Effect of a UV-C Automatic Last-Generation Mobile Robotic System on Multi-Drug Resistant Pathogens

Background: Healthcare-associated infections caused by multi-drug resistant (MDR) pathogens are associated with increased mortality and morbidity among hospitalized patients. Inanimate surfaces, and in particular high-touch surfaces, have often been described as the source for outbreaks of nosocomial infections. The present work aimed to evaluate the efficacy of a last-generation mobile (robotic) irradiation UV-C light device R2S on MDR microorganisms in inanimate surfaces and its translation to hospital disinfection. Methods: The efficacy of R2S system was evaluated in environmental high-touch surfaces of two separate outpatient rooms of Perugia Hospital in Italy. The static UV-C irradiation effect was investigated on both the bacterial growth of S. aureus, MRSA, P. aeruginosa, and K. pneumoniae KPC and photoreactivation. The antimicrobial activity was also tested on different surfaces, including glass, steel, and plastic. Results: In the environmental tests, the R2S system decreased the number of bacteria, molds, and yeasts of each high-touch spot surface (HTSs) compared with manual sanitization. UV-C light irradiation significantly inhibits in vitro bacterial growth, also preventing photoreactivation. UV-C light bactericidal activity on MDR microorganisms is affected by the type of materials of inanimate surfaces. Conclusions: The last-generation mobile R2S system is a more reliable sanitizing procedure compared with its manual counterpart.

Mitochondria structural integrity is essential for the protection of mitochondrial transplantation against UV-induced cell death

Background: Mitochondrial transplantation (MT) is a new technology developed in recent years, which injects healthy mitochondria directly into damaged tissues or blood vessels to play a therapeutic role. It has been studied in many animal models of various diseases, such as myocardial ischemia, cerebral stroke, liver and lung injury, and even has been successfully used in the treatment of childhood heart disease. MT can quickly improve tissue function within a few minutes after injection. This fast response is what is frequently questioned, for it is hard to understand how the whole mitochondria transport to the damaged sites, enter cells and function within such a short period of time. Are there any small molecules of mitochondrial component rather than the whole mitochondria that being responsible for the function of MT? To test this hypothesis, we established a much simple ultra-violet (UV)-irradiated HeLa cell model instead of the more complex animal models.Results: The results of colony formation, sulforhodamine B (SRB), and Hoechst 33342/PI double staining assay strongly indicated that MT exhibited a significant protective effect on UV irradiation damage. The UV irradiation-induced cell cycle arrest at S phase, apoptosis, mitochondrial membrane potential (MMP) decreasing, and the related apoptosis signalling factors p-IKKα, p-p65, I-κB and the activation of caspase3 were all reversed by MT treatments to some extent. Furthermore, mechanisms of MT were evaluated through comparing the effect of thermal inactivation, ultrasonic crushing, and repeated freezing and thawing treatments on MT function. The results denied the above hypothesis that mitochondrial component may function to MT, excluded the function of ATP, mtDNA and other small molecules, and indicated that the mitochondria structural integrity is essential.Conclusions: Our data support a potent anti-UV irradiation effect of MT, and structural integrity of mitochondria is critical for its function.

Irradiation Suppresses IFNγ-Mediated PD-L1 and MCL1 Expression in EGFR-Positive Lung Cancer to Augment CD8+ T Cells Cytotoxicity

Tumor cells express immune checkpoints to exhaust CD8+ T cells. Irradiation damages tumor cells and augments tumor immunotherapy in clinical applications. However, the radiotherapy-mediated molecular mechanism affecting CD8+ T cell activity remains elusive. We aimed to uncover the mechanism of radiotherapy augmenting cytotoxic CD8+ T cells in non-small-cell lung cancer (NSCLC). EGFR-positive NSCLC cell lines were co-cultured with CD8+ T cells from healthy volunteers. Tumor cell viability and apoptosis were consequently measured. IFNγ was identified secreted by CD8+ T cells and PBMCs. Therefore, RNAseq was used to screen the IFNγ-mediated gene expression in A549 cells. The irradiation effect to IFNγ-mediated gene expression was investigated using qPCR and western blots. We found that the co-culture of tumor cells stimulated the increase of granzyme B and IFNγ in CD8+ T, but A549 exhibited resistance against CD8+ T cytotoxicity compared to HCC827. Irradiation inhibited A549 proliferation and enhanced apoptosis, augmenting PBMCs-mediated cytotoxicity against A549. We found that IFNγ simultaneously increased phosphorylation on STAT1 and STAT3 in EGFR-positive lung cancer, resulting in overexpression of PD-L1 (p < 0.05). In RNAseq analysis, MCL1 was identified and increased by the IFNγ-STAT3 axis (p < 0.05). We demonstrated that irradiation specifically inhibited phosphorylation on STAT1 and STAT3 in IFNγ-treated A549, resulting in reductions of PD-L1 and MCL1 (both p < 0.05). Moreover, knockdowns of STAT3 and MCL1 increased the PBMCs-mediated anti-A549 effect. This study demonstrated that A549 expressed MCL1 to resist CD8+ T cell-mediated tumor apoptosis. In addition, we found that irradiation suppressed IFNγ-mediated STAT3 phosphorylation and PD-L1 and MCL1 expression, revealing a potential mechanism of radiotherapy augmenting immune surveillance.