Papers by Yasir ALmuhanna
Effect of Ducrosia anethifolia methanol extract against methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms on excision wound in diabetic mice, 2024
Background: Ducrosia anethifolia is an aromatic desert plant used in Saudi folk medicine to treat... more Background: Ducrosia anethifolia is an aromatic desert plant used in Saudi folk medicine to treat skin infections. It is widely found in Middle Eastern countries. Methods: A methanolic extract of the plant was prepared, and its phytoconstituents were determined using LC-MS. In-vitro and in-vivo antibacterial and antibiofilm activities of the methanolic extract were evaluated against multidrug-resistant bacteria. The cytotoxic effect was assessed using HaCaT cell lines in-vitro. Diabetic mice were used to study the in-vivo antibiofilm and wound healing activity using the excision wound method. Results: More than 50 phytoconstituents were found in the extract after LC-MS analysis. The extract exhibited antibacterial activity against both the tested pathogens. The extract was free of irritant effects on mice skin, and no cytotoxicity was observed on HaCaT cells with an IC 50 value of 1381 µg/ml. The ointment formulation of the extract increased the healing of diabetic wounds. The microbial load of both pathogens in the wounded tissue was also reduced after the treatment. The extract was more effective against methicillinresistant Staphylococcus aureus (MRSA) than MDR-P. aeruginosa in both in vitro and in vivo experiments. Further, skin regeneration was also observed in histological studies. Conclusions: The results showed that D. anethifolia methanol extract supports wound healing in infected wounds in diabetic mice through antibacterial, antibiofilm, and wound healing activities.
Bookmarks Related papers MentionsView impact
Saudi Pharmaceutical Journal, Dec 31, 2023
Bookmarks Related papers MentionsView impact
Antibiotics, Nov 10, 2022
Bookmarks Related papers MentionsView impact
Molecules, Dec 5, 2022
Bookmarks Related papers MentionsView impact
Colonisation and chronic lung infection by the opportunistic pathogen Pseudomonas aeruginosa (PA)... more Colonisation and chronic lung infection by the opportunistic pathogen Pseudomonas aeruginosa (PA) is the leading cause of morbidity and mortality in cystic fibrosis patients. A critical key determinant of PA pathogenicity is the switch from planktonic to the biofilm mode of growth, which facilitates chronic infections and makes PA eradication extremely difficult. Biofilms are aggregates of microorganisms in which the cells are enclosed in an extracellular polymeric substance (EPS) that contains proteins, extracellular DNA (eDNA) and exopolysaccharides. Psl and Pel are two important exopolysaccharides utilised by PA to construct biofilms. While Psl is composed of D-mannose, D-glucose, and L-rhamnose, Pel contains N-acetylgalactosamine (GalNAc) and N-acetylglucosamine (GlcNAc). C-type lectins receptors (CLRs) are pattern recognition receptors (PRRs) that recognise carbohydrate motifs and are expressed by innate immune cells, including dendritic cells (DCs), macrophages and neutrophils. The overarching aim of this thesis is to investigate the interplay between PA and innate immune cells and how it is affected by biofilm formation. We hypothesise that engagement of CLRs through recognition of carbohydrate structures within PA biofilms could modulate the immune response and interfere with innate immune cells function, hence facilitating the persistence of infection. Previously, our lab demonstrated that PA biofilms and biofilm-associated carbohydrates purified from the Pel-deficient mutant ΔwspF Δpel, engage two CLRs, Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209) and Mannose receptor (MR, CD206). In this study, we show that Dectin-2 (CLEC6A) is another CLRs that binds PA biofilms and purified biofilm carbohydrates; Dectin-2 binds to biofilms formed by PA strains with different EPS composition as well as biofilms formed by PA wound isolates. Similarly to MR and DC-SIGN, Dectin-2 also recognised purified biofilm-associated carbohydrates. High and low molecular fractions of purified biofilm carbohydrates were tested in this study and Dectin-2, together with DC-SIGN and MR preferentially bound to the HMW preparations. Biofilm-associated HMW carbohydrates did not induce Dectin-2 signalling on huDectin-2 reporter cells or HEK-Blue™ mDectin-2 cells but showed antagonistic activity blocking the response of muDectin-2 reporter cells to the Dectin-2 ligand zymosan. To microscopically examine the distribution of CLRs ligands within the biofilms and to study the interaction of immune cells with biofilm, we optimised biofilm generation in substrates suitable for microscopic examination. Confocal analysis shows DC-SIGN, Dectin-2 and, weakly, MR ligands within PAO1 biofilms concentrated into discrete clusters with additional DC-SIGN ligands dispersed among bacteria aggregates. Monocyte-derived DCs (moDCs) (DC-SIGN+ and MR+) cultured with biofilms formed by strains that overexpress Psl (ΔwspF and ΔwspF Δpel) tend to display round morphology and similar findings were noted when moDCs were incubated with purified biofilm carbohydrates. In a different set of experiments cytokine production by human moDCs in response to biofilms was tested and no differences were seen among biofilms with different carbohydrate compositions or after addition of purified biofilm carbohydrates. Taken together, these data indicate that DC-SIGN, MR and Dectin-2 are receptors for PA biofilms and biofilm-associated carbohydrates. The results of this research support the idea that CLRs engagements upon biofilm recognition by innate immune cells might modulate immune cells function. As the first responder cells of the innate immune system, neutrophils possess a unique set of migration features. Several studies found that neutrophils were not able to eradicate infection caused by biofilm-forming PA, which might indicate that biofilm formation was hindering neutrophil’s activity. Here, we describe an in vitro assay that allows us to examine neutrophil behaviour, using live and confocal microscopy, following their interaction with PA, as a planktonic or biofilm cultures. Using live microscopy analysis, we observed that (1) biofilms reduced neutrophil velocity, net distance covered and the mean square displacement. Using confocal microscopy analysis, we observed that (2) neutrophils appeared unable to release granules when incubated with biofilms. Finally, (3) preliminary observations indicated that cells exhibit higher circularity when incubated with biofilm formed by strains expressing Psl or Psl-deficient biofilms in the presence of purified biofilm carbohydrates. The findings from this study have gone some way towards enhancing our understanding of the potential impact of biofilm formation on innate immune cells which might open new avenues for therapeutic approaches
Bookmarks Related papers MentionsView impact
Microorganisms, Mar 8, 2023
Bookmarks Related papers MentionsView impact
Microorganisms
The study developed a simple and inexpensive method to induce biofilm formation in-vivo for the e... more The study developed a simple and inexpensive method to induce biofilm formation in-vivo for the evaluation of the antibiofilm activity of pharmacological agents using Swiss albino mice. Animals were made diabetic using streptozocin and nicotinamide. A cover slip containing preformed biofilm along with MRSA culture was introduced into the excision wound in these animals. The method was effective in developing biofilm on the coverslip after 24 h incubation in MRSA broth which was confirmed by microscopic examination and a crystal violet assay. Application of preformed biofilm along with microbial culture induced a profound infection with biofilm formation on excision wounds in 72 h. This was confirmed by macroscopic, histological, and bacterial load determination. Mupirocin, a known antibacterial agent effective against MRSA was used to demonstrate antibiofilm activity. Mupirocin was able to completely heal the excised wounds in 19 to 21 days while in the base-treated group, healing t...
Bookmarks Related papers MentionsView impact
International Journal of Molecular Sciences
Achillea fragrantissima, a desert plant commonly known as yarrow, is traditionally used as an ant... more Achillea fragrantissima, a desert plant commonly known as yarrow, is traditionally used as an antimicrobial agent in folklore medicine in Saudi Arabia. The current study was undertaken to determine its antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug-resistant Pseudomonas aeruginosa (MDR-P. aeruginosa) using in vitro and in vivo studies. A biofilm model induced through an excision wound in diabetic mice was used to evaluate its effect in vivo. The skin irritation and cytotoxic effects of the extract were determined using mice and HaCaT cell lines, respectively. The Achillea fragrantissima methanolic extract was analyzed with LC-MS to detect different phytoconstituents, which revealed the presence of 47 different phytoconstituents. The extract inhibited the growth of both tested pathogens in vitro. It also increased the healing of biofilm-formed excision wounds, demonstrating its antibiofilm, antimicrobial, and wound-healing action in viv...
Bookmarks Related papers MentionsView impact
Brain Sciences
Objectives: The present study is aimed at determining the effect of cigarette smoking (CS) on ser... more Objectives: The present study is aimed at determining the effect of cigarette smoking (CS) on serum uric acid (UA) levels quantitatively before and after smoking cessation among people with MS (pwMS). Additionally, a possible correlation between UA levels and both disability progression and disease severity was also investigated. A retrospective cross-sectional study was conducted using the Nottingham University Hospitals MS Clinics database. It involves 127 people with definite MS recorded when reporting the latest smoking status and the clinical diagnosis. All necessary demographics and clinical characteristics were collected. We found that smoker pwMS had significantly lower serum UA levels than non-smoker pwMS (p-value = 0.0475), and this reduction was recovered after smoking cessation (p-value = 0.0216). However, the levels of disability or disease severity were not correlated with the levels of serum UA in current smoker pwMS, measured by the expanded disability status scale (...
Bookmarks Related papers MentionsView impact
Molecular Diversity
Bookmarks Related papers MentionsView impact
Drug Delivery
Bookmarks Related papers MentionsView impact
Antibiotics
Frankincense (Boswellia sacra oleo gum resin) is reported to possess antimicrobial activity again... more Frankincense (Boswellia sacra oleo gum resin) is reported to possess antimicrobial activity against several pathogens in-vitro. The antimicrobial effects of frankincense oil and its interaction with imipenem and gentamicin against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant P. aeruginosa were determined through in-vitro methods and an in-vivo study using a rat pneumonia model. Frankincense oil was subjected to GC-MS analysis to determine the different volatile components. Antibacterial effects against MRSA and MDR-P. aeruginosa was evaluated and its MIC and MBC were determined. For the rat pneumonia model (in-vivo), oil was administered at a dose of 500 mg/kg and 1000 mg/kg followed by determination of CFU in lung tissue and histological studies. Frankincense oil did not show a very potent inhibitory effect against MRSA or MDR-P. aeruginosa; the oil did not affect the zone of inhibition or FIC when combined with imipenem or gentamicin indicating a lack...
Bookmarks Related papers MentionsView impact
npj Biofilms and Microbiomes
Bacterial biofilms represent a challenge to the healthcare system because of their resilience aga... more Bacterial biofilms represent a challenge to the healthcare system because of their resilience against antimicrobials and immune attack. Biofilms consist of bacterial aggregates embedded in an extracellular polymeric substance (EPS) composed of polysaccharides, nucleic acids and proteins. We hypothesised that carbohydrates could contribute to immune recognition ofPseudomonas aeruginosabiofilms by engaging C-type lectins. Here we show binding of Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209), mannose receptor (MR, CD206) and Dectin-2 toP. aeruginosabiofilms. We also demonstrate that DC-SIGN, unlike MR and Dectin-2, recognises planktonicP. aeruginosacultures and this interaction depends on the presence of the common polysaccharide antigen. Within biofilms DC-SIGN, Dectin-2 and MR ligands appear as discrete clusters with dispersed DC-SIGN ligands also found among bacterial aggregates. DC-SIGN, MR and Dectin-2 bind to carbohydrates purifi...
Bookmarks Related papers MentionsView impact
Colonisation and chronic lung infection by the opportunistic pathogen Pseudomonas aeruginosa (PA)... more Colonisation and chronic lung infection by the opportunistic pathogen Pseudomonas aeruginosa (PA) is the leading cause of morbidity and mortality in cystic fibrosis patients. A critical key determinant of PA pathogenicity is the switch from planktonic to the biofilm mode of growth, which facilitates chronic infections and makes PA eradication extremely difficult. Biofilms are aggregates of microorganisms in which the cells are enclosed in an extracellular polymeric substance (EPS) that contains proteins, extracellular DNA (eDNA) and exopolysaccharides. Psl and Pel are two important exopolysaccharides utilised by PA to construct biofilms. While Psl is composed of D-mannose, D-glucose, and L-rhamnose, Pel contains N-acetylgalactosamine (GalNAc) and N-acetylglucosamine (GlcNAc). C-type lectins receptors (CLRs) are pattern recognition receptors (PRRs) that recognise carbohydrate motifs and are expressed by innate immune cells, including dendritic cells (DCs), macrophages and neutrophils. The overarching aim of this thesis is to investigate the interplay between PA and innate immune cells and how it is affected by biofilm formation. We hypothesise that engagement of CLRs through recognition of carbohydrate structures within PA biofilms could modulate the immune response and interfere with innate immune cells function, hence facilitating the persistence of infection. Previously, our lab demonstrated that PA biofilms and biofilm-associated carbohydrates purified from the Pel-deficient mutant ΔwspF Δpel, engage two CLRs, Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209) and Mannose receptor (MR, CD206). In this study, we show that Dectin-2 (CLEC6A) is another CLRs that binds PA biofilms and purified biofilm carbohydrates; Dectin-2 binds to biofilms formed by PA strains with different EPS composition as well as biofilms formed by PA wound isolates. Similarly to MR and DC-SIGN, Dectin-2 also recognised purified biofilm-associated carbohydrates. High and low molecular fractions of purified biofilm carbohydrates were tested in this study and Dectin-2, together with DC-SIGN and MR preferentially bound to the HMW preparations. Biofilm-associated HMW carbohydrates did not induce Dectin-2 signalling on huDectin-2 reporter cells or HEK-Blue™ mDectin-2 cells but showed antagonistic activity blocking the response of muDectin-2 reporter cells to the Dectin-2 ligand zymosan. To microscopically examine the distribution of CLRs ligands within the biofilms and to study the interaction of immune cells with biofilm, we optimised biofilm generation in substrates suitable for microscopic examination. Confocal analysis shows DC-SIGN, Dectin-2 and, weakly, MR ligands within PAO1 biofilms concentrated into discrete clusters with additional DC-SIGN ligands dispersed among bacteria aggregates. Monocyte-derived DCs (moDCs) (DC-SIGN+ and MR+) cultured with biofilms formed by strains that overexpress Psl (ΔwspF and ΔwspF Δpel) tend to display round morphology and similar findings were noted when moDCs were incubated with purified biofilm carbohydrates. In a different set of experiments cytokine production by human moDCs in response to biofilms was tested and no differences were seen among biofilms with different carbohydrate compositions or after addition of purified biofilm carbohydrates. Taken together, these data indicate that DC-SIGN, MR and Dectin-2 are receptors for PA biofilms and biofilm-associated carbohydrates. The results of this research support the idea that CLRs engagements upon biofilm recognition by innate immune cells might modulate immune cells function. As the first responder cells of the innate immune system, neutrophils possess a unique set of migration features. Several studies found that neutrophils were not able to eradicate infection caused by biofilm-forming PA, which might indicate that biofilm formation was hindering neutrophil’s activity. Here, we describe an in vitro assay that allows us to examine neutrophil behaviour, using live and confocal microscopy, following their interaction with PA, as a planktonic or biofilm cultures. Using live microscopy analysis, we observed that (1) biofilms reduced neutrophil velocity, net distance covered and the mean square displacement. Using confocal microscopy analysis, we observed that (2) neutrophils appeared unable to release granules when incubated with biofilms. Finally, (3) preliminary observations indicated that cells exhibit higher circularity when incubated with biofilm formed by strains expressing Psl or Psl-deficient biofilms in the presence of purified biofilm carbohydrates. The findings from this study have gone some way towards enhancing our understanding of the potential impact of biofilm formation on innate immune cells which might open new avenues for therapeutic approaches
Bookmarks Related papers MentionsView impact
Bacterial biofilms represent a challenge to the healthcare system because of their resilience aga... more Bacterial biofilms represent a challenge to the healthcare system because of their resilience against antimicrobials and immune attack. Biofilms consist of bacterial aggregates embedded in an extracellular polymeric substance (EPS) composed of carbohydrate polymers, nucleic acids and proteins. Carbohydrates within P. aeruginosa biofilms include neutral and mannose-rich Psl, and cationic Pel composed of N-acetyl-galactosamine and N-acetyl-glucosamine. Here we show that P. aeruginosa biofilms display ligands for the C-type lectin receptors mannose receptor (MR, CD206) and Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209). Binding of MR and DC-SIGN to P. aeruginosa biofilms is carbohydrate-and calcium-dependent and extends to biofilms formed by clinical isolates. Confocal analysis of P. aeruginosa biofilms shows abundant DC-SIGN ligands among bacteria aggregates while MR ligands concentrate into discrete clusters. DC-SIGN ligands are also ...
Bookmarks Related papers MentionsView impact
Infection and Immunity, 2018
Macrophages are important orchestrators of inflammation during bacterial infection, acting as bot... more Macrophages are important orchestrators of inflammation during bacterial infection, acting as both effector cells and regulators of neutrophil recruitment and life span. Differently activated macrophage populations with distinct inflammatory and microbicidal potentials have been described.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Yasir ALmuhanna