CHIPing away at immunity: the role of clonal hematopoiesis of indeterminate potential in bacterial pneumonia.

The occurrence of clonal hematopoiesis of indeterminate potential (CHIP), in which advantageous somatic mutations result in the clonal expansion of blood cells, increases with age, as do an increased risk of mortality and detrimental outcomes associated with CHIP. However, the role of CHIP in susceptibility to pulmonary infections, which also increase with age, is unclear. In this issue of the JCI, Quin and colleagues explored the role of CHIP in bacterial pneumonia. Using characterization of immune cells from human donors and mice lacking tet methylcytosine dioxygenase 2 (Tet2), the authors mechanistically link myeloid immune cell dysfunction to CHIP-mediated risk of bacterial pneumonia. The findings suggest that CHIP drives inflammaging and immune senescence, and provide Tet2 status in older adults as a potential prognostic tool for informing treatment options related to immune modulation.