Inhibitors Saquinavir Research Articles

Topical Protease Inhibitor Increases Tumor-Free and Overall Survival in CD4-Depleted Mouse Model of Anal Cancer.

Patients with immunodeficiencies and older age are at an increased risk of anal cancer. Transgenic K14E6/E7 mice with established high-grade anal dysplasia were treated topically at the anus with the protease inhibitor saquinavir (SQV) in the setting of CD4+ T-cell depletion to mimic immunodeficiency. To ensure tumor development, specific groups were treated with a topical carcinogen (7,12-Dimethylbenz[a]anthracene (DMBA)). The treatment groups included the vehicle (control), DMBA only, topical SQV, and topical SQV with DMBA, as well as the same four groups with CD4 depletion. The mice were monitored weekly for tumor development. Upon reaching 20 weeks of treatment, the mice were sacrificed, and their anal tissue was harvested for histological analysis. None of the mice in the SQV or control groups developed overt anal tumors, except three mice that were CD4-depleted. The CD4-depleted mice treated with DMBA had significantly increased tumor-free survival and overall survival as well as decreased tumor-volume growth over time when treated with SQV. These data suggest that topical SQV, in the setting of CD4 depletion and high-grade anal dysplasia, can increase tumor-free and overall survival; thus, it may represent a viable topical therapy to decrease the risk of progression of anal dysplasia to anal cancer.

Antiretroviral drugs from multiple classes induce loss of excitatory synapses between hippocampal neurons in culture.

Introduction: Antiretroviral (ARV) drugs have improved prognoses for people living with HIV. However, HIV-associated neurocognitive disorders (HAND) persist despite undetectable viral loads. Some ARVs have been linked to neuropsychiatric effects that may contribute to HAND. Synapse loss correlates with cognitive decline in HAND and synaptic deficits may contribute to the neuropsychiatric effects of ARV drugs. Methods: Using an automated high content assay, rat hippocampal neurons in culture expressing PSD95-eGFP to label glutamatergic synapses and mCherry to fill neuronal structures were imaged before and after treatment with 25 clinically used ARVs. Results and Discussion: At a concentration of 10μM the protease inhibitors nelfinavir and saquinavir, the non-nucleoside reverse transcriptase inhibitors etravirine and the 8-OH metabolite of efavirenz, the integrase inhibitor bictegravir, and the capsid inhibitor lenacapavir produced synaptic toxicity. Only lenacapavir produced synapse loss at the nanomolar concentrations estimated free in the plasma, although all 4 ARV drugs induced synapse loss at Cmax. Evaluation of combination therapies did not reveal synergistic synaptic toxicity. Synapse loss developed fully by 24h and persisted for at least 3days. Bictegravir-induced synapse loss required activation of voltage-gated Ca2+ channels and bictegravir, etravirine, and lenacapavir produced synapse loss by an excitotoxic mechanism. These results indicate that select ARV drugs might contribute to neuropsychiatric effects in combination with drugs that bind serum proteins or in disease states in which synaptic function is altered. The high content imaging assay used here provides an efficient means to evaluate new drugs and drug combinations for potential CNS toxicity.

Conformational diversity and protein–protein interfaces in drug repurposing in Ras signaling pathway

We focus on drug repurposing in the Ras signaling pathway, considering structural similarities of protein–protein interfaces. The interfaces formed by physically interacting proteins are found from PDB if available and via PRISM (PRotein Interaction by Structural Matching) otherwise. The structural coverage of these interactions has been increased from 21 to 92% using PRISM. Multiple conformations of each protein are used to include protein dynamics and diversity. Next, we find FDA-approved drugs bound to structurally similar protein–protein interfaces. The results suggest that HIV protease inhibitors tipranavir, indinavir, and saquinavir may bind to EGFR and ERBB3/HER3 interface. Tipranavir and indinavir may also bind to EGFR and ERBB2/HER2 interface. Additionally, a drug used in Alzheimer's disease can bind to RAF1 and BRAF interface. Hence, we propose a methodology to find drugs to be potentially used for cancer using a dataset of structurally similar protein–protein interface clusters rather than pockets in a systematic way.

HIV protease inhibitor saquinavir inhibits toll-like receptor 4 activation by targeting receptor dimerization

ObjectiveToll-like receptor 4 (TLR4) is crucial in induction of innate immune response through recognition of invading pathogens or endogenous alarming molecules. Ligand-triggered dimerization of TLR4 is essential for the activation of NF-κB and IRF3 through MyD88- or TRIF-dependent pathways. Saquinavir (SQV), an FDA-approved HIV protease inhibitor, has been shown to attenuate the activation of NF-κB induced by HMGB1 by blocking TLR4-MyD88 association in proteasome independent pathway. This study aims to define whether SQV is an HMGB1-specific and MyD88-dependent TLR4 signaling inhibitor and which precise signaling element of TLR4 is targeted by SQV.Materials and methodsPMA differentiated human THP-1 macrophages or reconstituted HEK293 cells were pretreated with SQV before stimulated by different TLR agonists. TNF-α level was evaluated through ELISA assay. NF-κB activation was analyzed using NF-κB SEAP reporting system. The levels of MyD88/TRIF pathways-related factors were examined by immunoblot. TLR4 endocytosis was assessed by immunocytochemistry. TLR4 dimerization was determined using immunoprecipitation between different tagged TLR4 and an in silico molecular docking experiment was performed to explore the possible binding site of SQV on its target.ResultsOur data showed that SQV suppresses both MyD88- and TRIF-dependent pathways in response to lipopolysaccharide (LPS), a critical sepsis inducer and TLR4 agonist, leading to downregulation of NF-κB and IRF3. SQV did not suppress MyD88-dependent pathway triggered by TLR1/2 agonist Pam3csk4. In the only TRIF-dependent pathway, SQV did not alleviate IRF3 phosphorylation induced by TLR3 agonist Poly(I:C). Furthermore, dimerization of TLR4 following LPS or HMGB1 stimulation was decreased by SQV.ConclusionWe concluded that TLR4 receptor complex is one of the mammalian targets of SQV, and TLR4-mediated immune responses and consequent risk for uncontrolled inflammation could be modulated by FDA-approved drug SQV.

Topical Protease Inhibitor Decreases Anal Carcinogenesis in a Transgenic Mouse Model of HPV Anal Disease.

Anal cancer is a major health problem. This study seeks to determine if the topical protease inhibitor Saquinavir (SQV), is effective at the prevention of anal cancer in transgenic mice with established anal dysplasia. K14E6/E7 mice were entered into the study when the majority spontaneously developed high-grade anal dysplasia. To ensure carcinoma development, a subset of the mice was treated with a topical carcinogen: 7,12-Dimethylbenz[a]anthracene (DMBA). Treatment groups included: no treatment, DMBA only, and topical SQV with/without DMBA. After 20 weeks of treatment, anal tissue was harvested and evaluated histologically. SQV was quantified in the blood and anal tissue, and tissue samples underwent analysis for E6, E7, p53, and pRb. There was minimal systemic absorption of SQV in the sera despite high tissue concentrations. There were no differences in tumor-free survival between SQV-treated and respective control groups but there was a lower grade of histological disease in the mice treated with SQV compared to those untreated. Changes in E6 and E7 levels with SQV treatment suggest that SQV may function independently of E6 and E7. Topical SQV decreased histological disease progression in HPV transgenic mice with or without DMBA treatment without local side effects or significant systemic absorption.

Short-Term Administration of HIV Protease Inhibitor Saquinavir Improves Skull Bone Healing with Enhanced Osteoclastogenesis.

Using immunomodulatory methods to address the challenging issue of craniofacial bone repair may be a potentially effective approach. The protease inhibitor saquinavir has been shown to inhibit the inflammatory response by targeting the toll-like receptor 4/myeloid differentiation primary response complex. Independently, inhibition of toll-like receptor 4 or myeloid differentiation primary response led to enhanced skull bone repair. Therefore, the authors aimed to investigate the effects of saquinavir on skull bone healing. The effects of saquinavir on skull bone healing were assessed by means of gene expression, histology, immunohistochemistry, and tomography in a mouse calvarial defect model. Subsequently, the role of saquinavir in cell viability, migration, and osteogenic and osteoclastogenic differentiation was also evaluated in vitro. One-week saquinavir administration improved skull bone healing based on micro-computed tomographic and histomorphometric analyses. Compared to the vehicle control, 1-week saquinavir treatment (1) enhanced osteoclast infiltration (tartrate-resistant acid phosphatase staining) at day 7, but not at days 14 and 28; (2) induced more CD206 + M2 macrophage infiltration, but not F4/80 + M0 macrophages at days 7, 14, and 28; and (3) elevated osteoclastogenic gene RANKL (quantitative polymerase chain reaction) expression and other osteogenic and cytokine expression. Furthermore, in vitro data showed that saquinavir administration did not influence MC3T3-E1 cell migration or mineralization, whereas higher concentrations of saquinavir inhibited cell viability. Saquinavir treatment also enhanced the osteoclastic differentiation of bone marrow-derived precursors, and partially reversed high-mobility group box 1-driven osteoclastogenesis inhibition and elevated proinflammatory cytokine expression. The improved skull bone repair following short-term saquinavir treatment may involve enhanced osteoclastogenesis and modulated inflammatory response following skull injury. The authors' work demonstrates improved skull bone healing by short-term application of saquinavir, a drug traditionally used in the treatment of acquired immunodeficiency syndrome. As such, saquinavir may be repurposed for skeletal repair.

Oral and Inhaled Fosamprenavir Reverses Pepsin-Induced Damage in a Laryngopharyngeal Reflux Mouse Model.

More than 20% of the US population suffers from laryngopharyngeal reflux. Although dietary/lifestyle modifications and alginates provide benefit to some, there is no gold standard medical therapy. Increasing evidence suggests that pepsin is partly, if not wholly, responsible for damage and inflammation caused by laryngopharyngeal reflux. A treatment specifically targeting pepsin would be amenable to local, inhaled delivery, and could prove effective for endoscopic signs and symptoms associated with nonacid reflux. The aim herein was to identify small molecule inhibitors of pepsin and test their efficacy to prevent pepsin-mediated laryngeal damage in vivo. Drug and pepsin binding and inhibition were screened by high-throughput assays and crystallography. A mouse model of laryngopharyngeal reflux (mechanical laryngeal injury once weekly for 2 weeks and pH 7 solvent/pepsin instillation 3 days/week for 4 weeks) was provided inhibitor by gavage or aerosol (fosamprenavir or darunavir; 5 days/week for 4 weeks; n=3). Larynges were collected for histopathologic analysis. HIV protease inhibitors amprenavir, ritonavir, saquinavir, and darunavir bound and inhibited pepsin with IC50 in the low micromolar range. Gavage and aerosol fosamprenavir prevented pepsin-mediated laryngeal damage (i.e., reactive epithelia, increased intraepithelial inflammatory cells, and cell apoptosis). Darunavir gavage elicited mild reactivity and no discernable protection; aerosol protected against apoptosis. Fosamprenavir and darunavir, FDA-approved therapies for HIV/AIDS, bind and inhibit pepsin, abrogating pepsin-mediated laryngeal damage in a laryngopharyngeal reflux mouse model. These drugs target a foreign virus, making them ideal to repurpose. Reformulation for local inhaled delivery could further improve outcomes and limit side effects. NA. Laryngoscope, 133:S1-S11, 2023.

Effects of the G48M mutant on the dynamics properties and binding mechanism of PR with SQV and ATV

ABSTRACT The resistance of HIV-1 protease (PR) mutations seriously affects the efficiency of current drugs in the clinical treatment of AIDS. Therefore, it is important to understand the resistance mechanism of mutated residues for the development of PR inhibitors. In this work, the mechanism of G48M mutant PR to inhibitors Saquinavir and Atazanavir was studied by using molecular dynamics simulation combined with free energy prediction. The analysis results showed that, compared with the WT PR, the distance of the flap tip from the protease catalytic binding site and the dihedral angles in the flap regions in the mutant type complexes was changed. These changes resulted in a significant reduction in the occupancy of most of the hydrogen bonds in the mutant complex and the interaction energy of key residues with the inhibitor, which is the main reason for the resistance of the mutation to these inhibitors. This study can provide important guidance for the design of effective inhibitors against HIV-1 PR.

The HIV protease inhibitor Saquinavir attenuates sepsis-induced acute lung injury and promotes M2 macrophage polarization via targeting matrix metalloproteinase-9

Imbalance of macrophage polarization plays an indispensable role in acute lung injury (ALI), which is considered as a promising target. Matrix metalloproteinase-9 (MMP-9) is expressed in the macrophage, and has a pivotal role in secreting inflammatory cytokines. We reported that saquinavir (SQV), a first-generation human immunodeficiency virus-protease inhibitor, restricted exaggerated inflammatory response. However, whether MMP-9 could regulate macrophage polarization and inhibit by SQV is still unknown. We focused on the important role of macrophage polarization in CLP (cecal ligation puncture)-mediated ALI and determined the ability of SQV to maintain M2 over M1 phenotype partially through the inhibition of MMP-9. We also performed a limited clinical study to determine if MMP-9 is a biomarker of sepsis. Lipopolysaccharide (LPS) increased MMP-9 expression and recombinant MMP-9 (rMMP-9) exacerbated LPS-mediated M1 switching. Small interfering RNA to MMP-9 inhibited LPS-mediated M1 phenotype and SQV inhibition of this switching was reversed with rMMP-9, suggesting an important role for MMP-9 in mediating LPS-induced M1 phenotype. MMP-9 messenger RNA levels in peripheral blood mononuclear cells of these 14 patients correlated with their clinical assessment. There was a significant dose-dependent decrease in mortality and ALI after CLP with SQV. SQV significantly inhibited LPS-mediated M1 phenotype and increased M2 phenotype in cultured RAW 264.7 and primary murine bone marrow-derived macrophages as well as lung macrophages from CLP-treated mice. This study supports an important role for MMP-9 in macrophage phenotypic switching and suggests that SQV-mediated inhibition of MMP-9 may be involved in suppressing ALI during systemic sepsis.

Determination of four protease inhibitors in chicken by ultra performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of four protease inhibitors (saquinavir, ritonavir, nelfinavir and indinavir) in chicken using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by shaking with 30% (v/v) acetonitrile aqueous solution (containing 1% (v/v) trichloroacetic acid), and purified by using mixed-mode cationic-exchanger (MCX) cartridges. The samples were separated on a Luna® C8 column (150 mm×2 mm, 3 μm) using 0.2% (v/v) formic acid aqueous solution (containing 5 mmol/L ammonium acetate) and acetonitrile as the mobile phases with gradient elution. The determination was carried out by using an electrospray ion source in the positive and multiple-reaction monitoring (MRM) modes. The calibration curves showed good linearities in the range of 0.1-20.0 μg/L, and the correlation coefficients (r2) were greater than 0.99. The limits of quantification (LOQs, S/N=10) of the four protease inhibitors varied from 0.20 μg/kg to 0.90 μg/kg. At the spiked levels of 1.0, 2.0, and 10.0 μg/kg, the average recoveries of the four protease inhibitors were ranging from 69.0% to 106.0%. The intra-day and inter-day relative standard deviations (RSDs) were 2.2%-13.8% (n=6) and 3.6%-14.6% (n=3), respectively. The method is simple, efficient, sensitive and accurate, and it can be used to detect residues of saquinavir, ritonavir, nelfinavir and indinavir in chicken.

Protease Inhibitors, Saquinavir and Darunavir, Inhibit Oligodendrocyte Maturation: Implications for Lysosomal Stress.

Despite the introduction of antiretroviral (ARV) therapy (ART), approximately 30-50% of people living with human immunodeficiency virus-1 (HIV-1) will develop a spectrum of measurable neurocognitive dysfunction, collectively called HIV-associated neurocognitive disorder (HAND). While the clinical manifestations of HAND have changed with the advent of ART, certain pathological features have endured, including white matter alterations and dysfunction. The persistence of white matter alterations in the post-ART era suggests that ARV drugs themselves may contribute to HAND pathology. Our group has previously demonstrated that two ARV compounds from the protease inhibitor (PI) class, ritonavir and lopinavir, inhibit oligodendrocyte maturation and myelin protein production. We hypothesized that other members of the PI class, saquinavir and darunavir, could also negatively impact oligodendrocyte differentiation. Here we demonstrate that treating primary rat oligodendrocyte precursor cells with therapeutically relevant concentrations of either ARV drug results in a concentration-dependent inhibition of oligodendrocyte maturation in vitro. Furthermore, we show that acidifying endolysosomal pH via a mucolipin transient receptor potential channel 1 (TRPML1) agonist provides protection against saquinavir- and darunavir-induced inhibition of oligodendrocyte maturation. Moreover, our findings suggest, for the first time, an imperative role of proper endolysosomal pH in regulating OL differentation, and that therapeutic targeting of endolysosomes may provide protection against ARV-induced oligodendrocyte dysregulation. Graphical Abstract Treatment of primary rat oligodendrocyte precursor cells with therapeutically relevant concentrations of either antiretroviral compound of the protease inhibitor class, darunavir or saquinavir, results in a concentration-dependent inhibition of oligodendrocyte maturation in vitro. Additionally, in darunavir or saquinavir-treated cultures we observed a concentration-dependent decrease in the number of acidic lysosomes, via immunostaining with LysoTracker Red, compared with vehicle-treated cultures. Finally, we showed that acidifying endolysosomal pH via a mucolipin transient receptor potential channel 1 (TRPML1) agonist provides protection against saquinavir- or darunavir-induced inhibition of oligodendrocyte maturation. Our findings suggest, for the first time, a critical role of proper endolysosomal pH in regulating OL differentation, and that therapeutic targeting of endolysosomes may provide protection against antiretroviral-induced oligodendrocyte dysregulation.

HMGB1/TLR4 promotes hypoxic pulmonary hypertension via suppressing BMPR2 signaling

High mobility group box 1 (HMGB1), a critical nonclassical inflammatory cytokine, has been found up-regulated in patients with idiopathic pulmonary arterial hypertension (IPAH), but its role in vascular remodeling of pulmonary hypertension (PH) is still unknown. In present study, we demonstrated that the plasma level of inflammatory cytokine including HMGB1, interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) were elevated in hypoxia-induced pulmonary hypertension rats model. Moreover, expressions of HMGB1 and Toll like receptor-4 (TLR4) in pulmonary arteries were obviously up-regulated accompanied with down-regulation of bone morphogenetic protein receptor 2 (BMPR2) signaling, characterized by decline of phosphorylated Smad1/5/8 (p-Smsd1/5/8) and inhibitor of differention 1 (Id1) expression. In cultured primary pulmonary arterial smooth muscle cells (PASMCs), we found that HMGB1 incubation significantly promoted proliferation and migration of PASMCs, down-regulated p-Smsd1/5/8 and Id1 expression, which can be abrogated by HMGB1 inhibitors saquinavir, glycyrrhizn and TLR4 inhibitors TAK-242. Furthermore, saquinavir, glycyrrhizn and TAK-242 treatment significantly attenuated the development of PH in rats by recovering homodynamic parameters, pulmonary vascular remodeling and BMPR2 signaling pathway. In summary, our results suggest that HMGB1/TLR4 signaling promotes hypoxia-induced pulmonary hypertension via suppressing BMPR2 signaling.

HPLC-MS/MS quantification of the HIV-1 protease inhibitor saquinavir in mice plasma and brain

HPLC-MS/MS quantification of the HIV-1 protease inhibitor saquinavir in mice plasma and brain

Cathepsin L Promotes Vascular Intimal Hyperplasia after Arterial Injury

The inflammatory pathways that drive the development of intimai hyperplasia (IH) following arterial injury are not fully understood. We hypothesized that the lysosomal cysteine protease cathepsin L activates processes leading to IH after arterial injury. Using a mouse model of wire-induced carotid artery injury, we showed that cathepsin L activity peaks at d 7 and remains elevated for 28 d. Genetic deletion of cathepsin L prevented IH and monocyte recruitment in the carotid wall. The injury-induced increases in cathepsin L mRNA and activity were mitigated in mice with myeloid-specific deletion of toll-like receptor 4 (TLR4) or myeloid differentiation primary response gene 88 (MyD88). We further discovered that the HIV protease inhibitor saquinavir (SQV), which is known to block recombinant mouse cathepsin L activity in vitro, prevented IH after arterial injury. SQV also suppressed LPS (TLR4 agonist)-induced monocyte adhesion to endothelial monolayers. These findings establish cathepsin L as a critical regulator of the inflammation that leads to IH and that the TLR4-MyD88 pathway in myeloid lineages regulates cathepsin L expression in the vessel wall following wire injury. The Food and Drug Administration-approved drug SQV blocks IH though mechanisms that may include the suppression of cathepsin L.

Understanding the structural basis of substrate recognition by Plasmodium falciparum plasmepsin V to aid in the design of potent inhibitors.

Plasmodium falciparum plasmepsin V (PfPMV) is an essential aspartic protease required for parasite survival, thus, considered as a potential drug target. This study reports the first detailed structural analysis and molecular dynamics simulation of PfPMV as an apoenzyme and its complexes with the substrate PEXEL as well as with the inhibitor saquinavir. The presence of pro-peptide in PfPMV may not structurally hinder the formation of a functionally competent catalytic active site. The structure of PfPMV-PEXEL complex shows that the unique positions of Glu179 and Gln222 are responsible for providing the specificity of PEXEL substrate with arginine at P3 position. The structural analysis also reveals that the S4 binding pocket in PfPMV is occupied by Ile94, Ala98, Phe370 and Tyr472, and therefore, does not allow binding of pepstatin, a potent inhibitor of most pepsin-like aspartic proteases. Among the screened inhibitors, the HIV-1 protease inhibitors and KNI compounds have higher binding affinities for PfPMV with saquinavir having the highest value. The presence of a flexible group at P2 and a bulky hydrophobic group at P3 position of the inhibitor is preferred in the PfPMV substrate binding pocket. Results from the present study will aid in the design of potent inhibitors of PMV.

The HIV-protease inhibitor saquinavir reduces proliferation, invasion and clonogenicity in cervical cancer cell lines.

Innovative therapies in cervical cancer (CC) remain a priority. Recent data indicate that human immunodeficiency virus (HIV)-protease inhibitors used in highly active antiretroviral therapy can exert direct antitumor activities also in HIV-free preclinical and clinical models. The aim of the present study was to evaluate the antineoplastic effects of various HIV-protease inhibitors (indinavir, ritonavir and saquinavir) on primary and established CC cell lines. Two CC cell lines established in our laboratory and four commercially available CC cell lines were treated with indinavir, ritonavir and saquinavir at different concentrations and for different times. Proliferation, clonogenicity and radiosensitivity were evaluated by crystal violet staining. Proteasomal activities were assessed using a cell-based assay and immunoblotting. Cell cycle was analyzed by propidium iodide staining and flow cytometric analysis. Invasion was tested with Matrigel chambers. A t-test for paired samples was used for statistical analysis. In all cell lines, saquinavir was more effective than ritonavir in reducing cell proliferation and inhibiting proteasomal activities (P≤0.05). Conversely, indinavir exerted a negligible effect. The saquinavir concentrations required to modulate the proteasome activities were higher than those observed to be effective in inhibiting cell proliferation. In HeLa cells, saquinavir was strongly effective in inhibiting cell invasion and clonogenicity (P≤0.05) at concentrations much lower than those required to perturb proteasomal activities. Saquinavir did not contribute to increase the sensitivity of HeLa cells to X-rays. In conclusion, the present results demonstrate that saquinavir is able to significantly reduce cell proliferation, cell invasion and clonogenicity in a proteasome-independent manner in in vitro models of CC, and suggest that saquinavir could be a promising CC therapeutic agent.

Saquinavir Loaded Acetalated Dextran Microconfetti - a Long Acting Protease Inhibitor Injectable.

Since the adoption of highly active antiretroviral therapy, HIV disease progression has slowed across the world; however, patients are often required to take multiple medications daily of poorly bioavailable drugs via the oral route, leading to gastrointestinal irritation. Recently, long acting antiretroviral injectables that deliver drug for months at a time have moved into late phase clinical trials. Unfortunately, these solid phase crystal formulations have inherent drawbacks in potential dose dumping and a greater likelihood for burst release of drug compared to polymeric formulations. Using electrospinning, acetalated dextran scaffolds containing the protease inhibitor saquinavir were created. Grinding techniques were then used to process these scaffolds into injectables which are termed saquinavir microconfetti. Microconfetti was analyzed for in vitro and in vivo release kinetics. Highly saquinavir loaded acetalated dextran electrospun fibers were able to be formed and processed into saquinavir microconfetti while other polymers such as poly lactic-co-glycolic acid and polycaprolactone were unable to do so. Saquinavir microconfetti release kinetics were able to be tuned via drug loading and polymer degradation rates. In vivo, a single subcutaneous injection of saquinavir microconfetti released drug for greater than a week with large tissue retention. Microconfetti is a uniquely tunable long acting injectable that would reduce the formation of adherence related HIV resistance. Our findings suggest that the injectable microconfetti delivery system could be used for long acting controlled release of saquinavir and other hydrophobic small molecule drugs.

Inhibition of bile salt transport by drugs associated with liver injury in primary hepatocytes from human, monkey, dog, rat, and mouse

Interference of bile salt transport is one of the underlying mechanisms for drug-induced liver injury (DILI). We developed a novel bile salt transport activity assay involving in situ biosynthesis of bile salts from their precursors in primary human, monkey, dog, rat, and mouse hepatocytes in suspension as well as LC-MS/MS determination of extracellular bile salts transported out of hepatocytes. Glycine- and taurine-conjugated bile acids were rapidly formed in hepatocytes and effectively transported into the extracellular medium. The bile salt formation and transport activities were time‒ and bile-acid-concentration‒dependent in primary human hepatocytes. The transport activity was inhibited by the bile salt export pump (BSEP) inhibitors ketoconazole, saquinavir, cyclosporine, and troglitazone. The assay was used to test 86 drugs for their potential to inhibit bile salt transport activity in human hepatocytes, which included 35 drugs associated with severe DILI (sDILI) and 51 with non-severe DILI (non-sDILI). Approximately 60% of the sDILI drugs showed potent inhibition (with IC50 values <50 μM), but only about 20% of the non-sDILI drugs showed this strength of inhibition in primary human hepatocytes and these drugs are associated only with cholestatic and mixed hepatocellular cholestatic (mixed) injuries. The sDILI drugs, which did not show substantial inhibition of bile salt transport activity, are likely to be associated with immune-mediated liver injury. Twenty-four drugs were also tested in monkey, dog, rat and mouse hepatocytes. Species differences in potency were observed with mouse being less sensitive than other species to inhibition of bile salt transport. In summary, a novel assay has been developed using hepatocytes in suspension from human and animal species that can be used to assess the potential for drugs and/or drug-derived metabolites to inhibit bile salt transport and/or formation activity. Drugs causing sDILI, except those by immune-mediated mechanism, are highly associated with potent inhibition of bile salt transport.

HIV protease inhibitors in pulmonary hypertension: rationale and design of a pilot trial in idiopathic pulmonary arterial hypertension.

We propose an exploratory clinical study, the first of its kind to our knowledge, to determine the safety and potential clinical benefit of the combination of the HIV protease inhibitors (HIV-PIs) saquinavir and ritonavir (SQV+RIT) in patients with idiopathic pulmonary arterial hypertension (IPAH). This study is based on evidence that (1) HIV-PIs can improve pulmonary hemodynamics in experimental models; (2) both Toll-like receptor 4 and high-mobility group box 1 (HMGB1) participate in the pathogenesis of experimental pulmonary hypertension; and (3) a high-throughput screen for inhibitors of HMGB1-induced macrophage activation yielded HIV-PIs as potent inhibitors of HMGB1-induced cytokine production. In this proposed open-label, pre-post study, micro, low, and standard doses of SQV+RIT will be given to IPAH patients for 14 days. Patients will receive follow-up for the next 14 days. The primary outcome to be evaluated is change in HMGB1 level from baseline at 14 days. The secondary outcome is changes in tumor necrosis factor α, interleukin 1β, interleukin 6, C-reactive protein, pulmonary arterial pressure based on echocardiography parameters and New York Heart Association/World Health Organization functional class, and Brog dyspnea scale index from baseline at 14 days. Other secondary measurements will include N-terminal pro-brain natriuretic peptide, atrial natriuretic peptide, and 6-minute walk distance. We propose that SQV+RIT treatment will improve inflammatory disorders and pulmonary hemodynamics in IPAH patients. If the data support a potentially useful therapeutic effect and suggest that SQV+RIT is safe in IPAH patients, the study will warrant further investigation. (ClinicalTrials.gov identifier: NCT02023450.).

Enhancement of cellular uptake, transport and oral absorption of protease inhibitor saquinavir by nanocrystal formulation.

Saquinavir (SQV) is the first protease inhibitor for the treatment of HIV infection, but with poor solubility. The aim of this study was to prepare a colloidal nanocrystal suspension for improving the oral absorption of SQV. SQV nanocrystals were prepared using anti-solvent precipitation-high pressure homogenization method. The nanocrystals were characterized by a Zetasizer and transmission electron microscopy (TEM). Their dissolution, cellular uptake and transport across the human colorectal adenocarcinoma cell line (Caco-2) monolayer were investigated. Bioimaging of ex vivo intestinal sections of rats was conducted with confocal laser scanning microscopy. Pharmacokinetic analysis was performed in rats administered nanocrystal SQV suspension (50 mg/kg, ig), and the plasma SQV concentrations were measured with HPLC. The SQV nanocrystals were approximately 200 nm in diameter, with a uniform size distribution. The nanocrystals had a rod-like shape under TEM. The dissolution, cellular uptake, and transport across a Caco-2 monolayer of the nanocrystal formulation were significantly improved compared to those of the coarse crystals. The ex vivo intestinal section study revealed that the fluorescently labeled nanocrystals were located in the lamina propria and the epithelium of the duodenum and jejunum. Pharmacokinetic study showed that the maximal plasma concentration (Cmax) was 2.16-fold of that for coarse crystalline SQV suspension, whereas the area under the curve (AUC) of nanocrystal SQV suspension was 1.95-fold of that for coarse crystalline SQV suspension. The nanocrystal drug delivery system significantly improves the oral absorption of saquinavir.