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 Ptpn6spin mice), develop an autoinflammatory disease with inflamed footpads. Genetic crosses to study CD47 function in Ptpn6spin mice bred Ptpn6spin × Cd47-/- mice that were not born at the expected Mendelian ratio. Ptpn6spin 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 Ptpn6spin 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 Ptpn6spin mice.

Neutro"feels" lethal toxin.

Discussion on lethal toxin-induced acute IL-1ß production as dependent on NLRP1b and caspase-1, PAD4, cell-free DNA and neutrophils.

Leishmania major degrades murine CXCL1 - An immune evasion strategy.

Leishmaniasis is a global health problem with an estimated report of 2 million new cases every year and more than 1 billion people at risk of contracting this disease in endemic areas. The innate immune system plays a central role in controlling L. major infection by initiating a signaling cascade that results in production of pro-inflammatory cytokines and recruitment of both innate and adaptive immune cells. Upon infection with L. major, CXCL1 is produced locally and plays an important role in the recruitment of neutrophils to the site of infection. Herein, we report that L. major specifically targets murine CXCL1 for degradation. The degradation of CXCL1 is not dependent on host factors as L. major can directly degrade recombinant CXCL1 in a cell-free system. Using mass spectrometry, we discovered that the L. major protease cleaves at the C-terminal end of murine CXCL1. Finally, our data suggest that L. major metalloproteases are involved in the direct cleavage and degradation of CXCL1, and a synthetic peptide spanning the CXCL1 cleavage site can be used to inhibit L. major metalloprotease activity. In conclusion, our study has identified an immune evasion strategy employed by L. major to evade innate immune responses in mice, likely reservoirs in the endemic areas, and further highlights that targeting these L. major metalloproteases may be important in controlling infection within the reservoir population and transmittance of the disease.