Janet Robinson

Gut Epithelial Barrier Dysfunction and Innate Immune Activation Predict Mortality in Treated HIV Infection

BACKGROUND While inflammation predicts mortality in treated human immunodeficiency virus (HIV) infection, the prognostic significance of gut barrier dysfunction and phenotypic T-cell markers remains unclear. METHODS We assessed immunologic predictors of mortality in a case-control study within the Longitudinal Study of the Ocular Complications of AIDS (LSOCA), using conditional logistic regression. Sixty-four case patients who died within 12 months of treatment-mediated viral suppression were each matched to 2 control individuals (total number of controls, 128) by duration of antiretroviral therapy-mediated viral suppression, nadir CD4(+) T-cell count, age, sex, and prior cytomegalovirus (CMV) retinitis. A similar secondary analysis was conducted in the SCOPE cohort, which had participants with less advanced immunodeficiency. RESULTS Plasma gut epithelial barrier integrity markers (intestinal fatty acid binding protein and zonulin-1 levels), soluble CD14 level, kynurenine/tryptophan ratio, soluble tumor necrosis factor receptor 1 level, high-sensitivity C-reactive protein level, and D-dimer level all strongly predicted mortality, even after adjustment for proximal CD4(+) T-cell count (all P ≤ .001). A higher percentage of CD38(+)HLA-DR(+) cells in the CD8(+) T-cell population was a predictor of mortality before (P = .031) but not after (P = .10) adjustment for proximal CD4(+) T-cell count. Frequencies of senescent (defined as CD28(-)CD57(+) cells), exhausted (defined as PD1(+) cells), naive, and CMV-specific T cells did not predict mortality. CONCLUSIONS Gut epithelial barrier dysfunction, innate immune activation, inflammation, and coagulation-but not T-cell activation, senescence, and exhaustion-independently predict mortality in individuals with treated HIV infection with a history of AIDS and are viable targets for interventions.

A Mucosal IgA-Mediated Excretory Immune System In Vivo

The capacity of mucosal IgA Abs to serve as an excretory immune system in vivo was investigated. Mice expressing a transgenic TCR were immunized intragastrically with the cognate Ag to elicit a vigorous mucosal IgA Ab response. Soon after i.v. challenge, Ag was detected within the epithelial cells of the small intestinal crypts and to a lesser degree within the epithelial cells higher up the villi, paralleling the gradient in expression of the polymeric Ig receptor and the transport of its ligand, oligomeric IgA. Uptake of Ag into the epithelial cells occurred only from the basolateral aspect and only when Ag complexed to IgA Ab could be present in the lamina propria. The results support the concept that local IgA Abs can excrete Ags from the body by transporting them directly through mucosal epithelial cells, using the same mechanism that transports free IgA into the mucosal secretions.

Cutting edge: spontaneous development of IL-17-producing gamma delta T cells in the thymus occurs via a TGF-beta 1-dependent mechanism.

In naive animals, γδ T cells are innate sources of IL-17, a potent proinflammatory cytokine mediating bacterial clearance as well as autoimmunity. However, mechanisms underlying the generation of these cells in vivo remain unclear. In this study, we show that TGF-β1 plays a key role in the generation of IL-17+ γδ T cells and that it mainly occurs in the thymus particularly during the postnatal period. Interestingly, IL-17+ γδ TCR+ thymocytes were mainly CD44highCD25low cells, which seem to derive from double-negative 4 γδ TCR+ cells that acquired CD44 and IL-17 expression. Our findings identify a novel developmental pathway during which IL-17–competent γδ T cells arise in the thymus by a TGF-β1–dependent mechanism.

Rosuvastatin reduces vascular inflammation and T-cell and monocyte activation in HIV-infected subjects on antiretroviral therapy.

Background:Despite suppressive antiretroviral therapy (ART), increased levels of immune activation persist in HIV-infected subjects. Statins have anti-inflammatory effects and may reduce immune activation in HIV disease. Methods:Stopping Atherosclerosis and Treating Unhealthy bone with RosuvastatiN in HIV (SATURN-HIV) is a randomized, double-blind placebo-controlled trial assessing the effect of rosuvastatin (10 mg daily) on markers of cardiovascular risk and immune activation in ART-treated patients. T-cell activation was measured by expression of CD38, HLA-DR, and PD1. Monocyte activation was measured with soluble markers (sCD14 and sCD163) and by enumeration of monocyte subpopulations and tissue factor expression. Markers of systemic and vascular inflammation and coagulation were also measured. SATURN-HIV is registered on clinicaltrials.gov (identifier: NCT01218802). Results:Rosuvastatin, compared with placebo, reduced sCD14 (−10.4% vs 0.5%, P = 0.006), lipoprotein-associated phospholipase A2 (−12.2% vs −1.7%, P = 0.0007), and IP-10 (−27.5 vs −8.2%, P = 0.03) levels after 48 weeks. The proportion of tissue factor-positive patrolling (CD14DimCD16+) monocytes was also reduced by rosuvastatin (−41.6%) compared with placebo (−18.8%, P = 0.005). There was also a greater decrease in the proportions of activated (CD38+HLA-DR+) T cells between the arms (−38.1% vs −17.8%, P = 0.009 for CD4+ cells, and −44.8% vs −27.4%, P = 0.003 for CD8+ cells). Conclusions:Forty-eight weeks of rosuvastatin treatment reduced significantly several markers of inflammation and lymphocyte and monocyte activation in ART-treated subjects.

Rosuvastatin Treatment Reduces Markers of Monocyte Activation in HIV-Infected Subjects on Antiretroviral Therapy

BACKGROUND Statins, or 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, have anti-inflammatory effects that are independent of their lipid-lowering properties. Despite suppressive antiretroviral therapy (ART), elevated levels of immune activation and inflammation often persist. METHODS The Stopping Atherosclerosis and Treating Unhealthy Bone With Rosuvastatin in HIV (SATURN-HIV) trial is a randomized, double-blind, placebo-controlled study, designed to investigate the effects of rosuvastatin (10 mg/daily) on markers of cardiovascular disease risk in ART-treated human immunodeficiency virus (HIV)-infected subjects. A preplanned analysis was to assess changes in markers of immune activation at week 24. Subjects with low-density lipoprotein cholesterol <130 mg/dL and heightened immune activation (%CD8(+)CD38(+)HLA-DR(+) ≥19%, or plasma high-sensitivity C-reactive protein ≥2 mg/L) were randomized to receive rosuvastatin or placebo. We measured plasma (soluble CD14 and CD163) and cellular markers of monocyte activation (proportions of monocyte subsets and tissue factor expression) and T-cell activation (expression of CD38, HLA-DR, and PD1). RESULTS After 24 weeks of rosuvastatin, we found significant decreases in plasma levels of soluble CD14 (-13.4% vs 1.2%, P = .002) and in proportions of tissue factor-positive patrolling (CD14(Dim)CD16(+)) monocytes (-38.8% vs -11.9%, P = .04) in rosuvastatin-treated vs placebo-treated subjects. These findings were independent of the lipid-lowering effect and the use of protease inhibitors. Rosuvastatin did not lead to any changes in levels of T-cell activation. CONCLUSIONS Rosuvastatin treatment effectively lowered markers of monocyte activation in HIV-infected subjects on antiretroviral therapy. CLINICAL TRIALS REGISTRATION NCT01218802.

Cutting edge: Spontaneous development of IL-17-producing γδ T cells in the thymus occurs via a TGF-β1-dependent mechanism

In naive animals, γδ T cells are innate sources of IL-17, a potent proinflammatory cytokine mediating bacterial clearance as well as autoimmunity. However, mechanisms underlying the generation of these cells in vivo remain unclear. In this study, we show that TGF-β1 plays a key role in the generation of IL-17+ γδ T cells and that it mainly occurs in the thymus particularly during the postnatal period. Interestingly, IL-17+ γδ TCR+ thymocytes were mainly CD44highCD25low cells, which seem to derive from double-negative 4 γδ TCR+ cells that acquired CD44 and IL-17 expression. Our findings identify a novel developmental pathway during which IL-17–competent γδ T cells arise in the thymus by a TGF-β1–dependent mechanism.

TGFβ-mediated BIM expression and apoptosis are regulated through SMAD3-dependent expression of the MAPK phosphatase MKP2

Transforming growth factor‐β (TGFβ) induces the expression of the pro‐apoptotic protein BIM, and mediates apoptosis in hepatocytes and B lymphocytes. BIM is regulated through a post‐translational mechanism involving ERK‐dependent phosphorylation and ubiquitin‐mediated proteasomal degradation. Here, we show that TGFβ induces BIM through its rapid inhibition of ERK, thereby preventing the phosphorylation and degradation of BIM. TGFβ, through a SMAD3‐dependent mechanism, transcriptionally induces the mitogen‐activated protein kinase (MAPK) phosphatase MKP2, encoded by an immediate early gene, to attenuate ERK and promote the accumulation of BIM protein. Overexpression of MKP2 in hepatocytes modulates ERK‐mediated phosphorylation of BIM and apoptosis in the absence of TGFβ, whereas its ablation in pro‐B cells, derived from MKP2‐deficient mice, protects cells from TGFβ‐mediated apoptosis, and blocks TGFβ‐induced ERK inhibition and BIM induction. Furthermore, in pro‐B cells derived from SMAD3‐deficient mice, induction of MKP2 by TGFβ, inhibition of ERK, induction of BIM and apoptosis do not occur. Our results indicate that MKP2 mediates TGFβ‐dependent apoptosis by linking SMAD3 to the modulation of ERK activity and mitochondrial‐mediated pro‐apoptotic events.

Sevelamer Does Not Decrease Lipopolysaccharide or Soluble CD14 Levels But Decreases Soluble Tissue Factor, Low-Density Lipoprotein (LDL) Cholesterol, and Oxidized LDL Cholesterol Levels in Individuals With Untreated HIV Infection

UNLABELLED Abnormal levels of inflammation are associated with cardiovascular disease and mortality in human immunodeficiency virus (HIV)-infected patients. Microbial translocation, which may cause inflammation, is decreased by sevelamer in patients undergoing hemodialysis. In this single-arm study, we evaluated the effects of 8 weeks of sevelamer therapy on 36 HIV-infected subjects who were not receiving antiretroviral therapy. Sevelamer did not significantly change markers of microbial translocation, inflammation, or T-cell activation. During sevelamer treatment, however, levels of soluble tissue factor, low-density lipoprotein (LDL) cholesterol, and oxidized LDL cholesterol decreased significantly, whereas D-dimer levels increased. Thus, in this study population, sevelamer did not reduce microbial translocation but may have yielded cardiovascular benefits. CLINICAL TRIALS REGISTRATION NCT 01543958.

Microbial IgA Protease Removes IgA Immune Complexes from Mouse Glomeruli In Vivo: Potential Therapy for IgA Nephropathy

The hallmark of IgA nephropathy (IgAN), the most common form of glomerulonephritis, is the presence of mesangial deposits containing IgA, specifically the IgA1 subclass, as the most prominent component. The deposited IgA is considered to be part of an immune complex. The family of enzymes known as bacterial IgA proteases exhibits substrate specificity that is essentially limited to the hinge region of IgA1. Here we demonstrate the ability of systemically administered IgA protease to remove glomerular IgA immune complexes, both the antigen and antibody components, in a passive mouse model of IgAN. Thus, IgA protease may have potential as a therapeutic agent for human IgAN.

Differential Reduction in Monocyte Activation and Vascular Inflammation With Integrase Inhibitor–Based Initial Antiretroviral Therapy Among HIV-Infected Individuals

BACKGROUND Little is known about how different antiretrovirals effect inflammation and monocyte activation in human immunodeficiency virus (HIV) infection. METHODS We examined plasma specimens obtained during a randomized, double-blinded trial in antiretroviral therapy (ART)-naive HIV-infected adults which compared the efficacy of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/c/FTC/TDF) with that of efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF). From a random sample achieving an HIV type 1 RNA load of <50 copies/mL by week 48, changes over 24 and 48 weeks in levels of biomarkers of monocyte activation (soluble CD14 [sCD14] and soluble CD163 [sCD163]), systemic inflammation (soluble tumor necrosis factor α receptor I [sTNF-RI], interleukin 6 [IL-6], and high-sensitivity C-reactive protein [hsCRP]), and vascular inflammation (lipoprotein-associated phospholipase A2 [Lp-PLA2]) were compared. Multivariable linear regression was used. RESULTS A total of 200 participants were included. Significant differences favoring EVG/c/FTC/TDF were noted for changes in sCD14, hsCRP, and Lp-PLA2 levels. Factors independently associated with a larger decrease in the sCD14 level included random assignment to receive EVG/c/FTC/TDF, higher baseline sCD14 level, and larger decreases in hsCRP and sCD163 levels; factors associated with a larger Lp-PLA2 decrease included higher baseline Lp-PLA2 and IL-6 levels, smaller increases in total cholesterol and triglycerides levels, a larger decrease in the sCD14 level, and a smaller decrease in the sCD163 level. CONCLUSIONS EVG/c/FTC/TDF led to greater decreases in sCD14, hsCRP, and Lp-PLA2 levels, compared with EFV/FTC/TDF. Randomization group independently predicted the change in sCD14 level, and changes in monocyte activation independently predicted the change in Lp-PLA2 level. There appears to be a more favorable effect of the integrase inhibitor EVG over efavirenz on immune activation, which may affect vascular inflammation.