The infection characteristics and autophagy defect of dermal macrophages in STZ-induced diabetic rats skin wound Staphylococcus aureus infection model

The Application of Rat Models in Staphylococcus aureus Infections

Staphylococcus aureus (S. aureus) is a major human pathogen and can cause a wide range of diseases, including pneumonia, osteomyelitis, skin and soft tissue infections (SSTIs), endocarditis, mastitis, bacteremia, and so forth. Rats have been widely used in the field of infectious diseases due to their unique advantages, and the models of S. aureus infections have played a pivotal role in elucidating their pathogenic mechanisms and the effectiveness of therapeutic agents. This review outlined the current application of rat models in S. aureus infections and future prospects for rat models in infectious diseases caused by S. aureus.

Correlation between inflammatory factors, autophagy protein levels, and infection in granulation tissue of diabetic foot ulcer

OBJECTIVE

To observe the expression of inflammatory factors and autophagy-related proteins in granulation tissue of diabetic foot ulcer (DFU) patients and analyze their relationship with infection.

METHODS

This is a retrospective cohort study. One hundred and fifty-two patients with DFU in our hospital from July 2020 to March 2022 were selected as the DFU group, including 98 cases in infection stage group and 54 cases in infection control group. The patients were further graded as the mild (51 cases), the moderate (65 cases), and the severe infection group (36 cases) according to the Wagner grading criteria. Sixty-seven patients with foot burns during the same period were selected as the control group. The distribution of pathogenic bacteria on the ulcer surface was examined using fully automated bacterial analyzer. The expression of inflammatory factors (procalcitonin [PCT], tumor necrosis factor-α [TNF-α], and interleukin-6 [IL-6]) was valued by real-time fluorescence quantitative PCR (qRT-PCR). Protein expression was measured by immunohistochemistry (IHC). The correlation was analyzed by Pearson.

RESULTS

The surface infection of DFU patients was mostly induced by gram-negative and gram-positive bacteria, with Pseudomonas aeruginosa predominating among the Gram-negative bacteria and Staphylococcus aureus among the gram-positive bacteria. The infection stage group had higher content of PCT, TNF-α, and IL-6 and lower content of Beclin-1 and LC3 than the infection control group (p < .001). The levels of PCT, TNF-α, and IL-6 in the DFU patients with cardiovascular events were higher than those in the nonoccurrence group (p < .001). Glycated hemoglobin in patients with DFU was positively correlated with PCT, TNF-α, and IL-6 levels (p < .05), and negatively correlated with Beclin-1 and LC3 levels (p < .001).

CONCLUSION

P. aeruginosa and S. aureus were predominant bacterial in DFU infections. Inflammatory factor and autophagy protein expression were closely correlated with the degree of infection.

Validation of spectrophotometric and colorimetric methods to quantify clindamycin in skin tissue: application to in vitro release and ex vivo dermatokinetic studies from separable effervescent microarray patch loaded bacterially sensitive microparticle

Diabetes mellitus can cause diabetic foot infection (DFI) complications. DFI is generally caused by infection from bacteria and Methicillin-Resistant Staphylococcus aureus (MRSA) which is resistant to several antibiotics. Application therapy of clindamycin (CLY) administration with the oral route has low bioavailability and non-selective distribution of antibiotics towards bacteria intravenously. In this research, CLY was developed into bacterially sensitive microparticles (MPs) which were further incorporated into a separable effervescent microarray patch (SEMAP) system to increase the selective and responsive to DFI-causing bacteria of CLY. To support this formulation, we explore the potential of silver nanoparticles (AgNPs) towards the UV-Vis spectrophotometry method. The analytical method was validated in phosphate-buffered saline (PBS), tryptic soy broth (TSB), and skin tissue to quantify CLY, CLY loaded in microparticle, and SEMAP system. The developed analytical method was suitable for the acceptance criteria of ICH guidelines. The results showed that the correlation coefficients were linear ≥ 0.999. The values of LLOQ towards PBS, TSB, and skin tissue were 2.02 µg/mL, 4.29 µg/mL, and 2.31 µg/mL, respectively. These approaching methods were also found to be accurate and precise without being affected by dilution integrity. The presence of Staphylococcus aureus bacteria culture can produce lipase enzymes that can lysing the microparticle matrix. Drug release studies showed that bacterial infection in the high drug release microparticle sensitive bacteria and high drug retention in ex vivo dermatokinetic in rat skin tissue media. In addition, in vivo studies were required to quantify the CLY inside in further analytical validation methods.

Investigation of the potential roles of adipose stem cells and substances of natural origin in the healing process of E. coli infected wound model in Rats

Skin infections by pathogenic microorganisms are a serious problem due to the potential of dissemination through the bloodstream to various organs causing toxic effects that may be up to mortality. Escherichia coli (E. coli) is one of the most predominant Gram-negative bacterial species present globally with great attention for investigation. The current study is designed to investigate the possible role of adipose tissue-derived stem cells (ADSCs), as well as natural products such as Trichoderma viride (T. viride) extract, Saccharomyces boulardii (S. boulardii) solution in the enhancement of wound healing process in the infected skin with E. coli. Ninety-six female rats were divided into 8 groups (12 animal/group): normal skin, wounded skin, wounded skin infected with E. coli, infected-wounded skin treated by ADSCs, infected-wounded skin treated by T. viride extract, infected-wounded skin treated by S. boulardii solution, infected-wounded skin treated a combination of treatments, infected-wounded skin treated by gentamicin. At day 21 animal weights and bacterial count were detected and compared. Animals were sacrificed and skin from various groups was investigated using a light microscope for sections stained by (hematoxylin eosin, Masson trichrome, and PCNA) as well as transmission electron microscopy. Pro-inflammatory (IL-1β, TNF- α, and IL-13), anti-inflammatory cytokine (IL-4), and antioxidant enzymes (Superoxide dismutase, glutathione, and catalase) were assessed in various groups revealing that ADSCs lightly shift levels of these parameters in various rat groups to regular levels, while administration of T. viride extract, S. boulardii solution, their combination with ADSCs and gentamicin treatment drive the tested cytokines and enzymes to significant levels similar to a normal level where combination therapy gave the best result. The current findings revealed the possibility of using certain natural products as possible substitutes to regularly applied antibiotics with successive protective results in the wound infection model.

Identification of autophagy-related genes in diabetic foot ulcer based on bioinformatic analysis

Diabetic foot ulcer (DFU) complications involve autophagy dysregulation. This study aimed to identify autophagy-related bioindicators in DFU. Differentially expressed genes (DEGs) between DFU and healthy samples were analysed from the Gene Expression Omnibus (GEO) datasets, GSE7014 and GSE29221. The roles of autophagy-related DEGs were investigated using protein-protein interaction (PPI) networks, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, Gene Ontology (GO) enrichment, and Gene Set Enrichment Analysis (GSEA). Immune cell infiltration's correlation with these DEGs was also assessed. From the Human Autophagy Database (HADB), 232 autophagy-related genes (ARGs) were identified, with an intersection of 17 key DEGs between GSE7014 and GSE29221. These genes are involved in pathways like autophagy-animal, NOD-like receptor signalling, and apoptosis. In the protein network, epidermal growth factor receptor (EGFR) and phosphatase and tensin homologue (PTEN) showed significant interactions with ARGs. Survival analysis indicated the prognostic importance of calpain 2 (CAPN2), integrin subunit beta 1 (ITGB1), and vesicle-associated membrane protein 3 (VAMP3). Lower immune scores were observed in the type 2 diabetes mellitus (DM2) group than in controls. Autophagy and ARGs significantly influence DFU pathophysiology.

The role of programmed cell death in diabetic foot ulcers

Diabetic foot ulcer, is a chronic complication afflicting individuals with diabetes, continue to increase worldwide, immensely burdening society. Programmed cell death, which includes apoptosis, autophagy, ferroptosis, necroptosis and pyroptosis, has been increasingly implicated in the pathogenesis of diabetic foot ulcer. This review is based on an exhaustive examination of the literature on 'programmed cell death' and 'diabetic foot ulcers' via PubMed. The findings revealed that natural bioactive compounds, noncoding RNAs and certain proteins play crucial roles in the healing of diabetic foot ulcers through various forms of programmed cell death, including apoptosis, autophagy, ferroptosis and pyroptosis.

Deciphering The Emerging Role of Programmed Cell Death in Diabetic Wound Healing

Diabetic wounds are characterized by delayed and incomplete healing. As one of the most common complications of diabetes, diabetic wounds can be fatal in some cases. Programmed cell death (PCD) is an active and ordered cell death mode determined by genes, including apoptosis, autophagy, pyroptosis, necroptosis, ferroptosis, and cuproptosis. It is currently believed that PCD plays a crucial role in diabetic wound healing. Diabetic hyperglycemic environments can lead to abnormal PCD in various cells during healing processes, thereby affecting the activity and function of cells and interfering with diabetic wound healing. Therefore, this review focuses on the new roles and mechanisms of PCD in diabetic wound healing. Moreover, the challenges and perspectives related to PCD in diabetic wound healing are presented, which will bring new insights to improve diabetic wound healing.

Staphylococcus xylosus and Staphylococcus aureus as commensals and pathogens on murine skin

Skin ulcers, skin dermatitis and skin infections are common phenomena in colonies of laboratory mice and are often found at increased prevalence in certain immunocompromised strains. While in many cases these skin conditions are mild, in other cases they can be severe and lead to animal morbidity. Furthermore, the presence of skin infections and ulcerations can complicate the interpretation of experimental protocols, including those examining immune cell activation. Bacterial species in the genus Staphylococcus are the most common pathogens recovered from skin lesions in mice. In particular, Staphylococcus aureus and Staphylococcus xylosus have both been implicated as pathogens on murine skin. Staphylococcus aureus is a well-known pathogen of human skin, but S. xylosus skin infections in humans have not been described, indicating that there is a species-specific difference in the ability of S. xylosus to serve as a skin pathogen. The aim of this review is to summarize studies that link S. aureus and S. xylosus to skin infections of mice and to describe factors involved in their adherence to tissue and their virulence. We discuss potential differences in mouse and human skin that might underlie the ability of S. xylosus to act as a pathogen on murine skin, but not human skin. Finally, we also describe mouse mutants that have shown increased susceptibility to skin infections with staphylococcal bacteria. These mutants point to pathways that are important in the control of commensal staphylococcal bacteria. The information here may be useful to researchers who are working with mouse strains that are prone to skin infections with staphylococcal bacteria.

The infection characteristics and autophagy defect of dermal macrophages in STZ-induced diabetic rats skin wound Staphylococcus aureus infection model

INTRODUCTION

Diabetic foot ulcer infection (DFI) is an infectious disease of the skin and soft tissue in diabetics notorious for making rapid progress and being hard to cure. Staphylococcus aureus (S. aureus), most frequently detected in DFI, recently was suggested as an intracellular pathogen that can invade and survive within mammalian host cells. Autophagy in macrophages plays a vital immune role in combating intracellular pathogens through bacterial destruction, but there is a lack of empirical research about the infection characteristics and autophagy in diabetic skin infection.

METHODS

Here, we used streptozotocin-induced Sprague Dawley rats as a diabetic skin wound model to examine the S. aureus clearance ability and wound healing in vitro. Western blot and immunofluorescence staining were used to evaluate the autophagic flux of the macrophages in diabetic rats dermis, even with S. aureus infection.

RESULTS

We demonstrated that infections in diabetic rats appeared more severe and more invasive with weakened pathogen clearance ability of the host immune system, which coincided with the suppressed autophagic flux in dermal macrophages, featured by a significant increase in endogenous LC3II/I and in p62.

CONCLUSIONS

Our results first provided convincing evidence that autophagy of macrophages was dysfunctional in diabetes, especially after being infected by S. aureus, which weakens the intracellular killing of S. aureus, potentially worsens the infections, and accelerates the infection spread in the diabetic rat model. Further understanding of the special immune crosstalk between diabetes host and S. aureus infection through autophagic factors will help to explain the complex clinical phenomenon and guarantee the development of effective therapies for diabetic foot infections.