Excessive release of neutrophil extracellular traps (NETs) is associated with disease severity and contributes to tissue injury, followed by severe organ damage. Pharmacological or genetic inhibition of NET release reduces pathology in multiple inflammatory disease models, indicating that NETs are potential therapeutic targets. Here, we demonstrate using a preclinical basket approach that our therapeutic anti-citrullinated protein antibody (tACPA) has broad therapeutic potential. Treatment with tACPA prevents disease symptoms in various mouse models with plausible NET-mediated pathology, including inflammatory arthritis (IA), pulmonary fibrosis, inflammatory bowel disease and sepsis. We show that citrulline residues in the N-termini of histones 2A and 4 are specific targets for therapeutic intervention, whereas antibodies against other N-terminal post-translational histone modifications have no therapeutic effects. Because citrullinated histones are generated during NET release, we investigated the ability of tACPA to inhibit NET formation. tACPA suppressed NET release from human neutrophils triggered with physiologically relevant human diseaserelated stimuli. Moreover, tACPA diminished NET release and potentially initiated NET uptake by macrophages in vivo, which was associated with reduced tissue damage in the joints of a chronic arthritis mouse model of IA. To our knowledge, we are the first to describe an antibody with NET-inhibiting properties and thereby propose tACPA as a drug candidate for NET-mediated inflammatory diseases, as it eliminates the noxious triggers that lead to continued inflammation and tissue damage in a multidimensional manner.

The synthetic matrix metalloproteinase inhibitor batimastat was tested for its ability to inhibit growth and metastatic spread of the B16-BL6 murine melanoma in syngeneic C57BL/6N mice. Intraperitoneal administration of batimastat resulted in a significant inhibition in the number of lung colonies produced by B16-BL6 cells injected i.v. The effect of batimastat on spontaneous metastases was examined in mice inoculated in the hind footpad with B16-BL6 melanoma. The primary tumor was removed surgically after 26-28 days. Batimastat was administered twice a day from day 14 to day 28 (pre-surgery) or from day 26 to day 44 (post-surgery). With both protocols, the median number of lung metastases was not significantly affected, but there was a significant reduction in the weight of the metastases. Finally, the effect of batimastat was examined on s.c. growth of B16-BL6 melanoma. Batimastat administered daily, starting at day of tumor transplantation, resulted in a significant growth delay, whereas treatment starting at advanced stage tumor only reduced tumor growth marginally. Our results indicate that a matrix metalloproteinase inhibitor can not only prevent the colonization of secondary organs by B16-BL6 cells but also limit the growth of solid tumors.

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The neuronal protein tyrosine phosphatases encoded by mouse gene Ptprr (PTPBR7, PTP-SL, PTPPBSc-42 and PTPPBSc-37) have been implicated in mitogen-activated protein (MAP) kinase deactivation on the basis of transfection experiments. To determine their physiological role in vivo, we generated mice that lack all PTPRR isoforms. The cerebellum is the major centre of fine motor coordination in the central nervous system, and in addition serves in cognitive processing and sensory discrimination. Abbreviations used: DUSP, dual-specificity phosphatase; ERK, extracellular signal-regulated kinase; KIM, kinase interaction motif; MAPK, mitogen-activated protein kinase; PTP, protein tyrosine phosphatase.

Citrullinated histone epitopes are involved in the very early stages of inflammatory responses. An important early event is the activation of neutrophils. It has been shown that Peptidyl Arginine Deiminase (PAD) expression levels increase upon pro-inflammatory signalling followed by activation of neutrophils. Subsequently, PAD enzymes cause histone citrullination in the activated neutrophils. Histone citrullination is involved in various processes. One of the most important is NETosis, which results in the release of citrullinated histones to the extracellular space. There, they are involved in Neutrophil Extracellular Trap (NET) formation, which intensifies the inflammatory response. The central role of citrullinated histones in early inflammation makes NETs an attractive target for inflammatory disease intervention. Moreover, the safety profile is expected to be superior to immune-suppressing biologicals, like anti-Tumour Necrosis Factor (TNF) drugs. It is anticipated that shielding citrullinated histone epitopes from the immune system, as well as interfering with their putative roles in the inflammatory response, will have a broad applicability in preventing and treating various inflammatory diseases, including multiple sclerosis.