Inflammatory pathways confer resistance to chemoradiotherapy in anal squamous cell carcinoma

Anal squamous cell carcinoma (ASCC) is associated with immunosuppression and infection with human papillomavirus (HPV). Response to standard chemoradiotherapy (CRT) varies considerably. A comprehensive molecular characterization of CRT resistance is lacking, and little is known about the interplay between tumor immune contexture, host immunity, and immunosuppressive and/or immune activating effects of CRT. Patients with localized ASCC, treated with CRT at three different sites of the German Cancer Consortium (DKTK) were included. Patient cohorts for molecular analysis included baseline formalin fixed paraffin embedded biopsies for immunohistochemistry (n = 130), baseline RNA sequencing (n = 98), peripheral blood immune profiling (n = 47), and serum cytokine measurement (n = 35). Gene set enrichment analysis showed that pathways for IFNγ, IFNα, inflammatory response, TNFα signaling via NF-κB, and EMT were significantly enriched in poor responders (all p < 0.001). Expression of interferon-induced transmembrane protein 1 (IFITM1), both on mRNA and protein levels, was associated with reduced Freedom from locoregional failure (FFLF, p = 0.037) and freedom from distant metastasis (FFDM, p = 0.014). An increase of PD-L1 expression on CD4+ T-cells (p < 0.001) and an increase in HLA-DR expression on T-cells (p < 0.001) was observed in the peripheral blood after CRT. Elevated levels of regulatory T-cells and CXCL2 were associated with reduced FFLF (p = 0.0044 and p = 0.004, respectively). Inflammatory pathways in tissue in line with elevated levels of regulatory T-cells and CXCL2 in peripheral blood are associated with resistance to CRT. To counteract this resistance mechanism, the RADIANCE randomized phase-2 trial currently tests the addition of the immune checkpoint inhibitor durvalumab to standard CRT in locally advanced ASCC.

Single cell sequencing reveals endothelial plasticity with transient mesenchymal activation after myocardial infarction

 

After myocardial infarct (MI), followed by ischemia and scar formation, interstitial cells play key roles in the adaptation to injury. Endothelial cells (ECs), for instance, can clonally expand, migrate into the infarct area and facilitate crucial functions promoting revascularization, reestablishment of oxygen supply and secretion of paracrine factors. Moreover, ECs can transiently undergo changes towards a mesenchymal phenotype (Endothelial-to-mesenchymal transition; EndMT). Whether this process contributes to long-term cardiac fibrosis or helps to facilitate post-ischemic vessel growth remains controversial. Here, we aim to delineate kinetics and characteristics of phenotypic changes in ECs with single cell RNA-sequencing (scRNA-seq).

We performed a time course (homeostasis or 0 day (d), 1d, 3d, 5d, 7d, 14d, 28d post-MI) in mice and isolated the non-cardiomyocyte fraction for scRNA-seq (n=35,312 cells). Pecam1/Cdh5 double positive ECs showed expression of apoptosis, hypoxia and inflammation markers at 3d. Bioinformatic cell cycle analysis predicted high association with proliferative capacities at 3d, indicative of EC turnover post-MI. Metabolism, recently linked to regulate EndMT, was altered. We found genes of the glycolysis and the TCA-cycle pathway upregulated at 1d to 3d, and a decrease of fatty acid signaling genes. At 3d, mesenchymal markers Fn1, Vim, S100a4, Serpine1 transiently increased compared to homeostasis (&gt;1.6-fold, p&lt;0.05) together with a reduction of EC genes such as Pecam1. Interestingly, mesenchymal transition was transient and returned to baseline levels at 28d after MI. Cell fate trajectory analysis confirmed these findings by identifying an EC state characterized by high proliferation and mesenchymal but low EC properties. At 3d to 7d the majority of the ECs were assigned to this state, based on their transcriptomic profile.

We additionally used Cdh5-CreERT2; R26-mT/mG mice followed by scRNA-seq to trace the fate of ECs. Bioinformatic analysis of GFP-positive ECs confirmed the gain in mesenchymal marker but revealed no full transition to the mesenchymal state at later timepoints. This suggests a transient mesenchymal activation of ECs rather than a complete lineage transition. We further induced EndMT with TGF-β2 in ECs in vitro and observed reversibility of the phenotype after withdrawal of the stimulus. After treatment, ECs upregulated various mesenchymal marker genes. Withdrawal of TGF-β2 at 3d or 7d, reverted expression to baseline levels. We further determined DNA methylation of EndMT gene loci to assess if TGF-β2 leads to a true fate change but did not observe changes after TGF-β2 stimulation and withdrawal. Taken together, our data suggests that ECs undergo a transient mesenchymal activation concomitant with a metabolic adaptation early after MI but do not acquire a long-term mesenchymal fate. This activation may facilitate EC migration and clonal expansion to regenerate the vascular network.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Center of Cardiovascular Research (DZHK), Deutsche Forschungsgemeinschaft (DFG) CRC1366 Project B4

Single-cell profiling reveals heterogeneity and functional patterning of GPCR expression in the vascular system

G-protein-coupled receptor (GPCR) expression is extensively studied in bulk cDNA, but heterogeneity and functional patterning of GPCR expression in individual vascular cells is poorly understood. Here, we perform a microfluidic-based single-cell GPCR expression analysis in primary smooth muscle cells (SMC) and endothelial cells (EC). GPCR expression is highly heterogeneous in all cell types, which is confirmed in reporter mice, on the protein level and in human cells. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and we identify functionally relevant subgroups of cells that are characterized by specific GPCR patterns. We further show that dedifferentiating SMC upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Taken together, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases.

GPCRs are key regulators of vascular functions. By analysing single-cell GPCRs expression in vascular smooth muscle and endothelial cells from healthy and diseased murine vessels, Kaur et al. show that GPCR expression is highly heterogeneous in all cell types and that disease causes GPCR repertoire changes depending on cell type and vascular localization.

PAFAH1B1 and the lncRNA NONHSAT073641 maintain an angiogenic phenotype in human endothelial cells

AIM

Platelet-activating factor acetyl hydrolase 1B1 (PAFAH1B1, also known as Lis1) is a protein essentially involved in neurogenesis and mostly studied in the nervous system. As we observed a significant expression of PAFAH1B1 in the vascular system, we hypothesized that PAFAH1B1 is important during angiogenesis of endothelial cells as well as in human vascular diseases.

METHOD

The functional relevance of the protein in endothelial cell angiogenic function, its downstream targets and the influence of NONHSAT073641, a long non-coding RNA (lncRNA) with 92% similarity to PAFAH1B1, were studied by knockdown and overexpression in human umbilical vein endothelial cells (HUVEC).

RESULTS

Knockdown of PAFAH1B1 led to impaired tube formation of HUVEC and decreased sprouting in the spheroid assay. Accordingly, the overexpression of PAFAH1B1 increased tube number, sprout length and sprout number. LncRNA NONHSAT073641 behaved similarly. Microarray analysis after PAFAH1B1 knockdown and its overexpression indicated that the protein maintains Matrix Gla Protein (MGP) expression. Chromatin immunoprecipitation experiments revealed that PAFAH1B1 is required for active histone marks and proper binding of RNA Polymerase II to the transcriptional start site of MGP. MGP itself was required for endothelial angiogenic capacity and knockdown of both, PAFAH1B1 and MGP, reduced migration. In vascular samples of patients with chronic thromboembolic pulmonary hypertension (CTEPH), PAFAH1B1 and MGP were upregulated. The function of PAFAH1B1 required the presence of the intact protein as overexpression of NONHSAT073641, which was highly upregulated during CTEPH, did not affect PAFAH1B1 target genes.

CONCLUSION

PAFAH1B1 and NONHSAT073641 are important for endothelial angiogenic function.