Dynamics of Low-Level Viremia and Immune Activation after Switching to a Darunavir-Based Regimen.

There is an ongoing debate regarding whether low-level viremia (LLV), in particular persistent LLV, during HIV treatment with optimal adherence originates from low-level viral replication, viral production, or both. We performed an observational study in 30 individuals with LLV who switched to a boosted darunavir (DRV)-based therapy. In-depth virological analyses were used to characterize the viral population and the (activity) of the viral reservoir. Immune activation was examined using cell-bound and soluble markers. The primary outcome was defined as the effect on HIV-RNA and was categorized by responders (<50 cp/mL) or non-responders (>50 cp/mL). At week 24, 53% of the individuals were considered responders, 40% non-responders, and 7% could not be assigned. Sequencing showed no evolution or selection of drug resistance in the non-responders. Production of defective virus with mutations in either the protease (D25N) or RT active site contributed to persistent LLV in two individuals. We show that in about half of the study participants, the switch to a DRV-based regimen resulted in a viral response indicative of ongoing low-level viral replication as the cause of LLV before the switch. Our data confirm that in clinical management, high genetic barrier drugs like DRV are a safe choice, irrespective of the source of LLV.

Virological and immunological correlates of HIV posttreatment control after temporal antiretroviral therapy during acute HIV infection.

OBJECTIVE: People with HIV rarely control viral replication after cessation of antiretroviral therapy (ART). We present a person with HIV with extraordinary posttreatment control (PTC) for over 23 years after temporary ART during acute HIV infection (AHI) leading to a new insight in factors contributing to PTC. DESIGN/METHODS: Viral reservoir was determined by HIV qPCR, Intact Proviral DNA Assay, and quantitative viral outgrowth assay. Viral replication kinetics were determined in autologous and donor PBMC. IgG levels directed against HIV envelope and neutralizing antibodies were measured. Immune phenotyping of T cells and HIV-specific T-cell responses were analyzed by flow cytometry. RESULTS: The case presented with AHI and a plasma viral load of 2.7 million copies/ml. ART was initiated 2 weeks after diagnosis and interrupted after 26 months. Replicating virus was isolated shortly after start ART. At 18 years after treatment interruption, HIV-DNA in CD4 + T cells and low levels of HIV-RNA in plasma (<5 copies/ml) were detectable. Stable HIV envelope glycoprotein-directed IgG was present during follow-up, but lacked neutralizing activity. Strong antiviral CD8 + T-cell responses, in particular targeting HIV-gag, were detected during 25 years follow-up. Moreover, we found a P255A mutation in an HLA-B∗44 : 02 restricted gag-epitope, which was associated with decreased replication. CONCLUSION: We describe an exceptional case of PTC, which is likely associated with sustained potent gag-specific CD8 + T-cell responses in combination with a replication attenuating escape mutation in gag. Understanding the initiation and preservation of the HIV-specific T-cell responses could guide the development of strategies to induce HIV control.

Shock and kill within the CNS: A promising HIV eradication approach?

The most studied HIV eradication approach is the "shock and kill" strategy, which aims to reactivate the latent reservoir by latency reversing agents (LRAs) and allowing elimination of these cells by immune-mediated clearance or viral cytopathic effects. The CNS is an anatomic compartment in which (persistent) HIV plays an important role in HIV-associated neurocognitive disorder. Restriction of the CNS by the blood-brain barrier is important for maintenance of homeostasis of the CNS microenvironment, which includes CNS-specific cell types, expression of transcription factors, and altered immune surveillance. Within the CNS predominantly myeloid cells such as microglia and perivascular macrophages are thought to be a reservoir of persistent HIV infection. Nevertheless, infection of T cells and astrocytes might also impact HIV infection in the CNS. Genetic adaptation to this microenvironment results in genetically distinct, compartmentalized viral populations with differences in transcription profiles. Because of these differences in transcription profiles, LRAs might have different effects within the CNS as compared with the periphery. Moreover, reactivation of HIV in the brain and elimination of cells within the CNS might be complex and could have detrimental consequences. Finally, independent of activity on latent HIV, LRAs themselves can have adverse neurologic effects. We provide an extensive overview of the current knowledge on compartmentalized (persistent) HIV infection in the CNS and on the "shock and kill" strategy. Subsequently, we reflect on the impact and promise of the "shock and kill" strategy on the elimination of persistent HIV in the CNS.

Delayed ischaemic contracture onset by empagliflozin associates with NHE1 inhibition and is dependent on insulin in isolated mouse hearts.

AIMS: Sodium glucose cotransporter 2 (SGLT2) inhibitors have sodium-hydrogen exchanger (NHE) inhibition properties in isolated cardiomyocytes, but it is unknown whether these properties extend to the intact heart during ischaemia-reperfusion (IR) conditions. NHE inhibitors as Cariporide delay time to onset of contracture (TOC) during ischaemia and reduce IR injury. We hypothesized that, in the ex vivo heart, Empagliflozin (Empa) mimics Cariporide during IR by delaying TOC and reducing IR injury. To facilitate translation to in vivo conditions with insulin present, effects were examined in the absence and presence of insulin. METHODS AND RESULTS: Isolated C57Bl/6NCrl mouse hearts were subjected to 25 min I and 120 min R without and with 50 mU/L insulin. Without insulin, Empa and Cari delayed TOC by 100 and 129 s, respectively, yet only Cariporide reduced IR injury [infarct size (mean ± SEM in %) from 51 ± 6 to 34 ± 5]. Empa did not delay TOC in the presence of the NHE1 inhibitor Eniporide. Insulin perfusion increased tissue glycogen content at baseline (from 2 ± 2 µmol to 42 ± 1 µmol glycosyl units/g heart dry weight), amplified G6P and lactate accumulation at end-ischaemia, thereby decreased mtHKII and exacerbated IR injury. Under these conditions, Empa (1 µM) and Cariporide (10 µM) were without effect on TOC and IR injury. Empa and Cariporide both inhibited NHE activity, in isolated cardiomyocytes, independent of insulin. CONCLUSIONS: In the absence of insulin, Empa and Cariporide strongly delayed the time to onset of contracture during ischaemia. In the presence of insulin, both Empa and Cari were without effect on IR, possibly because of severe ischaemic acidification. Insulin exacerbates IR injury through increased glycogen depletion during ischaemia and consequently mtHKII dissociation. The data suggest that also in the ex vivo intact heart Empa exerts direct cardiac effects by inhibiting NHE during ischaemia, but not during reperfusion.