ABBREVIATIONSECM extracellular matrix MTT 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide ACKNOWLEDGEMENTSWe would like to acknowledge support from the University of Pennsylvania Center for Molecular Studies in Digestive and Liver Disease (NIH NIDDK P30 DK050306) through the Morphology Core, the Molecular Biology Core, and the Transgenic and Chimeric Mouse Facility, and from the NIH NCI through PO1-CA098101 ("Mechanisms of Esophageal Carcinogenesis"). We thank Dr. Hiroshi Nakagawa for reagents and advice. J.P.K. was supported by K08 and R03 Awards from the NIH NIDDK, a Measey Foundation Fellowship, and a GlaxoSmithKline Institute for Digestive Health Basic Research Award. Research Paper KLF4 and KLF5 Regulate Proliferation, Apoptosis and Invasion in Esophageal Cancer Cells ABSTRACTKLF4 and KLF5, members of the KLF family of transcription factors, play key roles in proliferation, differentiation, and carcinogenesis in a number of gastrointestinal tissues. While KLF4 is expressed in differentiating epithelial cells, KLF5 is found in proliferating cells of the gastrointestinal tract, including the esophagus. KLF4 regulates a number of genes vital for esophageal epithelial differentiation, and decreased expression of KLF4 is seen in esophageal squamous cancers. Nonetheless, the roles of KLF4 and KLF5 in esophageal tumor progression are not known. Here, using TE2 cells stably infected with retroviral vectors to express KLF4 or KLF5, we demonstrate that KLF4 and KLF5 are key players in a number of cellular processes critical for esophageal carcinogenesis. TE2 cells, derived from a patient with poorly differentiated esophageal squamous cancer, normally lack KLF4 and KLF5. Expression of KLF5 in TE2 cells inhibits proliferation, and both KLF4 and KLF5 decrease viability after treatment with hydrogen peroxide and increase anoikis. In response to DNA damage from UV irradiation, viability is decreased in KLF5 but not KLF4 infected cells. Both KLF4 and KLF5 upregulate the cdk inhibitor p21 waf1/cip1 following UV irradiation, but the pro-apoptotic protein BAX is markedly induced only by KLF5. Thus KLF4 may preferentially activate DNA repair pathways while KLF5 induces both DNA repair and apoptosis after UV irradiation. Expression of KLF4 or KLF5 in TE2 cells also inhibits invasion, consistent with a role for each in preventing tumor metastasis. In summary, KLF4 and KLF5 regulate esophageal carcinogenesis by affecting proliferation, apoptosis, and invasion.

Background and Aims Patients develop breakthrough COVID‐19 infection despite vaccination. The aim of this study was to identify outcomes in patients with cirrhosis who developed postvaccination COVID‐19. Methods We performed a retrospective cohort study among US veterans with cirrhosis and postvaccination or unvaccinated COVID‐19. Patients were considered fully vaccinated if COVID‐19 was diagnosed 14 days after the second dose of either the Pfizer BNT162b2, the Moderna 1273‐mRNA, or the single‐dose Janssen Ad.26.COV2.S vaccines and partially vaccinated if COVID‐19 was diagnosed 7 days after the first dose of any vaccine but prior to full vaccination. We investigated the association of postvaccination COVID‐19 with mortality. Results We identified 3242 unvaccinated and 254 postvaccination COVID‐19 patients with cirrhosis (82 after full and 172 after partial vaccination). In a multivariable analysis of a 1:2 propensity‐matched cohort including vaccinated ( n = 254) and unvaccinated ( n = 508) participants, postvaccination COVID‐19 was associated with reduced risk of death (adjusted HR [aHR], 0.21; 95% CI, 0.11–0.42). The reduction was observed after both full (aHR, 0.22; 95% CI, 0.08–0.63) and partial (aHR, 0.19; 95% CI, 0.07–0.54) vaccination, following the 1273‐mRNA (aHR, 0.12; 95% CI 0.04–0.37) and BNT162b2 (aHR, 0.27; 95% CI, 0.10–0.71) vaccines and among patients with compensated (aHR, 0.19; 95% CI, 0.08–0.45) and decompensated (aHR, 0.27; 95% CI, 0.08–0.90) cirrhosis. Findings were consistent in a sensitivity analysis restricted to participants who developed COVID‐19 after vaccine availability. Conclusions Though patients with cirrhosis can develop breakthrough COVID‐19 after full or partial vaccination, these infections are associated with reduced mortality.

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Krüppel-like factor 5 (Klf5; also called IKLF or BTEB2), a zinc-finger transcription factor with proproliferative and transforming properties in vitro, is expressed in proliferating cells of gastrointestinal tract epithelia, including in basal cells of the esophagus. Thus, Klf5 is an excellent candidate to regulate esophageal epithelial proliferation in vivo. Nonetheless, the function of Klf5 in esophageal epithelial homeostasis and tumorigenesis in vivo has not previously been determined. Here, we used the ED-L2 promoter of the Epstein-Barr virus to express Klf5 throughout esophageal epithelia. ED-L2/Klf5 transgenic mice were born at the appropriate Mendelian ratio, survived to at least 1 yr of age, and showed no evidence of esophageal dysplasia or cancer. Staining for bromodeoxyuridine (BrdU) demonstrated increased proliferation in the basal layer of ED-L2/Klf5 mice, but no proliferation was seen in suprabasal cells, despite ectopic expression of Klf5 in these cells. Notably, expression of the KLF family member Klf4, which binds the same DNA sequences as Klf5 and which inhibits proliferation and promotes differentiation, was not altered in ED-L2/Klf5 transgenic mice. In primary esophageal keratinocytes that overexpressed Klf5, expression of Klf4 still inhibited proliferation and promoted differentiation, providing a possible mechanism for the persistence of keratinocyte differentiation in ED-L2/Klf5 mice. To identify additional targets for Klf5 in esophageal epithelia, we performed functional genomic analyses and identified a total of 15 differentially expressed genes. In summary, while Klf5 positively regulates proliferation in basal cells, it is not sufficient to maintain proliferation in the esophageal epithelium.

Interferon-γ (IFN-γ), a pleiotropic lymphokine, has important regulatory effects on many cell types. Although IFN-γ is essential for the initiation of uterine vascular modifications and maintenance of decidual integrity, IFN-γ administration can also cause pregnancy failure in many species. However, little is known about the effector mechanisms involved. In this study, using an IFN-γ-induced abortion mouse model, we reported that no Dolichos biflorus agglutinin lectin-positive uterine natural killer (uNK) cells were observed in the uteri from IFN-γ-induced abortion mice. By contrast, the percentage of CD3−CD49b+ NK cells in the uterus and blood from a foetal resorption group was significantly higher than that of the control group. Similarly, significantly upregulated expression of CD49b (a pan-NK cell marker), CX3CL1 and CX3CR1 (CX3CL1 receptor) was detected in the uteri of IFN-γ-induced abortion mice. Using isolated uterine stromal cells, we showed that upregulated expression of CX3CL1 by IFN-γ was dependent on a Janus family kinase 2-signal transducers and activators of transcription 1 (JAK2-STAT1) pathway. We further demonstrated the chemotactic activity of CX3CL1 in uterine stromal cell conditioned medium on primary splenic NK cells. Finally, we observed increased recruitment of CD49b+ NK cells into the endometrium after exogenous CX3CL1 administration. Collectively, our findings indicate that IFN-γ can significantly increase uterine CX3CL1 expression via activation of the JAK2-STAT1 pathway, thus inducing CD49b+ NK cell uterine homing, and eventually provoke foetal loss. Thus, we provide a new line of evidence correlating the deleterious effects of IFN-γ on pregnancy with the aberrant regulation of CX3CL1 and CD49b+ NK cells.