Restoration of blood flow in skeletal muscle after a prolonged period of ischemia induces muscular ischemia–reperfusion injury, leading to local injury/dysfunction in muscles followed by systemic inflammatory responses. However, preventive/curative agents for skeletal muscle ischemia injury are unavailable in clinics to date. Increasing evidence has validated that carbon monoxide (CO) prevents the progression of ischemia–reperfusion injury in various organs owing to its versatile bioactivity. Previously, we developed a bioinspired CO donor, CO-bound red blood cells (CO-RBC), which mimics the dynamics of RBC-associated CO in the body. In the present study, we have tested the therapeutic potential of CO-RBC in muscular injury/dysfunction and secondary systemic inflammation induced by skeletal muscle ischemia–reperfusion. The results indicate that CO-RBC rather than RBC alone suppressed elevation of plasma creatine phosphokinase, a marker of muscular injury, in rats subjected to both hind limbs ischemia–reperfusion. In addition, the results of the treadmill walking test revealed a significantly decreased muscular motor function in RBC-treated rats subjected to both hind limbs ischemia–reperfusion than that in healthy rats, however, CO-RBC treatment facilitated sustained muscular motor functions after hind limbs ischemia–reperfusion. Furthermore, CO-RBC rather than RBC suppressed the production of tumour necrosis factor (TNF)-α and interleukin (IL)-6, which were upregulated by muscular ischemia–reperfusion. Interestingly, CO-RBC treatment induced higher levels of IL-10 compared to saline or RBC treatments. Based on these findings, we suggest that CO-RBC exhibits a suppressive effect against skeletal muscle injury/dysfunction and systemic inflammatory responses after skeletal muscle ischemia–reperfusion.

Trastuzumab, an anti-HER2 monoclonal antibody, is the mainstay treatment for of HER2-positive breast cancer. However, trastuzumab resistance is often observed during treatment. Therefore, new therapeutic strategies are needed to enhance the clinical benefits of trastuzumab. Maitake β-glucan MD-Fraction, isolated from Grifola frondosa, inhibits tumor growth by enhancing immune responses. In this study, we examined the effect of MD-Fraction on trastuzumab treatment of HER2-positive breast cancer. MD-Fraction did not directly inhibit the survival of HER2-positive breast cancer cells, alone or in the presence of trastuzumab in vitro. In HER2-positive xenograft models, the combination of MD-Fraction and trastuzumab was more effective than trastuzumab alone. Peripheral blood lymphocytes and splenic natural killer cells isolated from BALB/c nu/nu mice treated with MD-Fraction showed enhanced trastuzumab-induced antibody-dependent cellular cytotoxicity (ADCC) ex vivo. MD-Fraction-treated macrophages and neutrophils did not show enhanced trastuzumab cytotoxicity in the presence of heat-inactivated serum, but they showed enhanced cytotoxicity in the presence of native serum. These results suggest that MD-Fraction-treated macrophages and neutrophils enhance trastuzumab-induced complement-dependent cellular cytotoxicity (CDCC). Treatment of HER2-positive breast cancer cells with MD-Fraction in the presence of trastuzumab and native serum increased C3a release and tumor cell lysis in a dose-dependent manner, indicating that MD-Fraction enhanced trastuzumab-induced complement-dependent cytotoxicity (CDC) by activating the complement system. This study demonstrates that the combination of trastuzumab and MD-Fraction exerts a greater antitumor effect than trastuzumab alone by enhancing ADCC, CDCC, and CDC in HER2-positive breast cancer.

L-Lactate transport via monocarboxylate transporters (MCTs) in the central nervous system, represented by the astrocyte-neuron lactate shuttle (ANLS), is crucial for the maintenance of brain functions, including memory formation. Previously, we have reported that MCT1 contributes to L-lactate transport in normal human astrocytes. Therefore, in this study, we aimed to identify transporters that contribute to L-lactate transport in human neurons. SH-SY5Y cells, which are used as a model for human neurons, were differentiated using all-trans-retinoic acid. L-Lactate uptake was measured using radiolabeled L-lactate, and the expression of MCT proteins was confirmed Western blotting. L-Lactate transport was pH-dependent and saturated at high concentrations. Kinetic analysis suggested that L-lactate uptake was biphasic. Furthermore, MCT1, 2 selective inhibitors inhibited L-lactate transport. In addition, the expression of MCT1 and 2 proteins, but not MCT4, was confirmed. In this study, we demonstrated that MCT1 and 2 are major contributors to L-lactate transport in differentiated human neuroblastoma SH-SY5Y cells from the viewpoint of kinetic analysis. These results lead to a better understanding of ANLS in humans, and further exploration of the factors that can promote MCT1 and 2 functions is required.

The number of patients with type 2 diabetes is increasing worldwide. The mechanisms leading to type 2 diabetes and its complications is being researched; however, the pathological mechanisms of diabetes in the small intestine remain unclear. Therefore, we examined these pathological mechanisms in the small intestine using a mouse model of type 2 diabetes (KK-Ay/TaJcl) aged 10 and 50 weeks. The results showed that diabetes worsened with age in the mice with type 2 diabetes. In these mice, advanced glycation end products (AGEs) in the small intestine and mast cell expression increased, whereas diamine oxidase (DAO) decreased; increased tumor necrosis factor (TNF)-α and histamine levels in the plasma and small intestine were also detected. Additionally, the expression of zonula occludens (ZO)-1 and Claudin1 and cell adhesion molecules in the small intestine reduced. These results exacerbated with age. These findings indicate that type 2 diabetes causes AGE/mast cell/histamine and TNF-α signal transmission in the small intestine and decreases small intestinal wall cell adhesion molecules cause TNF-α and histamine to flow into the body, worsening the diabetic condition. In addition, this sequence of events is suggested to be strengthened in aged mice with type 2 diabetes, thus exacerbating the disease. These findings of this study may facilitate the elucidation of the pathological mechanisms of type 2 diabetes and its associated complications.

Several reports assume that myocardial necroptotic cell death is induced during the development of chronic heart failure. Although it is well accepted that angiotensin II induces apoptotic cell death of cardiac myocytes, the involvement of angiotensin II in the induction of myocardial necroptosis during the development of heart failure is still unknown. Therefore, we examined the role of angiotensin II in myocardial necroptosis using rat failing hearts following myocardial infarction and cultured cardiomyocytes. We found that administration of azilsartan, an angiotensin II AT₁ receptor blocker, or trandolapril, an angiotensin-converting enzyme inhibitor, to rats from the 2nd to the 8th week after myocardial infarction resulted in preservation of cardiac function and attenuation of mixed lineage kinase domain-like (MLKL) activation. Furthermore, the ratio of necroptotic cell death was increased in neonatal rat ventricular cardiomyocytes cultured with conditioned medium from rat cardiac fibroblasts in the presence of angiotensin II. This increase in necroptotic cells was attenuated by pretreatment with azilsartan. Furthermore, activated MLKL was increased in cardiomyocytes cultured in conditioned medium. Pretreatment with azilsartan also prevented the conditioned medium-induced increase in activated MLKL. These results suggest that angiotensin II contributes to the induction of myocardial necroptosis during the development of heart failure.