A pancreatic cancer organoid platform identifies an inhibitor specific to mutant KRAS.

KRAS mutations, mainly G12D and G12V, are found in more than 90% of pancreatic ductal adenocarcinoma (PDAC) cases. The success of drugs targeting KRASG12C suggests the potential for drugs specifically targeting these alternative PDAC-associated KRAS mutations. Here, we report a high-throughput drug-screening platform using a series of isogenic murine pancreatic organoids that are wild type (WT) or contain common PDAC driver mutations, representing both classical and basal PDAC phenotypes. We screened over 6,000 compounds and identified perhexiline maleate, which can inhibit the growth and induce cell death of pancreatic organoids carrying the KrasG12D mutation both in vitro and in vivo and primary human PDAC organoids. scRNA-seq analysis suggests that the cholesterol synthesis pathway is upregulated specifically in the KRAS mutant organoids, including the key cholesterol synthesis regulator SREBP2. Perhexiline maleate decreases SREBP2 expression levels and reverses the KRAS mutant-induced upregulation of the cholesterol synthesis pathway.

Long-term outcomes of endoscopic mucosal resection for early-stage esophageal adenocarcinoma.

BACKGROUND: With growing application of endoscopic therapy for early-stage esophageal cancer, we sought to review our experience of endoscopic mucosal resections (EMRs). The aim of our study was to understand the natural course of these patients, especially with positive margins. METHODS: A prospectively maintained database of all patients undergoing endoscopic therapies at Georgetown University Hospital for esophageal cancer was used for the analysis between 2010 and 2020. RESULTS: Of 80 patients in the EMR database, 35 were performed as index cases for esophageal adenocarcinoma. Majority (74.3%) had a pre-treatment ultrasound confirming absence of regional adenopathy. There were no post-EMR bleeding or perforation events requiring re-intervention. Complete R0 resection was achieved in 22/35 (62.9%) after initial EMR. Thirteen patients had positive margins. Of these 13 patients, only 7 patients underwent repeat endoscopic resection, 2 underwent subsequent esophagectomy, 2 received definitive radiation given poor surgical candidacy, and 2 were lost to follow-up. Overall and 5-year survival of all patients undergoing EMR was 67.9 months and 85%, respectively. Subset analysis of the 13 patients with R1 resection demonstrated an overall survival of 49.2 months and 60% 5-year survival vs overall survival of 78.9 months and 93% 5-year survival for R0 resection. At a median follow-up of 60.5 months, cancer recurrence occurred in 3 patients. All of them were successfully managed with repeat EMR. CONCLUSIONS: Endoscopic resections represent a safe and effective treatment for early-stage esophageal cancer. Patients with high-risk features should be counseled to undergo an esophagectomy if they are operable candidates.

Anatomical Characteristics Associated With Hypoattenuated Leaflet Thickening in Low-Risk Patients Undergoing Transcatheter Aortic Valve Replacement.

BACKGROUND/PURPOSE: This sub-analysis of the prospective Low Risk TAVR (LRT) trial determined anatomical characteristics associated with hypoattenuated leaflet thickening (HALT), which may contribute to early transcatheter heart valve (THV) degeneration. METHODS/MATERIALS: The LRT trial enrolled 200 low-risk patients between February 2016 and February 2018. All subjects underwent baseline and 30-day CT studies, analyzed by an independent core laboratory. Additional measurements, namely THV expansion, eccentricity, depth, and commissural alignment, were made by consensus of three independent readers. HALT was observed only in the Sapien 3 THV, so Evolut valves were excluded from this analysis. RESULTS: In the LRT trial, 177 subjects received Sapien 3 THVs, of whom 167 (94.3%) had interpretable 30-day CTs and were eligible for this analysis. Twenty-six subjects had HALT (15.6%). Baseline characteristics were similar between groups. There was no difference in THV size implanted and baseline aortic-root geometry between groups. In patients who developed HALT, THV implantation depth was shallower than in patients who did not develop HALT (2.6 ± 1.1 mm HALT versus 3.3 ± 1.8 mm no-HALT, p = 0.03). There were more patients in the HALT group with commissural malalignment (40% vs. 28%; p = 0.25), but this did not reach statistical significance. In a univariable regression model, no predetermined variables were shown to independently predict the development of HALT. CONCLUSIONS: This study did not find anatomical or THV implantation characteristics that predicted the development of HALT at 30 days. This study cannot exclude subtle effects or interaction between factors because of the small number of events.

Feasibility of Coronary Access and Aortic Valve Reintervention in Low-Risk TAVR Patients.

OBJECTIVES: The aim of this study was to evaluate the feasibility of coronary access and aortic valve reintervention in low-risk patients undergoing transcatheter aortic valve replacement (TAVR) with a balloon-expandable transcatheter heart valve (THV). BACKGROUND: Younger, low-risk TAVR patients are more likely than older, higher risk patients to require coronary angiography, percutaneous coronary intervention, or aortic valve reintervention, but their THVs may impede coronary access and cause coronary obstruction during TAVR-in-TAVR. METHODS: The LRT (Low Risk TAVR) trial (NCT02628899) enrolled 200 subjects with symptomatic severe aortic stenosis to undergo TAVR using commercially available THVs. Subjects who received balloon-expandable THVs and who had 30-day cardiac computed tomographic scans were included in this study. In a subgroup, the feasibility of intentional THV crimping on the delivery catheter to pre-determine commissural alignment was tested. RESULTS: In the LRT trial, 168 subjects received balloon-expandable THVs and had 30-day cardiac computed tomographic scans, of which 137 were of adequate image quality for analysis. The most challenging anatomy for coronary access (THV frame above and commissural suture post in front of a coronary ostium) was observed in 9% to 13% of subjects. Intentional THV crimping did not appear to meaningfully affect commissural alignment. The THV frame extended above the sinotubular junction in 21% of subjects, and in 13%, the distance between the THV and the sinotubular junction was <2 mm, signifying that TAVR-in-TAVR may not be feasible without causing coronary obstruction. CONCLUSIONS: TAVR may present challenges to future coronary access and aortic valve reintervention in a substantial number of low-risk patients.

Human interleukin-34-derived macrophages have increased resistance to HIV-1 infection.

The establishment of latent HIV-1 reservoirs in terminally differentiated cells represents a major impediment to the success of antiretroviral therapies. Notably, macrophages (Mϕs) are susceptible to HIV-1 infection and recent evidence suggests that they may be involved in long-term HIV-1 persistence. While the extensive functional heterogeneity seen across the Mϕ cell lineage parallels the spectrum of HIV-1 susceptibility reported across these cell subsets, the facets of Mϕ HIV-1 resistance and susceptibility remain to be fully defined. Notably, the differentiation of most Mϕ subsets depends on signaling through the macrophage colony-stimulating factor receptor (M-CSFR), which in addition to M-CSF, is now known to bind the unrelated interleukin-34 (IL-34) cytokine. The biological need for two M-CSFR ligands awaits full elucidation. Here, we report that Mϕs differentiated from human peripheral blood monocytes with IL-34 are substantially more resistant to HIV-1 infection than M-CSF-derived Mϕs. Moreover, while both Mϕ subsets express comparable surface protein levels of the HIV-1 receptor and co-receptor, CD4 and CCR5 respectively, the IL-34-Mϕs express significantly greater levels of pertinent restriction factor genes, potentially accounting for their greater resistance to HIV-1 infection than that observed in M-CSF-Mϕs. Together, our findings underline previously unexplored differentiation pathways resulting in HIV-1-susceptible and resistant Mϕ subsets and pave the way for further research that may overcome one of the last major hurdles in developing more successful antiretroviral therapy.

IL13Rα2 expression identifies tissue-resident IL-22-producing PLZF+ innate T cells in the human liver.

Innate lymphocytes are selectively enriched in the liver where they have important roles in liver immunology. Murine studies have shown that type I NKT cells can promote liver inflammation, whereas type II NKT cells have an anti-inflammatory role. In humans, type II NKT cells were found to accumulate in the gut during inflammation and IL13Rα2 was proposed as a marker for these cells. In the human liver, less is known about type I and II NKT cells. Here, we studied the phenotype and function of human liver T cells expressing IL13Rα2. We found that IL13Rα2 was expressed by around 1% of liver-resident memory T cells but not on circulating T cells. In support of their innate-like T-cell character, the IL13Rα2+ T cells had higher expression of promyelocytic leukaemia zinc finger (PLZF) compared to IL13Rα2- T cells and possessed the capacity to produce IL-22. However, only a minority of human liver sulfatide-reactive type II NKT cells expressed IL13Rα2. Collectively, these findings suggest that IL13Rα2 identifies tissue-resident intrahepatic T cells with innate characteristics and the capacity to produce IL-22.

MAIT cells are activated in acute Dengue virus infection and after in vitro Zika virus infection.

Dengue virus (DENV) and Zika virus (ZIKV) are members of the Flaviviridae and are predominantly transmitted via mosquito bites. Both viruses are responsible for a growing number of infections in tropical and subtropical regions. DENV infection can cause lethargy with severe morbidity and dengue shock syndrome leading to death in some cases. ZIKV is now linked with Guillain-Barré syndrome and fetal malformations including microcephaly and developmental disorders (congenital Zika syndrome). The protective and pathogenic roles played by the immune response in these infections is unknown. Mucosal-associated invariant T (MAIT) cells are a population of innate T cells with potent anti-bacterial activity. MAIT cells have also been postulated to play a role in the immune response to viral infections. In this study, we evaluated MAIT cell frequency, phenotype, and function in samples from subjects with acute and convalescent DENV infection. We found that in acute DENV infection, MAIT cells had elevated co-expression of the activation markers CD38 and HLA-DR and had a poor IFNγ response following bacterial stimulation. Furthermore, we found that MAIT cells can produce IFNγ in response to in vitro infection with ZIKV. This MAIT cell response was independent of MR1, but dependent on IL-12 and IL-18. Our results suggest that MAIT cells may play an important role in the immune response to Flavivirus infections.

MAIT cells are reduced in frequency and functionally impaired in human T lymphotropic virus type 1 infection: Potential clinical implications.

HTLV-1 infection is associated with several inflammatory disorders, including the neurodegenerative condition HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is unclear why a minority of infected subjects develop HAM/TSP. The cellular immune response has been implicated in the development of inflammatory alterations in these patients; however the pathogenic mechanisms for disease progression remain unclear. Furthermore, HTLV-1-infected individuals have an increase incidence of Mycobacterium tuberculosis (Mtb) infection, suggesting that immunological defect are associated with HTLV-1 infection. Evidence suggests an important role for Mucosal-associated invariant T (MAIT) cells in the early control of Mtb infection. Chronic viral infections like HIV and HCV have been associated with decreased frequency and functionality of MAIT cells. We hypothesized that HTLV-1 infection is associated with similar perturbations in MAIT cells. We investigated MAIT cell frequency, phenotype, and function by flow cytometry in a cohort of 10 asymptomatic and 10 HAM/TSP HTLV-1 infected patients. We found that MAIT cells from HTLV-1-infected subjects were reduced and showed high co-expression of the activation markers CD38 and HLA-DR but normal levels of CCR6 and CD127. MAIT cells had a lower expression of the transcription factor PLZF in HAM/TSP patients. Unlike Tax-specific CD8+T cells, which are hyperfunctional, MAIT cells from HTLV-1-infected subjects had a poor IFNγ response following antigen stimulation. MAIT cell perturbations in HTLV-1 infection were not associated with HTLV-1 proviral load and MAIT cells were not infected by HTLV-1 in vivo. Rather, MAIT cells loss was associated with immune activation. Overall, our results do not support a role for MAIT cells in HAM/TSP pathogenesis but reduced numbers of MAIT cells, together with their poor functionality, could contribute to the increased susceptibility of HTLV-1-infected individuals to other infectious agents.