Resolution of Inflammation, Infection and Tissue Regeneration

Cancer therapy reduces tumor burden by killing tumor cells, yet simultaneously creates tumor cell debris that may stimulate inflammation and tumor growth. Thus, conventional cancer therapy is inherently a double-edged sword. Here, we show that tumor cells killed by chemotherapy or targeted therapy (“tumor cell debris”) stimulated primary tumor growth when co-injected with a subthreshold (non-tumorigenic) inoculum of tumor cells, by triggering macrophage pro-inflammatory cytokine release following phosphatidylserine exposure. Debris-stimulated tumors were inhibited by anti-inflammatory and pro-resolving lipid autacoids, namely resolvin (Rv) D1, RvD2, or RvE1. These mediators specifically inhibited debris-stimulated cancer progression by enhancing clearance of debris via macrophage phagocytosis in multiple tumor types. Resolvins counter-regulated release of cytokines/chemokines, including TNFα, IL-6, IL-8, CCL4, and CCL5, by human macrophages stimulated with cell debris. These results demonstrate that enhancing endogenous clearance of tumor cell debris is a new therapeutic target that may complement cytotoxic cancer therapies.

Clearance of apoptotic cells (ACs) by macrophages (efferocytosis) is a key resolution effector function. We have revealed the presence of a positive-feedback cycle in which activation of the efferocytosis receptor MerTK by ACs promotes the synthesis of 5-lipoxygenase-derived resolution mediators. In terms of efferocytosis itself, macrophages must be able to rapidly internalize multiple ACs ("continued efferocytosis"). For example, in mice in which macrophages can clear one AC normally but have a defect in continued efferocytosis, the accumulation of uncleared dead cells and consequent tissue necrosis and inflammation are prominent. Continued efferocytosis has two fundamental requirements: (1) recycling of membranes such that internalization of the plasma membrane during phagocytosis of the 1^st AC is rapidly followed by vesicular trafficking of phagolysosomal membrane to the cell surface, i.e., to enable restoration of plasma membrane surface area for 2^nd AC phagocytosis; and (2) "cargo handling" by the macrophage in response to the large load of molecules, e.g., amino acids and fatty acids, resulting from the phagolysosomal degradation of the 1^st AC. We have shown that the first process is mediated by a mitochondrial fission-calcium pathway and that the second process features a specific amino acid metabolism-Rac1 pathway that licenses the macrophage to internalize a 2^nd AC. In summary, efferocytosis is a key arm of the resolution response that participates in a mediator « effector positive-feedback cycle of resolution, and in order for efferocytosis to function properly, macrophages must carry out specific signaling and metabolism pathways to enable the uptake of multiple ACs.

Pain is often associated with inflammation and is a cardinal features of inflammation. In collaboration with Dr. Serhan, we have demonstrated that specialized pro-resolution mediators (SPMs) such as resolvins (RvD1, RvE1, RvD2), protectins (eg. protectin D1/neuroprotectin D1 (PD1/NPD1) and maresin (MaR1) produce potent analgesic effects in animal models of inflammatory pain. As expected, the analgesic effects of SPMs could be associated with their regulation of inflammation (anti-inflammation and pro-resolution). However, we also found the existence of functional SPM receptors (e.g., ChemR23) in neurons, especially in primary sensory neurons in dorsal root ganglion (DRG) that can sense various nociceptive signals. Strikingly, SPMs rapidly modulate the function of ion channels, such as TRPV1 and TRPA1 that are critically involved in the induction of inflammatory pain. Electrophysiology revealed that resolvin E1 (RvE1) can potentially suppress the TRPV1 current induced by capsaicin in mouse and human DRG neurons. This effect is mediated by ChemR23 and beta-arrestin-2. I will also show evidence that SPMs prevent the development of neuropathic pain by controlling neuroinflammation such as activation of glial cells in the spinal cord. We also found a loss of SPMs (such as RvD1) during the development of chronic pain. Finally, I will demonstrate signaling mechanisms by which SPMs regulate phagocytosis and phenotypes of macrophages. Together, our data demonstrate that SPMs control the resolution of pain by both neural and immune regulations.

Inflammation and its resolution impact on multiple organ systems and multiple disease processes including atherosclerosis and cancer, yet until recently there has been no proof of concept that lowering inflammation could lower the risks of these life-threatening disorders. The Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS), conducted between 2010 and 2017 in 39 countries and involving over 1000 investigators, randomly allocated 10,061 post-myocardial infarction patients with elevated hsCRP to placebo or one of three doses of canakinumab, a monoclonal antibody targeting intereukin-1-beta (50mg, 150mg, 300mg SC once every 3 months). Primary results of CANTOS demonstrate for the first time that, in the absence of lipid lowering or blood pressure reduction, inhibition of IL-1-beta and consequent lowering of IL-6 and hsCRP results in statistically significant benefits for major cardiovascular events as well as incident lung cancer. In his talk, Dr Ridker will provide updates on multiple CANTOS sub-studies as they relate to diabetes, kidney disease, chronic anemia, gout, and other rheumatologic conditions, emphasizing the “systems biology” approach used to design and run the trial and the importance of recognizing and treating “residual inflammatory risk”.

Unresolved inflammation is central to the pathophysiology of commonly occurring vascular diseases such as atherosclerosis, aneurysm, and deep vein thrombosis—conditions that are responsible for considerable morbidity and mortality across the globe. Surgical or catheter-based procedures performed to treat vascular disease induce acute on chronic inflammatory responses. The resolution of vascular inflammation is an important driver of vessel wall healing and functional recovery in these clinical settings. Specialized pro-resolving lipid mediators (SPMs) derived from omega-3 polyunsaturated fatty acids orchestrate key cellular processes driving resolution and return to homeostasis. The identification of their potent effects in classic animal models of sterile inflammation triggered interest in their vascular properties. Recent studies have demonstrated that SPMs are locally synthesized in vascular tissues, have direct effects on vascular cells and their interactions with leukocytes, and play a protective role in the acute injury response. Early translational work has established the potential for SPMs as vascular therapeutics, and as candidate biomarkers in vascular disease. Specifically, targeted delivery of SPM to sites of vascular injury has emerged as a potential therapeutic approach to enhance vascular healing and patency. Further investigations are needed to understand the molecular and cellular mechanisms of resolution in the vasculature, improve tools for clinical measurement, and to better define the potential for resolution pharmaco-biology in cardiovascular patients.

Non-resolving inflammation is the underpinning of several prevalent diseases including atherosclerosis. Understanding new mechanisms to promote the resolution of inflammation in atherosclerosis are of interest. Resolution is mediated in part by specialized pro-resolving mediators, including resolvins such as Resolvin D1 (RvD1). We recently showed that RvD1 prevents lesional necrosis in Ldlr^-/- mice. However, the mechanisms underlying RvD1’s protective actions remain unknown. In this regard, the accumulation of necroptotic cells has recently emerged as a driver of plaque necrosis. Necroptotic cells are particularly harmful because they possess a highly pro-inflammatory and proteolytic phenotype. Because RvD1 decreased lesional necrosis, we questioned whether RvD1’s actions were through limiting necroptotic cells in plaques. Briefly, we administered RvD1 to Ldlr^-/- mice during advanced atherosclerosis and observed a significant decrease in necroptotic cells and overall lesion necrosis compared with vehicle controls. To explore mechanism, we developed a method to quantify efferocytosis of necroptotic cells with the use of ImageStream flow cytometry as well as confocal imaging.  Briefly, we found that necroptotic cells have defective clearance mechanisms that can be rescued by RvD1. This talk will focus on mechanisms underlying delayed efferocytosis of necroptotic cells and how RvD1 rescues this impairment.

Understanding processes occurring within the vasculature may shed light onto events leading to both vascular as well as peripheral tissue disease. We recently found that during both sterile and infectious inflammation n-3 docospaentaenoic acid is precursor to two novel autacoid families termed as D-series resolvins (RvD_{n-3 DPA}) and 13-series resolvins (RvT). These mediators carry potent leukocyte and endothelial-directed actions counter-regulating the production of inflammatory mediators including prostaglandins and leukotrienes. Using liquid chromatography-tandem mass spectrometry-based lipid mediator profiling we found that RvD_{n-3 DPA} are diurnally regulated in the plasma of healthy volunteers. These changes in peripheral blood RvD_{n-3 DPA} correlated with a circadian regulation of peripheral blood leukocyte and platelet activation. The diurnal regulation of RvD_{n-3 DPA} was lost in patients with cardiovascular disease (CVD) that also displayed increase platelet and leukocyte activation. Of note, addition of RvD_{n-3 DPA} to peripheral blood from CVD patients led to a significant downregulation of activation markers on both platelet and leukocytes. RvT were also found to display potent actions in the circulation regulating systemic inflammation via downregulating the levels of inflammation initiating factors including PAI-1 and inflammasome components and the upregulation of circulating prostacyclin during bacterial infections. In addition, we found that these autacoids were responsible for mediating the host protective actions of statins during both sterile and infectious inflammation. Together these findings establish the vasculo-protective actions of n-3 docospaentaenoic acid derived resolvins. They also identify novel biomarkers in assessing vascular inflammation and the effectiveness therapeutics at regulating local and systemic inflammation.

Endogenous mechanisms that govern resolutions programs during acute inflammation are essential for hose defense. Specialized pro-resolving mediators (SPM) including lipoxins, resolvins, protectins and maresins constitute a superfamily of potent endogenous lipid mediators that stimulate resolution of inflammation and infection. We identified several G Protein-coupled Receptors (GPCR) that contribute to pro-resolving actions of SPM, including ALX, ERV1/ChemR23, DRV1/GPR32 and recently identified DRV2/GPR18 (Chiang and Serhan, Mol Aspects Med. 2017). As an example, the RvD2-receptor (DRV2/GPR18) resolution axis activates intracellular signaling pathways, contributing to endogenous resolution mechanisms in bacterial infections, sepsis and intrinsic organ protection (Chiang et al., J Exp Med. 2015 and J Immunol. 2017). These SPM receptors provide a template for resolution physiology and pharmacology that may offer new opportunities to control unwanted inflammation and infection.

We recently identified new pathway of mediators termed Maresin Conjugates in Tissue Regeneration (MCTR), including MCTR1, MCTR2 and MCTR3. We addressed whether each MCTR can impact known vascular actions of cysteinyl leukotrienes. Leukotriene D₄ (LTD₄, 1.5 nmol/mouse) initiated vascular leakage in mouse cremaster vessels that was markedly reduced (>75%) by MCTR1 and MCTR2 (0.15 nmol each). With isolated Ciona intestinalis (sea squirt) primordial hearts, LTD₄ (1-100 nM) gave negative inotropic action, lowering heartbeats 20-30%. Each MCTR (1-100nM) blocked LTD₄-reduced heart rates. With human cysteinyl leukotriene receptor-1 (CysLT1) expressed in CHO cells, each MCTR (10-100nM) significantly reduced LTD₄-initiated signaling. To assess the contribution of CysLT1 in MCTR’s pro-resolving actions, we carried out human macrophage phagocytosis. Each MCTR (0.1-10nM) stimulated human macrophage phagocytosis of live E. coli, while LTD₄ did not stimulate phagocytosis. MCTR-activated phagocytosis was significantly blocked by a pharmacological receptor antagonist (MK571). With both CHO-CysLT1 and human macrophages, each MCTR competed for specific ³H-LTD binding with apparent lower affinity than LTD₄. Thus, each MCTR functionally interact with human CysLT1 to pharmacologically counter-regulate vascular responses and stimulate physiologic phagocytosis with macrophages (Chiang et al., FASEB J. 2018). Taken together, these findings demonstrate the opposing bioactions of CysLTs and MCTR in vivo and in vitro, that open new opportunities to address the pharmacologic interactions of these mediators and potentially to the physiologic roles of MCTRs.

This work was supported in part by NIH grants GM38765 and P01-GM095467 (CNS).

The mechanisms by which regular exercise prevents the development and progression of chronic inflammatory diseases are largely unknown. We find that exercise (Exe) enhances resolution of acute inflammation by promoting macrophage (Mɸ) phagocytosis and by augmenting resolvin D1 (RvD1) levels. When compared with sedentary controls (Sed), mice adapted to a 4-week treadmill exercise regimen displayed 1.48-fold higher Mɸ phagocytotic activity, enhanced RvD1 levels (Sed 28.08±1.5 vs Exe 48.01±8.6 pg/mL, n=6), and earlier neutrophilic clearance (ΔRi ~7 h) during peritonitis. Peritonitis cell extracts from exercise-adapted mice showed elevated expression of Alox15 (48 h: Sed 0.97±0.15 vs Exe 1.5±0.16 relative expression, n=8-9), Alox5 (48 h: Sed 0.77±0.15 vs Exe 1.7±0.27 relative expression, n=4-5), and RvD1 levels (48 h: 29.0±2.1 vs 52.6±8.9 pg/mL, n=5). Because exercise stimulates epinephrine (Epi) release, which has immunomodulatory effects, we questioned if Epi exerts pro-resolving actions on macrophages. Epi-treated macrophages displayed higher 15-lipoxygenase 1 expression and RvD1 levels, which were prevented by incubation with the α1 adrenergic receptor (AR-α1) blocker, Prazosin (Praz). During zymosan-induced peritonitis, Praz abrogated exercise-enhanced neutrophilic clearance (48 h: Exe+Veh 2.07±0.41 vs Exe+Praz 5.2±1.04 x106 PMN, n=5), Mɸ phagocytosis (Exe+Veh 33463.0±2174.0 vs Exe+Praz 8303.0±2748.0 MFI, n=5-7), and RvD1 biosynthesis (Exe+Veh 211.0±55.4 vs Exe+Praz 81.79±11.8 pg/mL, n=6). These results suggest that exercise-stimulated Epi release enhances resolution of acute inflammation in an AR-α1 dependent manner. These findings provide new mechanistic insights into the pro-resolving effects of exercise and may lead to the identification of novel pathways to stimulate resolution biology.

Inflammation limiting non-steroidal pain-relievers magnifies myocardial infarction (MI) and re-admission in heart failure (HF) patients. However, the molecular and cellular basis of this provocative adverse effect is unclear. To determine whether carprofen (CAP) impede splenic leukocyte directed acute inflammation- resolving response in cardiac injury. After subacute CAP exposure, mice were subjected to coronary occlusion maintaining non-CAP MI- and naïve-controls. Post ligation, acute decompensated HF developed in CAP and MI-controls within 24 hour. Subacute CAP over activated don’t eat me signal with preactivation of splenic neutrophils and reduced total and reparative macrophages compared with control in left ventricle (LV) and spleen. Subacute CAP exposure facilitated leukocyte death in LV and was more evident post-MI compared with MI-control. Post-MI, CAP preactivated neutrophils were intensified and reduced reparative neutrophils and macrophages in LV was indicative of non-resolving inflammation compared with MI-control. In CAP, preactivated splenic neutrophils tailored the macrophage phagocytosis thereby increased splenocardiac leukocyte death. CAP over amplified cyclooxygenase (COX)-1 and COX-2 compared with MI-control and failed to limit prostaglandins and thromboxane in post-MI setting. Further, CAP reduced cardiac protective epoxyeicosatrienoic acids and over amplified inflammatory cytokines and reduced reparative cytokines thereby non-resolving inflammation. Subacute CAP exposure intensified marked neutrophil swarming indicative of inflammation-resolution-deficit in cardiac injury. Thus, pre-clinical and clinical studies are warranted to determine inflammation-resolution deficit in HF.

Specialized pro-resolving lipid mediators (SPM) generated during the resolution phase of acute inflammation have been shown to blunt tissue infiltration of neutrophils and to promote the removal of apoptotic cells by macrophages. Emerging evidence indicates that SPM play diverse roles during tissue injury and actively promote the transition from inflammation to tissue repair and regeneration. Using murine models of acute sterile tissue injury, including chemical or exercise-induced skeletal muscle damage, our recent results indicate that D-series resolvins and related SPM are biosynthesized by distinct immune cell subsets and actively signal tissue repair in part by modulating transcriptional programs in macrophages. This presentation will highlight our recent results on the biosynthesis and actions of SPM in tissue repair.

Inflammation is a protective response to injurious stimuli, but when left unchecked, chronic inflammation can lead to tissue damage and disease. It is now known that resolution of inflammation is an active process mediated by a recently discovered family of specialized pro-resolving lipid mediators (SPMs). Tobacco smoking is the leading preventable cause of multiple respiratory diseases including lung cancer and COPD. It is a profound pro-inflammatory stimulus. Importantly, chronic inflammation persists long after smoking cessation in both humans and animal models, suggesting that tobacco smoke impairs the normal mechanisms of resolution. Using patient samples, in vitro systems, and preclinical animal models of tobacco smoke exposure, we will identify how smoke dysregulates resolution mechanisms, and investigate potential therapeutic use of SPMs in lung disease. Pro-resolving lipid mediators have anti-inflammatory and pro-resolving effects in primary human lung fibroblasts, epithelial cells and alveolar macrophages when stimulated with either cigarette smoke or other pro-inflammatory mediators. RvD1 profoundly inhibits lung inflammation in an acute mouse model of cigarette smoke exposure, accelerates resolution and inhibits the develop of emphysema when given concurrently with cigarette smoke over 16 weeks. RvD1 also dampens lung inflammation and enhances clearance of Nontypeable Haemophilus influenzae, a Gram-negative pathogen that frequently causes bronchitis and pneumonia in patients with underlying lung disease. Taken together, our data demonstrate that pro-resolving lipid mediators are effective in therapeutically promoting a pro-resolving phenotype in human lung cells and animal models of smoke-induced lung disease and have tremendous therapeutic potential.

Acute lung inflammation is fundamentally important to host defense, but chronic or excessive inflammation can lead to several important diseases. The resolution of inflammation is an active process that is directed, in part, by specialized pro-resolving mediators that are enzymatically derived from polyunsaturated fatty acids. In health, cell-cell interactions at the onset of acute inflammation establish biosynthetic circuits for these pro-resolving mediators, including the omega-3 fatty acid-derived resolvins, protectins and maresins, which serve as agonists to orchestrate a return of the inflamed tissue to homeostasis. Understanding the cellular and molecular mechanisms for pro-resolving mediators in catabasis is providing new insights into lung tissue responses for resolution of inflammation in health and the pathophysiology of disease; as well as opportunities for therapeutic intervention.

E-series and D-series resolvins are enzymatically derived from the essential omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid, respectively. Protectin D1 and maresin 1 (MaR1) are also derived from DHA. Relevant to lung inflammation, lipoxin A₄ (LXA₄), Resolvin E1 (RvE1), resolvin D1 (RvD1) and protectin D1 (PD1) are generated in murine lung. LXA₄ and PD1 are generated in human lung. Receptors for LXA₄ and RvD1 (ALX/FPR2) and for RvE1 (ERV1) are expressed in lung and are dynamically regulated with lung inflammation. Evidence will be presented for cellular and molecular mechanisms for representative SPMs in their protective actions in the regulation of airway inflammation during innate and adaptive immune responses.

Cystic fibrosis (CF) is characterized by chronic infection and inflammation in the airways. We previously reported that levels of airway HMGB1, significantly elevated in CF patients and animals, can compromise innate immunity against bacterial infections via impairing phagocytic function of macrophages, contributing to the poor clinical outcomes in the lungs. In this study, we show that CF epithelial IB3 cells (with CFTR deficiency) release more HMGB1 at basal levels as well as upon stimulation with bacterial components than their genetically corrected epithelia S9 cells. CF macrophages treated with LPS also released more HMGB1 than WT ones. In addition, CF IB3 cells exhibited significantly less NO release upon exposure to LPS. These data suggest that CFTR deficiency contributes to the decreased bacterial killing capacity in CF by releasing more HMGB1 into the airways from both airway epithelia and macrophages and impairing NO production upon infections. Both alveolar macrophages (AM) and bone marrow derived macrophages (BMDM) from CF mice had significantly lower phagocytic functions than their wildtype counterparts. The extent of such impairment is more prominent in AM, suggesting microenvironment in CF airways also contributes to the compromised macrophage functions. To investigate if neutralizing airway HMGB1 pharmacologically can improve innate immunity against bacterial infections, ODSH, that can block HMGB1 binding to its receptors, was used to treat both AM and BMDM in the presence of rHMGB1. Indeed, ODSH improved macrophage phagocytic functions compromised by rHMGB1, while exhibited no effects on macrophages in the absence of rHMGB1. CF Mice treated with ODSH had significantly reduced bacterial load in the lungs and attenuated acute lung injury with improved epithelial lining integrity upon bacterial infections. These data demonstrate that airway HMGB1 released by epithelial cells and macrophages in CF contribute to the compromised innate immunity, by compromising bacterial clearance. ODSH may provide a targeted therapeutic approach by attenuating the effects of airway HMGB1 in bacterial clearance to improve clinical outcomes in CF.

During infection distinct arms of innate inflammatory responses establish counter regulatory cytokine and lipid mediator networks that ultimately determine the outcome of infection. We have studied these processes in the context of pulmonary infection with Mycobacterium tuberculosis, which is the causative agent of TB and currently the single most deadly global pathogen. We found that IL-1 and Type I IFN driven inflammation is tightly linked to eicosanoids and that manipulation of the host lipid mediators during TB is a promising avenue for host-directed therapies in TB. Understanding different classes of inflammation and the corresponding innate effector cells, lipids, and cytokines that orchestrate protective versus detrimental inflammatory responses will provide critical insight for the development of new treatment strategies for a variety of inflammatory diseases, including non-infectious chronic inflammatory conditions.

The failure of effective resolution underlies chronic inflammatory conditions including complications of diabetes such as kidney disease and atherosclerosis. The identification of endogenously generated molecules including lipoxins, [LXs], which promote the physiologic resolution of inflammation suggests that these bioactions may have therapeutic potential in the context of chronic inflammation. Here we investigated the potential of LXA₄ and a synthetic LX mimetics to modulate diabetic complications in the streptozotocin-induced diabetic ApoE^-/- mice and in human carotid plaque tissue ex vivo.

Diabetes-induced kidney disease including albuminuria, mesangial expansion and collagen deposition was attenuated by LXs in mice administered LXs 10 weeks after disease onset, with evidence of preserved kidney function. Kidney transcriptome profiling defined a diabetic signature [725 genes; FDR P≤0.05]. Comparison of this murine gene signature with human DKD identified shared renal pro-inflammatory/pro-fibrotic signals (TNF-α, IL-1β, NF-κB). In diabetic mice we identified transcripts regulated by LXs and pathway analysis identified established (TGF-β1, PDGF, TNF-α, NF-κB) and novel (Early growth response-1 - EGR-1) networks activated in diabetes and regulated by LXs.

The development of diabetes-induced aortic plaques and associated inflammatory responses were significantly attenuated by LXs in diabetic ApoE-/- mice. In mice with established atherosclerosis, treatment with LXs led to a significant reduction in aortic arch plaque development. Treatment of human carotid plaques explants with LXs ex vivo attenuated secretion of distinct protein networks. LXs inhibited PDGF-stimulated vascular smooth muscle cells proliferation and transmigration and endothelial cell inflammation. These data demonstrate that LXs can reverse established diabetic complications and support a therapeutic paradigm to promote the resolution of inflammation in this context.

The endocannabinoid system plays an important role in resolution of inflammation. Lenabasum is a synthetic analog of D⁸-tetrahydrocannabinol (THC)-11-oic acid, currently in clinical development for the treatment of rare chronic inflammatory/fibrotic diseases such as systemic sclerosis, dermatomyositis, lupus and Cystic Fibrosis. Lenabasum is a selective CB2 agonist having demonstrated promising clinical benefit and a favorable safety profile in three double-blind placebo-controlled clinical studies for systemic sclerosis, dermatomyositis and Cystic Fibrosis, respectively. In each of these studies, lenabasum treatment for 12 weeks resulted in clinical benefit as seen by an improvement in the ACR combined response index of systemic sclerosis (CRISS) score; an improvement in the cutaneous dermatomyositis disease area and severity index (CDASI) score; and a reduction in the number of and time to pulmonary exacerbations in Cystic Fibrosis. A clinical study was also conducted in a human model of acute inflammation triggered by intradermal injection of ultraviolet light-killed E coli on the forearms of healthy subjects followed by blister formation to tap the inflammatory exudate.  Lenabasum increased blood flow during the resolution phase; reduced IL-8 levels and neutrophil counts in blister exudates post-challenge; reduced the proinflammatory lipid mediators LTB4, PGF₂a, TxB₂ and PGE₂; increased the specialized pro-resolution lipid mediators (SPMs), lipoxins (LXA₄, LXB₄) and resolvins (RvD1, RvD3, RvD5); and hastened bacterial clearance. Thus, lenabasum exerts a profound therapeutic effect by accelerating the resolution phase of the innate immune response and supports the hypothesis that endocannabinoids play a natural role to trigger resolution through CB2 agonism.

The acute inflammatory response is a protective reaction if resolved. However uncontrolled inflammation is the underlying basis of many chronic diseases including asthma, rheumatoid arthritis, diabetes, and cardiovascular and neurological diseases. The studies by Serhan and collaborators have identified powerful specialized pro-resolving mediators (SPMs) that are central in the resolution of inflammation and tissue repair. These SPMs include the recently discovered sulfido conjugates of maresin, protectin and resolvin. In order to fully characterize these new SPMs we have prepared them by total organic syntheses and verified their structures by spectroscopic techniques. Serhan and collaborators compared these synthetic SPMs with native derived materials by LC-MS-MS and bioassays and confirmed their identity. Our chemical syntheses not only provide sufficient amounts for the initial biological testing but help to assist the pharmacological testing. The final goal is to develop robust synthetic routes that ultimately allow the large scale production of SPMs from readily available starting materials for clinical trials. We have evaluated several SPMs in the animal model of sepsis and have found increased survival with reduced bacterial load. New mechanisms of action were discovered that could have a profound impact on infection control and might be an addition or alternative to the current antibiotic therapy.

The periodontal diseases are the most common inflammatory diseases of man.  Gingivitis is ubiquitous affecting >90% of people, but periodontitis with irreversible tissue destruction affects more than 47% of the US population. Periodontitis is an infectious/inflammatory disease associated with dysbiosis of the commensal oral microbiome. Importantly, recent studies demonstrate a relationship between oral infectious/inflammatory conditions, in particular periodontal disease, and risk for the development of cardiovascular disease and stroke, and studies in diabetics have revealed that untreated periodontal disease can lead to diabetic complications and have a direct impact on glycemic control. As our understanding of pathways of inflammation has matured, a better understanding of the molecular basis of resolution of inflammation, which is distinct from pharmacologic anti-inflammation, has emerged. Resolution of inflammation is an active; receptor agonist mediated well-orchestrated return of tissue homeostasis, not inhibition of proinflammatory pathways. The isolation and characterization of endogenous lipid mediators of resolution, called lipoxins and resolvins, has open new doorways for the management of periodontitis and systemic inflammatory diseases. Preclinical studies have demonstrated that specialized proresolving mediators (SPMs) are potent when topically applied in the prevention and treatment of periodontitis. Characterization of the molecular basis for these findings has changed our understanding of the relationship between infection and inflammation in the oral cavity. Moreover, the inflammatory mechanistic link between systemic conditions, including cardiovascular disease and type 2 diabetes, is revealed to be modifiable with SPMs. This presentation will review resolution of inflammation in the context of periodontal disease and the role of inflammation and its control in the link between periodontal inflammation and inflammatory systemic diseases, including type 2 diabetes and cardiovascular disease.