Street medicine: An interprofessional elective to address the unhoused population crisis.

BACKGROUND AND PURPOSE: The homelessness crisis continues to escalate nationwide, yet many healthcare providers are not adequately prepared to provide care for unhoused patients. An interprofessional Street Medicine elective was developed to address identified knowledge gaps in the unhoused population healthcare needs. EDUCATIONAL ACTIVITY AND SETTING: The course comprised didactic and clinical elements focused on empathetic communication, resource utilization, and medical management for unhoused patients. Course learning outcomes were evaluated via thematic analysis of students' post-course reflective essays. Additionally, students completed a voluntary survey to evaluate course effectiveness in preparing students for healthcare in the unhoused population and to identify areas for course improvement. FINDINGS: Thirty students completed the course (17 osteopathic medical, five pharmacy, eight joint physician assistant/public health). All enrolled students submitted mandatory post-course reflections and 57% completed the voluntary survey. Thematic analysis of reflections indicated that the course content challenged biases toward unhoused populations, equipped students with new perspectives on the unique healthcare needs for unhoused patients, and provided interprofessional approaches to address these needs. Voluntary survey results demonstrated students' preparedness to provide effective care for local unhoused patients without bias or stigma. Most students reported they were likely to incorporate the knowledge/skills acquired from the course in their future clinical practice and were satisfied with the course content and organization. SUMMARY: The Street Medicine elective provided a structured interprofessional curricular opportunity on specialized care for unhoused individuals. This course can be adapted by other healthcare professional programs to empower students to address the growing homelessness crisis.

Genome-wide open reading frame profiling identifies fibroblast growth factor signaling as a driver of PD-L1 expression in head and neck squamous cell carcinoma.

Head and neck squamous cell carcinomas (HNSCC) are associated with significant treatment-related morbidity and poor disease-free and disease-specific survival, especially in the recurrent and metastatic (R/M HNSCC) setting. Inhibition of the programmed death-1/ligand-1 (PD-1/PD-L1) immune checkpoint is accepted as a first-line treatment strategy for R/M HNSCC and has expanded into the neoadjuvant, definitive, and adjuvant settings. To understand cellular signals modulating the PD-L1 in HNSCC, we profiled a HNSCC cell-line with a genome-wide open reading frame (ORF) library of 17,000 individual constructs (14,000 unique genes). We identified 335 ORFs enriched in PD-L1high cells and independently validated five of these ORFs (FGF6, IL17A, CD300C, KLR1C and NFKBIA) as drivers of PD-L1 upregulation. We showed that exogenous FGF ligand is sufficient to induce PD-L1 expression in multiple HNSCC cell lines and human immature dendritic cells. Accordingly, overexpression of FGFR1, FGFR3 or the FGFR3 S249C and D786N mutants common to HNSCC tumors also induced PD-L1 overexpression on tumor cells. Small molecule inhibition of FGF signaling abrogated PD-L1 upregulation in these models and also blocked "classical" IFNγ-regulated PD-L1 expression in a STAT1-independent manner. Finally, we found that FGF specifically upregulated a glycosylated form of PD-L1 in our study, and exogenous FGF led to concomitant upregulation of glycosyltransferases that may stabilize PD-L1 on the surface of HNSCC cells. Taken together, our study supports a potential role for FGF/FGFR pathway signaling as a mechanism driving immune escape and rationalizes further exploration of novel combination therapies to improve clinical responses to PD-1/PD-L1 axis inhibition in HNSCC.

Microbe-Mediated Activation of Toll-like Receptor 2 Drives PDL1 Expression in HNSCC.

As immunotherapies targeting the PDL1 checkpoint have become a mainstay of treatment for a subset of head and neck squamous cell carcinoma (HNSCC) patients, a detailed understanding of the mechanisms underlying PDL1-mediated immune evasion is needed. To elucidate factors regulating expression of PDL1 in HNSCC cells, a genome-wide CRISPR profiling approach was implemented to identify genes and pathways conferring altered PDL1 expression in an HNSCC cell line model. Our screen nominated several candidate PDL1 drivers, including Toll-like Receptor 2 (TLR2). Depletion of TLR2 blocks interferon-γ-induced PDL1 expression, and stimulation of TLR2 with either Staphylococcus aureus or a bacterial lipopeptide mimetic, Pam3CSK4, enhanced PDL1 expression in multiple models. The data herein demonstrate a role for TLR2 in modulating the expression of PDL1 in HNSCC models and suggest that microbiota may directly modulate immunosuppression in cancer cells. Our study represents a step toward disentangling the diverse pathways and stimuli regulating PDL1 expression in HNSCC and underscores a need for future work to characterize the complex microbiome in HNSCC patients treated with immunotherapy.