Regulator of G protein signaling 5 restricts neutrophil chemotaxis and trafficking.

Neutrophils are white blood cells that are mobilized to damaged tissues and to sites of pathogen invasion, providing the first line of host defense. Chemokines displayed on the surface of blood vessels promote migration of neutrophils to these sites, and tissue- and pathogen-derived chemoattractant signals, including N-formylmethionylleucylphenylalanine (fMLP), elicit further migration to sites of infection. Although nearly all chemoattractant receptors use heterotrimeric G proteins to transmit signals, many of the mechanisms lying downstream of chemoattractant receptors that either promote or limit neutrophil motility are incompletely defined. Here, we show that regulator of G protein signaling 5 (RGS5), a protein that modulates G protein activity, is expressed in both human and murine neutrophils. We detected significantly more neutrophils in the airways of Rgs5-/- mice than WT counterparts following acute respiratory virus infection and in the peritoneum in response to injection of thioglycollate, a biochemical proinflammatory stimulus. RGS5-deficient neutrophils responded with increased chemotaxis elicited by the chemokines CXC motif chemokine ligand 1 (CXCL1), CXCL2, and CXCL12 but not fMLP. Moreover, adhesion of these cells was increased in the presence of both CXCL2 and fMLP. In summary, our results indicate that RGS5 deficiency increases chemotaxis and adhesion, leading to more efficient neutrophil mobilization to inflamed tissues in mice. These findings suggest that RGS5 expression and activity in neutrophils determine their migrational patterns in the complex microenvironments characteristic of inflamed tissues.

Rate and predictors of carotid artery intima media thickness progression in antiretroviral-naive HIV-infected and uninfected adults: a 48-week matched prospective cohort study.

BACKGROUND: Carotid intima media thickness (CIMT) progresses faster in HIV-infected adults on antiretroviral therapy (ART) than the general population. It is unclear if the rate of progression is similarly faster in ART-naive, HIV-infected adults. METHODS: This was a 48-week prospective cohort study to compare change in CIMT and inflammation markers in ART-naive, HIV-infected adults in no immediate need of ART (HIV-positive/ART-naive) and age/sex/body mass index (BMI)-matched controls (HIV-negative). RESULTS: A total of 85 HIV-positive/ART-naive and 45 HIV-negative participants were enrolled. In the HIV-positive/ART-naive group, median baseline CD4+ T-cell count and HIV-1 RNA were 535 cells/mm3 and 6,916 copies/ml. Baseline common carotid artery (CCA) and bulb CIMTs were similar between groups. Changes in CIMT to 48 weeks at both sites were not different within- or between-groups (median [IQR] change in HIV-positive/ART-naive versus HIV-negative CCA CIMT -0.0071 mm [-0.0267-0.0233] versus 0.0113 mm [-0.0117-0.0306]; P = 0.19 between-groups; and bulb CIMT 0.0017 mm [-0.0367-0.06167] versus 0.01 mm [-0.0383-0.0625]; P = 0.54). After adjustment for cardiovascular disease (CVD) risk factors, change in CCA CIMT was greater in HIV-negative participants (-0.0046 versus 0.0177 mm for HIV-positive/ART-naive versus HIV-negative; P = 0.01). In HIV-positive/ART-naive, interleukin (IL)-6, soluble tumour necrosis factor-α receptor (sTNFR)-II, vascular cell adhesion molecule-1 and intercellular adhesion molecule (ICAM)-1 were higher at both time points and D-dimer was higher at week 48 (P < 0.01 for all). IL-6, sTNFR-I and D-dimer increased over 48 weeks in HIV-positive/ART-naive participants (P < 0.01 for all). In HIV-positive/ART-naive participants, independent predictors of greater change in CCA CIMT were higher BMI (P = 0.05) and family history of CVD (P < 0.01) and of greater change in bulb CIMT were higher sTNFR-I (P = 0.03) and higher diastolic blood pressure (P < 0.01). CONCLUSIONS: In ART-naive HIV-infected adults at low risk of HIV disease progression and low cardiovascular risk, CIMT progression rate was similar to matched controls. In addition to traditional CVD risk factors, higher levels of sTNFR-I predicted greater bulb CIMT changes.

Elevated D-dimer is independently associated with endothelial dysfunction: a cross-sectional study in HIV-infected adults on antiretroviral therapy.

BACKGROUND: D-Dimer elevations have been associated with a striking increase in mortality in HIV-infected patients. However, D-Dimer has not been directly linked to endothelial dysfunction in HIV. METHODS: In this cross-sectional study, we used flow-mediated dilation (FMD) of the brachial artery to measure endothelial function and several biomarkers to measure systemic inflammation and coagulation activation in HIV-infected adults on stable antiretroviral therapy with HIV-1 RNA levels <400 copies/ml. Multivariable linear regression was used to model FMD by these markers, traditional cardiovascular risk factors and HIV-related characteristics. RESULTS: Analysis included 98 subjects (88% male, median age 47.5 years, CD4(+) T-cells 578.5 cells/mm(3)); all on ART (52% on protease inhibitors). The only factors independently associated with FMD were D-Dimer and body mass index. CONCLUSIONS: We show for the first time an independent association between D-Dimer and endothelial dysfunction in virologically suppressed, HIV-infected adults on stable antiretroviral therapy, potentially explaining the link between D-Dimer and mortality in HIV.

Omega-3 fatty acids do not improve endothelial function in virologically suppressed HIV-infected men: a randomized placebo-controlled trial.

Omega-3 fatty acids decrease cardiovascular disease (CVD) mortality possibly due to antiinflammatory effect. Inflammation and endothelial dysfunction likely play a role in the heightened CVD risk in HIV. Our goal was to evaluate the effect of omega-3 fatty acids primarily on endothelial function and inflammation in HIV-infected adults with moderate CVD risk on stable antiretroviral therapy. We conducted a 24-week, randomized, double-blind, placebo-controlled study to evaluate the effect of omega-3-acid ethyl esters 1 g twice a day. Flow-mediated dilation (FMD) of the brachial artery, lipoproteins and markers of inflammation, endothelial activation, coagulation, and insulin resistance were measured at entry and week 24. There were no within- or between-group differences in change in FMD over 24 weeks (mean change in FMD -0.13% vs. 1.5% for treatment vs. placebo; p=0.21). There were no between-group differences in changes in lipoprotein levels or biomarkers tested, except soluble tumor necrosis factor receptor-I, which favored omega-3-acid ethyl esters. Omega-3 fatty acids did not improve endothelial function or activation, coagulation, or insulin resistance in virologically suppressed, HIV-infected men with moderate CVD risk; however, inflammation tended to improve. This suggests that omega-3 fatty acids may not be potent enough to counteract the enhanced inflammation and endothelial dysfunction due to HIV and antiretrovirals.

Salsalate is poorly tolerated and fails to improve endothelial function in virologically suppressed HIV-infected adults.

In this 13-week, open-label, randomized study of the anti-inflammatory salsalate versus usual care, there were no significant improvements in flow-mediated dilation of the brachial artery, endothelial activation, inflammation or coagulation markers, homeostasis model assessment of insulin resistance or lipoproteins with salsalate or between groups in virologically suppressed, HIV-infected adults on antiretrovirals. Tinnitus and transaminitis occurred frequently in the salsalate group. Dose reduction due to toxicities encountered and low level of inflammation may explain these results.