Multiplexed Human Gene Expression Analysis Reveals a Central Role of the TLR/mTOR/PPARγ and NFkB Axes in Burn and Inhalation Injury-Induced Changes in Systemic Immunometabolism and Long-Term Patient Outcomes

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-proinflammatory 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 proinflammatory 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.

An Appraisal of Pharmacotherapy-Pertinent Literature Published in 2021 and 2022 for Clinicians Caring for Patients With Thermal or Inhalation Injury

Studies focusing on pharmacotherapy interventions to aid patients after thermal injury are a minor focus in burn injury-centered studies and published across a wide array of journals, which challenges those with limited resources to keep their knowledge current. This review is a renewal of previous years' work to facilitate extraction and review of the most recent pharmacotherapy-centric studies in patients with thermal and inhalation injury. Twenty-three geographically dispersed, board-certified pharmacists participated in the review. A Medical Subject Heading-based, filtered search returned 2336 manuscripts over the previous 2-year period. After manual review, 98 (4%) manuscripts were determined to have a potential impact on current pharmacotherapy practice. The top 10 scored manuscripts are discussed. Only 17% of those reviewed were assessed to likely have little effect on current practice. The overall impact of the current cohort was higher than previous editions of this review, which is encouraging. There remains a need for investment in well-designed, high-impact, pharmacotherapy-pertinent research for patients sustaining thermal or inhalation injuries.

In silico screening of phytoconstituents as potential anti-inflammatory agents targeting NF-κB p65: an approach to promote burn wound healing

Chronic burn wounds are frequently characterised by a prolonged and dysregulated inflammatory phase that is mediated by over-activation of NF-κB p65. Synthetic wound healing drugs used for treatment of inflammation are primarily associated with several shortcomings which reduce their therapeutic index. In this scenario, phytoconstituents that exhibit multifaceted biological activities including anti-inflammatory effects have emerged as a promising therapeutic alternative. However, identification and isolation of phytoconstituents from medicinal herbs is a cumbersome method that is linked to profound uncertainty. Hence, present study aimed to identify prospective phytoconstituents as inhibitors of RHD of NF-κB p65 by utilizing in silico approach. Virtual screening of 2821 phytoconstituents was performed against protein model. Out of 2821 phytoconstituents, 162 phytoconstituents displayed a higher binding affinity (≤ -8.0 kcal/mol). These 162 phytoconstituents were subjected to ADMET predictions, and 15 of them were found to satisfy Lipinski's rule of five and showed favorable pharmacokinetic properties. Among these 15 phytoconstituents, 5 phytoconstituents with high docking scores i.e. silibinin, bismurrayaquinone A, withafastuosin B, yuccagenin, (+)-catechin 3-gallate were selected for molecular dynamics (MD) simulation analysis. Results of MD simulation indicated that withafastuosin B, (+)-catechin 3-gallate and yuccagenin produced a compact and stable complex with protein without significant variations in conformation. Relative binding energy analysis of best hit molecules indicate that withafastuosin B, and (+)-catechin 3-gallate exhibit high binding affinity with target protein among other lead molecules. Findings of study suggest that these phytoconstituents could serve as promising anti-inflammatory agents for treatment of burn wounds by inhibiting the RHD of NF-κB p65.Communicated by Ramaswamy H. Sarma.

PPARG stimulation restored lung mRNA expression of core clock, inflammation- and metabolism-related genes disrupted by reversed feeding in male mice

The circadian rhythm system regulates lung function as well as local and systemic inflammations. The alteration of this rhythm might be induced by a change in the eating rhythm. Peroxisome proliferator-activated receptor gamma (PPARG) is a key molecule involved in circadian rhythm regulation, lung functions, and metabolic processes. We described the effect of the PPARG agonist pioglitazone (PZ) on the diurnal mRNA expression profile of core circadian clock genes (Arntl, Clock, Nr1d1, Cry1, Cry2, Per1, and Per2) and metabolism- and inflammation-related genes (Nfe2l2, Pparg, Rela, and Cxcl5) in the male murine lung disrupted by reversed feeding (RF). In mice, RF disrupted the diurnal expression pattern of core clock genes. It decreased Nfe2l2 and Pparg and increased Rela and Cxcl5 expression in lung tissue. There were elevated levels of IL-6, TNF-alpha, total cells, macrophages, and lymphocyte counts in bronchoalveolar lavage (BAL) with a significant increase in vascular congestion and cellular infiltrates in male mouse lung tissue. Administration of PZ regained the diurnal clock gene expression, increased Nfe2l2 and Pparg expression, and reduced Rela, Cxcl5 expression and IL-6, TNF-alpha, and cellularity in BAL. PZ administration at 7 p.m. was more efficient than at 7 a.m.

Involvement of extracellular vesicles in the progression, diagnosis, treatment, and prevention of whole-body ionizing radiation-induced immune dysfunction

Acute radiation syndrome (ARS) develops after exposure to high doses of ionizing radiation and features immune suppression and organ failure. Currently, there are no diagnostics to identify the occurrence or severity of exposure and there are limited treatments and preventative strategies to mitigate ARS. Extracellular vesicles (EVs) are mediators of intercellular communication that contribute to immune dysfunction across many diseases. We investigated if EV cargo can identify whole body irradiation (WBIR) exposure and if EVs promote ARS immune dysfunction. We hypothesized that beneficial EVs derived from mesenchymal stem cells (MSC-EVs) would blunt ARS immune dysfunction and might serve as prophylactic radioprotectants. Mice received WBIR (2 or 9 Gy) with assessment of EVs at 3 and 7 days after exposure. LC-MS/MS proteomic analysis of WBIR-EVs found dose-related changes as well as candidate proteins that were increased with both doses and timepoints (34 total) such as Thromboxane-A Synthase and lymphocyte cytosolic protein 2. Suprabasin and Sarcalumenin were increased only after 9 Gy suggesting these proteins may indicate high dose/lethal exposure. Analysis of EV miRNAs identified miR-376 and miR-136, which were increased up to 200- and 60-fold respectively by both doses of WBIR and select miRNAs such as miR-1839 and miR-664 were increased only with 9 Gy. WBIR-EVs (9 Gy) were biologically active and blunted immune responses to LPS in RAW264.7 macrophages, inhibiting canonical signaling pathways associated with wound healing and phagosome formation. When given 3 days after exposure, MSC-EVs slightly modified immune gene expression changes in the spleens of mice in response to WBIR and in a combined radiation plus burn injury exposure (RCI). MSC-EVs normalized the expression of certain key immune genes such as NFκBia and Cxcr4 (WBIR), Map4k1, Ccr9 and Cxcl12 (RCI) and lowered plasma TNFα cytokine levels after RCI. When given prophylactically (24 and 3 hours before exposure), MSC-EVs prolonged survival to the 9 Gy lethal exposure. Thus, EVs are important participants in ARS. EV cargo might be used to diagnose WBIR exposure, and MSC-EVs might serve as radioprotectants to blunt the impact of toxic radiation exposure.