Aminoguanidine treatment increased NOX2 response in diabetic rats: Improved phagocytosis and killing of Candida albicans by neutrophils

The mechanism of in vitro non-enzymatic glycosylation inhibition by Tartary buckwheat's rutin and quercetin

Tartary buckwheat is rich in rutin, quercetin, and other flavonoids, which exert prominent effects by inhibiting non-enzymatic glycosylation. In this study, an in vitro non-enzymatic glycosylation model was established, and the inhibitory effects of rutin and quercetin on the early, middle, and late products of non-enzymatic glycosylation were determined. Furthermore, their effects on the formation of advanced glycation end products (AGEs) and on protein functional groups and secondary structure were analyzed. These findings provided a theoretical basis for further investigation of the mechanism via which Tartary buckwheat's rutin and quercetin inhibited non-enzymatic glycosylation. The results showed that rutin and quercetin inhibited the formation of fructosamine, dicarbonyl compounds, and fluorescent AGE in a concentration-dependent manner. Rutin and quercetin exhibited antioxidant activity and could reduce the formation of protein oxidation products. The highest clearance rates for DPPH and ABTS⁺ were 62.74 % and 71.14 %, respectively.

Treatment of Fungal-Infected Diabetic Wounds with Low Temperature Plasma

Diabetes mellitus renders patients susceptible to chronic wounds and various infections. Regarding the latter, fungal infections are of particular concern since, although they are the source of significant morbidity and mortality in immunocompromised patients, they are generally resistant to conventional treatment and a definite treatment strategy has not yet been established. Herein, we report the treatment of skin wounds in a diabetic rat model, infected by Candida albicans, with low temperature helium plasma generated in a hand-held atmospheric jet device. A fungal infection was induced on two dorsal skin wounds of the diabetic rats, and one wound was treated with the plasma jet whereas the other served as a control. Histological analysis revealed accelerated skin wound healing and decreased evidence of fungal infection in the plasma-treated group, as compared to the control group. Regeneration of the epidermis and dermis, collagen deposition, and neovascularization were all observed as a result of plasma treatment, but without wound contraction, scar formation or any evidence of thermal damage to the tissue. These findings demonstrate that the He plasma jet is remarkably effective in diabetic skin wounds infected by Candida albicans, thereby providing a promising medical treatment option for diabetes mellitus patients with skin wound and fungal infections.

Inducible nitric oxide synthase blockade with aminoguanidine, protects mice infected with Nocardia brasiliensis from actinomycetoma development

Mycetoma is a chronic infectious disease that can be caused by fungi or bacteria, Madurella mycetomatis and Nocardia brasiliensis are frequent etiologic agents of this disease. Mycetoma produced by bacteria is known as actinomycetoma. In mycetoma produced by fungi (eumycetoma) and actinomycetoma, diagnosis of the disease is based on clinical findings: severe inflammation, with deformities of affected tissues, abscesses, fistulae, sinuses and discharge of purulent material that contains micro colonies of the etiologic agent. Microscopic examination of infected tissue is similar regardless of the offending microbe; hallmark of infected tissue is severe inflammation with abundant neutrophils around micro colonies and granuloma formation with macrophages, lymphocytes, dendritic and foamy cells. Even though medical treatment is available for mycetoma patients, amputation, or surgical intervention is frequently needed. The pathogenesis of actinomycetoma is little known, most information was obtained from experimental animal models infected with bacteria. In other experimental mice infections with different microbes, it was demonstrated that nitric oxide is responsible for the intracellular killing of Mycobacterium tuberculosis by activated macrophages. Nitric oxide is a free radical with potent stimulatory and suppressive effects in innate and adaptive immunity. The unstable nitric oxide molecule is produced by action of nitric oxide synthases on L-arginine. There are three nitric oxide synthases expressed in different cells and tissues, two are constitutively expressed one in neurons, and the other in endothelial cells and one that is inducible in macrophages. Aminoguanidine is a competitive inhibitor of inducible nitric oxide synthase. Its administration in experimental animals may favor or harm them. We used aminoguanidine in mice infected with Nocardia brasiliensis, and demonstrated that all treated animals were protected from actinomycetoma development. Anti N. brasiliensis antibodies and T cell proliferation were not affected, but inflammation was reduced.

Different roles of intracellular and extracellular reactive oxygen species of neutrophils in type 2 diabetic mice with invasive aspergillosis

Diabetic patients have an increased risk of invasive aspergillosis (IA), but the mechanism is still unclear. Reactive oxygen species (ROS) produced by neutrophils play a key role in defense against Aspergillus infection. Since diabetes mellitus affects the production of ROS from neutrophils, the purpose of this study is to investigate whether this effect is related to the susceptibility of diabetic mice to IA. C57BL/6 mice were used to establish type 2 diabetes mellitus (T2DM) model, and IA was induced by airway infection with Aspergillus fumigatus. After infection, the fungal load, neutrophil count and ROS content in the lung tissues of T2DM mice were higher than those in the control mice, and the inflammation of the lung tissue was more serious. After being exposed to hyphae in vitro, compared with the control group, neutrophils in T2DM mice had higher apoptosis rate and intracellular ROS content, as well as lower viability, extracellular ROS content and fungicidal ability. In summary, after T2DM mice are infected with A. fumigatus, the reduction of extracellular ROS produced by neutrophils may lead to a decrease in fungicidal ability, while the increase of intracellular ROS is related to neutrophil and lung tissue damage.

Candida sp. Infections in Patients with Diabetes Mellitus

Candidiasis has increased substantially worldwide over recent decades and is a significant cause of morbidity and mortality, especially among critically ill patients. Diabetes mellitus (DM) is a metabolic disorder that predisposes individuals to fungal infections, including those related to Candida sp., due to a immunosuppressive effect on the patient. This review aims to discuss the latest studies regarding the occurrence of candidiasis on DM patients and the pathophysiology and etiology associated with these co-morbidities. A comprehensive review of the literature was undertaken. PubMed, Scopus, Elsevier’s ScienceDirect, and Springer’s SpringerLink databases were searched using well-defined search terms. Predefined inclusion and exclusion criteria were applied to classify relevant manuscripts. Results of the review show that DM patients have an increased susceptibility to Candida sp. infections which aggravates in the cases of uncontrolled hyperglycemia. The conclusion is that, for these patients, the hospitalization periods have increased and are commonly associated with the prolonged use of indwelling medical devices, which also increase the costs associated with disease management.

Evaluating All Potential Oral Complications of Diabetes Mellitus

Diabetes mellitus (DM) is associated with several microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, and cardiovascular diseases. The pathogenesis of these complications is complex, and involves metabolic and hemodynamic disturbances, including hyperglycemia, insulin resistance, dyslipidemia, hypertension, and immune dysfunction. These disturbances initiate several damaging processes, such as increased reactive oxygen species (ROS) production, inflammation, and ischemia. These processes mainly exert their damaging effect on endothelial and nerve cells, hence the susceptibility of densely vascularized and innervated sites, such as the eyes, kidneys, and nerves. Since the oral cavity is also highly vascularized and innervated, oral complications can be expected as well. The relationship between DM and oral diseases has received considerable attention in the past few decades. However, most studies only focus on periodontitis, and still approach DM from the limited perspective of elevated blood glucose levels only. In this review, we will assess other potential oral complications as well, including: dental caries, dry mouth, oral mucosal lesions, oral cancer, taste disturbances, temporomandibular disorders, burning mouth syndrome, apical periodontitis, and peri-implant diseases. Each oral complication will be briefly introduced, followed by an assessment of the literature studying epidemiological associations with DM. We will also elaborate on pathogenic mechanisms that might explain associations between DM and oral complications. To do so, we aim to expand our perspective of DM by not only considering elevated blood glucose levels, but also including literature about the other important pathogenic mechanisms, such as insulin resistance, dyslipidemia, hypertension, and immune dysfunction.

Neutrophil Functional Heterogeneity: Identification of Competitive Phagocytosis

Introduction

Phagocytosis by neutrophils is a key process in the innate immune response against invading microorganisms. Despite reported heterogeneity in other neutrophils functions, little is known regarding differences in phagocytosis by individual cells. Therefore, we tested the hypothesis that heterogeneity is present in the neutrophil compartment in its potency to phagocytize bacteria.

Methods

Phagocytosis assays were performed in suspension with isolated neutrophils and Staphylococcus aureus expressing different fluorescent proteins at MOIs between 1 and 10. Repetitive addition of bacteria with different fluorescent proteins and MOIs was used to compare the phagocytic capacity of S. aureus-green fluorescent protein (GFP)-positive and negative neutrophils and exclude randomness.

Results

The percentage and mean fluorescence intensity (MFI) of S. aureus-GFP-positive neutrophils increased with higher MOIs. The increase in MFI was due to phagocytosis of multiple bacteria per neutrophil as was confirmed by confocal imaging. Sequential phagocytosis of GFP- and mCherry-expressing S. aureus showed a non-random process, as S. aureus-GFP-positive neutrophils preferentially phagocytized S. aureus-mCherry.

Conclusion

All neutrophils were able to phagocytize S. aureus, but some were much more potent than others. Therefore, at physiologically relevant MOIs these potent phagocytizing neutrophils will outcompete the uptake of bacteria by less competent cells in a process we propose to name “competitive phagocytosis.”