Chronic inflammation and aging: DNA damage tips the balance

► The aging immune system is more prone to inflammation but less protective. ► DNA damage reduces stem cell renewal, depleting lymphoid and promoting myeloid progenitors. ► Poor DNA repair perpetuates damage and alters mature lymphocyte function. ► Aged T and B lymphocytes are less antigen-dependent and more inflammatory. ► Cytokine production by senescent cells exacerbates inflammation.