NOX2-dependent ATM kinase activation dictates pro-inflammatory macrophage phenotype and improves effectiveness to radiation therapy

Abstract

Although tumor-associated macrophages have been extensively studied in the control of response to radiotherapy, the molecular mechanisms involved in the ionizing radiation-mediated activation of macrophages remain elusive. Here we show that ionizing radiation induces the expression of interferon regulatory factor 5 (IRF5) promoting thus macrophage activation toward a pro-inflammatory phenotype. We reveal that the activation of the ataxia telangiectasia mutated (ATM) kinase is required for ionizing radiation-elicited macrophage activation, but also for macrophage reprogramming after treatments with γ-interferon, lipopolysaccharide or chemotherapeutic agent (such as cisplatin), underscoring the fact that the kinase ATM plays a central role during macrophage phenotypic switching toward a pro-inflammatory phenotype through the regulation of mRNA level and post-translational modifications of IRF5. We further demonstrate that NADPH oxidase 2 (NOX2)-dependent ROS production is upstream to ATM activation and is essential during this process. We also report that the inhibition of any component of this signaling pathway (NOX2, ROS and ATM) impairs pro-inflammatory activation of macrophages and predicts a poor tumor response to preoperative radiotherapy in locally advanced rectal cancer. Altogether, our results identify a novel signaling pathway involved in macrophage activation that may enhance the effectiveness of radiotherapy through the reprogramming of tumor-infiltrating macrophages.

The Emerging Roles of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 2 in Skeletal Muscle Redox Signaling and Metabolism

“…More recently, Ser486 in the so-called NOX-specific insertion sequence in the C-terminal NADPHbinding region was suggested to be an inhibitory phosphorylation site targeted by ataxia telangiectasia mutated kinase (ATM) (26). Since the NOX2 complex activates ATM (26,387), this might constitute a negative feedback loop to terminate the NOX2 activity. Interestingly, both ATM and PKC are expressed in skeletal muscle.…”

ATM-mediated DNA damage response in macrophages primes phagocytosis and immune checkpoint regulation

“…Interestingly, a study demonstrated that NBN (Q9R207; S398, S605, S638, S644, S645), which was highly phosphorylated in our analysis, a subunit of MRN complex plays a role in macrophage functional activity. Moreover, several studies reported that ATM is involved in diverse macrophage function, inflammatory response, antimicrobial response, and protection against sepsis (11)(12)(13)(14)(15).…”

“…Compelling evidence suggests the interplay and overlap between the DDR and innate immune responses: Some pathogens can induce genotoxic stress (8,9), while macrophages generate potent genotoxic species -ROS and NOS, during infections and tissue injury (10). Notably, the DDR has been reported to be involved in diverse macrophage functions such as inflammatory and antimicrobial responses and in the protection against sepsis (11)(12)(13)(14)(15). Specifically, ROS plays a role in differentiation of alternatively activated macrophages, while NOX2-induced ATM activation causes pro-inflammatory macrophage activation (13).…”

“…Notably, the DDR has been reported to be involved in diverse macrophage functions such as inflammatory and antimicrobial responses and in the protection against sepsis (11)(12)(13)(14)(15). Specifically, ROS plays a role in differentiation of alternatively activated macrophages, while NOX2-induced ATM activation causes pro-inflammatory macrophage activation (13). Additionally, chemo-and radiotherapy induces DNA lesions leading to a DDR that consequently triggers the apoptotic demise or senescence of cancer cells (16).…”

Macrophages in radiation injury: a new therapeutic target

“…However, several in vitro studies underscore the direct effect of IR in macrophage activation. 16–18 After in vitro cumulative ionizing radiation doses (2Gy/fraction/day), human monocyte-derived macrophages remain viable despite DNA damages, with an active metabolism. Cumulative doses of 10Gy increased proinflammatory, and decreased anti-inflammatory markers in macrophages.…”