Skin repair and infection control in diabetic, obese mice using bioactive laser-activated sealants.

Conventional wound approximation devices, including sutures, staples, and glues, are widely used but risk of wound dehiscence, local infection, and scarring can be exacerbated in these approaches, including in diabetic and obese individuals. This study reports the efficacy and quality of tissue repair upon photothermal sealing of full-thickness incisional skin wounds using silk fibroin-based laser-activated sealants (LASEs) containing copper chloride salt (Cu-LASE) or silver nanoprisms (AgNPr-LASE), which absorb and convert near-infrared (NIR) laser energy to heat. LASE application results in rapid and effective skin sealing in healthy, immunodeficient, as well as diabetic and obese mice. Although lower recovery of epidermal structure and function was seen with AgNPr-LASE sealing, likely because of the hyperthermia induced by laser and presence of this material in the wound space, this approach resulted in higher enhancement in recovery of skin biomechanical strength compared to sutures and Cu-LASEs in diabetic, obese mice. Histological and immunohistochemical analyses revealed that AgNPr-LASEs resulted in significantly lower neutrophil migration to the wound compared to Cu-LASEs and sutures, indicating a more muted inflammatory response. Cu-LASEs resulted in local tissue toxicity likely because of effects of copper ions as manifested in the form of a significant epidermal gap and a 'depletion zone', which was a region devoid of viable cells proximal to the wound. Compared to sutures, LASE-mediated sealing, in later stages of healing, resulted in increased angiogenesis and diminished myofibroblast activation, which can be indicative of lower scarring. AgNPr-LASE loaded with vancomycin, an antibiotic drug, significantly lowered methicillin-resistant Staphylococcus aureus (MRSA) load in a pathogen challenge model in diabetic and obese mice and also reduced post-infection inflammation of tissue compared to antibacterial sutures. Taken together, these attributes indicate that AgNPr-LASE demonstrated a more balanced quality of tissue sealing and repair in diabetic and obese mice and can be used for combating local infections, that can result in poor healing in these individuals.

In situ light-activated materials for skin wound healing and repair: A narrative review.

Dermal wounds are a major global health burden made worse by common comorbidities such as diabetes and infection. Appropriate wound closure relies on a highly coordinated series of cellular events, ultimately bridging tissue gaps and regenerating normal physiological structures. Wound dressings are an important component of wound care management, providing a barrier against external insults while preserving the active reparative processes underway within the wound bed. The development of wound dressings with biomaterial constituents has become an attractive design strategy due to the varied functions intrinsic in biological polymers, such as cell instructiveness, growth factor binding, antimicrobial properties, and tissue integration. Using photosensitive agents to generate crosslinked or photopolymerized dressings in situ provides an opportunity to develop dressings rapidly within the wound bed, facilitating robust adhesion to the wound bed for greater barrier protection and adaptation to irregular wound shapes. Despite the popularity of this fabrication approach, relatively few experimental wound dressings have undergone preclinical translation into animal models, limiting the overall integrity of assessing their potential as effective wound dressings. Here, we provide an up-to-date narrative review of reported photoinitiator- and wavelength-guided design strategies for in situ light activation of biomaterial dressings that have been evaluated in preclinical wound healing models.

Inflammasome modulation with P2X7 inhibitor A438079-loaded dressings for diabetic wound healing.

The inflammasome is a multiprotein complex critical for the innate immune response to injury. Inflammasome activation initiates healthy wound healing, but comorbidities with poor healing, including diabetes, exhibit pathologic, sustained activation with delayed resolution that prevents healing progression. In prior work, we reported the allosteric P2X7 antagonist A438079 inhibits extracellular ATP-evoked NLRP3 signaling by preventing ion flux, mitochondrial reactive oxygen species generation, NLRP3 assembly, mature IL-1ß release, and pyroptosis. However, the short half-life in vivo limits clinical translation of this promising molecule. Here, we develop a controlled release scaffold to deliver A438079 as an inflammasome-modulating wound dressing for applications in poorly healing wounds. We fabricated and characterized tunable thickness, long-lasting silk fibroin dressings and evaluated A438079 loading and release kinetics. We characterized A438079-loaded silk dressings in vitro by measuring IL-1ß release and inflammasome assembly by perinuclear ASC speck formation. We further evaluated the performance of A438079-loaded silk dressings in a full-thickness model of wound healing in genetically diabetic mice and observed acceleration of wound closure by 10 days post-wounding with reduced levels of IL-1ß at the wound edge. This work provides a proof-of-principle for translating pharmacologic inhibition of ATP-induced inflammation in diabetic wounds and represents a novel approach to therapeutically targeting a dysregulated mechanism in diabetic wound impairment.

Bioactive nanomaterials kickstart early repair processes and potentiate temporally modulated healing of healthy and diabetic wounds.

Slow-healing and chronic wounds represent a major global economic and medical burden, and there is significant unmet need for novel therapies which act to both accelerate wound closure and enhance biomechanical recovery of the skin. Here, we report a new approach in which bioactives that augment early stages of wound healing can kickstart and engender effective wound closure in healthy and diabetic, obese animals, and set the stage for subsequent tissue repair processes. We demonstrate that a nanomaterial dressing made of silk fibroin and gold nanorods (GNR) stimulates a pro-neutrophilic, innate immune, and controlled inflammatory wound transcriptomic response. Further, Silk-GNR, lasered into the wound bed, in combination with exogeneous histamine, accelerates early-stage processes in tissue repair leading to effective wound closure. Silk-GNR and histamine enhanced biomechanical recovery of skin, increased transient neoangiogenesis, myofibroblast activation, epithelial-to-mesenchymal transition (EMT) of keratinocytes and a pro-resolving neutrophilic immune response, which are hitherto unknown activities for these bioactives. Predictive and temporally coordinated delivery of growth factor nanoparticles that modulate later stages of tissue repair further accelerated wound closure in healthy and diabetic, obese animals. Our approach of kickstarting healing by delivering the "right bioactive at the right time" stimulates a multifactorial, pro-reparative response by augmenting endogenous healing and immunoregulatory mechanisms and highlights new targets to promote tissue repair.

Rescue of dendritic cells from glycolysis inhibition improves cancer immunotherapy in mice.

Inhibition of glycolysis in immune cells and cancer cells diminishes their activity, and thus combining immunotherapies with glycolytic inhibitors is challenging. Herein, a strategy is presented where glycolysis is inhibited in cancer cells using PFK15 (inhibitor of PFKFB3, rate-limiting step in glycolysis), while simultaneously glycolysis and function is rescued in DCs by delivery of fructose-1,6-biphosphate (F16BP, one-step downstream of PFKFB3). To demonstrate the feasibility of this strategy, vaccine formulations are generated using calcium-phosphate chemistry, that incorporate F16BP, poly(IC) as adjuvant, and phosphorylated-TRP2 peptide antigen and tested in challenging and established YUMM1.1 tumours in immunocompetent female mice. Furthermore, to test the versatility of this strategy, adoptive DC therapy is developed with formulations that incorporate F16BP, poly(IC) as adjuvant and mRNA derived from B16F10 cells as antigens in established B16F10 tumours in immunocompetent female mice. F16BP vaccine formulations rescue DCs in vitro and in vivo, significantly improve the survival of mice, and generate cytotoxic T cell (Tc) responses by elevating Tc1 and Tc17 cells within the tumour. Overall, these results demonstrate that rescuing glycolysis of DCs using metabolite-based formulations can be utilized to generate immunotherapy even in the presence of glycolytic inhibitor.

Succinate in the tumor microenvironment affects tumor growth and modulates tumor associated macrophages.

Succinate is an important metabolite that modulates metabolism of immune cells and cancer cells in the tumor microenvironment (TME). Herein, we report that polyethylene succinate (PES) microparticles (MPs) biomaterial mediated controlled delivery of succinate in the TME modulates macrophage responses. Administering PES MPs locally with or without a BRAF inhibitor systemically in an immune-defective aging mice with clinically relevant BRAFV600E mutated YUMM1.1 melanoma decreased tumor volume three-fold. PES MPs in the TME also led to maintenance of M1 macrophages with up-regulation of TSLP and type 1 interferon pathway. Impressively, this led to generation of pro-inflammatory adaptive immune responses in the form of increased T helper type 1 and T helper type 17 cells in the TME. Overall, our findings from this challenging tumor model suggest that immunometabolism-modifying PES MP strategies provide an approach for developing robust cancer immunotherapies.

Succinate based polymers drive immunometabolism in dendritic cells to generate cancer immunotherapy.

Boosting the metabolism of immune cells while restricting cancer cell metabolism is challenging. Herein, we report that using biomaterials for the controlled delivery of succinate metabolite to phagocytic immune cells activates them and modulates their metabolism in the presence of metabolic inhibitors. In young immunocompetent mice, polymeric microparticles, with succinate incorporated in the backbone, induced strong pro-inflammatory anti-melanoma responses. Administration of poly(ethylene succinate) (PES MP)-based vaccines and glutaminase inhibitor to young immunocompetent mice with aggressive and large, established B16F10 melanoma tumors increased their survival three-fold, a result of increased cytotoxic T cells expressing RORγT (Tc17). Mechanistically, PES MPs directly modulate glutamine and glutamate metabolism, upregulate succinate receptor SUCNR1, activate antigen presenting cells through and HIF-1alpha, TNFa and TSLP-signaling pathways, and are dependent on alpha-ketoglutarate dehydrogenase for their activity, which demonstrates correlation of succinate delivery and these pathways. Overall, our findings suggest that immunometabolism-modifying PES MP strategies provide an approach for developing robust cancer immunotherapies.

Alpha-ketoglutaric acid based polymeric particles for cutaneous wound healing.

Metabolites are not only involved in energy pathways but can also act as signaling molecules. Herein, we demonstrate that polyesters of alpha-ketoglutararte (paKG) can be generated by reacting aKG with aliphatic diols of different lengths, which release aKG in a sustained manner. paKG polymer-based microparticles generated via emulsion-evaporation technique lead to faster keratinocyte wound closures in a scratch assay test. Moreover, paKG microparticles also led to faster wound healing responses in an excisional wound model in live mice. Overall, this study shows that paKG MPs that release aKG in a sustained manner can be used to develop regenerative therapeutic responses.

Temporal evaluation of efficacy and quality of tissue repair upon laser-activated sealing.

Injuries caused by surgical incisions or traumatic lacerations compromise the structural and functional integrity of skin. Immediate approximation and robust repair of skin are critical to minimize occurrences of dehiscence and infection that can lead to impaired healing and further complication. Light-activated skin sealing has emerged as an alternative to sutures, staples, and superficial adhesives, which do not integrate with tissues and are prone to scarring and infection. Here, we evaluate both shorter- and longer-term efficacy of tissue repair response following laser-activated sealing of full-thickness skin incisions in immunocompetent mice and compare them to the efficacy seen with sutures. Laser-activated sealants (LASEs) in which, indocyanine green was embedded within silk fibroin films, were used to form viscous pastes and applied over wound edges. A hand-held, near-infrared laser was applied over the incision, and conversion of the light energy to heat by the LASE facilitated rapid photothermal sealing of the wound in approximately 1 min. Tissue repair with LASEs was evaluated using functional recovery (transepidermal water loss), biomechanical recovery (tensile strength), tissue visualization (ultrasound [US] and photoacoustic imaging [PAI]), and histology, and compared with that seen in sutures. Our studies indicate that LASEs promoted earlier recovery of barrier and mechanical function of healed skin compared to suture-closed incisions. Visualization of sealed skin using US and PAI indicated integration of the LASE with the tissue. Histological analyses of LASE-sealed skin sections showed reduced neutrophil and increased proresolution macrophages on Days 2 and 7 postclosure of incisions, without an increase in scarring or fibrosis. Together, our studies show that simple fabrication and application methods combined with rapid sealing of wound edges with improved histological outcomes make LASE a promising alternative for management of incisional wounds and lacerations.

Mouse Models of Renal Allograft Transplant Rejection: Methods to Investigate Chemokine-GAG Interaction and Therapeutic Blockade.

Chemokine-glycosaminoglycan (GAG) interactions direct immune cell activation and invasion, e.g., directing immune cells to sites of infection or injury, and are central to initiating immune responses. Acute innate and also adaptive or antibody-mediated immune cell responses both drive damage to kidney transplants. These immune responses are central to allograft rejection and transplant failure. While treatment for acute rejection has advanced greatly, ongoing or chronic immune damage from inflammation and antibody-mediated rejection remains a significant problem, leading to transplant loss. There are limited numbers of organs available for transplant, and preventing chronic graft damage will allow for longer graft stability and function, reducing the need for repeat transplantation. Chemokine-GAG interactions are the basis for initial immune responses, forming directional gradients that allow immune cells to traverse the vascular endothelium and enter engrafted organs. Targeting chemokine-GAG interactions thus has the potential to reduce immune damage to transplanted kidneys.Mouse models for renal transplant are available, but are complex and require extensive microsurgery expertise. Here we describe simplified subcapsular and subcutaneous renal allograft transplant models, for rapid assessment of the roles of chemokine-GAG interactions during allograft surgery and rejection. These models are described, together with treatment using a unique chemokine modulating protein (CMP) M-T7 that disrupts chemokine-GAG interactions.

Virus-Derived Chemokine Modulating Protein Pre-Treatment Blocks Chemokine-Glycosaminoglycan Interactions and Significantly Reduces Transplant Immune Damage.

Immune cell invasion after the transplantation of solid organs is directed by chemokines binding to glycosaminoglycans (GAGs), creating gradients that guide immune cell infiltration. Renal transplant is the preferred treatment for end stage renal failure, but organ supply is limited and allografts are often injured during transport, surgery or by cytokine storm in deceased donors. While treatment for adaptive immune responses during rejection is excellent, treatment for early inflammatory damage is less effective. Viruses have developed highly active chemokine inhibitors as a means to evade host responses. The myxoma virus-derived M-T7 protein blocks chemokine: GAG binding. We have investigated M-T7 and also antisense (ASO) as pre-treatments to modify chemokine: GAG interactions to reduce donor organ damage. Immediate pre-treatment of donor kidneys with M-T7 to block chemokine: GAG binding significantly reduced the inflammation and scarring in subcapsular and subcutaneous allografts. Antisense to N-deacetylase N-sulfotransferase1 (ASONdst1) that modifies heparan sulfate, was less effective with immediate pre-treatment, but reduced scarring and C4d staining with donor pre-treatment for 7 days before transplantation. Grafts with conditional Ndst1 deficiency had reduced inflammation. Local inhibition of chemokine: GAG binding in donor organs immediately prior to transplant provides a new approach to reduce transplant damage and graft loss.

RNA Virus Gene Signatures Detected in Patients With Cardiomyopathy After Chemotherapy; A Pilot Study.

Background: Viral infections are pervasive and leading causes of myocarditis. Immune-suppression after chemotherapy increases opportunistic infections, but the incidence of virus-induced myocarditis is unknown. Objective: An unbiased, blinded screening for RNA viruses was performed after chemotherapy with correlation to cardiac function. Methods: High-throughput sequencing of RNA isolated from blood samples was analyzed following chemotherapy for hematological malignancies (N = 28) and compared with left ventricular ejection fraction (LVEF). Results: On initial rigorous analysis, low levels of influenza orthomyxovirus and avian paramyxovirus sequences were detectable, but without significant correlation to LVEF (r = 0.208). A secondary broad data mining analysis for virus sequences, without filtering human sequences, detected significant correlations for paramyxovirus with LVEF after chemotherapy (r = 0.592, P < 0.0096). Correlations were similar for LVEF pre- and post- chemotherapy for orthomyxovirus (R = 0.483, P < 0.0421). Retrovirus detection also correlated with LVEF post (r = 0.453, p < 0.0591), but not pre-chemotherapy, but is suspect due to potential host contamination. Detectable phage and anellovirus had no correlation. Combined sequence reads (all viruses) demonstrated significant correlation (r = 0.621, P < 0.0078). Reduced LVEF was not associated with chemotherapy (P = NS). Conclusions: This is the first report of RNA virus screening in circulating blood and association with changes in cardiac function among patients post chemotherapy, using unbiased, blinded, high-throughput sequencing. Influenza orthomyxovirus, avian paramyxovirus and retrovirus sequences were detectable in patients with reduced LVEF. Further analysis for RNA virus infections in patients with cardiomyopathy after chemotherapy is warranted.

Serp-1 Promotes Corneal Wound Healing by Facilitating Re-epithelialization and Inhibiting Fibrosis and Angiogenesis.

Purpose: Chemical corneal injuries carry a high morbidity and commonly lead to visual impairment. Here, we investigate the role of Serp-1, a serine protease inhibitor, in corneal wound healing. Methods: An alkaline-induced corneal injury was induced in 14 mice. Following injury, five mice received daily topical saline application while nine mice received Serp-1 100 µL topically combined with a daily subcutaneous injection of 100 ng/gram body weight of Serp-1. Corneal damage was monitored daily through fluorescein staining and imaging. Cross sectional corneal H&E staining were obtained. CD31 was used as marker for neovascularization. Results: Serp-1 facilitates corneal wound healing by reducing fibrosis and neovascularization while mitigating inflammatory cell infiltration with no noticeable harm related to its application. Conclusions: Serp-1 effectively mitigates inflammation, decreases fibrosis, and reduce neovascularization in a murine model of corneal injury without affecting other organs. Translational Relavence: Our study provides preclinical data for topical application of Serp-1 to treat corneal wounds.

Fibrinolytic Serine Proteases, Therapeutic Serpins and Inflammation: Fire Dancers and Firestorms.

The making and breaking of clots orchestrated by the thrombotic and thrombolytic serine protease cascades are critical determinants of morbidity and mortality during infection and with vascular or tissue injury. Both the clot forming (thrombotic) and the clot dissolving (thrombolytic or fibrinolytic) cascades are composed of a highly sensitive and complex relationship of sequentially activated serine proteases and their regulatory inhibitors in the circulating blood. The proteases and inhibitors interact continuously throughout all branches of the cardiovascular system in the human body, representing one of the most abundant groups of proteins in the blood. There is an intricate interaction of the coagulation cascades with endothelial cell surface receptors lining the vascular tree, circulating immune cells, platelets and connective tissue encasing the arterial layers. Beyond their role in control of bleeding and clotting, the thrombotic and thrombolytic cascades initiate immune cell responses, representing a front line, "off-the-shelf" system for inducing inflammatory responses. These hemostatic pathways are one of the first response systems after injury with the fibrinolytic cascade being one of the earliest to evolve in primordial immune responses. An equally important contributor and parallel ancient component of these thrombotic and thrombolytic serine protease cascades are the serine protease inhibitors, termed serpins. Serpins are metastable suicide inhibitors with ubiquitous roles in coagulation and fibrinolysis as well as multiple central regulatory pathways throughout the body. Serpins are now known to also modulate the immune response, either via control of thrombotic and thrombolytic cascades or via direct effects on cellular phenotypes, among many other functions. Here we review the co-evolution of the thrombolytic cascade and the immune response in disease and in treatment. We will focus on the relevance of these recent advances in the context of the ongoing COVID-19 pandemic. SARS-CoV-2 is a "respiratory" coronavirus that causes extensive cardiovascular pathogenesis, with microthrombi throughout the vascular tree, resulting in severe and potentially fatal coagulopathies.

PEGylated Serp-1 Markedly Reduces Pristane-Induced Experimental Diffuse Alveolar Hemorrhage, Altering uPAR Distribution, and Macrophage Invasion.

Diffuse alveolar hemorrhage (DAH) is one of the most serious clinical complications of systemic lupus erythematosus (SLE). The prevalence of DAH is reported to range from 1 to 5%, but while DAH is considered a rare complication there is a reported 50-80% mortality. There is at present no proven effective treatment for DAH and the therapeutics that have been tested have significant side effects. There is a clear necessity to discover new drugs to improve outcomes in DAH. Serine protease inhibitors, serpins, regulate thrombotic and thrombolytic protease cascades. We are investigating a Myxomavirus derived immune modulating serpin, Serp-1, as a new class of immune modulating therapeutics for vasculopathy and lung hemorrhage. Serp-1 has proven efficacy in models of herpes virus-induced arterial inflammation (vasculitis) and lung hemorrhage and has also proved safe in a clinical trial in patients with unstable coronary syndromes and stent implant. Here, we examine Serp-1, both as a native secreted protein expressed by CHO cells and as a polyethylene glycol modified (PEGylated) variant (Serp-1m5), for potential therapy in DAH. DAH was induced by intraperitoneal (IP) injection of pristane in C57BL/6J (B6) mice. Mice were treated with 100 ng/g bodyweight of either Serp-1 as native 55 kDa secreted glycoprotein, or as Serp-1m5, or saline controls after inducing DAH. Treatments were repeated daily for 14 days (6 mice/group). Serp-1 partially and Serp-1m5 significantly reduced pristane-induced DAH when compared with saline as assessed by gross pathology and H&E staining (Serp-1, p = 0.2172; Serp-1m5, p = 0.0252). Both Serp-1m5 and Serp-1 treatment reduced perivascular inflammation and reduced M1 macrophage (Serp-1, p = 0.0350; Serp-1m5, p = 0.0053), hemosiderin-laden macrophage (Serp-1, p = 0.0370; Serp-1m5, p = 0.0424) invasion, and complement C5b/9 staining. Extracellular urokinase-type plasminogen activator receptor positive (uPAR+) clusters were significantly reduced (Serp-1, p = 0.0172; Serp-1m5, p = 0.0025). Serp-1m5 also increased intact uPAR+ alveoli in the lung (p = 0.0091). In conclusion, Serp-1m5 significantly reduces lung damage and hemorrhage in a pristane model of SLE DAH, providing a new potential therapeutic approach.

Serine Proteases and Chemokines in Neurotrauma: New Targets for Immune Modulating Therapeutics in Spinal Cord Injury.

Progressive neurological damage after brain or spinal cord trauma causes loss of motor function and treatment is very limited. Clotting and hemorrhage occur early after spinal cord (SCI) and traumatic brain injury (TBI), inducing aggressive immune cell activation and progressive neuronal damage. Thrombotic and thrombolytic proteases have direct effects on neurons and glia, both healing and also damaging bidirectional immune cell interactions. Serine proteases in the thrombolytic cascade, tissue- and urokinase-type plasminogen activators (tPA and uPA), as well as the clotting factor thrombin, have varied effects, increasing neuron and glial cell growth and migration (tPA), or conversely causing apoptosis (thrombin) and activating inflammatory cell responses. tPA and uPA activate plasmin and matrix metalloproteinases (MMPs) that break down connective tissue allowing immune cell invasion, promoting neurite outgrowth. Serine proteases also activate chemokines. Chemokines are small proteins that direct immune cell invasion but also mediate neuron and glial cell communication. We are investigating a new class of therapeutics, virus-derived immune modulators; One that targets coagulation pathway serine proteases and a second that inhibits chemokines. We have demonstrated that local infusion of these biologics after SCI reduces inflammation providing early improved motor function. Serp-1 is a Myxomavirus-derived serine protease inhibitor, a serpin, that inhibits both thrombotic and thrombolytic proteases. M-T7 is a virus-derived chemokine modulator. Here we review the roles of thrombotic and thrombolytic serine proteases and chemoattractant proteins, chemokines, as potential therapeutic targets for SCI. We discuss virus-derived immune modulators as treatments to reduce progressive inflammation and ongoing nerve damage after SCI.

Adipose saturation reduces lipotoxic systemic inflammation and explains the obesity paradox.

Obesity sometimes seems protective in disease. This obesity paradox is predominantly described in reports from the Western Hemisphere during acute illnesses. Since adipose triglyceride composition corresponds to long-term dietary patterns, we performed a meta-analysis modeling the effect of obesity on severity of acute pancreatitis, in the context of dietary patterns of the countries from which the studies originated. Increased severity was noted in leaner populations with a higher proportion of unsaturated fat intake. In mice, greater hydrolysis of unsaturated visceral triglyceride caused worse organ failure during pancreatitis, even when the mice were leaner than those having saturated triglyceride. Saturation interfered with triglyceride's interaction and lipolysis by pancreatic triglyceride lipase, which mediates organ failure. Unsaturation increased fatty acid monomers in vivo and aqueous media, resulting in greater lipotoxic cellular responses and organ failure. Therefore, visceral triglyceride saturation reduces the ensuing lipotoxicity despite higher adiposity, thus explaining the obesity paradox.

The Role of Astrogliosis in Formation of the Syrinx in Spinal Cord Injury.

A massive localized trauma to the spinal cord results in complex pathologic events driven by necrosis and vascular damage which in turn leads to hemorrhage and edema. Severe, destructive and very protracted inflammatory response is characterized by infiltration by phagocytic macrophages of a site of injury which is converted into a cavity of injury (COI) surrounded by astroglial reaction mounted by the spinal cord. The tissue response to the spinal cord injury (SCI) has been poorly understood but the final outcome appears to be a mature syrinx filled with the cerebrospinal fluid with related neural tissue loss and permanent neurologic deficits. This paper reviews known pathologic mechanisms involved in the formation of the COI after SCI and discusses the integrative role of reactive astrogliosis in mechanisms involved in the removal of edema after the injury. A large proportion of edema fluid originating from the trauma and then from vasogenic edema related to persistent severe inflammation, may be moved into the COI in an active process involving astrogliosis and specifically over-expressed aquaporins.

Deriving Immune-Modulating Peptides from Viral Serine Protease Inhibitors (Serpins).

Viruses have devised highly effective approaches that modulate the host immune response, blocking immune responses that are designed to eradicate viral infections. Over millions of years of evolution, virus-derived immune-modulating proteins have become extraordinarily potent, in some cases working at picomolar concentrations when expressed into surrounding tissues and effectively blocking host defenses against viral invasion and replication. The marked efficiency of these immune-modulating proteins is postulated to be due to viral engineering of host immune modulators as well as design and development of new strategies (i.e., some derived from host proteins and some entirely unique). Two key characteristics of viral immune modulators confer both adaptive advantages and desirable functions for therapeutic translation. First, many virus-derived immune modulators have evolved structures that are not readily recognized or regulated by mammalian immune pathways, ensuring little to no neutralizing antibody responses or proteasome-mediated degradation. Second, these immune modulators tend to target early steps in central immune responses, producing a powerful downstream inhibitory "domino effect" which may alter cell activation and gene expression.We have proposed that peptide metabolites of these immune-modulating proteins can enhance and extend protein function. Active immunomodulating peptides have been derived from both mammalian and viral proteins. We previously demonstrated that peptides derived from computationally predicted cleavage sites in the reactive center loop (RCL) of a viral serine proteinase inhibitor (serpin ) from myxoma virus, Serp-1 , can modify immune response activation. We have also demonstrated modulation of host gut microbiota produced by Serp-1 and RCL-derived peptide , S7, in a vascular inflammation model. Of interest, generation of derived peptides that maintain therapeutic function from a serpin can act by a different mechanism. Whereas Serp-1 has canonical serpin-like function to inhibit serine proteases, S7 instead targets mammalian serpins. Here we describe the derivation of active Serp- RCL peptides and their testing in inflammatory vasculitis models.

Topical Application of Virus-Derived Immunomodulating Proteins and Peptides to Promote Wound Healing in Mouse Models.

Immune modulators play critical roles in the progression of wounds to normal or conversely delayed healing, through the regulation of normal tissue regrowth, scarring, inflammation, and growth factor expression. Many immune modulator recombinants are under active preclinical study or in clinical trial to promote improved acute or chronic wound healing and to reduce scarring. Viruses have evolved highly efficient immune modulators for the evasion of host-defensive immune responses that target and kill invasive viruses. Recent studies have proven that some of these virus-derived immune modulators can be used to promote wound healing with significantly improved speed and reduced scarring in rodent models. Mouse full-thickness excisional wound model is one of the most commonly used animal models used to study wound healing for its similarity to humans in the healing phases and associated cellular and molecular mechanisms. This chapter introduces this mouse dermal wound healing model in detail for application in studying viral immune modulators as new treatments to promote wound healing. Details of hydrogel, protein construction, and topical application methods for these therapeutic proteins are provided in this chapter.