Biology subjects

Eldesouky, H. E.

Publications and source records attributed to Eldesouky, H. E..

4 recordsLinked to original sources

bioRxiv2025

The pH gradient contributes to persistence in Mycobacterium tuberculosis

Tuberculosis (TB) remains difficult to cure due in part to poorly defined drug-tolerant persister cells formed by Mycobacterium tuberculosis (Mtb), which survive antibiotic treatment without evidence of genetic resistance. To better define this phenotype, we screened 2,336 FDA-approved drugs for compounds that target persistence. Unexpectedly, we identified a strong inducer of drug tolerance -- the antiparasitic niclosamide (NCA), which is known to disrupt proton motive force. In contrast to earlier reports that it harbors promising anti-TB activity, we found that NCA protected Mtb from bactericidal doses of isoniazid, rifampicin, and other standard TB drugs. Investigating further, we showed that disruption of the pH gradient and consequent intracellular acidification is needed to induce tolerance, while disruption of membrane potential is not, and also that protection is tunable by external pH. Transcriptomic analysis of these chemically-induced persister (CIP) cells implicated specific genes in this phenotype, and targeted knockdowns confirmed roles for three genes in either promoting or mitigating the tolerance state. These findings highlight that chemical disruption of the pH gradient is a facile and rapid means to induce drug tolerance, offering a potentially useful tool to probe persister biology in TB and other infectious diseases.

microbiology↗

bioRxiv2024

Netupitant Exhibits Potent Activity on Mycobacterium tuberculosis Persisters

In Mycobacterium tuberculosis (Mtb), persisters are genotypically drug-sensitive bacteria that nonetheless survive antibiotic treatment. Persisters represent a significant challenge to shortening TB treatment and preventing relapse, underscoring the need for new therapeutic strategies. In this study, we screened 2,336 FDA-approved compounds to identify agents that enhance the sterilizing activity of standard anti-TB drugs and prevent the regrowth of persisters. Netupitant (NTP), an FDA-approved antiemetic, emerged as a promising candidate with bacteriostatic activity on its own. However, in combination with isoniazid (INH) and rifampicin (RIF), NTP eliminated viable Mtb cells within 7 days, achieving a >6-log reduction in colony-forming units (CFUs) compared to the 2.5-log reduction observed with INH-RIF alone. NTP also demonstrated broad-spectrum efficacy, enhancing the activity of multiple TB drugs, including ethambutol, moxifloxacin, amikacin, and bedaquiline. Notably, NTP retained its potency under hypoxic and caseum-mimicking conditions, both of which are known to enrich for non-replicating, drug-tolerant cells. Interestingly, under hypoxic conditions, NTP demonstrated strong tuberculocidal activity, achieving an approximate 4-log CFU reduction, whereas high-dose INH-RIF was ineffective. Transcriptomic analysis revealed that NTP primarily disrupts cellular bioenergetics, with significant downregulation observed in activities associated with the electron transport chain, oxidative phosphorylation, NADH-ubiquinone oxidoreductase, succinate dehydrogenase, and ATP synthesis. While further studies are required to decipher the mechanism of action and resistance profile of NTP, and to assess its in vivo efficacy, these findings underscore its potential as a promising adjunct to existing TB therapies.

microbiology↗

bioRxiv2022

Fingerprint SRS Imaging Unveils Ergosteryl Ester as a Metabolic Signature of Azole-Resistant Candida albicans

Candida albicans (C. albicans), a major fungal pathogen, causes life-threatening infections in immunocompromised individuals. Fluconazole (FLC) is recommended as first-line therapy for treatment of invasive fungal infections. Yet, the widespread use of FLC has resulted in increased antifungal resistance among different strains of Candida, especially C. albicans, which is a leading source of hospital-acquired infections. Here, by hyperspectral stimulated Raman scattering (hSRS) imaging of single fungal cells in the fingerprint window and pixel-wise spectral unmixing, we report aberrant ergosteryl ester accumulation in azole-resistant C. albicans compared to azole-susceptible species. This accumulation was a consequence of de novo lipogenesis. Lipid profiling by mass spectroscopy identified ergosterol oleate to be the major species stored in azole-resistant C. albicans. Blocking ergosterol esterification by oleate and suppressing sterol synthesis by FLC synergistically suppressed the viability of C. albicans in vitro and limited the growth of biofilm on mouse skin in vivo. Our findings highlight a metabolic marker and a new therapeutic strategy for targeting azole-resistant C. albicans by interrupting the esterified ergosterol biosynthetic pathway. Significance StatementInvasive fungal infections and increasing antifungal resistance are emerging threats to public health with high morbidity and mortality. Despite the advances in azole resistance mechanisms, it remains unclear why some fungal species are intrinsically resistant to or easily acquire resistance to multiple antifungal drugs. Here, using fingerprint SRS microscopy, we uncovered a molecular signature, aberrant ergosteryl ester accumulation, linked to the azole resistance of Candida species. An antifungal treatment strategy combining oleate (inhibitor of ersgosteryl esterification) and azole significantly attenuates the azole resistance and the viability of C. albicans in vitro and in vivo. Our work opens a new way to detect and treat azole-resistant fungal infections by targeting ergosterol metabolism.

microbiology↗

bioRxiv2019

Repurposing approach identifies phenylpentanol derivatives as potent azole chemosensitizing agents effective against azole-resistant Candida species

The limited number of systemic antifungals and the emergence of azole-resistant Candida species constitute a growing challenge to human medicine. Combinatorial drug therapy represents an appealing approach to enhance the activity of, or restore the susceptibility to current antifungals. Here, we evaluated the fluconazole chemosensitization activity of the Pharmakon 1600 drug library against azole-resistant Candida albicans. We identified 33 non-antifungal drugs that were able to restore susceptibility to fluconazole in an azole-resistant C. albicans. Structural investigation of identified hits revealed phenylpentanol scaffold as a valuable pharmacophore for re-sensitizing azole-resistant Candida species to the effect of current azole antifungal drugs. All phenylpentanol derivatives displayed potent fluconazole chemosensitizing activities ({Sigma}FICI 0.13-0.28) and were able to reduce fluconazoles MIC by 15-31 fold against the tested strain. Particularly pitavastatin displayed the most potent fluconazole chemosensitizing activity ({Sigma}FICI 0.06-0.50). The pitavastatin-fluconazole combination displayed a broad-spectrum synergistic relationship against 90% of the tested strains, including strains of C. albicans, C. glabrata, and C. auris. Moreover, pitavastatin restored the susceptibility of the multidrug-resistant C. auris to the antifungal activities of itraconazole and voriconazole. Additionally, the pitavastatin-fluconazole combination significantly reduced the biofilm-forming abilities of the tested Candida species and successfully reduced the fungal burdens in a Caenorhabditis elegans infection model. Both pitavastatin and the plain phenylpentanol scaffold were able to interfere significantly with Candidas efflux activities as demonstrated by Nile Red efflux assays and flow cytometry. This study presents phenylpentanol derivatives as potent azole chemosensitizers that warrant further investigation.

microbiology↗