Stem cells are influenced by their surrounding microenvironment, or niche. In the testis, Sertoli cells are the key niche cells directing the population size and differentiation fate of spermatogonial stem cells (SSCs). Failure to properly regulate SSCs leads to infertility or germ cell hyperplasia. Several Sertoli cell-expressed genes, such as Gdnf and Cyp26b1, have been identified as being indispensable for the proper maintenance of SSCs in their niche, but the pathways that modulate their expression have not been identified. Although we have recently found that constitutively activating NOTCH signaling in Sertoli cells leads to premature differentiation of all prospermatogonia and sterility, suggesting that there is a crucial role for this pathway in the testis stem cell niche, a true physiological function of NOTCH signaling in Sertoli cells has not been demonstrated. To this end, we conditionally ablated recombination signal binding protein for immunoglobulin kappa J region (Rbpj), a crucial mediator of NOTCH signaling, in Sertoli cells using Amh-cre. Rbpj knockout mice had: significantly increased testis sizes; increased expression of niche factors, such as Gdnf and Cyp26b1; significant increases in the number of pre-and post-meiotic germ cells, including SSCs; and, in a significant proportion of mice, testicular failure and atrophy with tubule lithiasis, possibly due to these unsustainable increases in the number of germ cells. We also identified germ cells as the NOTCH ligand-expressing cells. We conclude that NOTCH signaling in Sertoli cells is required for proper regulation of the testis stem cell niche and is a potential feedback mechanism, based on germ cell input, that governs the expression of factors that control SSC proliferation and differentiation.

Introduction The purpose of this study was to test the short-term efficacy of four commercial mouthwashes versus water in reducing SARS-CoV-2 viral load in the oral cavity over clinically relevant time points. Methods In total, 32 subjects that were proven SARS-CoV-2-positive via polymerase chain reaction (PCR)-based diagnostic test were recruited and randomised into five parallel arms. Cycle threshold (Ct) values were compared in saliva samples between the groups, as well as within the groups at baseline (pre-rinse), zero hours, one hour and two hours post-rinse, using SARS-CoV-2 reverse transcription-PCR analysis. Results We observed a significant increase in Ct values in saliva samples collected immediately after rinsing with all the four mouthwashes - 0.12% chlorhexidine gluconate, 1.5% hydrogen peroxide, 1% povidone iodine, or Listerine - compared to water. A sustained increase in Ct values for up to two hours was only observed in the Listerine and chlorohexidine gluconate groups. We were not able to sufficiently power this clinical trial, so the results remain notional but encouraging and supportive of findings in other emerging mouthwash studies on COVID-19, warranting additional investigations. Conclusions Our evidence suggests that in a clinical setting, prophylactic rinses with Listerine or chlorhexidine gluconate can potentially reduce SARS-CoV-2 viral load in the oral cavity for up to two hours. While limited in statistical power due to the difficulty in obtaining this data, we advocate for pre-procedural mouthwashing, like handwashing, as an economical and safe additional precaution to help mitigate the transmission of SARS-CoV-2 from a potentially infected patient to providers.

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e19061 Background: The rapid spread of SARS-CoV-2 has elicited an equally rapid development of effective vaccines, leading to a reduction of COVID-19 severity and deaths. There is limited data on COVID-19-related immunity in chronic myeloid leukemia (CML) patients. Methods: SPARTA (SARS2 SeroPrevalence And Respiratory Tract Assessment) is an ongoing observational study for participants age ≥18 years to investigate immunity to SARS-CoV-2 after infection and/or vaccination. We included patients with CML and compared them with a non-cancer group. We collected saliva and peripheral blood to measure antigen levels by RT-PCR and antibodies (secretory IgG antibodies and neutralizing antibodies). Results: From October 1, 2021, to February 4, 2022, we prospectively enrolled 49 participants (23 CML, 26 non-cancer). Most were male (56.5%) in the CML group and female in the control group (61.5%), mean age 56.39 y vs. 51.96 y, respectively, and self-identified as white (87% vs. 76.9%). In the CML group, 11 (47.8%) had ≥1 comorbidities, vs 13 (50%) in the control group. Twenty-one (91.3%) CML patients were receiving tyrosine-kinase inhibitors; 4 (18.2%) non-cancer subjects reported taking any medication. Most participants in both groups had received at least one dose of COVID-19 vaccine (73.9% vs. 73.1%); 100% of CML patients received two doses vs. 84.2% of controls; the CML group had a higher percentage of subjects fully vaccinated (66.7% vs. 25%). The CML group had a lower percentage of patients previously diagnosed with COVID-19 (8.8% vs. 57.7%). However, there was no difference in the detection of SARS-CoV-2 antigen at the time of enrollment (0% vs. 4%). SARS-CoV-2 IgG antibodies were detected in most of the participants regardless of cancer status (78.3% in the CML cohort and 88% in the non-cancer cohort), and neutralizing antibodies were detected in 82.6% and 95.6%, respectively. The two groups had comparable IgG (mean 146.3 Ru/ml vs. 148.9 Ru/ml) and neutralizing (mean 1329.1 ng/ml vs. 1112 ng/ml) antibody levels. Conclusions: Our preliminary data comparing concomitant cohorts with similar socio-demographic characteristics and medical history indicate that a diagnosis of CML did not impact the development of antibodies against SARS-CoV-2. We are conducting continuous analysis of antibodies levels over time to assess the evolution of antibody immunity and functional studies including cellular immunity assessments.[Table: see text]