Impairment of the gastrointestinal mucosal barrier contributes to progression of HIV infection. The purpose of this study was to investigate the effect of highly active antiretroviral therapy (HAART) on the HIV-induced intestinal barrier defect and to identify underlying mechanisms.
Methods:
Epithelial barrier function was characterised by impedance spectroscopy and [3H]mannitol fluxes in duodenal biopsies from 11 untreated and 8 suppressively treated HIV-infected patients, and 9 HIV-seronegative controls. The villus/crypt ratio was determined microscopically. Epithelial apoptoses were analysed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) and caspase-3 staining. Tight junction protein expression was quantified by densitometric analysis of immunoblots. Mucosal cytokine production was determined by cytometric bead array.
Results:
Only in untreated but not in treated HIV-infected patients, epithelial resistance was reduced (13 (1) vs 23 (2) Ω cm2, p<0.01) and mannitol permeability was increased compared with HIV-negative controls (19 (3) vs 9 (1) nm/s, p<0.05). As structural correlates, epithelial apoptoses and expression of the pore-forming claudin-2 were increased while expression of the sealing claudin-1 was reduced in untreated compared with treated patients and HIV-negative controls. Furthermore, villous atrophy was evident and mucosal production of interleukin 2 (IL2), IL4 and tumour necrosis factor α (TNFα) was increased in untreated but not in treated HIV-infected patients. Incubation with IL2, IL4, TNFα and IL13 reduced the transepithelial resistance of rat jejunal mucosa.
Conclusions:
Suppressive HAART abrogates HIV-induced intestinal barrier defect and villous atrophy. The HIV-induced barrier defect is due to altered tight junction protein composition and elevated epithelial apoptoses. Mucosal cytokines are mediators of the HIV-induced mucosal barrier defect and villous atrophy.
Abstract Background Chronic immune activation is a hallmark of HIV infection and has been postulated as major factor in the pathogenesis of AIDS. Recent evidence suggests that activation of immune cells is triggered by microbial translocation through the impaired gastrointestinal barrier. Methods To determine the association between microbial translocation and disease progression, we have retrospectively analyzed microbial products, viral load and markers of immune activation in a cohort of 37 simian immunodeficiency virus‐infected rhesus monkeys, divided in two groups with distinct disease courses. Results As seen in HIV‐infected patients, we found elevated levels of lipopolysaccharide (LPS) in infected animals. However, LPS levels or LPS control mechanisms like endotoxin core antibodies or LPS‐binding protein did not differ between groups with different disease progression. In contrast, neopterin, a metabolic product of activated macrophages, was higher in fast progressors than in slow progressors. Conclusion Our data indicate that translocation of microbial products is not the major driving force of immune activation in HIV infection.
Vpu as a human‐immunodeficiency‐virus‐type‐1‐encoded 81‐amino‐acid integral‐membrane protein was expressed in Escherichia coli using the inducible p trc promoter of an ATG fusion vector. Recombinant Vpu is associated with membranes of E. coli and could be partially solubilized by detergents. Recombinant Vpu was phosphorylated in vitro with purified porcine casein kinase II (CKII) as well as with a CKII‐related protein kinase found in cytoplasmic extracts of human and hamster cells. Recombinant Vpu associated with E. coli membranes has turned out to be the best substrate for in vitro phosphorylation with CKII. This reaction can be inhibited by heparin and the ATP analogue 5,6‐dichloro‐1‐(β‐D‐ribofuranosyl)benzimidazole (DRB), both known to be potent inhibitors of CKII. Radiolabelled γATP and γGTP were used as phosphate donors for in vitro phosphorylation of recombinant Vpu. In vivo phosphorylation of Vpu‐1‐infected H9 cells was also inhibited by DRB. We concluded therefrom that the Vpu protein is phosphorylated by the ubiquitous CKII in HIV‐1‐infected human host cells. Two seryl residues in the sequence of Vpu (position 52 and 56) correspond to the consensus s / T XX D / E for CKII. These potential phosphorylation sites are located within a well‐conserved dodecapeptide of Vpu (residues 47–58), which is found in different HIV‐1 strains as well as in a Vpu‐like protein of SIV CPZ. Monoclonal and polyclonal antibodies directed against two different epitopes of Vpu were used for immunoprecipitation of Vpu from HIV‐1‐infected cells and for detection of Vpu in Western blot analyses. Vpu from HIV‐1‐infected cells as well as recombinant Vpu expressed in E. coli were determined by SDS/PAGE using 6 M urea to be 9 kDa, which corresponds to the calculated molecular mass of Vpu.
We analyzed the relationship between statin continuation or discontinuation and outcome after spontaneous intracerebral hemorrhage (ICH).From a databank with 447 data sets, we selected patients with hypertensive or anticoagulation-related hemorrhage (volume 10-250 mL). Of 323 patients available for analysis, 63 were taking statins. This group was divided into those who discontinued (N.=18) or continued therapy (N.=45). Statin users were matched by age, sex, and National Institutes of Health Stroke Scale (NIHSS) status in 1:4 ratio to nonusers. Mortality after 30 days, 3 months, and 12 months was analyzed using Cox regression. The Glasgow Outcome Scale (GOS) scores at discharge and at least 6 months after ICH onset were recorded.Baseline characteristics of patients with continued and discontinued statin use were not different. Patients who discontinued statin therapy were very similar to their matched-cases; however, the control-matched cases for patients who continued statins had lower incidences of diabetes mellitus and cardiovascular diseases. In multivariate analysis, statin discontinuation was associated with a 6.9-fold (95% CI 2.09-23.13, P=0.002) higher risk of death within the first 30 days after ICH onset compared to patients who continued therapy. Patients who discontinued also had an increased risk of death within 30 days of ICH onset compared to their matched-controls (HR=3.87, 95% CI 1.69-8.87, P=0.001). The continued statin group displayed only a slight reduction in mortality risk after 3 month (HR=0.67, 95% CI 0.37-1.21, P=0.19) compared to matched-controls, but the chance to be discharge with a better neurological (NIHSS<15) was increased among patients with continued statin use (51% versus 33%, P=0.02).The continued use of statins after an ICH led to a small mortality reduction, whereas discontinuing statins might be related to increased mortality. Randomized clinical trials are needed to define the role of statin use in the management of acute ICH.
