Cytokine and Adhesion Molecule Expression Induced by Different Strains of Staphylococcus aureus in Type 1 Diabetic Rats: Role of Insulin

Biopolymeric Insulin Membranes for Antimicrobial, Antioxidant, and Wound Healing Applications

Delayed wound healing increases the wound's vulnerability to possible infections, which may have lethal outcomes. The treatments available can be effective, but the urgency is not fully encompassed. The drug repositioning strategy proposes effective alternatives for enhancing medical therapies for chronic diseases. Likewise, applying wound dressings as biodegradable membranes is extremely attractive due to their ease of application, therapeutic effectiveness, and feasibility in industrial manufacturing. This article aims to demonstrate the pleiotropic effects during insulin repositioning in wound closure by employing a biopolymeric membrane-type formulation with insulin. We prepared biopolymeric membranes with sodium alginate cross-linked with calcium chloride, supported in a mixture of xanthan gum and guar gum, and plasticized with glycerol and sorbitol. Human insulin was combined with poloxamer 188 as a protein stabilizing agent. Our investigation encompassed physicochemical and mechanical characterization, antioxidant and biological activity through antibacterial tests, cell viability assessments, and scratch assays as an in vitro and in vivo wound model. We demonstrated that our biopolymeric insulin membranes exhibited adequate manipulation and suitable mechanical resistance, transparency, high swelling capability (1100%), and 30% antioxidant activity. Furthermore, they exhibited antibacterial activity (growth inhibition of S. aureus at 85% and P. aeruginosa at 75%, respectively), and insulin promoted wound closure in vitro with a 5.5-fold increase and 72% closure at 24 h. Also, insulin promoted in vivo wound closure with a 3.2-fold increase and 92% closure at 10 days compared with the groups without insulin, and this is the first report that demonstrates this therapeutic effect with two administrations of 0.7 IU. In conclusion, we developed a multifunctional insulin-loaded biopolymeric membrane in this study, with the main activity derived from insulin's role in wound closure and antioxidant activity, augmented by the antimicrobial effect attributed to the polymer poloxamer 188. The synergistic combination of excipients enhances its usefulness and highlights our innovation as a promising material in wound healing materials.

Pathogenesis of Staphylococcus haemolyticus on primary human skin fibroblast cells

STAPHYLOCOCCUS HAEMOLYTICUS

(S. haemolyticus) is one of the Coagulase-negative staphylococci (CoNS) that inhabits the skin as a commensal. It is increasingly implicated in opportunistic infections, including diabetic foot ulcer (DFU) infections. In contrast to the abundance of information available for S. aureus and S. epidermidis, little is known about the pathogenicity of S. haemolyticus, despite the increased prevalence of this pathogen in hospitalized patients. We described, for the first time, the pathogenesis of different clinical isolates of S. haemolyticus isolated from DFU on primary human skin fibroblast (PHSF) cells. Virulence-related genes were investigated, adhesion and invasion assays were carried out using Giemsa stain, transmission electron microscopy (TEM), MTT and flowcytometry assays. Our results showed that most S. haemolyticus carried different sets of virulence-related genes. S. haemolyticus adhered to the PHSF cells to variable degrees. TEM showed that the bacteria were engulfed in a zipper-like mechanism into a vacuole inside the cell. Bacterial internalization was confirmed using flowcytometry and achieved high intracellular levels. PHSF cells infected with S.haemolyticus suffered from amarked decrease in viability and increased apoptosis when treated with whole bacterial suspensions or cell-free supernatants but not with heat-treated cells. After co-culture with PBMCs, S. haemolyticus induced high levels of pro-inflammatory cytokines. This study highlights the significant development of S. haemolyticus, which was previously considered a contaminant when detected in cultures of clinical samples. Their high ability to adhere, invade and kill the PHSF cells illustrate the severe damage associated with DFU infections.

ABBREVIATIONS

CoNS, coagulase-negative staphylococci; DFU, diabetic foot ulcer; DM, diabetes mellitus; DMEM, Dulbecco's Modified Eagle Medium; MTT, 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide; PBMCs,peripheral blood mononuclear cells; PHSF, primary human skin fibroblast; CFU, colony-forming unit.

Evaluation of Hypoglycemic Therapy Through Physical Exercise in n5STZ-Induced Diabetes Rats

BACKGROUND

Diabetes mellitus is a syndrome with multiple etiologies involving insulin, in which there is a lack of production and/or loss of sensitivity to this hormone resulting in insulin resistance. Treatment and control of this disease requires changes in diet, use of medication, and lifestyle, such as physical activity. These modifications may compromise quality-of-life if there is no proper guidance for the treatment or alert to possible complications caused by the disease.

METHODS

This study aimed to evaluate biochemical and hematological parameters, and to assess brain derived neurotrophic factor levels in diabetic Wistar rats submitted to chronic physical exercise.

RESULTS

The results demonstrated an increase in plasma concentration of brain-derived neurotrophic factor (BDNF) in association with hyperglycemia reduction in diabetic animals.

DISCUSSION

The results obtained suggest that there is a regulation of glucose homeostasis between peripheral tissues and the central nervous system. Exercise-induced BDNF also improved levels of glycemia, body weight, and dyslipidemia. In hematological evaluation, BDNF increase was positively correlated with an improvement in leukocyte parameters. Electrophoresis analyses demonstrated a reduction in levels of pro-inflammatory proteins, lipoprotein fractions, and albumin preservation in diabetic animals trained with elevated concentration of plasma BDNF.

CONCLUSION

In conclusion, this study demonstrated that chronic exercise was able to elevate BDNF levels in plasma, which resulted directly in positive hypoglycemic activity in diabetic animals and a reduction of the metabolic syndrome associated with diabetes mellitus.