Publications

BACKGROUND

HIV infection is associated with an increased risk of coronary artery disease, but the contribution of inflammation versus antiretroviral drugs is not well understood. Fibrinogen is an inflammatory factor associated with atherosclerosis.

METHODS

A total of 1131 HIV-infected patients and 281 controls [from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a population-based study of cardiovascular risk assessment] in the Study of Fat Redistribution and Metabolic Change in HIV infection (FRAM) had plasma fibrinogen levels measured. Multivariable linear regression identified factors associated with fibrinogen.

RESULTS

HIV-infected patients had higher levels of fibrinogen compared with controls (males: 25 mg/dl higher, P = 0.006; females: 21 mg/dl higher, P = 0.39). Among HIV-infected persons, median levels of fibrinogen were 11% higher in patients currently using any protease inhibitor (PI) compared with those not using a PI (P < 0.0001). The strongest univariate associations were with the individual PIs, ritonavir and indinavir. Patients taking indinavir boosted with ritonavir had median fibrinogen levels 8% higher than those on indinavir alone (P = 0.049). Lower levels of fibrinogen were seen in those HIV-infected patients currently using any nonnucleoside reverse transcriptase inhibitor (NNRTI) compared to those not using an NNRTI (nevirapine -14.4%, P < 0.0001; efavirenz -7%, P = 0.0002). The associations of ritonavir, indinavir, efavirenz and nevirapine with fibrinogen levels persisted after multivariable analysis and were independent of other antiretroviral use.

CONCLUSION

Protease inhibitor use is associated with elevated fibrinogen levels which may contribute to increased risk of atherosclerosis in HIV-infected patients. Conversely, NNRTI use is associated with lower fibrinogen levels which may decrease risk of atherosclerosis.

We identified factors associated with shooting gallery attendance among injection drug users (IDUs) in two Mexico-US border cities. IDUs in Tijuana (n=222) and Ciudad Juarez (n=205), Mexico, who were >or=18 years and injected illicit drugs in the last month were recruited using respondent-driven sampling (RDS). An interviewer-administered survey collected sociodemographic and behavioral data. Logistic regression was used to examine correlates of shooting gallery attendance in each of the two cities. Homelessness and being arrested for syringe possession--both structural level factors--were associated with shooting gallery use in both cities. In Ciudad Juarez, younger age and having overdosed were also associated with shooting gallery use. Our study highlights the need for structural interventions that mitigate homelessness among IDUs and facilitate changes in law enforcement practices associated with shooting gallery use. Harm reduction interventions based within shooting galleries should also be considered to prevent transmission of blood-borne pathogens among IDUs.

Toll-like receptors (TLRs) are critical for the recognition of inhaled pathogens that deposit on the airway epithelial surface. The epithelial response to pathogens includes signaling cascades that activate the EGF receptor (EGFR). We hypothesized that TLRs communicate with EGFR via epithelial signaling to produce certain innate immune responses. Airway epithelium expresses the highest levels of TLR2, TLR3, TLR5, and TLR6, and here we found that ligands for these TLRs increased IL-8 and VEGF production in normal human bronchial epithelial cells. These effects were prevented by treatment with a selective inhibitor of EGFR phosphorylation (AG-1478), a metalloprotease (MP) inhibitor, a reactive oxygen species (ROS) scavenger, and an NADPH oxidase inhibitor. In an airway epithelial cell line (NCI-H292), TNF-alpha-converting enzyme (TACE) small interfering RNA (siRNA) was used to confirm that TACE is the MP involved in TLR ligand-induced IL-8 and VEGF production. We show that transforming growth factor (TGF)-alpha is the EGFR ligand in this signaling cascade by using TGF-alpha neutralizing antibody and by showing that epithelial production of TGF-alpha occurs in response to TLR ligands. Dual oxidase 1 (Duox1) siRNA was used to confirm that Duox1 is the NADPH oxidase involved in TLR ligand-induced IL-8 and VEGF production. We conclude that multiple TLR ligands induce airway epithelial cell production of IL-8 and VEGF via a Duox1--> ROS--> TACE--> TGF-alpha--> EGFR phosphorylation pathway. These results show for the first time that multiple TLRs in airway epithelial cells produce innate immune responses by activating EGFR via an epithelial cell signaling cascade.