Uncovering the cytotoxic effects of air pollution with multi-modal imaging of in vitro respiratory models

Annually, an estimated seven million deaths are linked to exposure to airborne pollutants. Despite extensive epidemiological evidence supporting clear associations between poor air quality and a range of short- and long-term health effects, there are considerable gaps in our understanding of the specific mechanisms by which pollutant exposure induces adverse biological responses at the cellular and tissue levels. The development of more complex, predictive, in vitro respiratory models, including two- and three-dimensional cell cultures, spheroids, organoids and tissue cultures, along with more realistic aerosol exposure systems, offers new opportunities to investigate the cytotoxic effects of airborne particulates under controlled laboratory conditions. Parallel advances in high-resolution microscopy have resulted in a range of in vitro imaging tools capable of visualizing and analysing biological systems across unprecedented scales of length, time and complexity. This article considers state-of-the-art in vitro respiratory models and aerosol exposure systems and how they can be interrogated using high-resolution microscopy techniques to investigate cell-pollutant interactions, from the uptake and trafficking of particles to structural and functional modification of subcellular organelles and cells. These data can provide a mechanistic basis from which to advance our understanding of the health effects of airborne particulate pollution and develop improved mitigation measures.

Natural history of HIV-1 infection and predictors of survival in a cohort of HIV-1 seropositive injecting drug users

Injecting drug users represent a pivotal and increasing component of acquired immunodeficiency syndrome (AIDS) case reporting in the United States. This article describes the natural history of human immunodeficiency virus (HIV) disease in a New York City cohort of 328 HIV-infected injecting drug users. The study sample of nearly two-thirds men (predominately African Americans and Latino Americans) underwent follow-up from December 1988 through December 1993. Male injecting drug users reported a longer injecting drug use history and were more likely to share needles/works than female injecting drug users. Eighty-nine of 328 study subjects died during the 5 years of observation. Comparing African Americans and Latinos, race/ethnicity was not related to survival. Survival was related to baseline CD4 count and hemoglobin level. Zidovudine use and PCP prophylaxis did not predict survival. Because of the continuing and increasing impact of HIV disease on injecting drug users and communities of color, there remains an unquestionable need to develop effective prevention programs, to understand the natural history of HIV disease, and to develop appropriate therapeutic interventions to treat those with HIV disease.

Decline in HIV-1 seroprevalence and low seroconversion rate among injecting drug users at a methadone maintenance program in New York City

To monitor the trend of HIV-1 seroprevalence, 2,194 newly admitted injecting drug users (IDUs) in a methadone maintenance program in New York City were tested from June 1988 through June 1992. This was a blinded study and unlabeled blood specimens were collected during the required physical examination. There was a significant linear trend (p = .01) toward decline in HIV-1 seropositivity by year of admission as follows: 47.0% in 1988, 43.4% in 1989, 43.2% in 1990, 39.8% in 1991, and 39.1% in 1992. From January 1988 through December 1992, admissions data that included the newly admitted IDUs showed a significant decrease (p < .0002) in self-reported current needle sharing from 11.3% to 5.4%. These two data sources suggest that a continued decline in HIV-1 seroprevalence among new admissions may be related to decreased needle sharing. A volunteer cohort of 235 HIV-1 seronegative IDUs was also enrolled from April 1990 through June 1991 in a study of HIV-1 seroconversion. Follow-up data were available on 177 patients for up to 12 months. For a total observation time of 155 person-years, there were two conversions (1.3 conversions per 100 person-years). A continued decline in HIV-1 seroprevalence among new admissions and a low HIV-1 seroconversion rate among existing patients have contributed to a lower overall HIV-1 prevalence in clinic patients of about 40%. This stands in contrast to 1985-86 estimates of HIV-1 seroprevalence that plateaued at 60%.

Short-term declines in CD4 levels associated with cocaine use in HIV-1 seropositive, minority injecting drug users

This study evaluates the association of cocaine use with short-term change in CD4 counts among human immunodeficiency virus type 1 (HIV-1) seropositive, minority injecting drug users prior to the introduction of zidovudine (AZT). Ninety-eight HIV-1 seropositive subjects were recruited from six inner-city, methadone maintenance clinics. A baseline assessment included a short questionnaire regarding drug behavior and quantitation of CD4 cell counts. These measures were repeated on all subjects 3 to 4 months later. Thirty-eight subjects reported using cocaine between baseline and 4-month follow-up evaluations. Males and African Americans were more likely to be cocaine users (P < .01). Cocaine users were more likely to engage in heroin and needle use (P < .001). Cocaine users experienced a significant decline in CD4 cells compared with nonusers (P = .013); no marked difference in CD4 decline was noted between heroin users and nonusers (P = .19). Multivariate analysis showed that a decline in CD4 counts was 2.82 times more likely to occur in cocaine users than in cocaine nonusers (90% two-sided confidence interval of 1.08, 7.37). These findings support the hypothesis of a possible link between cocaine use and short-term CD4 decline in HIV-1 seropositive injecting drug users.

No seroconversions among steady sex partners of methadone-maintained HIV-1-seropositive injecting drug users in New York City

OBJECTIVE

To assess the incidence of heterosexual HIV-1 transmission from seropositive methadone-maintained injecting drug users (IDU) to their seronegative, non-IDU steady sex partners.

DESIGN

A prospective, longitudinal study.

SETTING

HIV-1-seropositive IDU and their HIV-1-seronegative, non-IDU steady sex partners were recruited from six methadone-maintenance clinics in the New York City boroughs of Brooklyn and Manhattan.

PATIENTS, PARTICIPANTS

Between December 1988 and October 1991, 60 research participants were recruited [30 methadone-maintained, HIV-1-seropositive IDU (index subjects) and their non-IDU HIV-1-seronegative steady partners]. Baseline and follow-up (every 3-4 months) data included a structured questionnaire and blood testing for HIV infection and CD4+ cell subsets.

RESULTS

Demographic characteristics of the 30 steady sex partners were evaluated as follows: sex (22 women, eight men); age (mean, 32 years; range, 21-55 years) and race (African-American, 13; Hispanic, 13; other, 4). The average duration of relationship between index subject and partner at study entry was 7.5 years (range, 4 months to 19.4 years). At entry, 27 of the 30 partners reported no or intermittent use of condoms with the index subject during a typical 12-month period. Follow-up data (median follow-up, 298 days; range, 85-992 days) were available for 22 partners. Of these, 15 reported no or intermittent condom use. For a total study observation time of 23 person-years, there were no seroconversions. The upper 95% confidence interval for the observed seroconversion rate of 0% is 13%.

CONCLUSIONS

These results suggest that the likelihood of heterosexual HIV-1 transmission from seropositive methadone-maintained IDU to their seronegative, non-IDU steady sex partners is low.