Browsing by Author "El Masry, Mohamed"

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    Pseudomonas Aeruginosa Theft Biofilm Require Host Lipids of Cutaneous Wound
    (Wolters Kluwer, 2023) Sinha, Mithun; Ghosh, Nandini; Wijesinghe, Dayanjan S.; Mathew-Steiner, Shomita S.; Das, Amitava; Singh, Kanhaiya; El Masry, Mohamed; Khanna, Savita; Inoue, Hiroyuki; Yamazaki, Katsuhisa; Kawada, Manabu; Gordillo, Gayle M.; Roy, Sashwati; Sen, Chandan K.; Surgery, School of Medicine
    Objective: This work addressing complexities in wound infection, seeks to test the reliance of bacterial pathogen Pseudomonas aeruginosa (PA) on host skin lipids to form biofilm with pathological consequences. Background: PA biofilm causes wound chronicity. Both CDC as well as NIH recognizes biofilm infection as a threat leading to wound chronicity. Chronic wounds on lower extremities often lead to surgical limb amputation. Methods: An established preclinical porcine chronic wound biofilm model, infected with PA or Pseudomonas aeruginosa ceramidase mutant (PA ∆Cer ), was used. Results: We observed that bacteria drew resource from host lipids to induce PA ceramidase expression by three orders of magnitude. PA utilized product of host ceramide catabolism to augment transcription of PA ceramidase. Biofilm formation was more robust in PA compared to PA ∆Cer . Downstream products of such metabolism such as sphingosine and sphingosine-1-phosphate were both directly implicated in the induction of ceramidase and inhibition of peroxisome proliferator-activated receptor (PPAR)δ, respectively. PA biofilm, in a ceram-idastin-sensitive manner, also silenced PPARδ via induction of miR-106b. Low PPARδ limited ABCA12 expression resulting in disruption of skin lipid homeostasis. Barrier function of the wound-site was thus compromised. Conclusions: This work demonstrates that microbial pathogens must co-opt host skin lipids to unleash biofilm pathogenicity. Anti-biofilm strategies must not necessarily always target the microbe and targeting host lipids at risk of infection could be productive. This work may be viewed as a first step, laying fundamental mechanistic groundwork, toward a paradigm change in biofilm management.
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    Swine Model of Biofilm Infection and Invisible Wounds
    (MyJove Corporation, 2023-06-16) El Masry, Mohamed; Bhasme, Pramod; Mathew-Steiner, Shomita S.; Smith, Jessica; Smeenge, Thomas; Roy, Sashwati; Sen, Chandan K.; Surgery, School of Medicine
    Biofilm infection is a major contributor to wound chronicity. The establishment of clinically relevant experimental wound biofilm infection requires the involvement of the host immune system. Iterative changes in the host and pathogen during the formation of such clinically relevant biofilm can only occur in vivo. The swine wound model is recognized for its advantages as a powerful pre-clinical model. There are several reported approaches for studying wound biofilms. In vitro and ex vivo systems are deficient in terms of the host immune response. Short-term in vivo studies involve acute responses and, thus, do not allow for biofilm maturation, as is known to occur clinically. The first long-term swine wound biofilm study was reported in 2014. The study recognized that biofilm-infected wounds may close as determined by planimetry, but the skin barrier function of the affected site may fail to be restored. Later, this observation was validated clinically. The concept of functional wound closure was thus born. Wounds closed but deficient in skin barrier function may be viewed as invisible wounds. In this work, we seek to report the methodological details necessary to reproduce the long-term swine model of biofilm-infected severe burn injury, which is clinically relevant and has translational value. This protocol provides detailed guidance on establishing an 8 week wound biofilm infection using P. aeruginosa (PA01). Eight full-thickness burn wounds were created symmetrically on the dorsum of domestic white pigs, which were inoculated with (PA01) at day 3 post-burn; subsequently, noninvasive assessments of the wound healing were conducted at different time points using laser speckle imaging (LSI), high-resolution ultrasound (HUSD), and transepidermal water loss (TEWL). The inoculated burn wounds were covered with a four-layer dressing. Biofilms, as established and confirmed structurally by SEM at day 7 post-inoculation, compromised the functional wound closure. Such an adverse outcome is subject to reversal in response to appropriate interventions.