Abozeid, D. O., F. A. T. H. Y. M. SOLIMAN, G. A. Fawzy, N. F. Abdeltawab, A. M. Al-mahallaw, K. A. F. Emam, W. H. Marcus, and M. Y. Issa, "In vitro and in vivo studies of natural anti-acne treatments from pomegranate pericarp extract and essential oils of bitter orange, sweet marjoram, and tea tree", Future Journal of Pharmaceutical Sciences, vol. 11, issue 1, pp. 110, 2025.
Eisa, M., N. Flores, O. Khedr, E. Gomez-Escobar, N. Bédard, N. F. Abdeltawab, J. Bruneau, A. Grakoui, and N. H. Shoukry, "Activation-Induced Marker Assay to Identify and Isolate HCV-Specific T Cells for Single-Cell RNA-Seq Analysis.", Viruses, vol. 16, issue 10, 2024. Abstract

Identification and isolation of antigen-specific T cells for downstream transcriptomic analysis is key for various immunological studies. Traditional methods using major histocompatibility complex (MHC) multimers are limited by the number of predefined immunodominant epitopes and MHC matching of the study subjects. Activation-induced markers (AIM) enable highly sensitive detection of rare antigen-specific T cells irrespective of the availability of MHC multimers. Herein, we have developed an AIM assay for the detection, sorting and subsequent single-cell RNA sequencing (scRNA-seq) analysis of hepatitis C virus (HCV)-specific T cells. We examined different combinations of the activation markers CD69, CD40L, OX40, and 4-1BB at 6, 9, 18 and 24 h post stimulation with HCV peptide pools. AIM CD4 T cells exhibited upregulation of CD69 and CD40L as early as 6 h post-stimulation, while OX40 and 4-1BB expression was delayed until 18 h. AIM CD8 T cells were characterized by the coexpression of CD69 and 4-1BB at 18 h, while the expression of CD40L and OX40 remained low throughout the stimulation period. AIM CD4 and CD8 T cells were successfully sorted and processed for scRNA-seq analysis examining gene expression and T cell receptor (TCR) usage. scRNA-seq analysis from this one subject revealed that AIM CD4 T (CD69 CD40L) cells predominantly represented Tfh, Th1, and Th17 profiles, whereas AIM CD8 T (CD69 4-1BB) cells primarily exhibited effector and effector memory profiles. TCR analysis identified 1023 and 160 unique clonotypes within AIM CD4 and CD8 T cells, respectively. In conclusion, this approach offers highly sensitive detection of HCV-specific T cells that can be applied for cohort studies, thus facilitating the identification of specific gene signatures associated with infection outcome and vaccination.

Abdeltawab, N. F., R. K. Aziz, R. Kansal, S. L. Rowe, Y. Su, L. Gardner, C. Brannen, M. M. Nooh, R. R. Attia, H. A. Abdelsamed, et al., "An unbiased systems genetics approach to mapping genetic loci modulating susceptibility to severe streptococcal sepsis", PLoS pathogens, vol. 4, no. 4: Public Library of Science San Francisco, USA, pp. e1000042, 2008. Abstract
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Aziz, R. K., R. Kansal, N. F. Abdeltawab, S. L. Rowe, Y. Su, D. Carrigan, M. M. Nooh, R. R. Attia, C. Brannen, L. A. Gardner, et al., "Susceptibility to severe Streptococcal sepsis: use of a large set of isogenic mouse lines to study genetic and environmental factors", Genes & Immunity, vol. 8, no. 5: Nature Publishing Group, pp. 404–415, 2007. Abstract
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Wasfi, R., H. Moussa, R. Bakr, N. Abdeltawab, and S. Megahed, "Anaerobic biodegradation of anthracene by oral Firmicutes isolates from smokers and its potential pathway", International Biodeterioration & Biodegradation, vol. 180, pp. 105598, 2023.
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Elhakim, Y. A., A. E. Ali, A. E. - D. M. S. Hosny, and N. F. Abdeltawab, "Zinc Deprivation as a Promising Approach for Combating Methicillin-Resistant : A Pilot Study.", Pathogens (Basel, Switzerland), vol. 10, issue 10, 2021. Abstract

Methicillin-resistant (MRSA) infections are a global health burden with an urgent need for antimicrobial agents. Studies have shown that host immune responses limit essential metals such as zinc during infection, leading to the limitation of bacterial virulence. Thus, the deprivation of zinc as an important co-factor for the activity of many enzymes can be a potential antimicrobial approach. However, the effect of zinc deprivation on and MRSA is not fully understood. Therefore, the current study aimed to dissect the effects of zinc deprivation on hemolytic activity and biofilm formation through employing biochemical and genetic approaches to study the effect of zinc deprivation on growth and virulence. Chemically defined media (CDM) with and without ZnCl, was used to assess the effect of zinc deprivation on growth, biofilm formation, and hemolytic activity in methicillin-susceptible (MSSA) RN6390 and MRSA N315 strains. Zinc deprivation decreased the growth of RN6390 and N315 strains significantly by 1.5-2 folds, respectively compared to the zinc physiological range encountered by the bacteria in the human body (7-20 µM) ( < 0.05). Zinc deprivation significantly reduced biofilm formation by 1.5 folds compared to physiological levels ( < 0.05). Moreover, the hemolytic activity of RN6390 and N315 strains was significantly decreased by 20 and 30 percent, respectively compared to physiological zinc levels ( < 0.05). Expression of biofilm-associated transcripts levels at late stage of biofilm formation (20 h) murein hydrolase activator A () and were downregulated by 3 and 5 folds, respectively ( < 0.05) suggested an effect on extracellular DNA production. Expression of hemolysins-associated genes () was downregulated by 3, 5, and 10 folds, respectively, in absence of zinc ( < 0.001). Collectively the current study showed that zinc deprivation in vitro affected growth, biofilm formation, and hemolytic activity of . Our in vitro findings suggested that zinc deprivation can be a potential supportive anti-biofilm formation and antihemolytic approach to contain MRSA topical infections.

Abdelhamed, F. M., N. F. Abdeltawab, M. T. Elrakaiby, R. N. Shamma, and N. A. Moneib, "Antibacterial and Anti-Inflammatory Activities of Essential Oil Nanoemulsion on Acne Vulgaris.", Microorganisms, vol. 10, issue 9, 2022. Abstract

Antibiotics are frequently used in acne treatment and their prolonged use has led to an emergence of resistance. This study aimed to investigate the use of natural antimicrobials as an alternative therapy. The antimicrobial and anti-inflammatory activities of five commonly used essential oils (EOs) (tea tree, clove, thyme, mentha and basil EOs), and their possible mechanisms of action against and , were explored. The effect of the most potent EO on membrane permeability was elucidated and its anti-inflammatory action, when formulated as nanoemulsion, was tested in an in vivo acne model. The in vitro studies showed that thyme EO had the most potent antimicrobial and antibiofilm activity, with phenolics and terpenoids as main antimicrobial constituents of EO. Thyme EO affected cell membrane permeability of both bacterial species, evident by the detection of the leakage of intracellular ions and membrane integrity by the leakage of nucleic acids. Morphological alteration in bacterial cells was confirmed by transmission electron microscopy. Thyme EO nanoemulsion led to the suppression of an inflammatory response in acne animal models along with a bacterial load decrease and positive histopathological changes. Collectively, thyme EO nanoemulsion showed potent antimicrobial and anti-inflammatory effects compared to the reference antibiotics, suggesting its effectiveness as a natural alternative in acne treatment.

Kayed, A. E., O. Kutkat, A. Kandeil, Y. Moatasim, A. El Taweel, M. El Sayes, R. El-Shesheny, B. E. Aboulhoda, N. F. Abdeltawab, G. Kayali, et al., "Comparative pathogenic potential of avian influenza H7N3 viruses isolated from wild birds in Egypt and their sensitivity to commercial antiviral drugs.", Archives of virology, vol. 168, issue 3, pp. 82, 2023. Abstract

Active surveillance and studying the virological features of avian-origin influenza viruses are essential for early warning and preparedness for the next potential pandemic. During our active surveillance of avian influenza viruses in wild birds in Egypt in the period 2014-2017, multiple reassortant low-pathogenic avian influenza H7N3 viruses were isolated. In this study, we investigated and compared the infectivity, pathogenicity, and transmission of four different constellation forms of Egyptian H7N3 viruses in chickens and mice and assessed the sensitivity of these viruses to different commercial antiviral drugs in vitro. Considerable variation in virus pathogenicity was observed in mice infected with different H7N3 viruses. The mortality rate ranged from 20 to 100% in infected mice. Infected chickens showed only ocular clinical signs at three days postinfection as well as systemic viral infection in different organs. Efficient virus replication and transmission in chickens was observed within each group, indicating that these subtypes can spread easily from wild birds to poultry without prior adaptation. Mutations in the viral proteins associated with antiviral drug resistance were not detected, and all strains were sensitive to the antiviral drugs tested. In conclusion, all of the viruses studied had the ability to infect mice and chickens. H7N3 viruses circulating among wild birds in Egypt could threaten poultry production and public health.

Hammouda, Z. K., R. Wasfi, and N. F. Abdeltawab, "Hormonal drugs: Influence on growth, biofilm formation, and adherence of selected gut microbiota.", Frontiers in cellular and infection microbiology, vol. 13, pp. 1147585, 2023. Abstract

Many studies have reported the influence of hormonal drugs on gut microbiota composition. However, the underlying mechanism of this interaction is still under study. Therefore, this study aimed to evaluate the possible changes in selected members of gut bacteria exposed to oral hormonal drugs used for years. Selected members of gut bacteria were , representing the four main phyla in the gut. Selected hormonal drugs used for a long time were estradiol, progesterone, and thyroxine. The effect of intestinal concentrations of these drugs on the selected bacterial growth, biofilm formation, and adherence to Caco-2/HT-29 cell line was assessed. Short-chain fatty acids (SCFAs) have been included in host functions including the gut, immune and nervous functions; thus, the drug's effects on their production were assayed using High- Performance Liquid Chromatography. Sex steroids significantly increased the growth of all tested bacteria except , similarly, thyroxine increased the growth of tested Gram-negative bacteria however reducing that of tested Gram-positive bacteria. The effect of drugs on biofilm formation and bacterial adherence to cell lines cocultures was variable. Progesterone decreased the biofilm formation of tested Gram-positive bacteria, it nevertheless increased adherence to Caco-2/HT-29 cell line cell lines coculture. By contrast, progesterone increased biofilm formation by Gram-negative bacteria and increased adherence of to the cell lines coculture. Moreover, thyroxine and estradiol exhibited antibiofilm activity against , while thyroxine increased the ability of to form a biofilm. Moreover, hormones affected bacterial adherence to cell lines independently of their effect on hydrophobicity suggesting other specific binding factors might contribute to this effect. Tested drugs affected SCFAs production variably, mostly independent of their effect on bacterial growth. In conclusion, our results showed that the microbiota signature associated with some hormonal drug consumption could be the result of the direct effect of these drugs on bacterial growth, and adherence to enterocytes besides the effect of these drugs on the host tissue targets. Additionally, these drugs affect the production of SCFAs which could contribute to some of the side effects of these drugs.

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