Reactive Oxygen Species in Pathogen Clearance: The Killing Mechanisms, the Adaption Response, and the Side Effects

Abstract

Reactive oxygen species (ROS) are attractive weapons in both antibiotic-mediated killing and host-mediated killing. However, the involvement of ROS in antibiotic-mediated killing and complexities in host environments challenge the paradigm. In the case of bacterial pathogens, the examples of some certain pathogens thriving under ROS conditions prompt us to focus on the adaption mechanism that pathogens evolve to cope with ROS. Based on these, we here summarized the mechanisms of ROS-mediated killing of either antibiotics or the host, the examples of bacterial adaption that successful pathogens evolved to defend or thrive under ROS conditions, and the potential side effects of ROS in pathogen clearance. A brief section for new antibacterial strategies centered around ROS was also addressed.

Influence of the Metabolic Activity of Microorganisms on Disinfection Efficiency of the Visible Light and P25 TiO2 Photocatalyst

“…The phenomenon of visible light activated TiO 2 could be compared to some effects of antibiotics: if primary damage of the specific targets is severe enough, it can result in death directly. Otherwise, primary damage stimulates a pathway that leads to the accumulation of ROS, causing secondary damage [21] leading to the possible death of bacteria. However, bacteria are constantly adapting to their environment and they have a well-developed antioxidant system which allows them to survive.…”

“…[19,20]. Different bacteria transcription factors, such as OxyR, PerR, OhrR, and SoxRS can be activated by direct oxidation of their sensor proteins, and then can adjust the bacterial response appropriately [21]. Moreover, bacteria with and without specific antioxidant systems, can reduce the suffered oxidative damage by remodeling their metabolism [21].…”

“…Different bacteria transcription factors, such as OxyR, PerR, OhrR, and SoxRS can be activated by direct oxidation of their sensor proteins, and then can adjust the bacterial response appropriately [21]. Moreover, bacteria with and without specific antioxidant systems, can reduce the suffered oxidative damage by remodeling their metabolism [21]. Altogether this means that photocatalytic disinfection efficiency of microorganisms depends on at least the following three factors: photocatalyst properties, irradiation characteristics, and specific microorganism response to the oxidative stress.…”

Metabolic Implications of Oxidative Stress and Inflammatory Process in SARS-CoV-2 Pathogenesis: Therapeutic Potential of Natural Antioxidants

“…The physiologic role of reactive species is also evident from both innate and adaptive immune mediated reactive species generation that targets pathogen infiltration into the host system ( Lam et al., 2010 ). During exposure to pathogens, phagocytes generate ROS via oxidative burst to attack pathogens ( Li et al., 2021 ). If some pathogens escape this response, adaptive immune response is then initiated, which uses pathogen-derived antigenic peptides produced by phagocytosis and digestion that are presented to T lymphocytes ( Gasteiger and Rudensky, 2014 ).…”

The Reactive Oxygen Species Singlet Oxygen, Hydroxy Radicals, and the Superoxide Radical Anion—Examples of Their Roles in Biology and Medicine

“…These radicals could then cause subsequent damage to SARS-CoV-2, the virus which causes COVID-19. Possibly related is the complex behaviour of ROS with pathogens, where the precise conditions can lead to ROS-mediated pathogen killing or adaption, allowing pathogens to defend or thrive under ROS conditions [45].…”