CD47 halts Ptpn6-deficient neutrophils from provoking lethal inflammation

Mice with SHP1 proteins, which have a single amino acid substitution from tyrosine-208 residue to asparagine (hereafter Ptpn6(spin) mice), develop an autoinflammatory disease with inflamed footpads. Genetic crosses to study CD47 function in Ptpn6(spin) mice bred Ptpn6(spin) × Cd47(−/−) mice that were not born at the expected Mendelian ratio. Ptpn6(spin) bone marrow cells, when transferred into lethally irradiated Cd47-deficient mice, caused marked weight loss and subsequent death. At a cellular level, Ptpn6-deficient neutrophils promoted weight loss and death of the lethally irradiated Cd47(−/−) recipients. We posited that leakage of gut microbiota promotes morbidity and mortality in Cd47(−/−) mice receiving Ptpn6(spin) cells. Colonic cell death and gut leakage were substantially increased in the diseased Cd47(−/−) mice. Last, IL-1 blockade using anakinra rescued the morbidity and mortality observed in the diseased Cd47(−/−) mice. These data together demonstrate a protective role for CD47 in tempering pathogenic neutrophils in the Ptpn6(spin) mice.