Atovaquone suspension for treatment of Pneumocystis carinii pneumonia in HIV-infected patients

Potential anti-Pythium insidiosum therapeutics identified through screening of agricultural fungicides

Pythiosis is a life-threatening infectious disease caused by the oomycete Pythium insidiosum. Clinical manifestations of pythiosis include an eye, blood vessel, skin, or gastrointestinal tract infection. Pythiosis has been increasingly reported worldwide, with an overall mortality rate of 28%. Radical surgery is required to save patients' lives due to the limited efficacy of antimicrobial drugs. Effective medical treatments are urgently needed for pythiosis. This study aims to find anti-P. insidiosum agents by screening 17 agricultural fungicides that inhibit plant-pathogenic oomycetes and validating their efficacy and safety. Cyazofamid outperformed other fungicides as it can potently inhibit genetically diverse P. insidiosum isolates while exhibiting minimal cellular toxicities. The calculated therapeutic scores determined that the concentration of cyazofamid causing significant cellular toxicities was eight times greater than the concentration of the drug effectively inhibiting P. insidiosum. Furthermore, other studies showed that cyazofamid exhibits low-to-moderate toxicities in animals. The mechanism of cyazofamid action is likely the inhibition of cytochrome b, an essential component in ATP synthesis. Molecular docking and dynamic analyses depicted a stable binding of cyazofamid to the Qi site of the P. insidiosum's cytochrome b orthologous protein. In conclusion, our search for an effective anti-P. insidiosum drug indicated that cyazofamid is a promising candidate for treating pythiosis. With its high efficacy and low toxicity, cyazofamid is a potential chemical for treating pythiosis, reducing the need for radical surgeries, and improving recovery rates. Our findings could pave the way for the development of new and effective treatments for pythiosis.IMPORTANCEPythiosis is a severe infection caused by Pythium insidiosum. The disease is prevalent in tropical/subtropical regions. This infectious condition is challenging to treat with antifungal drugs and often requires surgical removal of the infected tissue. Pythiosis can be fatal if not treated promptly. There is a need for a new treatment that effectively inhibits P. insidiosum. This study screened 17 agricultural fungicides that target plant-pathogenic oomycetes and found that cyazofamid was the most potent in inhibiting P. insidiosum. Cyazofamid showed low toxicity to mammalian cells and high affinity to the P. insidiosum's cytochrome b, which is involved in energy production. Cyazofamid could be a promising candidate for the treatment of pythiosis, as it could reduce the need for surgery and improve the survival rate of patients. This study provides valuable insights into the biology and drug susceptibility of P. insidiosum and opens new avenues for developing effective therapies for pythiosis.

Atovaquone: An Antiprotozoal Drug Suppresses Primary and Resistant Breast Tumor Growth by Inhibiting HER2/β-Catenin Signaling

Breast cancer is the second leading cause of cancer-related mortality in women. In the current study, we evaluated the anticancer effects of an antiprotozoal drug, atovaquone, against several breast cancer cell lines. Our results showed that atovaquone treatment induced apoptosis and inhibited the growth of all the breast cancer cell lines tested, including several patient-derived cells. In addition, atovaquone treatment significantly reduced the expression of HER2, β-catenin, and its downstream molecules such as pGSK-3β, TCF-4, cyclin D1, and c-Myc in vitro Efficacy of atovaquone was further evaluated in an in vivo tumor model by orthotropic implantation of two highly aggressive 4T1 and CI66 breast cancer cells in the mammary fat pad of female mice. Our results demonstrated that oral administration of atovaquone suppressed the growth of CI66 and 4T1 tumors by 70% and 60%, respectively. Paclitaxel is the first-line chemotherapeutic agent for metastatic breast cancer. We demonstrate that atovaquone administration suppressed the growth of 4T1 paclitaxel-resistant tumors by 40%. Tumors from atovaquone-treated mice exhibited reduced HER2, β-catenin, and c-Myc levels alongside an increase in apoptosis in all the three tumor models when analyzed by Western blotting, IHC, and TUNEL assay. Taken together, our results indicate that atovaquone effectively reduces the growth of primary and paclitaxel-resistant breast tumors. Atovaquone is already in the clinics with high safety and tolerability profile. Therefore, the findings from our studies will potentially prompt further clinical investigation into repurposing atovaquone for the treatment of patients with advanced breast cancer.

Treatment of Pneumocystis jirovecii pneumonia in HIV-infected patients: a review

INTRODUCTION

Pneumocystis pneumonia is a potentially life-threatening pulmonary infection that occurs in immunocompromised individuals and HIV-infected patients with a low CD4 cell count. Trimethoprim-sulfamethoxazole has been used as the first-line agent for treatment, but mutations within dihydropteroate synthase gene render potential resistance to sulfamide. Despite advances of combination antiretroviral therapy (cART), Pneumocystis pneumonia continues to occur in HIV-infected patients with late presentation for cART or virological and immunological failure after receiving cART. Areas covered: This review summarizes the diagnosis and first-line and alternative treatment and prophylaxis for Pneumocystis pneumonia in HIV-infected patients. Articles for this review were identified through searching PubMed. Search terms included: 'Pneumocystis pneumonia', 'Pneumocystis jirovecii pneumonia', 'Pneumocystis carinii pneumonia', 'trimethoprim-sulfamethoxazole', 'primaquine', 'trimetrexate', 'dapsone', 'pentamidine', 'atovaquone', 'echinocandins', 'human immunodeficiency virus infection', 'acquired immunodeficiency syndrome', 'resistance to sulfamide' and combinations of these terms. We limited the search to English language papers that were published between 1981 and March 2017. We screened all identified articles and cross-referenced studies from retrieved articles. Expert commentary: Trimethoprim-sulfamethoxazole will continue to be the first-line agent for Pneumocystis pneumonia given its cost, availability of both oral and parenteral formulations, and effectiveness or efficacy in both treatment and prophylaxis. Whether resistance due to mutations within dihydropteroate synthase gene compromises treatment effectiveness remains controversial. Continued search for effective alternatives with better safety profiles for Pneumocystis pneumonia is warranted.

A Review of Pneumocystis Pneumonia

Pneumocystis pneumonia remains one of the leading causes of morbidity and mortality in the HIV-infected population. Trimethoprim-sulfamethoxazole remains the drug of choice for both the treatment and prevention of this infection, although a high rate of side effects in HIV-infected patients often necessitates alternative treatment regimens. This article will review pneumocystis pneumonia, with a focus on the various therapeutic options, their side effects, and the immune reconstitution inflammatory syndrome as it relates to pneumocystis pneumonia infection.

Pneumocystis jirovecii pneumonia in patients receiving tumor-necrosis-factor-inhibitor therapy: implications for chemoprophylaxis

Pneumocystis jirovecii pneumonia (PJP) is an important opportunistic infection that has been increasingly reported in patients with rheumatic disease. Reported incidence among patients taking TNF inhibitors (TNFi) has varied, but has usually been low. Still, disease causes significant mortality among those affected and must be considered in patients with rheumatological disease presenting with dyspnea and cough. Diagnosis can be difficult in the non-HIV population, and our understanding of the epidemiology and natural history after exposure is changing. Trimethoprim-sulfamethoxazole is believed to be the most effective agent for treatment and prophylaxis, but is associated with significant adverse effects. Given the low incidence reported in most studies of patients on TNFi, prophylaxis is probably not beneficial for this patient population as a whole.

Pneumocystis jirovecii colonization in Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is associated with a chronic inflammatory response in airways and lung parenchyma that results in significant morbidity and mortality worldwide. Cigarette smoking considered as an important risk factor plays a role in pathogenesis of disease. Pneumocystis jirovecii is an atypical opportunistic fungus that causes pneumonia in immunosuppressed host, although the low levels of its DNA in patients without signs and symptoms of pneumonia, which likely represents colonization. The increased prevalence of P. jirovecii colonization in COPD patients has led to an interest in understanding its role in the disease. P. jirovecii colonization in these patients could represent a problem for public health since colonized patients could act as a major reservoir and source of infection for susceptible subjects. Using sensitive molecular techniques, low levels of P. jirovecii DNA have been detected in the respiratory tract of certain individuals. It is necessary to elucidate the role of P. jirovecii colonization in the natural history of COPD patients in order to improve the clinical management of this disease. In the current review paper, we discuss P. jirovecii colonization in COPD patients.

Therapy and prophylaxis of opportunistic infections in HIV-infected patients: a guideline by the German and Austrian AIDS societies (DAIG/ÖAG) (AWMF 055/066)

INTRODUCTION

There was a growing need for practical guidelines for the most common OIs in Germany and Austria under consideration of the local epidemiological conditions.

MATERIALS AND METHODS

The German and Austrian AIDS societies developed these guidelines between March 2010 and November 2011. A structured Medline research was performed for 12 diseases, namely Immune reconstitution inflammatory syndrome, Pneumocystis jiroveci pneumonia, cerebral toxoplasmosis, cytomegalovirus manifestations, candidiasis, herpes simplex virus infections, varizella zoster virus infections, progressive multifocal leucencephalopathy, cryptosporidiosis, cryptococcosis, nontuberculosis mycobacteria infections and tuberculosis. Due to the lack of evidence by randomized controlled trials, part of the guidelines reflects expert opinions. The German version was accepted by the German and Austrian AIDS Societies and was previously published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF; German Association of the Scientific Medical Societies).

CONCLUSION

The review presented here is a translation of a short version of the German-Austrian Guidelines of opportunistic infections in HIV patients. These guidelines are well-accepted in a clinical setting in both Germany and Austria. They lead to a similar treatment of a heterogeneous group of patients in these countries.

[Pulmonary fungal infection in patients with AIDS]

Fungal infections are the most common opportunistic infections (OI) occurring during the course of HIV infection, though their incidence has decreased dramatically with the introduction of highly active antiretroviral therapy (cART). Most cases occur in untreated patients, noncompliant patients or patients whose multiple antiretroviral regimens have failed and they are a good marker of the severity of cellular immunodepression. Pneumocystis jiroveci pneumonia is the second most frequent OI in France and cryptococcosis remains a major problem in the Southern Hemisphere. With the increase in travel, imported endemic fungal infection can occur and may mimic other infections, notably tuberculosis. Fungal infections often have a pulmonary presentation but an exhaustive search for dissemination should be made in patients infected with HIV, at least those at an advanced stage of immune deficiency. Introduction of cART in combination with anti-fungal treatment depends on the risk of AIDS progression and on the risk of cumulative toxicity and the immune reconstitution inflammatory syndrome (IRIS) if introduced too early. Fungal infections in HIV infected patients remain a problem in the cART era. IRIS can complicate the management and requires an optimised treatment regime.

Antimalarial pharmacology and therapeutics of atovaquone

Atovaquone is used as a fixed-dose combination with proguanil (Malarone) for treating children and adults with uncomplicated malaria or as chemoprophylaxis for preventing malaria in travellers. Indeed, in the USA, between 2009 and 2011, Malarone prescriptions accounted for 70% of all antimalarial pre-travel prescriptions. In 2013 the patent for Malarone will expire, potentially resulting in a wave of low-cost generics. Furthermore, the malaria scientific community has a number of antimalarial quinolones with a related pharmacophore to atovaquone at various stages of pre-clinical development. With this in mind, it is timely here to review the current knowledge of atovaquone, with the purpose of aiding the decision making of clinicians and drug developers involved in the future use of atovaquone generics or atovaquone derivatives.

Identification and validation of tetracyclic benzothiazepines as Plasmodium falciparum cytochrome bc1 inhibitors

Here we report the discovery of tetracyclic benzothiazepines (BTZs) as highly potent and selective antimalarials along with the identification of the Plasmodium falciparum cytochrome bc(1) complex as the primary functional target of this novel compound class. Investigation of the structure activity relationship within this previously unexplored chemical scaffold has yielded inhibitors with low nanomolar activity. A combined approach employing genetically modified parasites, biochemical profiling, and resistance selection validated inhibition of cytochrome bc(1) activity, an essential component of the parasite respiratory chain and target of the widely used antimalarial drug atovaquone, as the mode of action of this novel compound class. Resistance to atovaquone is eroding the efficacy of this widely used antimalarial drug. Intriguingly, BTZ-based inhibitors retain activity against atovaquone resistant parasites, suggesting this chemical class may provide an alternative to atovaquone in combination therapy.

Systematic review on the etiology and antibiotic treatment of pneumonia in human immunodeficiency virus-infected children

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected children.

OBJECTIVES AND METHODS

A systematic review of studies that were published between January 1990 and February 2009 on the etiology and antimicrobial or adjunctive systemic management of CAP in HIV-infected children.

RESULTS

Pneumocystis jirovecii had the strongest association with HIV infection, with a summary odds ratio of 10.1 (95% confidence interval [CI], 17.7-62.1) and 9.1 (95% CI, 2.5-33.1) in antemortem and postmortem studies, respectively. Cytomegalovirus was strongly associated with HIV positivity among fatal cases of pneumonia (summary odds ratio = 14.4 [95% CI, 6.7-30.8]). There was a trend toward a greater prevalence of Staphylococcus aureus (odds ratio, 2.5; 95% CI, 0.95-6.4) in HIV-infected children. Major limitations identified included substantial methodological heterogeneity across studies, limited sensitivity of assays for diagnosing bacterial pneumonia, and studies primarily being undertaken in the absence of antiretroviral treatment or cotrimoxazole prophylaxis. No a priori-planned randomized controlled trials on antimicrobial management of CAP in HIV-infected children were identified.

CONCLUSIONS

A World Health Organization panel used this review as well as analysis of risks and benefits to revise recommendations for antimicrobial treatment of CAP. Ampicillin plus gentamicin or ceftriaxone is now recommended as first-line empiric regimens for treating severe and very severe CAP in HIV-infected children. In addition, treatment with cloxacillin or vancomycin is recommended in settings with a high incidence of methicillin-resistant S. aureus, and particularly if clinical or microbiological evidence of S. aureus pneumonia exist. Further studies in HIV-infected children on CAP etiology and antibiotic treatment are required in the era of antiretroviral treatment.

Pneumocystis jirovecii Pneumonia

Pneumocystis jirovecii has gained attention during the last decade in the context of the AIDS epidemic and the increasing use of cytotoxic and immunosuppressive therapies. This article summarizes current knowledge on biology, pathophysiology, epidemiology, diagnosis, prevention, and treatment of pulmonary P jirovecii infection, with a particular focus on the evolving pathophysiology and epidemiology. Pneumocystis pneumonia still remains a severe opportunistic infection, associated with a high mortality rate.

Characterization of nebulized buparvaquone nanosuspensions—effect of nebulization technology

The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis carinii pneumonia (PCP) lung infections. Physically stable nanosuspensions were formulated in order to deliver the drug at the site of infection using nebulization. The aerosolization characteristics of two buparvaquone nanosuspensions were determined with commercial jet and ultrasonic nebulizer devices. Aerosol droplet size distribution was determined with laser diffractometry (LD). Nebulization of the nanosuspensions and dispersion media surfactant solutions produced aerosol droplets diameters in the range from 3 to 5 microm for Respi-jet Kendall, Pari Turbo Boy system and Multisonic nebulizers and particles around 9-10 microm with Omron U1. Fractions of the nanosuspensions from the nebulizer reservoir and of aerosol produced were collected to investigate changes in the size of the drug nanocrystals influenced by the nebulization technology. Comparisons were performed measuring the drug nanocrystals with photon correlation spectroscopy (PCS) and LD of the samples. Drug particle aggregates were detected in the fractions of aerosol collected from jet nebulizers. Nebulizer technology (jet vs. ultrasonic) showed influence on the stability of the drug particle size distribution of buparvaquone nanocrystals during the nebulization time evaluated.

Antimicrobial peptides as microbicidal contraceptives: prophecies for prophylactics--a mini review

The global increase in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and sexually transmitted infections (STIs) has led to the introduction of barrier methods, such as condoms. However, drawbacks associated with condoms, such as men being reluctant to use them and women being unable to negotiate their use, have led to the search for better and acceptable alternatives, namely the microbicides. These are gel formulations that, when used prior to sexual intercourse, protect against the transmission of HIV and other STIs. However, after observing the side-effects of nonoxynol-9, a component of the microbicidal formulations available on the market, the focus has shifted to natural available compounds demonstrating the preferred protective effects. Antimicrobial peptides (AMPs) are one such group of compounds present in a wide range of organisms from bacteria to humans. The existing 750 or so, low-molecular-weight, cationic charged peptides are classified into five major groups based on their three-dimensional structure obtained by nuclear magnetic resonance studies. The hypothesized mode of action seems to be the interaction of the positively charged peptides with the negatively charged phospholipids present on the surface of the cell membrane. Various studies have demonstrated the effect of several AMPs, namely, defensins, protegrins, cathelicidins, cecropins, polyphemusins, magainins and melittins, against various STI-causing pathogens and HIV/herpes simplex virus, both in vitro and in vivo. The contraceptive efficacies of magainin and nisin in vitro and in vivo are worth mentioning. We believe these peptides are suitable candidates in the development of newer mechanism-based microbicides in future.

Pneumocystis jiroveci Pneumonia in Adult Patients with AIDS

Pneumocystis jiroveci (P. carinii) is an opportunistic pathogen that has gained particular prominence since the onset of the AIDS epidemic. Among several important advances in diagnosis and management, appropriately targeting chemoprophylaxis to HIV-infected patients at high clinical risk for P. jiroveci pneumonia and the introduction of effective combination anti-retroviral therapy (including highly active antiretroviral therapy [HAART]) have contributed to the reduced incidence of P. jiroveci pneumonia. Despite the success of these clinical interventions, P. jiroveci pneumonia remains the most common opportunistic pneumonia and the most common life-threatening infectious complication in HIV-infected patients. Trimethoprim/sulfamethoxazole (cotrimoxazole) remains the first-line agent for effective therapy and chemoprophylaxis, and corticosteroids represent an important adjunctive agent in the treatment of moderate-to-severe P. jiroveci pneumonia. However, problems of chemoprophylaxis and treatment failures, high rates of adverse drug reactions and drug intolerance to first-line antimicrobials, high rates of relapse or recurrence with second-line agents, and newer concerns about the development of P. jiroveci drug resistance represent formidable challenges to the management and treatment of AIDS-related P. jiroveci pneumonia. With the expanding global problem of HIV infection, the intolerance or unavailability of HAART to many individuals and limited access to healthcare for HIV-infected patients, P. jiroveci pneumonia will remain a major worldwide problem in the HIV-infected population. New drugs under development as anti-Pneumocystis agents such as echinocandins and pneumocandins, which inhibit beta-glucan synthesis, or sordarins, which inhibit fungal protein synthesis, show promise as effective agents. Continued basic research into the biology and genetics of P. jiroveci and host defense response to P. jiroveci will allow the development of newer antimicrobials and immunomodulatory therapeutic agents to more effectively treat life-threatening pneumonia caused by this organism.

Microbicides: a new approach to preventing HIV and other sexually transmitted infections

Many chemical agents can block human immunodeficiency virus (HIV) infection in the laboratory. Scientists are investigating which of these, used intravaginally by women, will safely prevent the sexual transmission of HIV in humans. Several such products - microbicides - will soon be tested in populations at high risk for HIV, and others are waiting in the wings. Microbicides will provide a low-cost method, controlled by women, for protection against HIV, other sexually transmitted pathogens and unwanted pregnancy, and will therefore have global public-health benefits.

Are cytochrome b gene mutations the only cause of atovaquone resistance in Pneumocystis?

There is evidence that exposure of the opportunistic pathogen Pneumocystis to atovaquone enhances the development of resistance to the drug. Atovaquone is a structural analog of ubiquinone, which binds to the mitochondrial cytochrome bc(1) complex and inhibits electron transport. Like the parasites Plasmodium and Toxoplasma, atovaquone resistance can result from mutations in the cytochrome b gene of Pneumocystis. However, atovaquone resistance cannot be explained by cytochrome b gene mutations in all cases. The discovery that atovaquone also inhibits biosynthesis of ubiquinone in P. carinii may unfold other mechanisms by which drug resistance develops.