PrEP facilitators and barriers in substance use bridge clinics for women who engage in sex work and who use drugs.

BACKGROUND: Women who engage in sex work and use drugs (WSWUD) experience disproportionate HIV risks. Substance use treatment bridge clinics offer an opportunity to increase HIV pre-exposure prophylaxis (PrEP) delivery to WSWUD, but research on best practices is lacking. Therefore, we explored facilitators and barriers to PrEP across the PrEP care continuum in these settings. METHODS: Bridge clinic and affiliated harm reduction health service providers and WSWUD from Boston were recruited using passive and active outreach between December 2021 and August 2022. Participants were invited to take part in semi-structured phone or in-person interviews to explore HIV prevention and PrEP care experiences overall and within bridge clinic settings. Deductive codes were developed based on HIV risk environment frameworks and the Information-Motivation-Behavioral Skills model and inductive codes were added based on transcript review. Grounded content analysis was used to generate themes organized around the PrEP care continuum. RESULTS: The sample included 14 providers and 25 WSWUD. Most WSWUD were aware of PrEP and more than half had initiated PrEP at some point. However, most who initiated PrEP did not report success with daily oral adherence. Providers and WSWUD described facilitators and barriers to PrEP across the steps of the care continuum: Awareness, uptake, adherence, and retention. Facilitators for WSWUD included non-stigmatizing communication with providers, rapid wraparound substance use treatment and HIV services, having a PrEP routine, and service structures to support PrEP adherence. Barriers included low HIV risk perceptions and competing drug use and survival priorities. Provider facilitators included clinical note templates prompting HIV risk assessments and training. Barriers included discomfort discussing sex work risks, competing clinical priorities, and a lack of PrEP adherence infrastructure. CONCLUSION: WSWUD and bridge clinic providers favored integrated HIV prevention and substance use services in harm reduction and bridge clinic settings. Harm reduction and bridge clinic programs played a key role in HIV prevention and PrEP education for WSWUD. Effective behavioral and structural interventions are still needed to improve PrEP adherence for WSWUD.

Transitions from mono- to co- to tri-culture uniquely affect gene expression in breast cancer, stromal, and immune compartments.

Heterotypic interactions in cancer microenvironments play important roles in disease initiation, progression, and spread. Co-culture is the predominant approach used in dissecting paracrine interactions between tumor and stromal cells, but functional results from simple co-cultures frequently fail to correlate to in vivo conditions. Though complex heterotypic in vitro models have improved functional relevance, there is little systematic knowledge of how multi-culture parameters influence this recapitulation. We therefore have employed a more iterative approach to investigate the influence of increasing model complexity; increased heterotypic complexity specifically. Here we describe how the compartmentalized and microscale elements of our multi-culture device allowed us to obtain gene expression data from one cell type at a time in a heterotypic culture where cells communicated through paracrine interactions. With our device we generated a large dataset comprised of cell type specific gene-expression patterns for cultures of increasing complexity (three cell types in mono-, co-, or tri-culture) not readily accessible in other systems. Principal component analysis indicated that gene expression was changed in co-culture but was often more strongly altered in tri-culture as compared to mono-culture. Our analysis revealed that cell type identity and the complexity around it (mono-, co-, or tri-culture) influence gene regulation. We also observed evidence of complementary regulation between cell types in the same heterotypic culture. Here we demonstrate the utility of our platform in providing insight into how tumor and stromal cells respond to microenvironments of varying complexities highlighting the expanding importance of heterotypic cultures that go beyond conventional co-culture.