Delivery of Nitric Oxide by Chondroitin Sulfate C Increases the Rate of Wound Healing through Immune Modulation.

Chronic wounds impact 2.5% of the United States population and will continue to be a major clinical challenge due to increases in population age, chronic disease diagnoses, and antibiotic-resistant infection. Nitric oxide (NO) is an endogenous signaling molecule that represents an attractive, simple therapeutic for chronic wound treatment due to its innate antibacterial and immunomodulatory function. Unfortunately, modulating inflammation for extended periods by low levels of NO is not possible with NO gas. Herein, we report the utility of a NO-releasing glycosaminoglycan biopolymer (GAG) for promoting wound healing. GAGs are naturally occurring biopolymers that are immunomodulatory and known to be involved in the native wound healing process. Thus, the combination of NO and GAG biopolymers represents an attractive wound therapeutic due to these known independent roles. The influence and contribution of chondroitin sulfate C (CSC) modified to facilitate controlled and targeted delivery of NO (CSC-HEDA/NO) was evaluated using in vitro cell proliferation and migration assays and an in vivo wound model.

Multimodal Nuclear Factor-Erythroid-2-Related Factor (NRF2) Therapy in the Context of Mammalian Target of Rapamycin (mTOR) Inhibition Reprograms the Acute Systemic and Pulmonary Immune Response after Combined Burn and Inhalation Injury.

ABSTRACT: Severe burn injuries induce acute and chronic susceptibility to infections, which is largely attributed to a hyper-pro-inflammatory response followed by a chronic anti-inflammatory response. Concurrent inhalation injury (B + I) causes airway inflammation. Pulmonary macrophages and neutrophils are "hyperactive" with increased reactive oxygen (ROS) and nitrogen species (RONS) activity, but are unable to clear infection, causing airway damage upon activation. Nuclear Factor-Erythroid-2-Related Factor (NRF2) is a critical immunomodulatory component that induces compensatory anti-inflammatory pathways when activated. On the other hand, inhibition of Mammalian Target of Rapamycin (mTOR) reduces pro-inflammatory responses. The therapeutic use of these targets is limited, as known modulators of these pathways are insoluble in saline and require long-term administration. A biocompatible NRF2 agonist (CDDO) and rapamycin (RAPA) poly (lactic-co-glycolic acid) (PLGA) microparticles (MP) were created, which we hypothesized would reduce the acute hyper-inflammatory response in our murine model of B + I injury. BI-injured mice that received CDDO-MP or both CDDO-MP and RAPA-MP (Combo-MP) an hour after injury displayed significant changes in the activation patterns of pulmonary and systemic immune genes and their associated immune pathways 48 h after injury. For example, mice treated with Combo-MP showed a significant reduction in inflammatory gene expression compared to untreated or CDDO-MP-treated mice. We also hypothesized that Combo-MP therapy would acutely decrease bacterial susceptibility after injury. BI-injured mice that received Combo-MP an hour after injury, inoculated 48 h later with Pseudomonas aeruginosa (PAO1), and sacrificed 48 h after infection, displayed significantly decreased bacterial counts in the lungs and liver versus untreated B + I mice. This reduction in infection was accompanied by significantly altered lung and plasma cytokine profiles and immune reprogramming of pulmonary and splenic cells. Our findings strongly suggest that multimodal MP-based therapy holds considerable promise for reprogramming the immune response after burn injuries, particularly by mitigating the hyper-inflammatory phase, and preventing subsequent susceptibility to infection.