One Sentence Summary: Combined human and animal model studies conclusively implicate microbiota-triggered oral mucosal Th17 cells as drivers of local immunopathology and therapeutic targets in periodontitis.

Resolution of inflammation is essential for tissue homeostasis and a promising approach to inflammatory disorders. Here we found that DEL-1, a secreted protein inhibiting leukocyte-endothelial adhesion and inflammation initiation, also functions as a non-redundant downstream effector in inflammation clearance. In human and murine periodontitis, waning of inflammation correlated with DEL-1 upregulation, whereas resolution of experimental periodontitis failed in DEL-1 deficiency. This concept was mechanistically substantiated in acute monosodium urate crystal-induced inflammation, where the pro-resolution function of DEL-1 was attributed to effective apoptotic neutrophil clearance (efferocytosis). DEL-1-mediated efferocytosis induced liver-X-receptor-dependent macrophage reprogramming to pro-resolving phenotype and was required for optimal production of at least certain specific pro-resolving mediators. Experiments in transgenic mice with cell-specific overexpression of DEL-1 linked its anti-leukocyte recruitment action to endothelial-derived DEL-1 and its efferocytic/pro-resolving action to macrophage-derived DEL-1. Thus, the compartmentalized expression of DEL-1 facilitates distinct homeostatic functions in an appropriate context that can be harnessed therapeutically.

es. We show that Del-1, via its interaction with the αvβ3 integrin, promotes several critical functions in the niche, including HSC retention, hematopoietic progenitor cell cycle progression, and myeloid lineage commitment of HSCs. Del-1 thereby regulates myelopoiesis under steady-state conditions and in G-CSF-or inflammation-induced stress myelopoiesis, as well as myelopoiesis reconstitution under regenerative/transplantation conditions. Del-1 is hence a niche component that serves a juxtacrine homeostatic adaptation of the hematopoietic system in inflammation-related and regeneration myelopoiesis. ResultsDel-1 expression in the BM. First, we sought to investigate whether Del-1 is present in the BM. We initially studied the expression of the Del-1-encoding gene Edil3 in the BM niche and hematopoietic cell populations. We found that Edil3 mRNA expression was significantly higher in the endosteal region as compared with the central BM (cBM) ( Figure 1A), suggesting that Del-1 is enriched at the endosteal area of the BM. Analysis of sorted cells from CXCL12-GFP mice (33, 34) demonstrated that Edil3 was highly expressed integrin receptors (29-31). It consists of three N-terminal EGF-like repeats and two C-terminal discoidin I-like domains, and hence also is designated EGF-like repeats and discoidin-I-like domains-3 (EDIL3) (32). We have previously identified Del-1 as an endogenous modulator of leukocyte adhesion through interaction with integrin αLβ2 (LFA-1; CD11a/CD18) (29, 31). Moreover, Del-1 interacts with β3 integrin (CD61) via an Arg-Gly-Asp (RGD) motif on the second EGF-like repeat (30).In the present work, we observed that Del-1 is expressed by several major cellular components of the HSC niche, though not by hematopoietic progenitors. In particular, Del-1 is expressed by those niche cells that have a major role in the maintenance of HSCs, i.e., arteriolar endothelial cells and perivascular CAR cells (3,6,7,9,15). In addition, Del-1 is expressed by cells of the osteoblastic lineage that crucially mediate the engraftment of HSCs in the post-transplantation niche (3,17,18). This spatial distribution of Del-1 raised the possibility that it might be involved in the regulation of hematopoiesis. We addressed this hypothesis using in vivo models of steady-state, regenerative, and stress hematopoiesis and in vitro mechanistic approach-

Aim Human periodontitis is associated with overactivation of complement, which is triggered by different mechanisms converging on C3, the central hub of the system. We assessed whether the C3 inhibitor Cp40 inhibits naturally-occurring periodontitis in non-human primates. Materials and Methods Non-human primates with chronic periodontitis were intra-gingivally injected with Cp40 either once (5 animals) or three times (10 animals) weekly for six weeks followed by a 6-week follow-up period. Clinical periodontal examinations and collection of gingival crevicular fluid and biopsies of gingiva and bone were performed at baseline and during the study. A one-way repeated measures ANOVA was used for data analysis. Results Whether administered once or three times weekly, Cp40 caused a significant reduction in clinical indices that measure periodontal inflammation (gingival index and bleeding on probing), tissue destruction (probing pocket depth and clinical attachment level) or tooth mobility. These clinical changes were associated with significantly reduced levels of pro-inflammatory mediators and decreased numbers of osteoclasts in bone biopsies. The protective effects of Cp40 persisted, albeit at reduced efficacy, for at least six weeks following drug discontinuation. Conclusion Cp40 inhibits pre-existing chronic periodontal inflammation and osteoclastogenesis in non-human primates, suggesting a novel adjunctive anti-inflammatory therapy for treating human periodontitis.

Periodontitis is a prevalent inflammatory disease that leads to the destruction of the tooth-supporting tissues. Current therapies are not effective for all patients and this oral disease continues to be a significant public health and economic burden. Central to periodontal disease pathogenesis is a reciprocally reinforced interplay between microbial dysbiosis and destructive inflammation, suggesting the potential relevance of host-modulation therapies. This review summarizes and discusses clinical observations and pre-clinical intervention studies that collectively suggest that complement is hyperactivated in periodontitis and that its inhibition provides a therapeutic benefit. Specifically, interception of the complement cascade at its central component, C3, using a locally administered small peptidic compound (Cp40/AMY-101) protected non-human primates from induced or naturally occurring periodontitis. These studies indicate that C3-targeted intervention merits investigation as an adjunctive treatment of periodontal disease in humans.

Periodontitis is a chronic inflammatory disease associated with overactivation of the complement system. Recent preclinical studies suggest that host-modulation therapies may contribute to effective treatment of human periodontitis, which may lead to loss of teeth and function if untreated. We previously showed that locally administered AMY-101 (Cp40), a peptidic inhibitor of the central complement component C3, can inhibit naturally occurring periodontitis in non-human primates (NHPs) when given once a week. This study was undertaken to determine the local safety of increasing doses of the drug as well as its efficacy when given at a reduced frequency or after systemic administration. Our findings have determined a local dose of AMY-101 (0.1 mg/site) that is free of local irritation and effective when given once every 3 weeks. Moreover, a daily subcutaneous dose of AMY-101 (4 mg/kg bodyweight) was protective against NHP periodontitis, suggesting that patients treated for systemic disorders (e.g., paroxysmal nocturnal hemoglobinuria) can additionally benefit in terms of improved periodontal condition. In summary, AMY-101 appears to be a promising candidate drug for the adjunctive treatment of human periodontitis, a notion that merits investigation in human clinical trials.

Periodontitis is a dysbiotic inflammatory disease leading to the destruction of the tooth-supporting tissues. Current therapies are not always effective and this prevalent oral disease continues to be a significant health and economic burden. Early clinical studies have associated periodontitis with elevated complement activity. Consistently, subsequent genetic and pharmacological studies in rodents have implicated the central complement component C3 and downstream signaling pathways in periodontal host-microbe interactions that promote dysbiosis and inflammatory bone loss. This review discusses these mechanistic advances and moreover focuses on the compstatin family of C3 inhibitors as a novel approach to treat periodontitis. In this regard, local application of the current lead analog Cp40 was recently shown to block both inducible and naturally occurring periodontitis in non-human primates. These promising results from non-human primate studies and the parallel development of Cp40 for clinical use highlight the feasibility for developing an adjunctive, C3-targeted therapy for human periodontitis.

The causative role of inflammation in hypertension-related cardiovascular diseases is evident and calls for development of specific immunomodulatory therapies. We tested the therapeutic efficacy and mechanisms of action of developmental endothelial locus-1 (DEL-1), an endogenous antiinflammatory factor, in angiotensin II (ANGII)-and DOCA (deoxycorticosterone acetate)-saltinduced cardiovascular organ damage and hypertension. By using mice with endothelial overexpression of DEL-1 (EC-Del1) and performing preventive and interventional studies by injecting recombinant DEL-1 in mice, we showed that DEL-1 improved endothelial function and abrogated aortic adventitial fibrosis, medial thickening and loss of elastin. DEL-1 also protected the mice from cardiac concentric hypertrophy, interstitial and perivascular coronary fibrosis and improved left-ventricular function and myocardial coronary perfusion. DEL-1 prevented aortic stiffness and abolished the progression of hypertension. Mechanistically, DEL-1 acted by inhibiting αvβ3-integrin dependent activation of pro-MMP2 in mice and in human isolated aorta. Moreover, DEL-1 stabilized αvβ3-integrin dependent CD25+FoxP3+ Treg numbers and IL-10 levels, which were associated with decreased pro-inflammatory cell recruitment of inflammatory cells and reduced production of pro-inflammatory cytokines in cardiovascular organs. The demonstrated effects and immune-modulating mechanisms of DEL-1 in abrogation of cardiovascular remodeling and progression of hypertension identify DEL-1 as a potential therapeutic factor.