Effects of the phenotypic polarization state of human leukocytes on the optical absorbance spectrum

Effect of photobiomodulation as preventive treatment of diabetic foot ulcer: randomised, controlled, double-blind, clinical trial protocol

INTRODUCTION

The prevention of diabetic foot ulcer (DFU) involves the classification of risk, systemic care, regular examinations, foot care, therapeutic education and adjunct treatments. Photobiomodulation (PBM) has been successfully administered for the healing of DFU and its preventive effects have drawn the interest of researchers.

METHODS AND ANALYSIS

The purpose of the study is to assess the effect of PBM for the prevention of DFU through a randomised, controlled, double-blind, clinical trial. Individuals from 18 to 75 years of age of both sexes with type 2 diabetes mellitus (DM) at moderate to high risk of developing DFU will be randomly allocated to two groups of 32 participants each. The PBM group will wear a boot with 1344 light-emitting diodes (LEDs)-504 with a wavelength of 660 nm located on the sides of the boot (28.5 mW, 10 J per LED), 504 with a wavelength of 850 nm also on the sides of the boot (23 mW, 8 J per LED), 168 with a wavelength of 660 nm on the base of the boot (28.5 mW, 10 J per LED) and 168 with a wavelength of 850 nm also on the base of the boot (23 mW, 8 J per LED). The boot will be worn once a day for 6 min over 60 days and the participants will also receive therapeutic education. The control group will wear a non-therapeutic LED boot (sham) under the same conditions and will also receive therapeutic education. Assessments will be performed at the beginning of the study, after 30 days (clinical examination) and after 60 days (clinical examination, assessment of peripheral neuropathy (PN) and peripheral artery disease (PAD), blood and urine examinations and quality of life).

ETHICS AND DISSEMINATION

This protocol received approval from the Human Research Ethics Committee of Nove de Julho University and the Mandaqui Hospital Complex (certificate number: 66098522.0.3001.5511; final approval date: 22 June 2023). The findings will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT06353568, ClinicalTrials.gov.

Potential Protective Role of TRPM7 and Involvement of PKC/ERK Pathway in Blue Light-Induced Apoptosis in Retinal Pigment Epithelium Cells in Vitro

PURPOSE

Blue light triggers apoptosis of retinal pigment epithelium (RPE) cells and causes retinal damage. The aim of this study was to elucidate the protective role of transient receptor potential melastatin 7 (TRPM7) in photodamaged RPE cells.

METHODS

RPE cells were isolated from Sprague-Dawley (SD) rats and exposed to varying intensities of blue light (500-5000 lux) in vitro. Cell proliferation and metabolic activity were respectively assessed by bromodeoxyuridine (BrdU) incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Real-time polymerase chain reaction (RT-PCR) and western blotting were used to analyze the TRPM7, protein kinase C (PKC), extracellular signal-regulated kinase (ERK) and Bcl2-associated x/B-cell lymphoma 2 (Bax/Bcl-2) messenger RNA (mRNA) and protein expression levels. The cells were transfected with TRPM7 small interfering RNA (siRNA) or transduced with TRPM7-overexpressing lentiviruses and cultured with or without the pigment epithelium-derived factor (PEDF).

RESULTS

Blue light inhibited the proliferation and metabolic activity of RPE cells in an intensity-dependent manner when compared to nonirradiated controls (P < 0.05). Compared to the control, photodamaged RPE cells showed decreased levels of TRPM7, PKC, ERK, and Bax, and an increase in Bcl-2 levels (P < 0.01). Forced expression of TRPM7 partially rescued the proliferative capacity of RPE cells (P < 0.01) and restored the levels of TRPM7, PKC, ERK, and Bax (P < 0.01), whereas TRPM7 knockdown had the opposite effects (P < 0.01). TRPM7 and PEDF synergistically alleviated the damaging effects of blue light.

CONCLUSIONS

Blue light triggers apoptosis of RPE cells, and its deleterious effects can be partially attenuated by the synergistic action of TRPM7 and PEDF via the PKC/ERK signaling pathway.