High-Resolution Single Nucleotide Polymorphism Analysis Distinguishes Recrudescence and Reinfection in Recurrent Invasive Nontyphoidal Salmonella Typhimurium Disease

Invasive nontyphoidal Salmonella Typhimurium disease is a common and frequently recurrent cause of bacteremia across sub-Saharan Africa. We use high-resolution single nucleotide polymorphism analysis to distinguish between reinfection and recrudescence in disease recurrence within single individuals over time

Alveolar T-helper 17 responses to streptococcus pneumoniae are preserved in ART-untreated and treated HIV-infected Malawian adults.

We explored if HIV infection is associated with impaired T-Helper 17 responses against Streptococcus pneumoniae in the lung. We recruited 30 HIV-uninfected healthy controls, 23 asymptomatic HIV-infected adults not on ART, and 40 asymptomatic HIV-infected adults on ART (Median time 3.5yrs), in whom we collected bronchoalveolar lavage fluid. We measured alveolar CD4+ T cell immune responses following stimulation with pneumococcal cell culture supernatant using flow cytometry-based intracellular cytokine staining. We found that the proportion of alveolar CD4+ T cells producing IL-17A following stimulation with pneumococcal cell culture supernatant (CCS) was similar between HIV-uninfected controls and ART-naïve HIV-infected adults (0.10% vs. 0.14%; p = 0.9273). In contrast, the proportion and relative absolute counts of CD4+ T cells producing IL-17A in response to pneumococcal CCS were higher in ART-treated HIV-infected adults compared HIV-uninfected controls (0.22% vs. 0.10%, p = 0.0166; 5420 vs. 1902 cells/100 ml BAL fluid; p = 0.0519). The increase in relative absolute numbers of IL-17A-producing alveolar CD4+ T cells in ART-treated individuals was not correlated with the peripheral blood CD4+ T cell count (r=-0.1876, p = 0.1785). Alveolar Th17 responses against S. pneumoniae are preserved in HIV-infected adults. This suggests that there are other alternative mechanisms that are altered in HIV-infected individuals that render them more susceptible to pneumococcal pneumonia. [Abstract copyright: Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Asymptomatic HIV-infected Individuals on Antiretroviral Therapy Exhibit Impaired Lung CD4+T-Cell Responses to Mycobacteria

Rationale: HIV-infected persons on antiretroviral therapy (ART) remain at higher risk of pulmonary tuberculosis (TB) than HIV-uninfected individuals. This increased susceptibility may be caused by impairment of alveolar macrophage (AM) function and/or mycobacteria-specific alveolar CD4+ T-cell responses observed in HIV-infected ART-naive adults. Objectives: To determine whether ART was associated with improvement in both AM function, assessed by phagosomal proteolysis, and alveolar CD4+ T-cell responses to Mycobacterium in HIV-infected individuals. Methods: Peripheral blood was drawn and bronchoalveolar lavage (BAL) performed on healthy, 35 HIV-uninfected, 25 HIV-infected ART-naive, and 50 HIV-infected ART-treated asymptomatic adults. Phagosomal proteolysis of AM was assessed with fluorogenic beads. Mycobacteria-specific CD4+ T-cell responses were measured by intracellular cytokine staining. Measurements and Main Results: HIV-infected adults on ART exhibited lower plasma HIV viral load and higher blood CD4+ T-cell count than ART-naive adults. AM proteolysis and total mycobacteria-specific Th1 CD4+ T-cell responses in individuals on ART for greater than or equal to 4 years were similar to HIV-uninfected control subjects but those on ART for less than 4 years had impaired responses. Total influenza-specific alveolar Th1 CD4+ T-cell responses were intact in all individuals receiving ART. In contrast, BAL and blood mycobacteria-specific polyfunctional CD4+ T-cell responses were impaired in adults on ART irrespective of duration. Conclusions: AM and mycobacteria-specific alveolar CD4+ T-cell responses in HIV-infected adults on ART for less than 4 years are impaired and may partly explain the high risk of TB in HIV-infected individuals on ART. Strategies to augment ART to improve lung immune cell function and reduce the high incidence of TB in HIV-infected adults who initiate ART should be investigated

Invasive Non-typhoid Salmonellae Establish Systemic Intracellular Infection in HIV-Infected Adults: An Emerging Disease Pathogenesis

Background. Salmonellae are facultative intracellular pathogens. Non-typhoid salmonellae (NTS) cause selflimiting mucosal disease in immunocompetent adults but invasive, recurrent disease among human immunodeficiency virus (HIV)–infected adults in Africa. The importance of intracellular NTS infection in HIV is unknown. Methods. We performed quantitative pour-plate culture of blood samples obtained during febrile events among 495 Malawian adults on 871 occasions, and NTS were isolated at 158 events. Ninety-eight percent were HIV infected, with a median CD4 count of 67 cells/mL. Lysis of pour plates and gentamicin exclusion testing were used to investigate the presence of intracellular NTS in blood and bone marrow. Results. Total viable NTS counts in blood were low (1 colony-forming unit [CFU]/mL) but correlated independently with lower CD4 count and with IL-10 and IL-6 levels, especially at recurrence, suggesting failure to clear intracellular infection. Viable NTS load in blood and bone marrow were closely correlated at index events, but NTS were significantly concentrated in bone marrow, compared with blood samples, at recurrences (6 vs 1 CFU/mL), suggesting systemic tissue replication. Both lysis-pour-plating and gentamicin exclusion testing demonstrated intracellular infection with 11 CFU/cell in both blood and bone marrow specimens. Intracellular bacteria were demonstrated in bone marrow at both index and recurrent events, showing that this is an early and enduring feature of pathogenesis, but intracellular NTS were detected in blood only at index events, particularly in patients with a CD4 count !50 cells/mL. Intravascular NTS at recurrence may therefore reflect extracellular “overspill” from an intracellular sanctuary site, following failure of immunological control. Conclusions. Invasive NTS have established a new and emerging pathogenesis in the context of HIV infection in Africa

Differential localization and limited cytotoxic potential of duodenal CD8+Tcells

The duodenum is a major site of HIV persistence during suppressive antiretroviral therapy despite harboring abundant tissue-resident memory (Trm) CD8(+) T cells. The role of duodenal Trm CD8(+) T cells in viral control is still not well defined. We examined the spatial localization, phenotype, and function of CD8(+) T cells in the human duodenal tissue from people living with HIV (PLHIV) and healthy controls. We found that Trm (CD69(+)CD103(hi)) cells were the predominant CD8(+) T cell population in the duodenum. Immunofluorescence imaging of the duodenal tissue revealed that CD103(+)CD8(+) T cells were localized in the intraepithelial region, while CD103(–)CD8(+) T cells and CD4(+) T cells were mostly localized in the lamina propria (LP). Furthermore, HIV-specific CD8(+) T cells were enriched in the CD69(+)CD103(–/lo) population. However, the duodenal HIV-specific CD8(+) Trm cells rarely expressed canonical molecules for potent cytolytic function (perforin and granzyme B) but were more polyfunctional than those from peripheral blood. Taken together, our results show that duodenal CD8(+) Trm cells possess limited perforin-mediated cytolytic potential and are spatially separated from HIV-susceptible LP CD4(+) T cells. This could contribute to HIV persistence in the duodenum and provides critical information for the design of cure therapies

Household air pollution and the lung microbiome of healthy adults in Malawi: a cross-sectional study.

BACKGROUND: Domestic combustion of biomass fuels, such as wood, charcoal, crop residue and dung causes Household Air Pollution (HAP). These inhaled particulates affect more than half of the world\u27s population, causing respiratory problems such as infection and inflammatory lung disease. We examined whether the presence of black carbon in alveolar macrophages was associated with alterations in the lung microbiome in a Malawi population. METHODS: Bronchoalveolar lavage samples from 44 healthy adults were sequenced using 16S rDNA amplification to assess microbial diversity, richness and relative taxa abundance. Individuals were classified as high or low particulate exposure as determined by questionnaire and the percentage of black carbon within their alveolar macrophages. RESULTS: Subjects in the low and high particulate groups did not differ in terms of source of fuels used for cooking or lighting. There was no difference in alpha or beta diversity by particulate group. Neisseria and Streptococcus were significantly more abundant in samples from high particulate exposed individuals, and Tropheryma was found less abundant. Petrobacter abundance was higher in people using biomass fuel for household cooking and lighting, compared with exclusive use of electricity. CONCLUSIONS: Healthy adults in Malawi exposed to higher levels of particulates have higher abundances of potentially pathogenic bacteria (Streptococcus, Neisseria) within their lung microbiome. Domestic biomass fuel use was associated with an uncommon environmental bacterium (Petrobacter) associated with oil-rich niches. BMC Microbiol 2016 Aug 11; 16(1):182

HIV-associated disruption of lung cytokine networks is incompletely restored in asymptomatic HIV-infected Malawian adults on antiretroviral therapy.

Disruption of lung cytokine networks during chronic HIV infection is incompletely restored in individuals on antiretroviral therapy

Asymptomatic HIV-infected Individuals on Antiretroviral Therapy Exhibit Impaired Lung CD4 +

Rationale: HIV-infected persons on antiretroviral therapy (ART) remain at higher risk of pulmonary tuberculosis (TB) than HIV-uninfected individuals. This increased susceptibility may be caused by impairment of alveolar macrophage (AM) function and/or mycobacteria-specific alveolar CD4+ T-cell responses observed in HIV-infected ART-naive adults. Objectives: To determine whether ART was associated with improvement in both AM function, assessed by phagosomal proteolysis, and alveolar CD4+ T-cell responses to Mycobacterium in HIV-infected individuals. Methods: Peripheral blood was drawn and bronchoalveolar lavage (BAL) performed on healthy, 35 HIV-uninfected, 25 HIV-infected ART-naive, and 50 HIV-infected ART-treated asymptomatic adults. Phagosomal proteolysis of AM was assessed with fluorogenic beads. Mycobacteria-specific CD4+ T-cell responses were measured by intracellular cytokine staining. Measurements and Main Results: HIV-infected adults on ART exhibited lower plasma HIV viral load and higher blood CD4+ T-cell count than ART-naive adults. AM proteolysis and total mycobacteria-specific Th1 CD4+ T-cell responses in individuals on ART for greater than or equal to 4 years were similar to HIV-uninfected control subjects but those on ART for less than 4 years had impaired responses. Total influenza-specific alveolar Th1 CD4+ T-cell responses were intact in all individuals receiving ART. In contrast, BAL and blood mycobacteria-specific polyfunctional CD4+ T-cell responses were impaired in adults on ART irrespective of duration. Conclusions: AM and mycobacteria-specific alveolar CD4+ T-cell responses in HIV-infected adults on ART for less than 4 years are impaired and may partly explain the high risk of TB in HIV-infected individuals on ART. Strategies to augment ART to improve lung immune cell function and reduce the high incidence of TB in HIV-infected adults who initiate ART should be investigated