Répercussions hémodynamiques rénales de la surcharge salée aiguë isotonique chez le chien

Intrarenal hemodynamic changes during acute isotonic saline loading in the dog. 85Kr autoradiograms, perfusions of silastic and injections of thioflavine S labelled red blood cells (R.B.C.) have been used to study the intrarenal hemodynamic changes induced in the dog by an acute isotonic expansion of the extracellular fluid volume. The silastic injected specimens showed a generalized vasodilatation, without however, any change of the diameter of the glomerular tufts. As the ratio of the number of labelled R.B.C. of the superficial glomeruli to the number of the R.B.C. of the juxtamedullary glomeruli has decreased, we can conclude that the relative juxtamedullary glomerular capillary volume has increased. The autoradiographs showed that the velocity of the blood flow increased in the superficial cortex and the vasa recta and decreases in the juxtamedullary cortical region. This slowing seems to be due to the marked dilatation of the capillary bed of the latter region. It is then concluded that the natriuresis could be linked mainly to changes of peritubular factors induced by the vasodilatation which is itself more marked in the juxtamedullary cortex.Répercussions hémodynamiques rénales de la surcharge salée aiguë isotonique chez le chien. Les changements hémodynamiques intrarénaux ont été étudiés chez des chiens soumis à une surcharge salée isotonique aiguë, à l'aide d'autoradiographies au Kr85, de perfusion de silastic et d'injections de globules rouges marqués à la Thioflavine S. La surcharge a entraîné une vasodilatation rénale généralisée (moules au silastic). Le décompte des globules rouges marqués par glomérule montra une diminution du leur nombre dans les glomérules superficiels par rapport aux glomérules juxtamédullaires. Ceci traduit une augmentation relative du volume capillaire glomérulaire juxtamédullaire. Par ailleurs, la vitesse du flux sanguin (autoradiographies) a augments dans le cortex superficiel, les vasa recta et diminué dans la région juxtamédullaire. Une dilatation excessive du lit capillaire de cette dernière semble expliquer le ralentissement de son flux sanguin. Le diamètre des floculi glomérulaires n'a pas changé sous l'effet de la surcharge. La natriurèse peut ainsi être reliée principalement à la baisse de réabsorption tubulaire secondaire aux changements des facteurs péritubulaires induits par la vasodilatation, elle-même maximale au niveau du cortex interne

Endogenous IFNλ in Viral Hepatitis Patients

Besides type I interferons (IFNs), type III IFNs, including IFN lambda 1 (interleukin-29 [IL-29]), possess potent antiviral activity. In patients infected with the hepatitis C virus (HCV), it has been demonstrated that viral clearance is associated with genetic variation near the IFN lambda 3 (IL-28B) gene. The rapid influx of research being conducted on this family of cytokines has led to several inconsistencies and controversies, including the possible correlation of serum cytokine levels with disease in chronic viral hepatitis patients. In a detailed study, well-characterized cohorts of patients with HBV and HCV were evaluated with 3 different immunoassays, and no differences in the levels of serum IFN lambda were observed between patient groups, disease stages, or clinical parameters

Molecular Basis for Increased Susceptibility of Isolates with Atazanavir Resistance-Conferring Substitution I50L to Other Protease Inhibitors

Protease inhibitors (PIs) are highly effective drugs against the human immunodeficiency virus (HIV), yet long-term therapeutic use is limited by emergence of HIV type 1 (HIV-1) protease substitutions that confer cross-resistance to multiple protease inhibitor drugs. Atazanavir is a highly potent HIV protease inhibitor with a distinct resistance profile that includes effectiveness against most HIV-1 isolates resistant to one or two PIs. The signature resistance substitution for atazanavir is I50L, and it is frequently (53%) accompanied by a compensatory A71V substitution that helps restore viability and increases atazanavir resistance levels. We measured the binding affinities of wild-type (WT) and I50L/A71V HIV-1 proteases to atazanavir and other currently approved PIs (ritonavir, lopinavir, saquinavir, nelfinavir, indinavir, and amprenavir) by isothermal titration calorimetry. Remarkably, we find that all of the PIs have 2- to 10-fold increased affinities for I50L/A71V protease, except for atazanavir. The results are also manifested by thermal stability measures of affinity for WT and I50L/A71V proteases. Additional biophysical and enzyme kinetics experiments show I50L/A71V protease is a stable enzyme with catalytic activity that is slightly reduced (34%) relative to the WT. Computational modeling reveals that the unique resistance phenotype of I50L/A71V protease likely originates from bulky tert-butyl groups at P2 and P2′ (specific to atazanavir) that sterically clash with methyl groups on residue L50. The results of this study provide a molecular understanding of the novel hypersusceptibility of atazanavir-resistant I50L/A71V-containing clinical isolates to other currently approved PIs

IFN-λ-mediated IL-12 production in macrophages induces IFN-γ production in human NK cells

With increasing interest in alternative options to interferon-alpha-based treatments, IFN-λ has shown therapeutic promise in a variety of diseases. Although the antiviral activity of IFN-λ has been extensively studied, there is limited knowledge regarding the immunological functions of IFN-λ and how these differ from those of other classes of IFNs. In this study, we investigated the effects of IFN-λ on primary human NK cells, both in a direct and indirect capacity. We demonstrate that in contrast to interferon-alpha, IFN-λ is unable to directly stimulate NK cells, due to the absence of IFN-λ receptor chain 1 (IFN-λR1) on NK cells. However, IFN-λ, in combination with TLR4 challenge, is able to induce the production of select members of the IL-12 family of cytokines in monocyte-derived macrophages. We further show that through macrophage-mediated IL-12 production, IFN-λ is able to indirectly affect NK cells and ultimately induce IFN-γ production

Impairment of Type I but Not Type III IFN Signaling by Hepatitis C Virus Infection Influences Antiviral Responses in Primary Human Hepatocytes

<div><p>Peginterferon lambda-1a (Lambda), a type III interferon (IFN), acts through a unique receptor complex with limited cellular expression outside the liver which may result in a differentiated tolerability profile compared to peginterferon alfa (alfa). In Phase 2b clinical studies, Lambda administered in combination with ribavirin (RBV) was efficacious in patients with hepatitis C virus (HCV) infection representing genotypes 1 through 4, and was associated with more rapid declines in HCV RNA compared to alfa plus RBV. To gain insights into potential mechanisms for this finding, we investigated the effects of HCV replication on IFN signaling in primary human hepatocytes (PHH) and in induced hepatocyte-like cells (iHLCs). HCV infection resulted in rapid down-regulation of the type I IFN-α receptor subunit 1 (IFNAR1) transcript in hepatocytes while the transcriptional level of the unique IFN-λ receptor subunit IL28RA was transiently increased. In line with this observation, IFN signaling was selectively impaired in infected cells upon stimulation with alfa but not in response to Lambda. Importantly, in contrast to alfa, Lambda was able to induce IFN-stimulated gene (ISG) expression in HCV-infected hepatocytes, reflecting the onset of innate responses. Moreover, global transcriptome analysis in hepatocytes indicated that Lambda stimulation prolonged the expression of various ISGs that are potentially beneficial to antiviral defense mechanisms. Collectively, these observed effects of HCV infection on IFN receptor expression and signaling within infected hepatocytes provide a possible explanation for the more pronounced early virologic responses observed in patients treated with Lambda compared to alfa.</p></div

Modifications of the Human Immunodeficiency Virus Envelope Glycoprotein Enhance Immunogenicity for Genetic Immunization

In this study, we have investigated the effect of specific mutations in human immunodeficiency virus type 1 (HIV-1) envelope (Env) on antibody production in an effort to improve humoral immune responses to this glycoprotein by DNA vaccination. Mice were injected with plasmid expression vectors encoding HIV Env with modifications in regions that might affect this response. Elimination of conserved glycosylation sites did not substantially enhance humoral or cytotoxic-T-lymphocyte (CTL) immunity. In contrast, a modified gp140 with different COOH-terminal mutations intended to mimic a fusion intermediate and stabilize trimer formation enhanced humoral immunity without reducing the efficacy of the CTL response. This mutant, with deletions in the cleavage site, fusogenic domain, and spacing of heptad repeats 1 and 2, retained native antigenic conformational determinants as defined by binding to known monoclonal antibodies or CD4, oligomer formation, and virus neutralization in vitro. Importantly, this modified Env, gp140ΔCFI, stimulated the antibody response to native gp160 while it retained its ability to induce a CTL response, a desirable feature for an AIDS vaccine

Productive HCV replication represses IFNAR1 expression in infected hepatocytes.

<p>iHLCs were infected with HCVcc (MOI of 0.2), GT-1b HCVser or mock infected, and subsequently maintained in culture with medium replacement every 2 days. At 24 h post-infection, the NS3 PI ASV (0.5 μM) or vehicle control dimethyl sulfoxide (DMSO) was added to cell cultures during media replenishment. (A) Persistent HCVcc replication as measured by the detection of the virally-encoded core antigen and expression of type I (IFNAR1, IFNAR2) and type III IFN (IL28RA, IL10RB) co-receptor subunits in cells were monitored by Western immunoblotting at the indicated time points, with β-actin used as loading control. Right panel; Relative intensity of IFNAR1 detected in HCVcc infected cells maintained in the presence (open triangle) or absence (open square) of ASV treatment was quantified by densitometry analysis, normalized to β-actin levels in each sample, and expressed as a percentage relative to mock-infected cells. Data are representative of three independent Western immunoblot analyses. (B) Co-localization of IFNAR1 and HCV-core positive iHLCs were assessed by fluorescence microscopy. On Day 6 post-infection, naive and HCVcc-infected iHLCs were fixed, permeabilized and stained with antibodies to IFNAR1 (red) and HCV core antigen (green) as indicated. Nuclei were counterstained with Hoechst dye (blue) as shown in the overlays. (C) iHLC cultures infected in parallel with GT-1b HCVser or HCVcc were harvested at the indicated time points and IFNAR1 copy numbers estimated by quantitative RT-PCR following normalization to cellular GAPDH levels in each sample. Results are expressed as mean ± standard deviations (n = 4). Statistical analysis was performed by Bonferroni’s multiple comparison tests: **, <i>P</i> < 0.05; ***, <i>P</i> < 0.001. (D) Cell lysates were harvested at the indicated time points and protein levels of IFNAR1 and IL28RA were examined by Western immunoblotting. Susceptibility of HCVser to the NS3 PI ASV was determined using an antibody directed against NS3. Arrows indicate the presence of the processed and unprocessed forms of the HCV-encoded NS3/4A protease in infected iHLCs. Detection of β-actin served as loading control. Right panel; Relative intensity of IFNAR1 detected in HCVser infected cells maintained in the presence (open triangle) or absence (open square) of ASV treatment was quantified by densitometry analysis, normalized to β-actin levels in each sample, and expressed as a percentage relative to mock-infected cells. Data are representative of two independent Western immunoblot analyses.</p