95% confidence interval [CI], 1.48 to 2.11; P=1.14×10-10 and OR 1.32 (95% CI, 1.20 to 1.47; P=4.95×10-8), respectively. Among six genes at 3p21.31, SLC6A20 encodes a known interaction partner with angiotensin converting enzyme 2 (ACE2). The association signal at 9q34 was located at the ABO blood group locus and a blood-group-specific analysis showed higher risk for A-positive individuals (OR=1.45, 95% CI, 1.20 to 1.75, P=1.48×10-4) and a protective effect for blood group O (OR=0.65, 95% CI, 0.53 to 0.79, P=1.06×10-5).[Conclusions] We herein report the first robust genetic susceptibility loci for the development of respiratory failure in Covid-19. Identified variants may help guide targeted exploration of severe Covid19 pathophysiology.The IKMB's core facilities received infrastructure support by the Deutsche Forschungsgemeinschaft (DFG) Cluster of Excellence "Precision Medicine in Chronic Inflammation" (PMI, EXC2167). The project also received support through a philanthropic donation by Stein Erik Hagen and Canica AS. L.V. was funded by the Fondazione IRCCS Ca’ Granda «COVID-19 Biobank» research grant. This work was also supported by the Ministero dell’Istruzione, dell’Università e della Ricerca – MIUR project "Dipartimenti di Eccellenza 2018 – 2022" (n° D15D18000410001) to the Department of Medical Sciences, University of Torino. The IKMB authors received financial support from the UKSH Foundation "Gutes Tun!" (special thanks to Alexander Eck, Jenspeter Horst and Jens Scholz) and the German Federal Ministry of Education and Research (BMBF; grant ID 01KI20197). HLA-Typing was performed and supported by the Stefan-MorschStiftung. M.A.H was supported by the Spanish Ministry of Science and Innovation ‘JdC fellowship IJC2018-035131-I.N

Stratified analyses refine association between TLR7 rare variants and severe COVID-19

Summary: Despite extensive global research into genetic predisposition for severe COVID-19, knowledge on the role of rare host genetic variants and their relation to other risk factors remains limited. Here, 52 genes with prior etiological evidence were sequenced in 1,772 severe COVID-19 cases and 5,347 population-based controls from Spain/Italy. Rare deleterious TLR7 variants were present in 2.4% of young (<60 years) cases with no reported clinical risk factors (n = 378), compared to 0.24% of controls (odds ratio [OR] = 12.3, p = 1.27 × 10−10). Incorporation of the results of either functional assays or protein modeling led to a pronounced increase in effect size (ORmax = 46.5, p = 1.74 × 10−15). Association signals for the X-chromosomal gene TLR7 were also detected in the female-only subgroup, suggesting the existence of additional mechanisms beyond X-linked recessive inheritance in males. Additionally, supporting evidence was generated for a contribution to severe COVID-19 of the previously implicated genes IFNAR2, IFIH1, and TBK1. Our results refine the genetic contribution of rare TLR7 variants to severe COVID-19 and strengthen evidence for the etiological relevance of genes in the interferon signaling pathway