Changes in lipid composition of host-derived extracellular vesicles following Salmonella infection.

IMPORTANCE: This study delves into the previously unexplored territory of extracellular vesicle (EV) cargo and composition, specifically focusing on lipid composition changes in EVs following Salmonella infection. EVs play crucial roles in intercellular communication, carrying a variety of biomolecules. Investigating how these EV cargo lipids change post-infection with Salmonella is significant for understanding the molecular mechanisms underlying lipid trafficking during infection. Given the impact of lipid composition on EV function, this research uncovers distinct differences in the lipid profiles of EVs at different time points post-infection and between infected and uninfected macrophages. This study identified lipids that are differentially abundant in EVs produced by the host during infection, offering novel insights into the dynamics of lipid profiles in EVs during cellular processes and infections. This work advances our understanding of host-pathogen interactions, specifically lipid-mediated EV functions during infection.

Identifying locally actionable strategies to increase participant acceptability and feasibility to participate in Phase I cancer clinical trials.

BACKGROUND: Recruitment of cancer clinical trial (CCT) participants, especially participants representing the diversity of the US population, is necessary to create successful medications and a continual challenge. These challenges are amplified in Phase I cancer trials that focus on evaluating the safety of new treatments and are the gateway to treatment development. In preparation for recruitment to a Phase I recurrent head and neck cancer (HNC) trial, we assessed perceived barriers to participation or referral and suggestions for recruitment among people with HNC and community physicians (oncologist, otolaryngologist or surgeon). METHODS: Between December 2020 and February 2022, we conducted a qualitative needs assessment via semistructured interviews with a race and ethnicity-stratified sample of people with HNC (n = 30: 12 non-Hispanic White, 9 non-Hispanic African American, 8 Hispanic and 1 non-Hispanic Pacific Islander) and community physicians (n = 16) within the University of Florida Health Cancer Center catchment area. Interviews were analyzed using a qualitative content analysis approach to describe perspectives and identify relevant themes. RESULTS: People with HNC reported thematic barriers included: concerns about side effects, safety and efficacy; lack of knowledge and systemic and environmental obstacles. Physicians identified thematic barriers of limited physician knowledge; clinic and physician barriers and structural barriers. People with HNC and physicians recommended themes included: improved patient education, dissemination of trial information and interpersonal communication between community physicians and CCT staff. CONCLUSIONS: The themes identified by people with HNC and community physicians are consistent with research efforts and recommendations on how to increase the participation of people from minoritized populations in CCTs. This community needs assessment provides direction on the selection of strategies to increase CCT participation and referral. PATIENT OR PUBLIC CONTRIBUTION: This study focused on people with HNC and community physicians' lived experience and their interpretations of how they would consider a future Phase I clinical trial. In addition to our qualitative data reflecting community voices, a community member reviewed the draft interview guide before data collection and both people with HNC and physicians aided interpretation of the findings.

Extracellular vesicles elicit protective immune responses against Salmonella infection.

Small extracellular vesicles (sEVs) produced by antigen-presenting cells represent a novel mechanism of cell-to-cell communication. The sEVs have been shown to drive Th1-type adaptive immune responses against intracellular infections such as Salmonella. In this study, we have demonstrated that an administration of sEVs produced by Salmonella-infected macrophages to BALB/c mice that were then challenged with Salmonella infection decreased bacterial load in infected animals and led to protection against a lethal dose of Salmonella. Second, the same sEVs induced a robust production of IgA anti-Salmonella antibodies (Abs) in BALB/c mice, including IgA anti-OmpD Abs. These results show that the nanoscale sEVs stimulate adaptive immune responses against intracellular pathogens and that these sEVs can be used to provide animals with complete protection against lethal infection, such as the systemic bacterial infection in immunodeficient BALB/c mice.

Erratum: A CTS Team Approach to Wastewater-Based Epidemiology of Non-Typhoidal Salmonella in Gainesville, FL - ERRATUM.

[This corrects the article DOI: 10.1017/cts.2022.23.].

Leishmania infection-derived extracellular vesicles drive transcription of genes involved in M2 polarization.

Although it is known that the composition of extracellular vesicles (EVs) is determined by the characteristics of the cell and its environment, the effects of intracellular infection on EV composition and functions are not well understood. We had previously shown that cultured macrophages infected with Leishmania parasites release EVs (LiEVs) containing parasite-derived molecules. In this study we show that LdVash, a molecule previously identified in LiEVs from L. donovani infected RAW264.7 macrophages, is widely distributed in the liver of L. donovani infected mice. This result shows for the first time that parasite molecules are released in EVs and distributed in infected tissues where they can be endocytosed by cells in the liver, including macrophages that significantly increase numbers as the infection progresses. To evaluate the potential impact of LiEVs on macrophage functions, we show that primary peritoneal exudate macrophages (PECs) express transcripts of signature molecules of M2 macrophages such as arginase 1, IL-10, and IL-4R when incubated with LiEVs. In comparative studies that illustrate how intracellular pathogens control the composition and functions of EVs released from macrophages, we show that EVs from RAW264.7 macrophages infected with Salmonella Typhimurium activate PECs to express transcripts of signature molecules of M1 macrophages such as iNOS, TNF alpha, and IFN-gamma and not M2 signature molecules. Finally, in contrast to the polarized responses observed in in vitro studies of macrophages, both M1 and M2 signature molecules are detected in L. donovani infected livers, although they exhibit differences in their spatial distribution in infected tissues. In conclusion, EVs produced by macrophages during Leishmania infection lead to the gene expression consistent with M2 polarization. In contrast, the EVs produced during S. Typhimurium infection stimulated the transcription of genes associated with M1 polarization.

Bacterial extracellular vesicles control murine norovirus infection through modulation of antiviral immune responses.

Human norovirus is the primary cause of non-bacterial gastroenteritis globally and is the second leading cause of diarrheal deaths in children in developing countries. However, effective therapeutics which prevent or clear norovirus infection are not yet available due to a lack of understanding regarding norovirus pathogenesis. Evidence shows that noroviruses can bind to the surface of commensal bacteria, and the presence of these bacteria alters both acute and persistent murine norovirus infection through the modulation of host immune responses. Interestingly, norovirus-bacterial interactions also affect the bacteria by inducing bacterial stress responses and increasing the production of bacterial extracellular vesicles. Given the established ability of these vesicles to easily cross the intestinal barriers, enter the lamina propria, and modulate host responses, we hypothesized that bacterial extracellular vesicles influence murine norovirus infection through modulation of the antiviral immune response. In this study, we show that murine norovirus can attach to purified bacterial vesicles, facilitating co-inoculation of target cells with both virus and vesicle. Furthermore, we have found that when murine noroviruses and vesicles are used to co-inoculate macrophages, viral infection is reduced compared to virus infection alone. Specifically, co-inoculation with bacterial vesicles results in higher production and release of pro-inflammatory cytokines in response to viral infection. Ultimately, given that murine norovirus infection increases bacterial vesicle production in vivo, these data indicate that bacterial vesicles may serve as a mechanism by which murine norovirus infection is ultimately controlled and limited to a short-term disease.

Undernutrition, food insecurity, and leprosy in North Gondar Zone, Ethiopia: A case-control study to identify infection risk factors associated with poverty.

BACKGROUND: Ethiopia has over 3,200 new cases of leprosy diagnosed every year. Prevention remains a challenge as transmission pathways are poorly understood. Susceptibility and disease manifestations are highly dependent on individual host-immune response. Nutritional deficiencies, such as protein-energy malnutrition, have been linked to reduced cell-mediated immunity, which in the case of leprosy, could lead to a higher chance of active leprosy and thus an increased reservoir of transmissible infection. METHODOLOGY/PRINCIPAL FINDINGS: Between June and August 2018, recently diagnosed patients with leprosy and individuals without known contact with cases were enrolled as controls in North Gondar regional health centers. Participants answered survey questions on biometric data, demographics, socioeconomic situation, and dietary habits. Descriptive statistics, univariate, and multivariate logisitic regression examined associations between undernutrition, specifically body mass index (BMI), middle upper arm circumference (MUAC), and leprosy. Eighty-one participants (40 cases of leprosy, 41 controls) were enrolled (75% male) with an average age of 38.6 years (SD 18.3). The majority of cases were multibacillary (MB) (90%). There was a high prevalence of undernutrition with 24 (29.6%) participants underweight (BMI <18.5) and 17 (21%) having a low MUAC. On multivariate analysis, underweight was significantly associated with leprosy (aOR = 9.25, 95% CI 2.77, 30.81). Also found to be associated with leprosy was cutting the size of meals/skipping meals (OR = 2.9, 95% CI 1.0, 8.32) or not having enough money for food (OR = 10, 95% CI 3.44 29.06). CONCLUSIONS/SIGNIFICANCE: The results suggest a strong association between leprosy and undernutrition, while also supporting the framework that food insecurity may lead to undernutrition that then could increase susceptibility to leprosy. In conclusion, this study highlights the need to study the interplay of undernutrition, food insecurity, and the manifestations of leprosy.

Antigen-encapsulating host extracellular vesicles derived from Salmonella-infected cells stimulate pathogen-specific Th1-type responses in vivo.

Salmonella Typhimurium is a causative agent of nontyphoidal salmonellosis, for which there is a lack of a clinically approved vaccine in humans. As an intracellular pathogen, Salmonella impacts many cellular pathways. However, the intercellular communication mechanism facilitated by host-derived small extracellular vesicles (EVs), such as exosomes, is an overlooked aspect of the host responses to this infection. We used a comprehensive proteome-based network analysis of exosomes derived from Salmonella-infected macrophages to identify host molecules that are trafficked via these EVs. This analysis predicted that the host-derived small EVs generated during macrophage infection stimulate macrophages and promote activation of T helper 1 (Th1) cells. We identified that exosomes generated during infection contain Salmonella proteins, including unique antigens previously shown to stimulate protective immune responses against Salmonella in murine studies. Furthermore, we showed that host EVs formed upon infection stimulate a mucosal immune response against Salmonella infection when delivered intranasally to BALB/c mice, a route of antigen administration known to initiate mucosal immunity. Specifically, the administration of these vesicles to animals stimulated the production of anti-Salmonella IgG antibodies, such as anti-OmpA antibodies. Exosomes also stimulated antigen-specific cell-mediated immunity. In particular, splenic mononuclear cells isolated from mice administered with exosomes derived from Salmonella-infected antigen-presenting cells increased CD4+ T cells secreting Th1-type cytokines in response to Salmonella antigens. These results demonstrate that small EVs, formed during infection, contribute to Th1 cell bias in the anti-Salmonella responses. Collectively, this study helps to unravel the role of host-derived small EVs as vehicles transmitting antigens to induce Th1-type immunity against Gram-negative bacteria. Understanding the EV-mediated defense mechanisms will allow the development of future approaches to combat bacterial infections.

Poor WASH (Water, Sanitation, and Hygiene) Conditions Are Associated with Leprosy in North Gondar, Ethiopia.

Access to safe water, sanitation, and hygiene (WASH) is critical for preventing the spread of neglected tropical diseases (NTDs) including leprosy. WASH-related transmission factors remain largely unexplored in the leprosy transmission cycle. The aim of this project is to better understand WASH exposures among leprosy cases through a case-control study in North Gondar, Ethiopia. We hypothesized that leprosy cases were more likely to have inadequate WASH access and were more likely to have concurrent schistosomiasis, as schistosomiasis immune consequences may facilitate leprosy infection. Forty leprosy cases (forty-one controls) were enrolled, tested for Schistosomamansoni, administered a demographic and WASH survey, and assigned a WASH index score. WASH factors significantly associated with leprosy on adjusted analyses included open defecation (aOR = 19.9, 95% CI 2.2, 176.3) and lack of access to soap (aOR = 7.3, 95% CI 1.1, 49.9). S. mansoni was detected in 26% of participants and in stratified analysis those with leprosy had a 3.6 (95% CI (0.8, 15.9)) greater odds of schistosomiasis in districts bordering the lake, compared to 0.33 lower odds of schistosomiasis in districts not bordering the lake (95% CI (0.09, 1.2)). Overall, results suggest that leprosy transmission may be related to WASH adequacy and access as well as to schistosomiasis co-infection.