Far-infrared protects vascular endothelial cells from advanced glycation end products-induced injury via PLZF-mediated autophagy in diabetic mice

Advances in far-infrared research: therapeutic mechanisms of disease and application in cancer detection

Far infrared (FIR) irradiation is commonly used as a convenient, non-contact, non-invasive treatment for diseases such as myocardial ischemia, diabetes, and chronic kidney disease. In this review, we focus on reviewing the potential therapeutic mechanisms of FIR and its cutting-edge applications in cancer detection. Firstly, we searched the relevant literature in the last decade for systematic screening and briefly summarized the biophysical properties of FIR. We then focused on the possible mechanisms of FIR in wound healing, cardiovascular diseases, and other chronic diseases. In addition, we review recent applications of FIR in cancer detection, where Fourier transform infrared spectroscopy and infrared thermography provide additional diagnostic methods for the medical diagnosis of cancer. Finally, we conclude and look into the future development of FIR for disease treatment and cancer detection. As a high-frequency non-ionizing wave, FIR has the advantages of safety, convenience, and low cost. We hope that this review can provide biological information reference and relevant data support for those who are interested in FIR and related high-frequency non-ionizing waves, to promote the further application of FIR in the biomedical field.

Different types of cell death in diabetic endothelial dysfunction

Diabetes mellitus is a metabolic disease caused by disorders of insulin secretion and utilization. Long-term hyperglycemia, insulin resistance, and disorders of glucose and lipid metabolism cause vascular endothelial cell damage. Endothelial dysfunction is a key feature of diabetic vascular complications such as diabetic nephropathy, retinopathy, neuropathy, and atherosclerosis. Importantly, cell death is thought to be a key factor contributing to vascular endothelial injury. Morphologically, cell death can be divided into three forms: type I apoptosis, type II autophagy, and type III necrosis. According to the difference in function, cell death can be divided into accidental cell death (ACD) and regulated cell death (RCD). RCD is a controlled process involving numerous proteins and precise signaling cascades. Multiple subroutines covered by RCD may be involved in diabetic endothelial dysfunction, including apoptosis, autophagy, necroptosis, pyroptosis, entosis, ferroptosis, ferroautophagy, parthanatos, netotic cell death, lysosome-dependent cell death, alkaliptosis, oxeiptosis, cuproptosis, and PANoptosis. This article briefly reviews the mechanism and significance of cell death associated with diabetic endothelial dysfunction, which will help deepen the understanding of diabetic endothelial cell death and provide new therapeutic ideas.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

ZBTB16 eases lipopolysaccharide‑elicited inflammation, apoptosis and degradation of extracellular matrix in chondrocytes during osteoarthritis by suppressing GRK2 transcription

Osteoarthritis (OA) is a chronic degenerative disease of the bone that is a major contributor of disability in the elderly population. Zinc finger and BTB domain-containing 16 (ZBTB16) is a transcription factor that has been previously revealed to be impaired in human OA tissues. The present study was designed to elaborate the potential impact of ZBTB16 on OA and to possibly assess any latent regulatory mechanism. ZBTB16 expression in human OA tissues was examined using the Gene Expression Series (GSE) database (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE169077) whereas ZBTB16 expression in chondrocytes was examined using reverse transcription-quantitative PCR (RT-qPCR) and western blotting. Cell viability was examined using a Cell Counting Kit-8 assay. A TUNEL assay and western blotting were used to assess cell apoptosis and apoptosis-related markers, including Bcl-2, Bax and cleaved caspase-3. The levels and expression of inflammatory factors, including TNF-α, IL-1β and IL-6, were determined by ELISA and western blotting. RT-qPCR and western blotting were also used to analyze the expression levels of extracellular matrix (ECM)-degrading enzymes, including MMP-13, a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs-5, aggrecan and collagen type II α1. After the potential binding of ZBTB16 with the G protein coupled receptor kinase type 2 (GRK2) promoter was predicted using the Cistrome DB database, GRK2 expression was confirmed by RT-qPCR and western blotting. Chromatin immunoprecipitation and luciferase reporter assays were then used to determine the potential interaction between ZBTB16 and the GRK2 promoter. Following GRK2 overexpression in ZBTB16-overexpressing chondrocytes by co-transfection of GRK2 and ZBTB16 overexpression plasmids, the aforementioned functional experiments were performed again. ZBTB16 expression was found to be reduced in human OA tissues compared with in normal cartilage tissues and lipopolysaccharide (LPS)-stimulated chondrocytes. ZBTB16 overexpression increased cell viability whilst decreasing apoptosis, inflammation and ECM degradation by LPS-treated chondrocytes. In addition, GRK2 expression was found to be increased in LPS-stimulated chondrocytes. ZBTB16 successfully bound to the GRK2 promoter, which negatively modulated GRK2 expression. GRK2 upregulation reversed the effects of ZBTB16 overexpression on the viability, apoptosis, inflammation and ECM degradation by LPS-challenged chondrocytes. In conclusion, these data suggest that ZBTB16 may inhibit the development of OA through the transcriptional inactivation of GRK2.

Endothelial Autophagy Dysregulation in Diabetes

Diabetes mellitus is a major public health issue that affected 537 million people worldwide in 2021, a number that is only expected to increase in the upcoming decade. Diabetes is a systemic metabolic disease with devastating macro- and microvascular complications. Endothelial dysfunction is a key determinant in the pathogenesis of diabetes. Dysfunctional endothelium leads to vasoconstriction by decreased nitric oxide bioavailability and increased expression of vasoconstrictor factors, vascular inflammation through the production of pro-inflammatory cytokines, a loss of microvascular density leading to low organ perfusion, procoagulopathy, and/or arterial stiffening. Autophagy, a lysosomal recycling process, appears to play an important role in endothelial cells, ensuring endothelial homeostasis and functions. Previous reports have provided evidence of autophagic flux impairment in patients with type I or type II diabetes. In this review, we report evidence of endothelial autophagy dysfunction during diabetes. We discuss the mechanisms driving endothelial autophagic flux impairment and summarize therapeutic strategies targeting autophagy in diabetes.

Far-infrared radiation alleviates cisplatin-induced vascular damage and impaired circulation via activation of HIF-1α

Severe vascular damage and complications are often observed in cancer patients during treatment with chemotherapeutic drugs such as cisplatin. Thus, development of potential options to ameliorate the vascular side effects is urgently needed. In this study, the effects and the underlying mechanisms of far‐infrared radiation (FIR) on cisplatin‐induced vascular injury and endothelial cytotoxicity/dysfunction in mice and human umbilical vein endothelial cells (HUVECs) were investigated. An important finding is that the severe vascular stenosis and poor blood flow seen in cisplatin‐treated mice were greatly mitigated by FIR irradiation (30 minutes/day) for 1‐3 days. Moreover, FIR markedly increased the levels of phosphorylation of PI3K and Akt, and VEGF secretion, as well as the expression and the activity of hypoxia‐inducible factor 1α (HIF‐1α) in cisplatin‐treated HUVECs in a promyelocytic leukemia zinc finger protein (PLZF)‐dependent manner. However, FIR‐stimulated endothelial angiogenesis and VEGF release were significantly diminished by transfection with HIF‐1α siRNA. We also confirmed that HIF‐1α, PI3K, and PLZF contribute to the inhibitory effect of FIR on cisplatin‐induced apoptosis in HUVECs. Notably, FIR did not affect the anticancer activity and the HIF‐1α/VEGF cascade in cisplatin‐treated cancer cells under normoxic or hypoxic condition, indicating that the actions of FIR may specifically target endothelial cells. It is the first study to demonstrate that FIR effectively attenuates cisplatin‐induced vascular damage and impaired angiogenesis through activation of HIF‐1α–dependent processes via regulation of PLZF and PI3K/Akt. Taken together, cotreatment with the noninvasive and easily performed FIR has a therapeutic potential to prevent the pathogenesis of vascular complications in cancer patients during cisplatin treatment.

Suppressive role of E3 ubiquitin ligase FBW7 in type I diabetes in non-obese diabetic mice through mediation of ubiquitination of EZH2

The current study tried to uncover the molecular mechanism of E3 ubiquitin ligase F-box and WD repeat domain-containing 7 (FBW7) in a heritable autoimmune disease, type I diabetes (T1D). After streptozotocin-induced T1D model establishment in non-obese diabetic (NOD) mouse, the protein expression of FBW7, enhancer of zeste homolog 2 (EZH2), and Zinc finger and BTB domain containing 16 (ZBTB16) was quantified. Next, splenocytes and pancreatic beta cells were isolated to measure the production of pro-inflammatory cytokines in splenocytes, as well as islet beta-cell apoptosis. Additionally, the stability of EZH2 induced by FBW7 was analyzed by cycloheximide chase assay. The binding affinity of FBW7 and EZH2 and the consequence of ubiquitination were monitored by co-immunoprecipitation assay. Last, a chromatin immunoprecipitation assay was employed to analyze the accumulation of EZH2 and H3K27me3 at the ZBTB16 promoter region. Our study demonstrated downregulated FBW7 and ZBTB16 and upregulated EZH2 in diabetic NOD mice. Overexpression of FBW7 in the NOD mice inhibited pro-inflammatory cytokine release in the splenocytes and the apoptosis of islets beta cells. FBW7 destabilized EZH2 and accelerated ubiquitin-dependent degradation. EZH2 and H3K27me3 downregulated the ZBTB16 expression by accumulating in the ZBTB16 promoter and methylation. FBW7 upregulates the expression of ZBTB16 by targeting histone methyltransferase EZH2 thus reducing the occurrence of T1D.

The Effect of Far-Infrared Therapy on the Peritoneal Membrane Transport Characteristics of Uremic Patients Undergoing Peritoneal Dialysis: An Open-Prospective Proof-of-Concept Study

Long-term peritoneal dialysis (PD) can lead to detrimental changes in peritoneal membrane function, which may be related to the accumulation of glucose degradation products. A previous study demonstrated that 6 months of far-infrared (FIR) therapy may decrease glucose degradation products in PD dialysate. Due to limited literature on this matter, this study aims to investigate the effect of FIR therapy on the peritoneal membrane transport characteristics of PD patients. Patients were grouped according to baseline peritoneal transport status: lower transporters (low and low-average) and higher transporters (high-average and high). Both groups underwent 40 min of FIR therapy twice daily for 1 year. In lower transporters, FIR therapy increased weekly dialysate creatinine clearance (6.91 L/wk/1.73 m²; p = 0.04) and D/P creatinine (0.05; p = 0.01). In higher transporters, FIR therapy decreased D/P creatinine (−0.05; p = 0.01) and increased D/D0 glucose (0.05; p = 0.006). Fifty percent of high transporter patients shifted to high-average status after FIR therapy. FIR therapy may decrease D/P creatinine for patients in the higher transporter group and cause high transporters to shift to high-average status, which suggests the potential of FIR therapy in improving peritoneal membrane function in PD patients.

Sunlight and health: shifting the focus from vitamin D3 to photobiomodulation by red and near-infrared light

Both sun exposure and serum vitamin D levels have been associated with lower risks of all-cause mortality and chronic age-related diseases, e.g., cancer, diabetes and cardiovascular disease, in epidemiological studies. These associations have mainly been ascribed to beneficial effects of vitamin D. However, a vast body of randomized controlled trials (RCTs) and Mendelian randomization studies have failed to confirm any major health benefits from vitamin D supplementation. In this review, we present tentative evidence showing that red and near-infrared light, both being present in sunlight, could explain the associations between sunlight exposure and better health status. Body irradiation with red and near-infrared light, usually termed as photobiomodulation (PBM), has demonstrated beneficial effects in animal models of chronic diseases. Beyond this, preliminary evidence from RCTs suggest potential clinical benefit from PBM for chronic diseases. PBM is currently being investigated in many pre-registered clinical trials, results of which will eventually clarify the role of red and near-infrared light in the prevention and treatment of common age-related chronic diseases.

miR-548aq-3p is a novel target of Far infrared radiation which predicts coronary artery disease endothelial colony forming cell responsiveness

Non-invasive far infrared radiation (FIR) has been observed to improve the health of patients with coronary artery disease (CAD). Endothelial colony forming cells (ECFCs) contribute to vascular repair and CAD. The goal of this study was to uncover the role of FIR in ECFCs function and to reveal potential biomarkers for indication of FIR therapy in CAD patients. FIR significantly enhanced in vitro migration (transwell assay) and tube formation (tube length) capacities in a subpopulation of CAD ECFCs. Clinical parameters associated with the responsiveness of ECFCs to FIR include smoking and gender. ECFCs from CAD patients that smoke did not respond to FIR in most cases. In contrast, ECFCs from females showed a higher responsiveness to FIR than ECFCs from males. To decipher the molecular mechanisms by which FIR modulates ECFCs functions, regardless of sex, RNA sequencing analysis was performed in both genders of FIR-responsive and FIR-non/unresponsive ECFCs. Gene Ontology (GO) analysis of FIR up-regulated genes indicated that the pathways enriched in FIR-responsive ECFCs were involved in cell viability, angiogenesis and transcription. Small RNA sequencing illustrated 18 and 14 miRNAs that are up- and down-regulated, respectively, in FIR-responsive CAD ECFCs in both genders. Among the top 5 up- and down-regulated miRNAs, down-regulation of miR-548aq-3p in CAD ECFCs after FIR treatment was observed in FIR-responsive CAD ECFCs by RT-qPCR. Down-regulation of miR-548aq-3p was correlated with the tube formation activity of CAD ECFCs enhanced by FIR. After establishment of the down-regulation of miR-548aq-3p by FIR in CAD ECFCs, we demonstrated through overexpression and knockdown experiments that miR-548aq-3p contributes to the inhibition of the tube formation of ECFCs. This study suggests the down-regulation of miR-548aq-3p by FIR may contribute to the improvement of ECFCs function, and represents a novel biomarker for therapeutic usage of FIR in CAD patients.

Far-infrared Ray-mediated Antioxidant Potentials are Important for Attenuating Psychotoxic Disorders

Far-infrared ray (FIR) is an electromagnetic wave that produces various health benefits against pathophysiological conditions, such as diabetes mellitus, renocardiovascular disorders, stress, and depression etc. However, the therapeutic ap-plication on the FIR-mediated protective potentials remains to be further extended. To achieve better understanding on FIR-mediated therapeutic potentials, we summarized additional findings in the present study that exposure to FIR ameliorates stressful condition, memory impairments, drug dependence, and mitochondrial dysfunction in the central nervous system. In this review, we underlined that FIR requires modulations of janus kinase 2 / signal transducer and activator of transcription 3 (JAK2/STAT3), nuclear factor E2-related factor 2 (Nrf-2), muscarinic M1 acetylcholine receptor (M1 mAChR), dopamine D1 receptor, protein kinase C δ gene, and glutathione peroxidase-1 gene for exerting the protective potentials in response to neuropsychotoxic conditions

Inhibition of autophagy of Cajal mesenchymal cells by gavage of tong bian decoction based on the rat model of chronic transit constipation

The objective of this research was to study the effect of tong bian decoction on colon transport function of interstitial cells of Cajal (ICC) in chronic transit constipation (CTC) and the inhibition of autophagy of ICC, so as to achieve the free movement of the bowels. In this research, the experimental rats were divided into normal group (NG) and model group (MG) by random method, and the rat model of CTC was constructed by subdivision circulatory increasing operation gavage method of rhubarb. After the successful establishment of the model, the rats were divided into normal group, MG, tong bian decoction gavage group, mosapride group and normal recovery group. Then, rats in the NG and the MG were killed at the same time, and rats in the tong bian decoction gavage group, mosapride group and normal recovery group were killed at the same time. In this study, the transport function of colon of rats in each group was detected by activated carbon method, and the number of fecal residues in the colon was observed. The mRNA expression of c-kit gene in intestinal tissue of rat was detected by real-time quantitative polymerase chain reaction (RT-qPCR). In addition, the changes of ICC in rats treated with different drugs were detected by immunohistochemical method. The results revealed that in the tong bian decoction gavage group, the water content in the feces of rats was remarkably increased (P < 0.05), the amount of residual feces in the colon was remarkably reduced (P < 0.01), the percentage of carbon powder propulsion in small intestine was remarkably increased (P < 0.01), the staining area of ICC positive cells in colon tissue was remarkably increased (P < 0.05), and the expression of c-kit mRNA was remarkably increased (P < 0.01). It can be concluded that the tong bian decoction could effectively enhance the colon transport function in the rat model of CTC. This laxative mechanism promotes the regeneration and repair ability of ICC by inhibiting the autophagy of ICC, and provides power for the large intestine, so as to achieve the free movement of the bowels. Therefore, the results of this study have certain guiding meaning for the treatment of CTC with traditional Chinese medicine.

Detecting the limits of the biological effects of far-infrared radiation on epithelial cells

Far-infrared radiation (FIR) exerts numerous beneficial effects on health and cell physiology. Recent studies revealed that the biological effects of FIR are independent of thermal effects. There is no proper method for measuring the parameters of the non-thermal biological effects of FIR, which limits its biomedical application. In this study, we established a cell detection platform using epithelial cell migration to measure the limits of the biological effects of FIR. FIR promoted the migration of rat renal tubular epithelial cells as revealed by our standardized detection method. We defined the ratio of the FIR-promoted migration area to the migration area of the control group as the FIR biological index (FBI). An increase of the FBI was highly associated with FIR-promoted mitochondrial function. Through FBI detection, we revealed the limits of the biological effects of FIR, including effective irradiation time, wavelengths, and temperature. FBI detection can be used to clarify important parameters of the biological effects of FIR in biomedical studies and health industry applications.

Far infrared promotes wound healing through activation of Notch1 signaling

The Notch signaling pathway is critically involved in cell proliferation, differentiation, development, and homeostasis. Far infrared (FIR) has an effect that promotes wound healing. However, the underlying molecular mechanisms are unclear. In the present study, we employed in vivo and HaCaT (a human skin keratinocyte cell line) models to elucidate the role of Notch1 signaling in FIR-promoted wound healing. We found that FIR enhanced keratinocyte migration and proliferation. FIR induced the Notch1 signaling pathway in HaCaT cells and in a microarray dataset from the Gene Expression Omnibus database. We next determined the mRNA levels of NOTCH1 in paired normal and wound skin tissues derived from clinical patients using the microarray dataset and Ingenuity Pathway Analysis software. The result indicated that the Notch1/Twist1 axis plays important roles in wound healing and tissue repair. In addition, inhibiting Notch1 signaling decreased the FIR-enhanced proliferation and migration. In a full-thickness wound model in rats, the wounds healed more rapidly and the scar size was smaller in the FIR group than in the light group. Moreover, FIR could increase Notch1 and Delta1 in skin tissues. The activation of Notch1 signaling may be considered as a possible mechanism for the promoting effect of FIR on wound healing. FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model.

KEY MESSAGES

FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model.

Far-infrared suppresses skin photoaging in ultraviolet B-exposed fibroblasts and hairless mice

Ultraviolet (UV) induces skin photoaging, which is characterized by thickening, wrinkling, pigmentation, and dryness. Collagen, which is one of the main building blocks of human skin, is regulated by collagen synthesis and collagen breakdown. Autophagy was found to block the epidermal hyperproliferative response to UVB and may play a crucial role in preventing skin photoaging. In the present study, we investigated whether far-infrared (FIR) therapy can inhibit skin photoaging via UVB irradiation in NIH 3T3 mouse embryonic fibroblasts and SKH-1 hairless mice. We found that FIR treatment significantly increased procollagen type I through the induction of the TGF-β/Smad axis. Furthermore, UVB significantly enhanced the expression of matrix metalloproteinase-1 (MMP-1) and MMP-9. FIR inhibited UVB-induced MMP-1 and MMP-9. Treatment with FIR reversed UVB-decreased type I collagen. In addition, FIR induced autophagy by inhibiting the Akt/mTOR signaling pathway. In UVB-induced skin photoaging in a hairless mouse model, FIR treatment resulted in decreased skin thickness in UVB irradiated mice and inhibited the degradation of collagen fibers. Moreover, FIR can increase procollagen type I via the inhibition of MMP-9 and induction of TGF-β in skin tissues. Therefore, our study provides evidence for the beneficial effects of FIR exposure in a model of skin photoaging.