Publications

Cardiovascular complications are more common in human immunodeficiency virus-infected individuals than in age-matched uninfected individuals. Antiretroviral therapy reduces the risk of cardiovascular complications, suggesting that viral replication directly or indirectly causes vascular disease. Long-term effective antiretroviral therapy does not fully restore vascular health, and treated adults continue to have higher-than-expected rates of disease progression. Although this excess risk during therapy is likely due to multiple factors, a growing body of evidence suggests that chronic inflammation, which persists during effective antiretroviral therapy, is directly and causally associated with vascular dysfunction and the accelerated development of atherosclerosis.

Persistent immune activation and inflammation despite sustained antiretroviral therapy (ART)-mediated viral suppression has emerged as a major challenge of the modern HIV treatment era. While immune activation, inflammatory, and coagulation markers typically decline during suppressive ART, they remain abnormally elevated in many HIV-infected individuals and predict subsequent mortality and non-AIDS morbidities including cardiovascular disease. The goal of this review is to summarize the current state of our knowledge regarding the underlying causes of persistent immune activation during ART-mediated viral suppression as well as the link between persistent immune activation and morbidity and mortality in this setting. Several recent studies have linked surrogate markers of this persistent inflammatory state to clinical outcomes, validating persistent immune activation as a viable therapeutic target. Other recent studies have helped clarify the roles of persistent HIV expression and/or replication, microbial translocation, and co-infections in driving this persistent inflammatory state, identifying targets for novel interventions.

Tamoxifen, a prodrug used for adjuvant breast cancer therapy, requires conversion to the active metabolite endoxifen through CYP 2D6. We aimed to construct an algorithm to predict endoxifen concentrations based on a patient’s CYP 2D6 genotype, demographic factors, and co-medication use. Eighty-eight women enrolled in the UCSF TamGen II study and 81 women enrolled in a prospective study at Dana-Farber Cancer Institute were included in this analysis. All the women had been on tamoxifen for at least 3 months before blood collection. Demographic information included the patient’s age, race/ethnicity, body mass index (where available), and self-reported and measured medications and herbals that affect 2D6 activity. DNA was extracted and genotyped for 2D6 (Amplichip, Roche Diagnostics). An activity score was calculated based on genotypes and adjusted for use of medications known to inhibit 2D6. Serum was tested for tamoxifen and metabolite concentrations and for the presence of drugs by liquid chromatography/mass spectrometry. Univariate and multivariate regression analysis were computed for age, body mass index, ethnicity, and adjusted activity score to predict tamoxifen metabolite concentrations in the training data-set of UCSF patients, and the resulting algorithm was validated in the Dana-Farber patients. For the training set, the correlation coefficient (r2) for log endoxifen and N-desmethyltamoxifen:endoxifen ratio to activity score, age, and race, were 0.520 and 0.659, respectively; 0.324 and 0.567 for the validation; and 0.396 and 0.615 for both the datasets combined. An algorithm that incorporates genotype and demographic variables can be used to predict endoxifen concentrations for women on tamoxifen therapy. If endoxifen levels are confirmed to be predictive of tamoxifen benefit, then this algorithm may be helpful to determine which women warrant endoxifen testing.

BACKGROUND

Increasing evidence suggests that cytokine dysregulation in T-helper 1 and T-helper 2 (TH1/TH2) subsets contributes to the pathogenesis of Crohn disease (CD). The present pilot study examines the hypothesis that cytokine profiles differ between pediatric and adult patients with CD.

METHODS

Production of TH1 cytokines interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) and of TH2 cytokines interleukin-4 (IL-4) and IL-6 was analyzed in peripheral blood of patients with CD and healthy controls (n=20) using flow cytometry after in vitro stimulation.

RESULTS

In both pediatric and adult subjects, frequencies of TNF-α CD4+ T cells were higher in patients with CD than in controls (P=0.009 and P=0.047, respectively). Percentages of cells expressing IL-4 were slightly increased (P=0.036), whereas those for IFN-γ were decreased (P=0.009) in pediatric patients with CD compared with controls. As expected, the overall production of TH1 cytokines was higher in adults compared with pediatric subjects. When memory CD4+CD45RO+ T cells were considered, lower IFN-γ expression was observed in pediatric subjects with CD compared with controls (P=0.009), matching the trend seen in the general CD4+ T cell population. The percentage of CD4+CD45RO+ T cells was increased in adult patients with CD compared with pediatric patients with CD (P=0.016).

CONCLUSIONS

The present study describes a peripheral blood TH1/TH2 cytokine imbalance in CD and suggests different immunological mechanisms in children and adults for disease pathogenesis.

BACKGROUND

Linezolid is active against a broad range of gram-positive pathogens and has the potential to also affect production of bacterial toxins and host immune function.

OBJECTIVE

To assess the evidence for direct effects of linezolid on bacterial toxin synthesis and modulation of host immune responses.

METHODS

Literature searches were performed of the PubMed and OVID databases. Reviews and non-English language articles were excluded. Articles with information on the effect of linezolid on bacterial toxin synthesis and immune responses were selected for further review, and data were summarized.

RESULTS

Substantial in vitro evidence supports effects of linezolid on bacterial toxin production; however, the strength of the evidence and the nature of the effects are mixed. In the case of Staphylococcus aureus, repeated observations support the inhibition of production of certain staphylococcal toxins (Panton-Valentine leukocidin, protein A, and α- and β-hemolysin) by linezolid, whereas only solitary reports indicate inhibition (toxic shock syndrome toxin-1, coagulase, autolysins, and enterotoxins A and B) or stimulation (phenol-soluble modulins) of toxin production by linezolid. In the case of Streptococcus pyogenes, there are solitary reports of linezolid inhibition (protein M, deoxyribonuclease, and streptococcal pyrogenic exotoxins A, B, and F) or stimulation (immunogenic secreted protein 2 and streptococcal inhibitor of complement-mediated lysis) of toxin production, whereas published evidence for effects on streptolysin O production is conflicting. In vitro data are limited, but suggest that linezolid might also have indirect effects on host cytokine expression through inhibition of bacterial production of toxins. In vivo data from preclinical animal studies and a single clinical study in humans are limited and equivocal insofar as a potential role for linezolid in modulating the host inflammatory response; this is due in part to the difficulty in isolating antimicrobial effects and toxin synthesis inhibitory effects of linezolid from any secondary effects on host inflammatory response.

CONCLUSIONS

Available evidence supports the possibility that linezolid can inhibit, and in some cases stimulate, toxin production in clinically relevant pathogens. However, more research will be needed to determine the potential clinical relevance of those findings for linezolid.