HIV protease inhibitors impact on apoptosis

HIV and COVID-19 Disease

Despite effective antiretroviral therapy (ART), HIV infected individuals throughout the world remain at significant risk of respiratory infections and non-communicable disease. Severe disease from SARS-CoV-2 is associated with a hyperinflammatory phenotype which manifests in the lungs as pneumonia and in some cases can lead to acute respiratory failure. Progression to severe COVID-19 is associated with comorbid disease such as obesity, diabetes mellitus and cardiovascular disease, however data concerning the associated risks of HIV coinfection are still conflicting, with large population studies demonstrating poorer outcomes, whilst smaller, case-controlled studies showing better outcomes. Furthermore, underlying immunopathological processes within the lungs and elsewhere, including interactions with other opportunistic infections (OI), remain largely undefined. Nonetheless, new and repurposed anti-viral therapies and vaccines which have been developed are safe to use in this population, and anti-inflammatory agents are recommended with the caveat that the coexistence of opportunistic infections is considered and excluded. Finally, HIV infected patients remain reliant on good ART adherence practices to maintain HIV viral suppression, and some of these practices were disrupted during the COVID-19 pandemic, putting these patients at further risk for acute and long-term adverse outcomes.

Interactions of HIV and Antiretroviral Therapy With Neutrophils and Platelets

Neutrophils are important components of the innate immune system that mediate pathogen defense by multiple processes including phagocytosis, release of proteolytic enzymes, production of reactive oxygen species, and neutrophil extracellular trap formation. Abnormalities of neutrophil count and function have been described in the setting of HIV infection, with the majority of antiretroviral agents (ARVs), excluding zidovudine, having been reported to correct neutropenia. Questions still remain, however, about their impact on neutrophil function, particularly the possibility of persistent neutrophil activation, which could predispose people living with HIV to chronic inflammatory disorders, even in the presence of virally-suppressive treatment. In this context, the effects of protease inhibitors and integrase strand transfer inhibitors, in particular, on neutrophil function remain poorly understood and deserve further study. Besides mediating hemostatic functions, platelets are increasingly recognized as critical role players in the immune response against infection. In the setting of HIV, these cells have been found to harbor the virus, even in the presence of antiretroviral therapy (ART) potentially promoting viral dissemination. While HIV-infected individuals often present with thrombocytopenia, they have also been reported to have increased platelet activation, as measured by an upregulation of expression of CD62P (P-selectin), CD40 ligand, glycoprotein IV, and RANTES. Despite ART-mediated viral suppression, HIV-infected individuals reportedly have sustained platelet activation and dysfunction. This, in turn, contributes to persistent immune activation and an inflammatory vascular environment, seemingly involving neutrophil-platelet-endothelium interactions that increase the risk for development of comorbidities such as cardiovascular disease (CVD) that has become the leading cause of morbidity and mortality in HIV-infected individuals on treatment, clearly underscoring the importance of unraveling the possible etiologic roles of ARVs. In this context, abacavir and ritonavir-boosted lopinavir and darunavir have all been linked to an increased risk of CVD. This narrative review is therefore focused primarily on the role of neutrophils and platelets in HIV transmission and disease, as well as on the effect of HIV and the most common ARVs on the numbers and functions of these cells, including neutrophil-platelet-endothelial interactions.

A New Insight on the Radioprotective Potential of Epsilon-Aminocaproic Acid

Background and objectives: The aim of the study was to scrutinize the ability of epsilon-aminocaproic acid (EACA) to prevent radiation-induced damage to human cells. Materials and Methods: Human peripheral blood mononuclear cells (PBMCs) were exposed to ionizing radiation at three low doses (22.62 mGy, 45.27 mGy, and 67.88 mGy) in the presence of EACA at the concentration of 50 ng/mL. Results: EACA was able to prevent cell death induced by low-dose X-ray radiation and suppress the formation of reactive oxygen species (ROS). EACA also demonstrated a capacity to protect DNA from radiation-induced damage. The data indicated that EACA is capable of suppression of radiation-induced apoptosis. Comparative tests of antioxidative activity of EACA and a range of free radical scavengers showed an ability of EACA to effectively inhibit the generation of ROS. Conclusions: This study showed that the pretreatment of PBMCs with EACA is able to protect the cells from radiation-elicited damage, including free radicals' formation, DNA damage, and apoptosis.

Antiretroviral Therapy Concentrations Differ in Gut vs. Lymph Node Tissues and Are Associated With HIV Viral Transcription by a Novel RT-ddPCR Assay

BACKGROUND

Most HIV-infected cells during antiretroviral therapy (ART) persist in lymphoid tissues. Studies disagree on whether suboptimal tissue ART concentrations contribute to ongoing HIV replication during viral suppression.

METHODS

We performed a cross-sectional study in virally-suppressed HIV+ participants measuring lymphoid tissue ART [darunavir (DRV), atazanavir (ATV), and raltegravir (RAL)] concentrations by LC-MS/MS assay. Tissue and plasma ART concentrations were used to estimate TPRs and drug-specific tissue:inhibitory concentration ratios (TICs). HIV DNA and sequentially produced HIV RNA transcripts were quantified from rectal biopsies using droplet digital PCR (ddPCR) assays.

RESULTS

Tissue samples were collected in duplicate from 19 participants: 38 rectal, 8 ileal (4 RAL, 2 DRV, 2 ATV), and 6 lymph node (4 RAL, 2 DRV) samples. Overall, median TICs were higher for RAL than DRV or ATV (both P = 0.006). Median TICs were lower in lymph nodes vs. ileum (0.49 vs. 143, P = 0.028) or rectum (33, P = 0.019), and all ART levels were below target concentrations. Higher rectal TICs were associated with lower HIV RNA transcripts (read-through, long LTR, and Nef, P all < 0.026) and a lower long LTR RNA/long LTR DNA ratio (P = 0.021).

CONCLUSIONS

We observed higher tissue ART concentrations in ileum and rectum compared with lymph nodes. We observed higher HIV transcription in participants with lower rectal ART concentrations. These findings add to the limited data supporting the idea that viral transcription may be influenced by ART concentrations in lymphoid tissues. Further exploration of tissue pharmacokinetics is needed in future HIV eradication strategies.

The dual protease inhibitor lopinavir/ritonavir (LPV/r) exerts genotoxic stress on lung cells

The Sub-Saharan countries, particularly South Africa has the largest number of people living with HIV, accompanied by the largest antiretroviral treatment (ART) programme in the world. The Highly Active Antiretroviral Treatment (HAART) is the most effective regimen against HIV/AIDS and has improved the lifespan and quality of life of HIV positive patients. HAART has also led to a decrease in the incidence of AIDS defining cancers (ADCs) while there is an increased incidence of the non-AIDS Defining Cancers (NADCs), such as lung cancer in the HAART era. The association between lung tumourigenesis and the use of HAART components such as the dual protease inhibitor (PI) lopinavir/ritonavir (LPV/r) is poorly understood. Using cell and molecular biological approaches, this study aimed at elucidating the effects of LPV/r on the regulation of the cell cycle related genes in normal (MRC-5) and adenocarcinoma (A549) lung cells. Initially, the nuclear integrity of these cells in response to LPV/r was determined using DAPI staining. The effect of LPV/r on cell cycle genes was evaluated through the use of a RT2 PCR gene array of 84 genes related to the cell cycle signaling pathway. The PCR array data was validated by Real-Time Quantification PCR (RT-qPCR). Ingenuity Pathway Analysis (IPA) bio-informatics tool was employed to disclose the molecular mechanism/s observed at cellular and gene expression levels. Loss of nuclear integrity and the upregulation of the p53 DNA damage response (DDR) pathway was revealed by DAPI staining, differential gene expression and IPA core analysis. Furthermore, MAD2L2 and AURKB which also play a role in the DDR pathway were shown to be differentially expressed. The activation of the CASP3 gene in response to LPV/r in A549 cells was also observed. The findings of this study suggest genotoxic properties of LPV/r in healthy normal lung fibroblasts cells and anti-tumour properties in the A549 cells.

Apoptosis characterization in mononuclear blood leukocytes of HIV patients during dengue acute disease

Dengue virus (DENV) co-circulation in Brazil represents a challenge for treatment and vaccine development. Despite public health impact, the occurrence of coinfections with other viruses is a common event. Increased T cell activation and altered inflammatory response are found during DENV coinfection with Human Immunodeficiency Virus (HIV) impacting HIV-pathogenesis. Even with Antiretroviral therapy (ART), HIV- treated patients had chronic immune activation and lymphocyte apoptosis. However, apoptotic mechanisms have not been investigated during coinfection with DENV. Our attention was attracted to apoptotic cell markers expressions in PBMCs from DENV and DENV/HIV coinfected patients. We found CD4/CD8 ratio inversion in most coinfected patients. CD4 T and CD8 T-cell subsets from DENV and DENV/HIV groups expressed low levels of anti-apoptotic protein Bcl-2. Furthermore, CD8 CD95 double positive cells frequency expressing low levels of Bcl-2 were significantly higher in these patients. Additionally, the density of Bcl-2 on classical monocytes (CD14⁺⁺CD16⁻) was significantly lower during DENV infection. Upregulation of pro-apoptotic proteins and anti-apoptotic proteins were found in DENV and DENV/HIV, while catalase, an antioxidant protein, was upregulated mainly in DENV/HIV coinfection. These findings provide evidence of apoptosis triggering during DENV/HIV coinfection, which may contribute to knowledge of immunological response during DENV acute infection in HIV-patients treated with ART.

High IL-5 levels possibly contributing to HIV viremia in virologic non-responders at one year after initiation of anti-retroviral therapy

Lack of viral monitoring in HIV infected patients on anti-retroviral therapy in low income countries may result in missing virologic non-responders (VNR) who show immunologic recovery in spite of unsuppressed viral replication. Biomarkers and drug resistance patterns in these discordant patients in comparison to the concordant treatment failure group need to be studied to understand possible risk factors associated with this condition. HIV infected patients on anti-retroviral therapy for one year were enrolled under three categories namely VNRs (n = 25), treatment failures (n = 18) and treatment responders (n = 40). They were assessed for HIV drug resistance by sequencing, plasma cytokines by luminex assay, T cell activation status by flow cytometry and total IgE levels by ELISA. VNR and failure patients had significantly lower median baseline CD4 counts than the responders. VNRs had significantly higher CD4 counts but lower viral load than treatment failures at one year of ART. VNRs had the highest eosinophil counts and the highest IL-5 levels among all the groups. IL-5 levels in them correlated with their viral load values. Frequency of Treg cells was also highest among the VNR group participants. More than 60% of the viremic patients irrespective of their groups harboured multiple HIV drug resistance mutations and mutation pattern did not differ between the groups. Low baseline CD4 counts and presence of multiple drug resistance mutations in the viremic groups highlighted the importance of early ART initiation and viral load monitoring irrespective of presence of immunologic failure. High IL-5 levels in VNR group indicated a need for investigating causal relationship between IL-5 and viral replication to devise therapeutic strategies to control viremia.

NNRTI-induced HIV-1 protease-mediated cytotoxicity induces rapid death of CD4 T cells during productive infection and latency reversal

BACKGROUND

Current efforts towards HIV-1 eradication focus on the reactivation and elimination of the latent viral reservoir, so-called shock and kill therapy. However, work from several groups indicates that infected cell death following virus reactivation is not guaranteed. Thus, it is imperative to develop strategies to foster specific elimination of cells carrying integrated proviruses. It has been shown that some non-nucleoside reverse transcriptase inhibitors (NNRTIs) including efavirenz can induce premature HIV-1 GagPol dimerization in productively infected cells, resulting in intracellular HIV-1 Protease (PR) activation and a reduction in HIV-1 expressing cells.

RESULTS

Here, we document that NNRTI-induced PR activation triggers apoptotic death of productively infected resting or activated T cells in as little as 2 h via caspase-dependent and independent pathways. Rilpivirine, efavirenz and etravirine were the most potent NNRTIs, whereas nevirapine had almost no effect. NNRTI-induced cell killing was prevented by inhibitors of HIV-1 Protease (PR) activity including indinavir and nelfinavir. HIV-1 transmitter founder viruses induced cell killing similarly to lab-adapted HIV-1 except when NNRTI resistance conferring mutations were present in reverse transcriptase. Mutations in PR that confer PR inhibitor (PI) resistance restore NNRTI-induced killing in the presence of PI. Finally, we show that NNRTIs can rapidly eliminate cells in which latent viruses are stimulated to active expression.

CONCLUSIONS

This work supports the notion that select NNRTIs might help promote the elimination of HIV-1 producing cells as an adjuvant during shock and kill therapy.

Lopinavir, an HIV-1 peptidase inhibitor, induces alteration on the lipid metabolism of Leishmania amazonensis promastigotes

The anti-leishmania effects of HIV peptidase inhibitors (PIs) have been widely reported; however, the biochemical target and mode of action are still a matter of controversy in Leishmania parasites. Considering the possibility that HIV-PIs induce lipid accumulation in Leishmania amazonensis, we analysed the effects of lopinavir on the lipid metabolism of L. amazonensis promastigotes. To this end, parasites were treated with lopinavir at different concentrations and analysed by fluorescence microscopy and spectrofluorimetry, using a fluorescent lipophilic marker. Then, the cellular ultrastructure of treated and control parasites was analysed by transmission electron microscopy (TEM), and the lipid composition was investigated by thin-layer chromatography (TLC). Finally, the sterol content was assayed by gas chromatography-mass spectrometry (GC/MS). TEM analysis revealed an increased number of lipid inclusions in lopinavir-treated cells, which was accompanied by an increase in the lipophilic content, in a dose-dependent manner. TLC and GC-MS analysis revealed a marked increase of cholesterol-esters and cholesterol. In conclusion, lopinavir-induced lipid accumulation and affected lipid composition in L. amazonensis in a concentration-response manner. These data contribute to a better understanding of the possible mechanisms of action of this HIV-PI in L. amazonensis promastigotes. The concerted action of lopinavir on this and other cellular processes, such as the direct inhibition of an aspartyl peptidase, may be responsible for the arrested development of the parasite.

In-vitro effects of protease inhibitors on BAX, BCL- 2 and apoptosis in two human breast cell lines

Abstract Currently, the treatment of choice of HIV/AIDS in South Africa is the multidrug combination regimen known as HAART (highly active antiretroviral treatment). HAART, which commonly consists of nucleoside or non-nucleoside reverse transcriptase inhibitors and protease inhibitors, has radically decreased mortality and morbidity rates among people living with HIV/AIDS. The emphasis of the original development of the antiretroviral drugs was on clinical effectiveness (reducing mortality). Presently, emphasis has shifted from the initial short- term considerations to the long-term undesirable or harmful effects induced by this treatment regimen. Whether antiretroviral compounds are oncogenic is widely speculated, which led to this investigation into the effects of protease inhibitors on the expression of key apoptotic regulatory genes, BAX and BCL-2, in two human breast cell lines, MCF-7 and MCF-10A by real-time qPCR gene expression and immunofluorescence. The anti-apoptotic effects of the protease inhibitors – LPV/r were also investigated by cell death detection ELISA and acridine orange staining. This study also evaluated the cytotoxicity of the antiretroviral drugs in normal and cancer cell lines of the breast (at clinically relevant concentrations of the drugs and at different time points, 24–96 h), employing the neutral red uptake assay. The drugs and combinations tested did not alter BAX and BCL-2 gene expression and protein expression and localisation in both cell lines. In addition, the protease inhibitors–LPV/r did not inhibit camptothecin-induced apoptosis in both cell lines. We have shown that the protease inhibitors demonstrated varying degrees of cytotoxicity in the breast cells. The resulting DNA damage associated with cytotoxicity is strongly implicated in the processes of tumour initiation.

Treatment With Lopinavir/Ritonavir or Interferon-β1b Improves Outcome of MERS-CoV Infection in a Nonhuman Primate Model of Common Marmoset

Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe disease in human with an overall case-fatality rate of >35%. Effective antivirals are crucial for improving the clinical outcome of MERS. Although a number of repurposed drugs, convalescent-phase plasma, antiviral peptides, and neutralizing antibodies exhibit anti-MERS-CoV activity in vitro, most are not readily available or have not been evaluated in nonhuman primates. We assessed 3 repurposed drugs with potent in vitro anti-MERS-CoV activity (mycophenolate mofetil [MMF], lopinavir/ritonavir, and interferon-β1b) in common marmosets with severe disease resembling MERS in humans. The lopinavir/ritonavir-treated and interferon-β1b-treated animals had better outcome than the untreated animals, with improved clinical (mean clinical scores ↓50.9%–95.0% and ↓weight loss than the untreated animals), radiological (minimal pulmonary infiltrates), and pathological (mild bronchointerstitial pneumonia) findings, and lower mean viral loads in necropsied lung (↓0.59–1.06 log₁₀ copies/glyceraldehyde 3-phosphate dehydrogenase [GAPDH]; P < .050) and extrapulmonary (↓0.11–1.29 log₁₀ copies/GAPDH; P < .050 in kidney) tissues. In contrast, all MMF-treated animals developed severe and/or fatal disease with higher mean viral loads (↑0.15–0.54 log₁₀ copies/GAPDH) than the untreated animals. The mortality rate at 36 hours postinoculation was 67% (untreated and MMF-treated) versus 0–33% (lopinavir/ritonavir-treated and interferon-β1b-treated). Lopinavir/ritonavir and interferon-β1b alone or in combination should be evaluated in clinical trials. MMF alone may worsen MERS and should not be used.

Human immunodeficiency virus-1 (HIV-1)-mediated apoptosis: new therapeutic targets

HIV has posed a significant challenge due to the ability of the virus to both impair and evade the host’s immune system. One of the most important mechanisms it has employed to do so is the modulation of the host’s native apoptotic pathways and mechanisms. Viral proteins alter normal apoptotic signaling resulting in increased viral load and the formation of viral reservoirs which ultimately increase infectivity. Both the host’s pro- and anti-apoptotic responses are regulated by the interactions of viral proteins with cell surface receptors or apoptotic pathway components. This dynamic has led to the development of therapies aimed at altering the ability of the virus to modulate apoptotic pathways. These therapies are aimed at preventing or inhibiting viral infection, or treating viral associated pathologies. These drugs target both the viral proteins and the apoptotic pathways of the host. This review will examine the cell types targeted by HIV, the surface receptors exploited by the virus and the mechanisms whereby HIV encoded proteins influence the apoptotic pathways. The viral manipulation of the hosts’ cell type to evade the immune system, establish viral reservoirs and enhance viral proliferation will be reviewed. The pathologies associated with the ability of HIV to alter apoptotic signaling and the drugs and therapies currently under development that target the ability of apoptotic signaling within HIV infection will also be discussed.

Anti-apoptotic mechanisms of HIV: lessons and novel approaches to curing HIV

Past efforts at curing infection with the human immunodeficiency virus (HIV) have been blocked by the resistance of some infected cells to viral cytopathic effects and the associated development of a latent viral reservoir. Furthermore, current efforts to clear the viral reservoir by means of reactivating latent virus are hampered by the lack of cell death in the newly productively infected cells. The purpose of this review is to describe the many anti-apoptotic mechanisms of HIV, as well as the current limitations in the field. Only by understanding how infected cells avoid HIV-induced cell death can an effective strategy to kill infected cells be developed.

Peripheral T-cell apoptosis is not differentially affected by antiretroviral regimens in HIV-infected patients

BACKGROUND

HIV-induced CD4(+) and CD8(+) T-cell apoptosis decreases upon start of combination antiretroviral therapy (cART). Although in vitro evidence suggests an anti-apoptotic effect of protease inhibitors (PIs) as opposed to non-nucleoside reverse transcriptase inhibitors (NNRTIs), in vivo studies are inconclusive about effects of differential cART regimens on T-cell apoptosis.

METHODS

Peripheral T-cell apoptosis was evaluated in a cross-sectional study including 20 patients on PI- and 19 on NNRTI-based combination antiretroviral therapy (cART), all with backbone therapy of tenofovir and emtricitabine and undetectable viral loads 6 months before inclusion. Spontaneous T-cell apoptosis was measured in freshly isolated peripheral blood mononuclear cells (<4 h after venipuncture) using annexin V, propidium iodide and staining for caspase activity and levels of the anti-apoptotic protein Bcl-2.

RESULTS

The groups were comparable in general- and HIV-specific characteristics. In addition, T-cell activation was similar in both groups. We observed no difference in T-cell apoptosis as measured by annexin V, propidium iodide or caspase staining between PI- and NNRTI-treated patients. Interestingly, the level of anti-apoptotic protein Bcl-2 was higher in PI-treated than in NNRTI-treated patients.

CONCLUSIONS

In this cross-sectional study on HIV-infected patients, direct ex vivo spontaneous T-cell apoptosis rates are not differentially affected by NNRTI- or PI-based cART.

Kinetics of microbial translocation markers in patients on efavirenz or lopinavir/r based antiretroviral therapy

Objectives

We investigated whether there are differences in the effects on microbial translocation (MT) and enterocyte damage by different antiretroviral therapy (ART) regimens after 1.5 years and whether antibiotic use has impact on MT. In a randomized clinical trial (NCT01445223) on first line ART, patients started either lopinavir/r (LPV/r) (n = 34) or efavirenz (EFV) containing ART (n = 37). Lipopolysaccharide (LPS), sCD14, anti-flagellin antibodies and intestinal fatty acid binding protein (I-FABP) levels were determined in plasma at baseline (BL) and week 72 (w72).

Results

The levels of LPS and sCD14 were reduced from BL to w72 (157.5 pg/ml vs. 140.0 pg/ml, p = 0.0003; 3.13 ug/ml vs. 2.85 ug/ml, p = 0.005, respectively). The levels of anti-flagellin antibodies had decreased at w72 (0.35 vs 0.31 [OD]; p<0.0004), although significantly only in the LPV/r arm. I-FABP levels increased at w72 (2.26 ng/ml vs 3.13 ng/ml; p<0.0001), although significantly in EFV treated patients only. Patients given antibiotics at BL had lower sCD14 levels at w72 as revealed by ANCOVA compared to those who did not receive (Δ = −0.47 µg/ml; p = 0.015).

Conclusions

Markers of MT and enterocyte damage are elevated in untreated HIV-1 infected patients. Long-term ART reduces the levels, except for I-FABP which role as a marker of MT is questionable in ART-experienced patients. Why the enterocyte damage seems to persist remains to be established. Also antibiotic usage may influence the kinetics of the markers of MT.

Trial Registration

ClinicalTrials.gov NCT01445223

Effects of HIV-1 protease on cellular functions and their potential applications in antiretroviral therapy

Human Immunodeficiency Virus Type 1 (HIV-1) protease inhibitors (PIs) are the most potent class of drugs in antiretroviral therapies. However, viral drug resistance to PIs could emerge rapidly thus reducing the effectiveness of those drugs. Of note, all current FDA-approved PIs are competitive inhibitors, i.e., inhibitors that compete with substrates for the active enzymatic site. This common inhibitory approach increases the likelihood of developing drug resistant HIV-1 strains that are resistant to many or all current PIs. Hence, new PIs that move away from the current target of the active enzymatic site are needed. Specifically, allosteric inhibitors, inhibitors that prohibit PR enzymatic activities through non-competitive binding to PR, should be sought. Another common feature of current PIs is they were all developed based on the structure-based design. Drugs derived from a structure-based strategy may generate target specific and potent inhibitors. However, this type of drug design can only target one site at a time and drugs discovered by this method are often associated with strong side effects such as cellular toxicity, limiting its number of target choices, efficacy, and applicability. In contrast, a cell-based system may provide a useful alternative strategy that can overcome many of the inherited shortcomings associated with structure-based drug designs. For example, allosteric PIs can be sought using a cell-based system without considering the site or mechanism of inhibition. In addition, a cell-based system can eliminate those PIs that have strong cytotoxic effect. Most importantly, a simple, economical, and easy-to-maintained eukaryotic cellular system such as yeast will allow us to search for potential PIs in a large-scaled high throughput screening (HTS) system, thus increasing the chances of success. Based on our many years of experience in using fission yeast as a model system to study HIV-1 Vpr, we propose the use of fission yeast as a possible surrogate system to study the effects of HIV-1 protease on cellular functions and to explore its utility as a HTS system to search for new PIs to battle HIV-1 resistant strains.

The HIV-1 protease inhibitor nelfinavir activates PP2 and inhibits MAPK signaling in macrophages: a pathway to reduce inflammation

The HIV-1 PI NFV has off-target effects upon host enzymes, including inhibition of the 20S proteasome, resulting in activation of PP1. HIV-1-associated monocyte/macrophage activation, in part a result of systemically elevated levels of microbial products including LPS, is associated with risk of mortality, independent of viremia or CD4 T cell loss. This study tested the hypothesis that activation of protein phosphatases by NFV would reduce activation of monocytes/macrophages through dephosphorylation of signal transduction proteins. NFV uniquely blocked LPS-induced production by human monocyte-derived macrophages of the inflammatory cytokines TNF and IL-6, as well as sCD14. Although NFV failed to modulate NF-κB, NFV treatment reduced phosphorylation of AKT and MAPKs. Inhibition of PP2 with okadaic acid blocked the anti-inflammatory effect of NFV, whereas the PP1 inhibitor calyculin A failed to counter the anti-inflammatory effects of NFV. For in vivo studies, plasma sCD14 and LPS were monitored in a cohort of 31 pediatric HIV-1 patients for over 2 years of therapy. Therapy, including NFV, reduced sCD14 levels significantly compared with IDV or RTV, independent of ΔLPS levels, VL, CD4 T cell frequency, or age. The hypothesis was supported as NFV induced activation of PP2 in macrophages, resulting in disruption of inflammatory cell signaling pathways. In vivo evidence supports that NFV may offer beneficial effects independent of antiviral activity by reducing severity of chronic innate immune activation in HIV-1 infection.

Long-term beneficial effect of protease inhibitors on the intrinsic apoptosis of peripheral blood mononuclear cells in HIV-infected patients

BACKGROUND

Viral suppression by antiretroviral therapy (ART) inhibits HIV-induced apoptosis and CD4 T-cell loss. It has been suggested that protease inhibitors (PIs) have nonviral antiapoptotic effects by maintaining mitochondrial integrity. Long-term clinical effects of PI-based ART on mitochondrial toxicity and lymphocyte apoptosis beyond viral suppression have not been exploited to date.

METHODS

We conducted a 7-year study on HIV-1-infected patients from the Cologne HIV cohort with sufficient viral suppression under either a PI-based or nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimen. Eight patients on PI and eight on NNRTI were eligible for inclusion in the analysis. The primary outcome measure was defined as a change in the mitochondrial-to-nuclear DNA ratio in PBMCs. Further key molecules involved in extrinsic [tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), Fas ligand (FasL) and caspase 8], intrinsic [B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase 9 and lactate-to-pyruvate ratio] and overall apoptosis [Annexin+/7-aminoactinomycin D (7-AAD)- and caspase 3/7] and viral activity [negative regulatory factor (Nef), interferon-α (IFN-α) and myxovirus resistance protein A (MxA)] were measured.

RESULTS

Demographic and baseline clinical parameters were similar in the two groups, except that patients in the PI group had a higher mean age. After 7 years of treatment, CD4 T-cell count increased and the expression of genes encoding the proapoptotic viral protein Nef and HIV-induced cytokine IFN-α and its downstream effector MxA decreased in both groups. Focusing on the different pathways of apoptosis, only in the PI group intrinsic apoptosis decreased significant and in the inter-group comparison the decrease was significantly higher than in the NNRTI group.

CONCLUSIONS

Our study provides evidence that long-term therapy with a PI-based regimen may be superior to that with a NNRTI-based regimen with regard to its intrinsic antiapoptotic effect.

In vitro downregulation of matrix metalloproteinase-9 in rat glial cells by CCR5 antagonist maraviroc: therapeutic implication for HIV brain infection

Background

Matrix metalloproteinases (MMPs) released by glial cells are important mediators of neuroinflammation and neurologic damage in HIV infection. The use of antiretroviral drugs able to combat the detrimental effect of chronic inflammation and target the exaggerated MMP activity might represent an attractive therapeutic challenge. Recent studies suggest that CCR5 antagonist maraviroc (MVC) exerts immunomodulant and anti-inflammatory activity beyond its anti-HIV properties. We investigated the in vitro effect of MVC on the activity of MMPs in astrocyte and microglia cultures.

Methodology/Principal Findings

Primary cultures of rat astrocytes and microglia were activated by exposure to phorbol myristate acetate (PMA) or lypopolysaccharide (LPS) and treated in vitro with MVC. Culture supernatants were subjected to gelatin zymography and quantitative determination of MMP-9 and MMP-2 was done by computerized scanning densitometry. MMP-9 levels were significantly elevated in culture supernatants from both LPS- and PMA-activated astrocytes and microglia in comparison to controls. The treatment with MVC significantly inhibited in a dose-dependent manner the levels and expression of MMP-9 in PMA-activated astrocytes (p<0,05) and, to a lesser extent, in PMA-activated microglia. By contrast, levels of MMP-2 did not significantly change, although a tendency to decrease was seen in PMA-activated astrocytes after treatment with MVC. The inhibition of levels and expression of MMP-9 in PMA-activated glial cells did not depend on cytotoxic effects of MVC. No inhibition of MMP-9 and MMP-2 were found in both LPS-activated astrocytes and microglia.

Conclusions

The present in vitro study suggests that CCR5 antagonist compounds, through their ability to inhibit MMP-9 expression and levels, might have a great potential for the treatment of HIV-associated neurologic damage.

Beneficial effects of a switch to a Lopinavir/ritonavir-containing regimen for patients with partial or no immune reconstitution with highly active antiretroviral therapy despite complete viral suppression

The purpose of this study was to determine if switching to an Lopinavir/ritonavir (LPV/r)-containing regimen resulted in greater immune reconstitution in patients with immunologic failure despite complete viral suppression with highly active antiretroviral therapy (HAART). Twenty patients with partial or no immune response to HAART despite viral suppression were enrolled. Ten were randomized to stay on their current regimen and 10 were randomized to LPV/r plus their current NRTI backbone. T cell subsets, ex vivo apoptosis, and the percent of circulating cells with detectable intracellular HIV-1 RNA were measured. The mean increase in CD4(+) count at 6 months was 116/mm(3) (172-288) for the LPV/r-containing arm versus 32/mm(3) (264-296) for continuation regimens (p = 0.03). The number of patients with an increase ≥50 cells/mm(3) was also greater in the LPV/r arm (7/9 versus 2/10, p = 0.01). This paralleled a decrease in ex vivo apoptosis of naive CD4(+) T cells at 6 months (21.7-11.0% for the LPV/r arm versus 17.3-18.9% for the continuation arm, p = 0.04) and memory cells (21.1-14.1% for LPV/r versus 20.2-17.9% for continuation arm, NSS). Switching patients to an LPV/r-containing regimen improved CD4(+) counts in patients with prior immunologic failure, and this may be due to an effect of LPV/r on apoptosis.

Low CD4+ T-cell levels and B-cell apoptosis in vertically HIV-exposed noninfected children and adolescents

Lymphocyte subsets, activation markers and apoptosis were assessed in 20 HIV-exposed noninfected (ENI) children born to HIV-infected women who were or not exposed to antiretroviral (ARV) drugs during pregnancy and early infancy. ENI children and adolescents were aged 6-18 years and they were compared to 25 age-matched healthy non-HIV-exposed children and adolescents (Control). ENI individuals presented lower CD4(+) T cells/mm(3) than Control group (control: 1120.3 vs. ENI: 876.3; t-test, p = 0.030). ENI individuals had higher B-cell apoptosis than Control group (Control: 36.6%, ARV exposed: 82.3%, ARV nonexposed: 68.5%; Kruskal-Wallis, p < 0.05), but no statistical difference was noticed between those exposed and not exposed to ARV. Immune activation in CD4(+) T, CD8(+) T and in B cells was comparable in ENI and in Control children and adolescents. Subtle long-term immune alterations might persist among ENI individuals, but the clinical consequences if any are unknown, and these children require continued monitoring.

Apoptosis: a clinically useful measure of antiretroviral drug toxicity?

Antiretroviral therapy (ART) has improved life expectancy with HIV infection, but long-term toxicities associated with these medications are now a major global disease burden. There is a clear need to develop useful methods for monitoring patients on antiretroviral drugs for early signs of toxicity. Assays with predictive utility -- allowing therapy to be changed before serious end organ damage occurs -- would be ideal. Attempts to develop biochemical methods of monitoring ART toxicity have concentrated on the mitochondrial toxicity of nucleoside analogue reverse transcriptase inhibitors and have not generally lead to assays with widespread clinical applications. For example, plasma lactate and peripheral blood measurements of mitochondrial DNA associate with exposure to potentially toxic nucleoside analogue reverse transcriptase inhibitors but have not reliably predicted clinical toxicity. Better assays are needed, including markers of toxicity from additional drug classes. Apoptosis may be a potential marker of ART toxicity. Increased apoptosis has been demonstrated both in vitro and in vivo in association with various antiretroviral drug classes and a range of clinical toxicities. However, quantifying apoptosis on biopsy specimens of tissue (such as adipose tissue) is impractical for patient monitoring. Novel assays have been described that can quantify apoptosis using minute tissue samples and initial results from clinical samples suggest peripheral blood may have utility in predicting ART toxicities. The limitations and potential of such techniques for monitoring patients for drug side effects will be discussed.

The mitochondria-independent cytotoxic effect of nelfinavir on leukemia cells can be enhanced by sorafenib-mediated mcl-1 downregulation and mitochondrial membrane destabilization

Background

Nelfinavir is an HIV protease inhibitor that has been used for a long period of time to treat HIV-infected individuals. It has recently emerged that nelfinavir could represent a prospective new anti-cancer drug, prompting us to test the effect of nelfinavir on leukemia cells.

Methods

By combining in vitro and ex vivo studies, the effect of nelfinavir on leukemia cells and non-malignant, bone marrow-derived tissue cells was analyzed.

Results

At a concentration of 9 μg/ml, nelfinavir induced death of 90% of HL60, IM9, and Jurkat cells. At the same concentration and treatment conditions, less than 10% of aspirated human bone marrow cells showed nelfinavir-induced cell damage. Nelfinavir-induced death of leukemia cells was accompanied by activation of caspases 3, 7, and 8. Despite caspase activation, the upregulation of the anti-apoptotic bcl-2 family member protein mcl-1 that resulted from nelfinavir treatment stabilized the mitochondrial membrane potential, resulting in primarily mitochondria-independent cell death. Pharmacological downregulation of mcl-1 expression by treatment with sorafenib (2 μg/ml) significantly enhanced nelfinavir-induced apoptosis even at lower nelfinavir concentrations (5 μg/ml), but did not have additional detrimental effects on non-malignant bone marrow cells.

Conclusions

The ability of nelfinavir to induce apoptosis in leukemia cells as a single agent in a mitochondria-independent manner might suggest it could be used as a second or third line of treatment for leukemia patients for whom standard mitochondria-directed treatment strategies have failed. Combination treatment with nelfinavir and sorafenib might further enhance the efficacy of nelfinavir even on chemo-resistant leukemia cells.

Nelfinavir induces mitochondria protection by ERK1/2-mediated mcl-1 stabilization that can be overcome by sorafenib

The HIV protease inhibitor nelfinavir is an investigational drug for cancer treatment. We have previously demonstrated induction of apoptosis by nelfinavir even in chemo-resistant ovarian cancer cells. In contrast to the pro-apoptotic effect of nelfinavir on human cancer cells, we noticed a significant upregulation of the anti-apoptotic mitochondrial membrane protein mcl-1 by nelfinavir, resulting in a mitochondria-independent induction of apoptosis. Upregulation of mcl-1 was associated with enhanced phosphorylation of both mcl-1 and of ERK1/2 (extracellular signal-regulated kinases 1/2). ERK1/2 enhanced stability of mcl-1 protein expression by serine-163 phosphorylation. The combination of nelfinavir with sorafenib, a clinically applied inhibitor of the RAS/RAF/ERK1/2 pathway, inhibited nelfinavir-induced ERK1/2 activation and mcl-1 protein upregulation. Further, the combination of nelfinavir with sorafenib induced mitochondrial membrane potential disruption and resulted in an improved activity of nelfinavir on ovarian cancer cells. Thus, a combination of these two investigational anti-cancer drugs could be of interest especially because of their unique mechanism of apoptosis induction even in otherwise chemo-resistant human cancer cells.

Nelfinavir induces TRAIL receptor upregulation in ovarian cancer cells

HIV protease inhibitors are currently being discussed to be useful as new and alternative anti-cancer agents, especially as second line treatments for chemo-resistant human cancer types. Among three clinically applied HIV protease inhibitors tested, we found a high efficacy of nelfinavir on ovarian cancer cells, accompanied by apoptosis (annexin binding) and necrosis (propidium iodide permeability). In vitro, at concentrations used to induce cell death in ovarian cancer cells, nelfinavir had no effect on the cellular viability of fibroblasts or peripheral blood mononuclear leukocytes. Nelfinavir sensitized ovarian cancer cells to treatment with an apoptosis-inducing TRAIL receptor antibody due to upregulation of the TRAIL receptor DR5 as shown by RT-PCR and FACScan analysis. We conclude that nelfinavir, an already approved drug, is a highly efficient agent against ovarian cancer cells and could sensitize ovarian cancer cells to TRAIL treatment, either therapeutically applied or endogenously produced by cells of the immune system.