Role of Protein Kinase C and Nox2-Derived Reactive Oxygen Species Formation in the Activation and Maturation of Dendritic Cells by Phorbol Ester and Lipopolysaccharide

Optimization of a lipid nanoparticle-based protocol for RNA transfection into primary mononuclear phagocytes

The effective delivery of synthetic RNA into mononuclear phagocytes is a prerequisite for experimental research and therapeutic development. However, traditional methods are highly ineffective and toxic for these cells. Here, we aimed to optimize a transfection protocol for primary bone marrow-derived phagocytes, specifically dendritic cells and macrophages, using lipid nanoparticles generated by microfluidics. Our results show that a lipid mixture similar to that used in Moderna's COVID-19 messenger RNA vaccine outperforms the others tested. Improved messenger RNA transfection can be achieved by replacing uridine with methylpseudouridine but not methoxyuridine, which interferes with transfection. The addition of diphenyleneiodonium or apocynin can enhance transfection in a cell type-dependent manner without adverse effects, while apolipoprotein E provides no added value. These optimized transfection conditions can also be used for microRNA agonists and antagonists. In sum, this study offers a straightforward, highly efficient, reproducible, and nontoxic protocol to deliver RNA into different primary mononuclear phagocytes in culture.

Diabetic Retinopathy: New Treatment Approaches Targeting Redox and Immune Mechanisms

Diabetic retinopathy (DR) represents a severe complication of diabetes mellitus, characterized by irreversible visual impairment resulting from microvascular abnormalities. Since the global prevalence of diabetes continues to escalate, DR has emerged as a prominent area of research interest. The development and progression of DR encompass a complex interplay of pathological and physiological mechanisms, such as high glucose-induced oxidative stress, immune responses, vascular endothelial dysfunction, as well as damage to retinal neurons. Recent years have unveiled the involvement of genomic and epigenetic factors in the formation of DR mechanisms. At present, extensive research explores the potential of biomarkers such as cytokines, molecular and cell therapies, antioxidant interventions, and gene therapy for DR treatment. Notably, certain drugs, such as anti-VEGF agents, antioxidants, inhibitors of inflammatory responses, and protein kinase C (PKC)-β inhibitors, have demonstrated promising outcomes in clinical trials. Within this context, this review article aims to introduce the recent molecular research on DR and highlight the current progress in the field, with a particular focus on the emerging and experimental treatment strategies targeting the immune and redox signaling pathways.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

Stem Cell Therapy in Limb Ischemia: State-of-Art, Perspective, and Possible Impacts of Endometrial-Derived Stem Cells

As an evidence-based performance, the rising incidence of various ischemic disorders has been observed across many nations. As a result, there is a growing need for the development of more effective regenerative approaches that could serve as main therapeutic strategies for the treatment of these diseases. From a cellular perspective, promoted complex inflammatory mechanisms, after inhibition of organ blood flow, can lead to cell death in all tissue types. In this case, using the stem cell technology provides a safe and regenerative approach for ischemic tissue revascularization and functional cell formation. Limb ischemia (LI) is one of the most frequent ischemic disease types and has been shown to have a promising regenerative response through stem cell therapy based on several clinical trials. Bone marrow-derived mononuclear cells (BM-MNCs), peripheral blood CD34-positive mononuclear cells (CD34+ PB-MNCs), mesenchymal stem cells (MSCs), and endothelial stem/progenitor cells (ESPCs) are the main, well-examined stem cell types in these studies. Additionally, our investigations reveal that endometrial tissue can be considered a suitable candidate for isolating new safe, effective, and feasible multipotent stem cells for limb regeneration. In addition to other teams’ results, our in-depth studies on endometrial-derived stem cells (EnSCs) have shown that these cells have translational potential for limb ischemia treatment. The EnSCs are able to generate diverse types of cells which are essential for limb reconstruction, including endothelial cells, smooth muscle cells, muscle cells, and even peripheral nervous system populations. Hence, the main object of this review is to present stem cell technology and evaluate its method of regeneration in ischemic limb tissue.

Soluble C-Type Lectin-Receptor Ligands Stimulate ROS Production in Dendritic Cells and Potentiate Killing of MRSA as Well as the MRSA Induced IL-12 Production

Methicillin resistant Staphylococcus aureus (MRSA) has developed resistance to most β-lactam antibiotics leaving few treatment options against infections with MRSA. Through mannose receptors, mannan potentiates IL-12 production induced by Gram-positive bacteria, a cytokine crucial in the clearance of S. aureus infection. We investigated the IL-12 potentiating effect of mannan pre-treatment of bone marrow-derived dendritic cells prior to stimulation with clinical MRSA strains. Mannan almost doubled IL-12 as well as IFN-β production in response to USA300, also when USA300 was treated with the β-lactam cefoxitin. The MRSA-induced IL-12 production was dependent on bacterial uptake and reactive oxygen species (ROS). Mannan alone induced ROS production, and in combination with USA300, the ROS produced corresponded to the sum induced by mannan and USA300. Addition of a monoclonal antibody against the mannose receptor likewise enhanced USA300-induced IL-12 and induced ROS production. Mannan addition further increased the endocytosis as well as the rate of endosomal killing of bacteria. Pre-treatment with soluble β-glucans also induced ROS and potentiated the USA300-induced IL-12 indicating that other C-type receptors may play a similar role. In the presence of the pro-inflammatory mediators, GM-CSF or IFN-γ, the mannan-enhanced IL-12 production increased further. The USA300-induced and the mannan-facilitated enhanced IFN-β and IL-12 showed same dependency on MAPK c-Jun N-terminal kinase signaling, suggesting that mannan enhances the signals already induced by the bacteria, rather than changing them. We suggest that the C-type lectin-induced ROS production is a key factor in the IFN-β and IL-12 potentiation.

Dendritic cell-mediated chronic low-grade inflammation is regulated by the RAGE-TLR4-PKCβ1 signaling pathway in diabetic atherosclerosis

Background

The unique mechanism of diabetic atherosclerosis has been a central research focus. Previous literature has reported that the inflammatory response mediated by dendritic cells (DCs) plays a vital role in the progression of atherosclerosis. The objective of the study was to explore the role of DCs in diabetes mellitus complicated by atherosclerosis.

Methods

ApoE^−/− mice and bone marrow-derived DCs were used for in vivo and in vitro experiments, respectively. Masson’s staining and Oil-red-O staining were performed for atherosclerotic lesion assessment. The content of macrophages and DCs in plaque was visualized by immunohistochemistry. The expression of CD83 and CD86 were detected by flow cytometry. The fluctuations in the RNA levels of cytokines, chemokines, chemokine receptors and adhesions were analyzed by quantitative RT-PCR. The concentrations of IFN-γ and TNF-α were calculated using ELISA kits and the proteins were detected using western blot. Coimmunoprecipitation was used to detect protein–protein interactions.

Results

Compared with the ApoE^−/− group, the volume of atherosclerotic plaques in the aortic root of diabetic ApoE^−/− mice was significantly increased, numbers of macrophages and DCs were increased, and the collagen content in plaques decreased. The expression of CD83 and CD86 were significantly upregulated in splenic CD11c⁺ DCs derived from mice with hyperglycemia. Increased secretion of cytokines, chemokines, chemokine receptors, intercellular cell adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) also were observed. The stimulation of advanced glycation end products plus oxidized low-density lipoprotein, in cultured BMDCs, further activated toll-like receptor 4, protein kinase C and receptor of AGEs, and induced immune maturation of DCs through the RAGE-TLR4-PKCβ₁ signaling pathway that was bound together by intrinsic structures on the cell membrane. Administering LY333531 significantly increased the body weight of diabetic ApoE^−/− mice, inhibited the immune maturation of spleen DCs, and reduced atherosclerotic plaques in diabetic ApoE^−/− mice. Furthermore, the number of DCs and macrophages in atherosclerotic plaques was significantly reduced in the LY333531 group, and the collagen content was increased.

Conclusions

Diabetes mellitus aggravates chronic inflammation, and promotes atherosclerotic plaques in conjunction with hyperlipidemia, which at least in part through inducing the immune maturation of DCs, and its possible mechanism of action is through the RAGE-TLR4-pPKCβ₁ signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00431-6.

NOX2ko Mice Show Largely Increased Expression of a Mutated NOX2 mRNA Encoding an Inactive NOX2 Protein

Background: The superoxide-generating enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2 or gp91phox, the phagocytic isoform) was reported as a major source of oxidative stress in various human diseases. Genetic deletion is widely used to study the impact of NOX2-derived reactive oxygen species (ROS) on disease development and progression in various animal models. Here, we investigate why NOX2 knockout mice show no NOX2 activity but express NOX2 mRNA and protein. Methods and Results: Oxidative burst (NOX2-dependent formation of ROS) was measured by L-012-based chemiluminescence and was largely absent in whole blood of NOX2 knockout mice. Protein expression was still detectable in different tissues of the NOX2 knockout mice, at the expected and a slightly lower molecular weight (determined by Western blot). The NOX2 gene was even largely enhanced at its expressional level in NOX2 knockout mice. RNA sequencing revealed a modified NOX2 mRNA in the knockout mice that is obviously translated to a truncated inactive mutant enzyme. Conclusion: Although the commercial NOX2 knockout mice display no considerable enzymatic NOX2 activity, expression of the NOX2 gene (when using standard primers) and protein (when using antibodies binding to the carboxy-terminal end) can still be detected, which may lead to confusion among investigators.

Generating Bovine Monocyte-Derived Dendritic Cells for Experimental and Clinical Applications Using Commercially Available Serum-Free Medium

Advances in fundamental and applied immunology research often originate from pilot studies utilizing animal models. While cattle represent an ideal model for disease pathogenesis and vaccinology research for a number of human disease, optimized bovine culture models have yet to be fully established. Monocyte-derived dendritic cells (MoDC) are critical in activating adaptive immunity and are an attractive subset for experimental and clinical applications. The use of serum-supplemented culture medium in this ex vivo approach is undesirable as serum contains unknown quantities of immune-modulating components and may induce unwanted immune responses if not autologous. Here, we describe a standardized protocol for generating bovine MoDC in serum-free medium (AIM-V) and detail the MoDC phenotype, cytokine profile, and metabolic signature achieved using this culture methodology. MoDC generated from adult, barren cattle were used for a series of experiments that evaluated the following culture conditions: medium type, method of monocyte enrichment, culture duration, and concentration of differentiation additives. Viability and yield were assessed using flow cytometric propidium iodide staining and manual hemocytometer counting, respectively. MoDC phenotype and T cell activation and proliferation were assessed by flow cytometric analysis of surface markers (MHC class II, CD86, CD14, and CD205), and CD25 and CFSE respectively. Cytokine secretion was quantified using a multiplex bovine cytokine panel (IL-1α, IL-1β, IL-8, IL-10, IL-17A, IFN-γ, MIP-1α, TNF-α, and IL-4). Changes in cell metabolism following stimulation were analyzed using an Extracellular Flux (XFe96) Seahorse Analyzer. Data were analyzed using paired t-tests and repeated measures ANOVA. Immature MoDC generated in serum-free medium using magnetic-activated cell sorting with plate adhesion to enrich monocytes and cultured for 4 days have the following phenotypic profile: MHC class II⁺⁺⁺, CD86⁺, CD205⁺⁺, and CD14^-. These MoDC can be matured with PMA and ionomycin as noted by increased CD86 and CD40 expression, increased cytokine secretion (IL-1α, IL-10, MIP-1α, and IL-17A), a metabolic switch to aerobic glycolysis, and induction of T cell activation and proliferation following maturation. Cultivation of bovine MoDC utilizing our well-defined culture protocol offers a serum-free approach to mechanistically investigate mechanisms of diseases and the safety and efficacy of novel therapeutics for both humans and cattle alike.

Does Dysregulation of Redox State Underpin the Decline of Innate Immunity with Aging?

Significance: Antibacterial defense invokes the innate immune system as a first responder, with neutrophils phagocytozing and forming neutrophil extracellular traps around pathogens in a reactive oxygen species (ROS)-dependent manner. Increased NOX2 activity and mitochondrial ROS production in phagocytic, antigen-presenting cells (APCs) affect local cytokine secretion and proteolysis of antigens for presentation to T cells at the immune synapse. Uncontrolled oxidative post-translational modifications to surface and cytoplasmic proteins in APCs during aging can impair innate immunity. Recent Advances: NOX2 plays a role in the maturation of dendritic cells, but paradoxically NOX2 activity has also been shown to promote viral pathogenicity. Accumulating evidence suggests that a reducing environment is essential to inhibit pathogen proliferation, facilitate antigenic processing in the endosomal lumen, and enable an effective immune synapse between APCs and T cells. This suggests that the kinetics and location of ROS production and reducing potential are important for effective innate immunity. Critical Issues: During aging, innate immune cells are less well able to phagocytoze, kill bacteria/viruses, and process proteins into antigenic peptides-three key steps that are necessary for developing a specific targeted response to protect against future exposure. Aberrant control of ROS production and impaired Nrf2-dependent reducing potential may contribute to age-associated immune decline. Future Directions: Local changes in redox potential may be achieved through adjuvant formulations to improve innate immunity. Further work is needed to understand the timing of delivery for redox modulators to facilitate innate immune cell recruitment, survival, antigen processing and presentation activity without disrupting essential ROS-dependent bacterial killing.

Discovery of a novel protein kinase C activator from Croton tiglium for inhibition of non-small cell lung cancer

BACKGROUND

The incidence of non-small cell lung cancer (NSCLC) accounts for approximately 85-90% of lung cancer, which has been shown to be challenging for treatment owing to poorly understanding of pathological mechanisms. Natural products serve as a source of almost all pharmaceutical preparations or offer guidance for those chemicals that have entered clinical trials, especially in NSCLC.

PURPOSE

We investigated the effect of B10G5, a natural products isolated from the Croton tiglium, in human non-small cell lung canceras as a protein kinase C (PKC) activator.

METHODS

The cell viability assay was evaluated by the MTT assay. The apoptosis and cell cycle distribution were assessed by flow cytometry. Reactive oxygen species (ROS) production was determined by using the fluorescent probe DCFDA. Cell migration ability of H1975 cells was analyzed by using the wound healing assay. The inhibiting effect of B10G5 against the phosphorylation level of the substrate by PKCs was assessed by using homogeneous time-resolved fluorescence (HTRF) technology. The correlation between PKCs and overall survival (OS) of Lung Adenocarcinoma (LUAD) patients was analysis by TCGA portal. The binding mode between B10G5 and the PKC isoforms was explored by molecular docking. Protein expression was detected by western blotting analysis.

RESULTS

B10G5 suppressed cell proliferation and colony formation, as well as migration ability of NSCLC cells, without significant toxic effect on normal lung cells. B10G5 induced the cell apoptosis through the development of PARP cleavage, which is evidenced by means of the production of mitochondrial ROS. In addition, the B10G5 inhibitory effect was also related to the cell cycle arrest at G2/M phase. Mechanistically, molecular modelling technology suggested that the potential target of B10G5 was associated with PKC family. In vitro PKC kinase assay indicated that B10G5 effectively activated the PKC activity. Western blotting data revealed that B10G5 upregulated PKC to activate PKC-mediated RAF/MEK/ERK pathway.

CONCLUSION

Our results showed that B10G5, a naturally occurring phorbol ester, considered to be a potential and a valuable therapeutic chemical in the treatment of NSCLC.

Flavin Oxidase-Induced ROS Generation Modulates PKC Biphasic Effect of Resveratrol on Endothelial Cell Survival

Background: Dietary intake of natural antioxidants is thought to impart protection against oxidative-associated cardiovascular diseases. Despite many in vivo studies and clinical trials, this issue has not been conclusively resolved. Resveratrol (RES) is one of the most extensively studied dietary polyphenolic antioxidants. Paradoxically, we have previously demonstrated that high RES concentrations exert a pro-oxidant effect eventually elevating ROS levels leading to cell death. Here, we further elucidate the molecular determinants underpinning RES-induced oxidative cell death. Methods: Using human umbilical vein endothelial cells (HUVECs), the effect of increasing concentrations of RES on DNA synthesis and apoptosis was studied. In addition, mRNA and protein levels of cell survival or apoptosis genes, as well as protein kinase C (PKC) activity were determined. Results: While high concentrations of RES reduce PKC activity, inhibit DNA synthesis and induce apoptosis, low RES concentrations elicit an opposite effect. This biphasic concentration-dependent effect (BCDE) of RES on PKC activity is mirrored at the molecular level. Indeed, high RES concentrations upregulate the proapoptotic Bax, while downregulating the antiapoptotic Bcl-2, at both mRNA and protein levels. Similarly, high RES concentrations downregulate the cell cycle progression genes, c-myc, ornithine decarboxylase (ODC) and cyclin D1 protein levels, while low RES concentrations display an increasing trend. The BCDE of RES on PKC activity is abrogated by the ROS scavenger Tempol, indicating that this enzyme acts downstream of the RES-elicited ROS signaling. The RES-induced BCDE on HUVEC cell cycle machinery was also blunted by the flavin inhibitor diphenyleneiodonium (DPI), implicating flavin oxidase-generated ROS as the mechanistic link in the cellular response to different RES concentrations. Finally, PKC inhibition abrogates the BCDE elicited by RES on both cell cycle progression and pro-apoptotic gene expression in HUVECs, mechanistically implicating PKC in the cellular response to different RES concentrations. Conclusions: Our results provide new molecular insight into the impact of RES on endothelial function/dysfunction, further confirming that obtaining an optimal benefit of RES is concentration-dependent. Importantly, the BCDE of RES could explain why other studies failed to establish the cardio-protective effects mediated by natural antioxidants, thus providing a guide for future investigation looking at cardio-protection by natural antioxidants.

Oxymatrine‑mediated maturation of dendritic cells leads to activation of FOXP3+/CD4+ Treg cells and reversal of cisplatin‑resistance in lung cancer cells

The dendritic cell (DC)‑regulatory T (Treg) system serves a leading role in the immunosuppression of the tumor microenvironment, which is not conducive to radiotherapy and chemotherapy treatment for lung cancer. The present study aimed to investigate the effect of oxymatrine (OMT) on the DC‑Treg system in the tumor microenvironment in vitro and to examine its mechanism. The expressions of CD83 antigen, T‑lymphocyte activation antigen CD86, CD11 antigen‑like family member C and major histocompatibility complex II in DCs were increased upon treatment with 1 mg/ml OMT, as detected by flow cytometry. Following pretreatment with OMT, the DCs mediated the forkhead box protein P3 overexpression in primitive cluster of differentiation 4+ T cells at the protein and mRNA expression levels. The expression levels of anti‑inflammatory factors, including interleukin (IL)‑10, tumor growth factor‑β, IL‑35, and pro‑inflammatory cytokines, including interferon‑γ, IL‑12 and IL‑2, in the co‑culture supernatant were increased as measured by ELISA. When DCs and DC‑Tregs were co‑cultured with cisplatin‑resistant A549 cells, the proportion of apoptosis in the co‑culture groups was increased under treatment with cisplatin, which was detected by Annexin V/propidium Iodide staining and western blotting. The present results suggested that OMT may promote the maturation of DCs, mediate the differentiation of T cells into Treg cells, and reverse the resistance of tumor cells to cisplatin in vitro. It was suggested that OMT is an important adjunct to chemotherapy through the regulation of antitumor responses.

The Endothelin Receptor Antagonist Macitentan Improves Isosorbide-5-Mononitrate (ISMN) and Isosorbide Dinitrate (ISDN) Induced Endothelial Dysfunction, Oxidative Stress, and Vascular Inflammation

Objective

Organic nitrates such as isosorbide-5-mononitrate (ISMN) and isosorbide dinitrate (ISDN) are used for the treatment of patients with chronic symptomatic stable coronary artery disease and chronic congestive heart failure. Limiting side effects of these nitrovasodilators include nitrate tolerance and/or endothelial dysfunction mediated by oxidative stress. Here, we tested the therapeutic effects of the dual endothelin (ET) receptor antagonist macitentan in ISMN- and ISDN-treated animals.

Methods and Results

Organic nitrates (ISMN, ISDN, and nitroglycerin (GTN)) augmented the oxidative burst and interleukin-6 release in cultured macrophages, whereas macitentan decreased the oxidative burst in isolated human leukocytes. Male C57BL/6j mice were treated with ISMN (75 mg/kg/d) or ISDN (25 mg/kg/d) via s.c. infusion for 7 days and some mice in addition with 30 mg/kg/d of macitentan (gavage, once daily). ISMN and ISDN in vivo therapy caused endothelial dysfunction but no nitrate (or cross-)tolerance to the organic nitrates, respectively. ISMN/ISDN increased blood nitrosative stress, vascular/cardiac oxidative stress via NOX-2 (fluorescence and chemiluminescence methods), ET1 expression, ET receptor signaling, and markers of inflammation (protein and mRNA level). ET receptor signaling blockade by macitentan normalized endothelial function, vascular/cardiac oxidative stress, and inflammatory phenotype in both nitrate therapy groups.

Conclusion

ISMN/ISDN treatment caused activation of the NOX-2/ET receptor signaling axis leading to increased vascular oxidative stress and inflammation as well as endothelial dysfunction. Our study demonstrates for the first time that blockade of ET receptor signaling by the dual endothelin receptor blocker macitentan improves adverse side effects of the organic nitrates ISMN and ISDN.

The dual role of Reactive Oxygen Species in autoimmune and inflammatory diseases: evidence from preclinical models

Reactive oxygen species (ROS) are created in cells during oxidative phosphorylation by the respiratory chain in the mitochondria or by the family of NADPH oxidase (NOX) complexes. The first discovered and most studied of these complexes, NOX2, mediates the oxidative burst in phagocytes. ROS generated by NOX2 are dreadful weapons: while being essential to kill ingested pathogens they can also cause degenerative changes on tissue if production and release are not balanced by sufficient detoxification. In the last fifteen years evidence has been accumulating that ROS are also integral signaling molecules and are important for regulating autoimmunity and immune-mediated inflammatory diseases. It seems that an accurate redox balance is necessary to sustain an immune state that both prevents the development of overt autoimmunity (the bright side of ROS) and minimizes collateral tissue damage (the dark side of ROS). Herein, we review studies from rodent models of arthritis, lupus, and neurodegenerative diseases that show that low NOX2-derived ROS production is linked to disease and elaborate on the underlying cellular and molecular mechanisms and the translation of these results to disease in humans.

High-glucose-induced changes in macrophage secretome: regulation of immune response

Secretory products from infiltrating macrophages have been thought to play crucial roles in development and progression of diabetic complications in various tissues/organs. Nevertheless, diabetes-induced changes in macrophage secretory products remained largely unknown. We thus analyzed high-glucose (HG)-induced changes in secretome of human macrophages derived from U937 human monocytic cell line after phorbol 12-myristate 13-acetate (PMA) activation. Serum-free culture supernatants were collected from macrophages exposed to 5.5 mM glucose (NG-M-sup) (normal control), 25 mM glucose (HG-M-sup), or 5.5 mM glucose + 19.5 mM mannitol (MN-M-sup) (osmotic control) for 16 h. After dialysis and lyophilization, secreted proteins were subjected to 2-DE analysis (n = 5 gels derived from 5 independent cultures per group). Quantitative analysis and statistics revealed 23 protein spots whose secretory levels significantly differed among the three conditions. These proteins were successfully identified by nanoLC-ESI-MS/MS analyses and changes in levels of heat shock protein 90 (HSP90), HSP70, HSP60, and β-actin were confirmed by Western blotting. Global protein network and functional enrichment analyses revealed that the altered proteins in HG-M-sup were involved mainly in regulation of immune response that might communicate with other bystander cells through the release of extracellular vesicles. These data may lead to a wider view of pathogenic mechanisms of diabetic complications.

Control-released Alpha-lipoic acid-loaded PLGA microspheres enhance bone formation in type 2 diabetic rat model

Since diabetes lead to alterations in bone metabolism with reductions in bone mineral content and delayed bone formation, the most effective method for bone regeneration in diabetes remains to be determined. In this study, type 2 diabetes were successfully induced via a high-fat diet and low-dose streptozotocin intraperitoneal injection. Excess reactive oxygen species (ROS) has been implicated in diabetes mellitus. Overexpression of ROS can lead to oxidative stress and subsequently to H₂O₂-mediated impaired proliferation and delayed cellular differentiation. As a result, antioxidant alpha-lipoic acid (ALA)-loaded poly (lactic-co-glycolic acid) (PLGA) microspheres were fabricated using the emulsion solvent evaporation method, and a sustained and controlled release of ALA was observed up to 27 days. It was demonstrated that biodegradable PLGA microspheres loaded with ALA acted as ROS scavengers and partially recover the mesenchymal stem cell proliferation and differentiation. The bone formation of ALA loaded scaffolds in rat cranial bone defects were greater than the prime three-dimensional collagen scaffold. These results suggest the application of ALA loaded PLGA microsphere exhibit good bioactivity and bone forming ability in diabetes.