Early protection from burn-induced acute lung injury by deletion of preprotachykinin-A gene

A Murine Model of Vesicant-Induced Acute Lung Injury

Burn injuries including those caused by chemicals can result in systemic effects and acute lung injury (ALI). Cutaneous exposure to Lewisite, a warfare and chemical burn agent, also causes ALI. To overcome the limitations in conducting direct research on Lewisite-induced ALI in a laboratory setting, an animal model was developed using phenylarsine oxide (PAO) as a surrogate for Lewisite. Due to lack of a reliable animal model mimicking the effects of such exposures, development of effective therapies to treat such injuries is challenging. We demonstrated that a single cutaneous exposure to PAO resulted in disruption of the alveolar-capillary barrier as evidenced by elevated protein levels in the bronchoalveolar lavage fluid (BALF). BALF supernatant of PAO-exposed animals had increased levels of high mobility group box 1, a damage associated molecular pattern molecule. Arterial blood-gas measurements showed decreased pH, increased PaCO2, and decreased partial pressure of arterial O2, indicative of respiratory acidosis, hypercapnia, and hypoxemia. Increased protein levels of interleukin (IL)-6, CXCL-1, CXCL-2, CXCL-5, granulocyte-macrophage colony-stimulating factor, CXCL-10, leukemia inhibitory factor, leptin, IL-18, CCL-2, CCL-3, and CCL-7 were observed in the lung of PAO-exposed mice. Further, vascular endothelial growth factor levels were reduced in the lung. Pulmonary function evaluated using a flexiVent showed a downward shift in the pressure-volume loop, decreases in static compliance and inspiratory capacity, increases in respiratory elastance and tissue elastance. These changes are consistent with an ALI phenotype. These results demonstrate that cutaneous PAO exposure leads to ALI and that the model can be used as an effective surrogate to investigate vesicant-induced ALI. SIGNIFICANCE STATEMENT: This study presents a robust model for studying ALI resulting from cutaneous exposure to PAO, a surrogate for the toxic vesicating agent Lewisite. The findings in this study mimic the effects of cutaneous Lewisite exposure, providing a reliable model for investigating mechanisms underlying toxicity. The model can also be used to develop medical countermeasures to mitigate ALI associated with cutaneous Lewisite exposure.

Immunomodulatory role of mitochondrial DAMPs: a missing link in pathology?

In accordance with the endosymbiotic theory, mitochondrial components bear characteristic prokaryotic signatures, which act as immunomodulatory molecules when released into the extramitochondrial compartment. These endogenous immune triggers, called mitochondrial damage-associated molecular patterns (mtDAMPs), have been implicated in the pathogenesis of various diseases, yet their role remains largely unexplored. In this review, we summarise the available literature on mtDAMPs in diseases, with a special focus on respiratory diseases. We highlight the need to bolster mtDAMP research using a multipronged approach, to study their effect on specific cell types, receptors and machinery in pathologies. We emphasise the lacunae in the current understanding of mtDAMPs, particularly in their cellular release and the chemical modifications they undergo. Finally, we conclude by proposing additional effects of mtDAMPs in diseases, specifically their role in modulating the immune system.

Inflammation and Organ Injury the Role of Substance P and Its Receptors

Tightly controlled inflammation is an indispensable mechanism in the maintenance of cellular and organismal homeostasis in living organisms. However, aberrant inflammation is detrimental and has been suggested as a key contributor to organ injury with different etiologies. Substance P (SP) is a neuropeptide with a robust effect on inflammation. The proinflammatory effects of SP are achieved by activating its functional receptors, namely the neurokinin 1 receptor (NK1R) receptor and mas-related G protein-coupled receptors X member 2 (MRGPRX2) and its murine homolog MRGPRB2. Upon activation, the receptors further signal to several cellular signaling pathways involved in the onset, development, and progression of inflammation. Therefore, excessive SP-NK1R or SP-MRGPRX2/B2 signals have been implicated in the pathogenesis of inflammation-associated organ injury. In this review, we summarize our current knowledge of SP and its receptors and the emerging roles of the SP-NK1R system and the SP-MRGPRX2/B2 system in inflammation and injury in multiple organs resulting from different pathologies. We also briefly discuss the prospect of developing a therapeutic strategy for inflammatory organ injury by disrupting the proinflammatory actions of SP via pharmacological intervention.

Large animal models of thermal injury

Burn injury results in a triad of inter-related adaptive responses: a systemic inflammatory response, a stress response, and a consequent hypermetabolic state which supports the former two. These pathological responses extend beyond the site of injury to affect distant organs and influence long-term outcomes in the patient. Animal models have proven valuable in advancing our understanding of mechanisms underlying the multifactorial manifestations of burn injury. While rodent models have been unprecedented in providing insights into signaling pathways, metabolic responses, protein turnover, cellular and molecular changes; small animal models do not replicate hypermetabolism, hyperinflammation, and wound healing after a burn injury as seen in humans. Herein, we provide a concise review of preferred large animal models utilized to understand burn pathophysiology based on organ systems and associated dysfunction. Additionally, we present a detailed protocol of contact burn injury in the Yorkshire pig model with a focus on preoperative care, anesthesia, analgesia, wound excision and grafting, dressing application, and frequency of dressing changes.

Potential biomarkers for the early prediction of SARS-COV-2 disease outcome

The current pandemic due to the fast spreading of SARS-CoV-2 infection has caused severe impairment in health, social, economic, scientific, and medical sectors across the globe. Owing to the not so well understood mechanism of disease pathogenesis in terms of variations in immune responses, there remains obscure why some of the patients who are infected by the novel SARS-CoV-2 develop an unpredictable clinical course that rapidly causes severe and deadly complications/manifestations. Currently, several assays are available for the confirmation of SARS-CoV-2 infection at the point of care. However, none of these assays can predict the severity of the COVID-19 disease. Thus, the identification of a prognostic biomarker that forecasts the condition of SARS-CoV-2 patients to develop a severe form of the disease could enable the clinicians for more efficient patient triage and treatment. In this regard, the present review describes the role of selected biomolecules that are crucially involved in the immune-pathogenesis of SARS-CoV-2 infection such as hyper-immune responsiveness, bradykinin storm and vascular leakage assuming these may serve as an effective prognostic biomarker in COVID-19 to understand the outcome of the disease. Based on the review, we also propose the development of a cost-effective SERS-based prognostic biosensor for the detection and quantification of biomolecules for use as a point-of-care system during a disease outbreak.

The Controversy of Renin-Angiotensin-System Blocker Facilitation Versus Countering COVID-19 Infection

The ongoing COVID-19 pandemic has produced serious turmoil world-wide. Lung injury causing acute respiratory distress syndrome seems to be a most dreaded complication occurring in ∼30%. Older patients with cardiovascular comorbidities and acute respiratory distress syndrome have an increased mortality. Although the precise mechanisms involved in the development of lung injury have not been fully elucidated, the role of the extended renin-angiotensin system seems to be pivotal. In this context, angiotensin-converting enzyme 2 (ACE2), an angiotensin-converting enzyme homologue, has been recognized as a facilitator of viral entry into the host, albeit its involvement in other counter-regulatory effects, such as converting angiotensin (Ang) II into Ang 1-7 with its known protective actions. Thus, concern was raised that the use of renin-angiotensin system inhibitors by increasing ACE2 expression may enhance patient susceptibility to the COVID-19 virus. However, current data have appeased such concerns because there has been no clinical evidence of a harmful effect of these agents as based on observational studies. However, properly designed future studies will be needed to further confirm or refute current evidence. Furthermore, other pathways may also play important roles in COVID-19 transmission and pathogenesis; spike (S) protein proteases facilitate viral transmission by cleaving S protein that promotes viral entry into the host; neprilysin (NEP), a neutral endopeptidase known to cleave natriuretic peptides, degrades Ang I into Ang 1-7; NEP can also catabolize bradykinin and thus mitigate bradykinin's role in inflammation, whereas, in the same context, specific bradykinin inhibitors may also negate bradykinin's harmful effects. Based on these intricate mechanisms, various preventive and therapeutic strategies may be devised, such as upregulating ACE2 and/or using recombinant ACE2, and exploiting the NEP, bradykinin and serine protease pathways, in addition to anti-inflammatory and antiviral therapies. These issues are herein reviewed, available studies are tabulated and pathogenetic mechanisms are pictorially illustrated.

Targeting Neprilysin (NEP) pathways: A potential new hope to defeat COVID-19 ghost

COVID-19 is an ongoing viral pandemic disease that is caused by SARS-CoV2, inducing severe pneumonia in humans. However, several classes of repurposed drugs have been recommended, no specific vaccines or effective therapeutic interventions for COVID-19 are developed till now. Viral dependence on ACE-2, as entry receptors, drove the researchers into RAS impact on COVID-19 pathogenesis. Several evidences have pointed at Neprilysin (NEP) as one of pulmonary RAS components. Considering the protective effect of NEP against pulmonary inflammatory reactions and fibrosis, it is suggested to direct the future efforts towards its potential role in COVID-19 pathophysiology. Thus, the review aimed to shed light on the potential beneficial effects of NEP pathways as a novel target for COVID-19 therapy by summarizing its possible molecular mechanisms. Additional experimental and clinical studies explaining more the relationships between NEP and COVID-19 will greatly benefit in designing the future treatment approaches.

Rationally synthesized coumarin based pyrazolines ameliorate carrageenan induced inflammation through COX-2/pro-inflammatory cytokine inhibition

In the present work, coumarin based pyrazolines (7a-g) have been synthesized and investigated for their in vitro and in vivo anti-inflammatory potential. Amongst the synthesized compounds, compounds 7a, 7d and 7f exhibited significant in vitro anti-inflammatory activity as compared to the standard etoricoxib. Keeping this in mind, in vivo investigations were carried out via carrageenan induced inflammation and acetic acid induced writhing models in male Wistar rats and compound 7a was found to possess appreciable anti-inflammatory and analgesic potential. The mode of action of compound 7a was also investigated by using substance P as the biomarker, which shows promising results. Further, the selectivity of the most active compound 7a against the cyclooxygenase enzyme was supported by molecular docking studies which reveal that compound 7a has greater binding affinity towards COX-2 over COX-1 and 5-LOX enzymes. In silico ADME analysis of compound 7a confirms the drug-like characteristics and the in vivo acute toxicity study showed the safety of the compound even up to a 2000 mg kg-1 dose. Thus, compound 7a was identified as an effective anti-inflammatory agent, and can be explored for further analgesic/anti-inflammatory drug design and development.

Role of autophagy and its molecular mechanisms in mice intestinal tract after severe burn

BACKGROUND

Severe burn can lead to hypoxia/ischemia of intestinal mucosa. Autophagy is the process of intracellular degradation, which is essential for cell survival under stresses, such as hypoxia/ischemia and nutrient deprivation. The present study was designed to investigate whether there were changes in intestinal autophagy after severe burn in mice and further to explore the effect and molecular mechanisms of autophagy on intestinal injury.

METHODS

This study includes three experiments. Kunming species mice were subjected to 30% total body surface area third-degree burn. First, we determined protein of LC3 (light chain 3), beclin-1, and cleaved-caspase3 by Western blotting and immunohistochemical (paraffin) staining to investigate whether there were changes in intestinal autophagy after severe burn in mice. Then, changes of the status of enteric damage postburn were measured by observing intestinal mucosa morphology under a magnifier, hematoxylin and eosin staining, enzyme-linked immunosorbent assay, Western blotting under the condition that the intestinal autophagy was respectively activated by rapamycin and inhibited by 3-methyladenine. Finally, protein of the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, LC3-II and beclin-1 were assayed, and mice were treated with compound C before burn.

RESULTS

The protein of LC3 and beclin-1 were observed at 1 hour postburn and increased to peak-point at 24 hours, reaching the normal level at 96 hours. The cleaved caspase-3 expression increased at 1 hour postburn, but the peak point occurred at 12 hours and had dropped to normal level at 72 hours. In addition, rapamycin enhanced intestinal autophagy and alleviated burn-induced gut damage, while 3-methyladenine showed the against behavior. The AMPK/mTOR pathway which was inhibited decreased the expression of phosphorylated AMPK, LC3-II, and beclin-1, increasing the expression of phosphorylated mTOR.

CONCLUSION

Intestinal autophagy is activated and response to intestinal apoptosis after serious burn, which alleviated burn-induced intestinal injury. The AMPK/mTOR pathway may involve in the activation of burn-induced autophagy.

LEVEL OF EVIDENCE

Therapeutic/care management, levels of evidence are not applicable to some studies, such as in vitro work, animal models, cadaver studies.

Influence of sensory neuropeptides on human cutaneous wound healing process

BACKGROUND

Close interactions exist between primary sensory neurons of the peripheral nervous system (PNS) and skin cells. The PNS may be implicated in the modulation of different skin functions as wound healing.

OBJECTIVE

Study the influence of sensory neurons in human cutaneous wound healing.

METHODS

We incubated injured human skin explants either with rat primary sensory neurons from dorsal root ganglia (DRG) or different neuropeptides (vasoactive intestinal peptide or VIP, calcitonin gene-related peptide or CGRP, substance P or SP) at various concentrations. Then we evaluated their effects on the proliferative and extracellular matrix (ECM) remodeling phases, dermal fibroblasts adhesion and differentiation into myofibroblasts.

RESULTS

Thus, DRG and all studied neuromediators increased fibroblasts and keratinocytes proliferation and act on the expression ratio between collagen type I and type III in favor of collagen I, particularly between the 3rd and 7th day of culture. Furthermore, the enzymatic activities of matrix metalloprotesases (MMP-2 and MMP-9) were increased in the first days of wound healing process. Finally, the adhesion of human dermal fibroblasts and their differentiation into myofibroblasts were promoted after incubation with neuromediators. Interestingly, the most potent concentrations for each tested molecules, were the lowest concentrations, corresponding to physiological concentrations.

CONCLUSION

Sensory neurons and their derived-neuropeptides are able to promote skin wound healing.

Role of hydrogen sulfide in the pathology of inflammation

Hydrogen sulfide (H2S) is a well-known toxic gas that is synthesized in the human body from the amino acids cystathionine, homocysteine, and cysteine by the action of at least two distinct enzymes: cystathionine-γ-lyase and cystathionine-β-synthase. In the past few years, H2S has emerged as a novel and increasingly important biological mediator. Imbalances in H2S have also been shown to be associated with various disease conditions. However, defining the precise pathophysiology of H2S is proving to be a complex challenge. Recent research in our laboratory has shown H2S as a novel mediator of inflammation and work in several groups worldwide is currently focused on determining the role of H2S in inflammation. H2S has been implicated in different inflammatory conditions, such as acute pancreatitis, sepsis, joint inflammation, and chronic obstructive pulmonary disease (COPD). Active research on the role of H2S in inflammation will unravel the pathophysiology of its actions in inflammatory conditions and may help develop novel therapeutic approaches for several, as yet incurable, disease conditions.

CD166(pos) subpopulation from differentiated human ES and iPS cells support repair of acute lung injury

Previous efforts to derive lung progenitor cells from human embryonic stem (hES) cells using embryoid body formation or stromal feeder cocultures had been limited by low efficiencies. Here, we report a step-wise differentiation method to drive both hES and induced pluripotent stem (iPS) cells toward the lung lineage. Our data demonstrated a 30% efficiency in generating lung epithelial cells (LECs) that expresses various distal lung markers. Further enrichment of lung progenitor cells using a stem cell marker, CD166 before transplantation into bleomycin-injured NOD/SCID mice resulted in enhanced survivability of mice and improved lung pulmonary functions. Immunohistochemistry of lung sections from surviving mice further confirmed the specific engraftment of transplanted cells in the damaged lung. These cells were shown to express surfactant protein C, a specific marker for distal lung progenitor in the alveoli. Our study has therefore demonstrated the proof-of-concept of using iPS cells for the repair of acute lung injury, demonstrating the potential usefulness of using patient's own iPS cells to prevent immune rejection which arise from allogenic transplantation.

Contributions of TRPV1, endovanilloids, and endoplasmic reticulum stress in lung cell death in vitro and lung injury

Endogenous agonists of transient receptor potential vanilloid-1 (TRPV1) (endovanilloids) are implicated as mediators of lung injury during inflammation. This study tested the hypothesis that endovanilloids produced following lipopolysaccharide (LPS) treatment activate TRPV1 and cause endoplasmic reticulum stress/GADD153 expression in lung cells, representing a mechanistic component of lung injury. The TRPV1 agonist nonivamide induced GADD153 expression and caused cytotoxicity in immortalized and primary human bronchial, bronchiolar/alveolar, and microvascular endothelial cells, proportional to TRPV1 mRNA expression. In CF-1 mice, Trpv1 mRNA was most abundant in the alveoli, and intratracheal nonivamide treatment promoted Gadd153 expression in the alveolar region. Treatment of CF-1 mice with LPS increased Gadd153 in the lung, lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, and lung wet-to-dry weight ratio. Cotreating mice with LPS and the TRPV1 antagonist LJO-328 reduced Gadd153 induction and LDH in BAL but did not inhibit increases in lung wet-to-dry ratio. In Trpv1(-/-) mice treated with LPS, Gadd153 induction and LDH in BAL were reduced relative to wild-type mice, and the wet-to-dry weight ratios of lungs from both wild-type and Trpv1(-/-) mice decreased. Organic extracts of blood collected from LPS-treated mice were more cytotoxic to TRPV1-overexpressing cells compared with BEAS-2B cells and extracts from control mice, however, most pure endovanilloids did not produce cytotoxicity in a characteristic TRPV1-dependent manner. Collectively, these data indicate a role for TRPV1, and endogenous TRPV1 agonists, in ER stress and cytotoxicity in lung cells but demonstrate that ER stress and cytotoxicity are not essential for pulmonary edema.

The role of neutral endopeptidase in caerulein-induced acute pancreatitis

Substance P (SP) is well known to promote inflammation in acute pancreatitis (AP) by interacting with neurokinin-1 receptor. However, mechanisms that terminate SP-mediated responses are unclear. Neutral endopeptidase (NEP) is a cell-surface enzyme that degrades SP in the extracellular fluid. In this study, we examined the expression and the role of NEP in caerulein-induced AP. Male BALB/c mice (20-25 g) subjected to 3-10 hourly injections of caerulein (50 μg/kg) exhibited reduced NEP activity and protein expression in the pancreas and lungs. Additionally, caerulein (10(-7) M) also downregulated NEP activity and mRNA expression in isolated pancreatic acinar cells. The role of NEP in AP was examined in two opposite ways: inhibition of NEP (phosphoramidon [5 mg/kg] or thiorphan [10 mg/kg]) followed by 6 hourly caerulein injections) or supplementation with exogenous NEP (10 hourly caerulein injections, treatment of recombinant mouse NEP [1 mg/kg] during second caerulein injection). Inhibition of NEP raised SP levels and exacerbated inflammatory conditions in mice. Meanwhile, the severity of AP, determined by histological examination, tissue water content, myeloperoxidase activity, and plasma amylase activity, was markedly better in mice that received exogenous NEP treatment. Our results suggest that NEP is anti-inflammatory in caerulein-induced AP. Acute inhibition of NEP contributes to increased SP levels in caerulein-induced AP, which leads to augmented inflammatory responses in the pancreas and associated lung injury.

MicroRNA-1 transfected embryonic stem cells enhance cardiac myocyte differentiation and inhibit apoptosis by modulating the PTEN/Akt pathway in the infarcted heart

microRNAs (miRs) have emerged as critical modulators of various physiological processes including stem cell differentiation. Indeed, miR-1 has been reported to play an integral role in the regulation of cardiac muscle progenitor cell differentiation. However, whether overexpression of miR-1 in embryonic stem (ES) cells (miR-1-ES cells) will enhance cardiac myocyte differentiation following transplantation into the infarcted myocardium is unknown. In the present study, myocardial infarction (MI) was produced in C57BL/6 mice by left anterior descending artery ligation. miR-1-ES cells, ES cells, or culture medium (control) was transplanted into the border zone of the infarcted heart, and 2 wk post-MI, cardiac myocyte differentiation, adverse ventricular remodeling, and cardiac function were assessed. We provide evidence demonstrating enhanced cardiac myocyte commitment of transplanted miR-1-ES cells in the mouse infarcted heart as compared with ES cells. Assessment of apoptosis revealed that overexpression of miR-1 in transplanted ES cells protected host myocardium from MI-induced apoptosis through activation of p-AKT and inhibition of caspase-3, phosphatase and tensin homolog, and superoxide production. A significant reduction in interstitial and vascular fibrosis was quantified in miR-1-ES cell and ES cell transplanted groups compared with control MI. However, no statistical significance between miR-1-ES cell and ES cell groups was observed. Finally, mice receiving miR-1-ES cell transplantation post-MI had significantly improved heart function compared with respective controls (P < 0.05). Our data suggest miR-1 drives cardiac myocyte differentiation from transplanted ES cells and inhibits apoptosis post-MI, ultimately giving rise to enhanced cardiac repair, regeneration, and function.

Burn-induced alterations in toll-like receptor-mediated responses by bronchoalveolar lavage cells

Burn is associated with profound inflammation and activation of the innate immune system in multiple organ beds, including the lung. Similarly, toll-like receptors (TLR) are associated with innate immune activation. Nonetheless, it is unclear what impact burn has on TLR-induced inflammatory responses in the lung.

METHODS

Male C57BL/6 mice were subjected to burn (3rd degree, 25% TBSA) or sham procedure and 1, 3 or 7 days thereafter, bronchoalveolar lavage (BAL) fluid was collected and cells were isolated and cultured in vitro with specific TLR agonists as follows: Zymosan (TLR-2), LPS (TLR-4) and CpG-ODN (TLR-9). Supernatants were collected 48 h later and assayed for inflammatory cytokine levels (IL-1β, IL-6, IL-10, IL-17, TNF-α, KC, MCP-1, MIP-1α, MIP-1β and RANTES) by Bioplex.

RESULTS

BAL fluid from sham and burn mice did not contain detectable cytokine levels. BAL cells, irrespective of injury, were responsive to TLR-2 and TLR-4 activation. Seven days after burn, TLR-2 and TLR-4 mediated responses by BAL cells were enhanced as evidenced by increased production of IL-6, IL-17, TNF-α, MCP-1, MIP-1β and RANTES.

CONCLUSIONS

Burn-induced changes in TLR-2 and TLR-4 reactivity may contribute to the development of post-burn complications, such as acute lung injury (ALI) and adult respiratory distress syndrome (ARDS).

Expression of neutral endopeptidase activity during clinical and experimental acute lung injury

Background

Neutral endopeptidase (NEP), an enzyme that cleaves inflammatory bioactive peptides, may play a protective role in the pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). However, its low extracellular activity hinders the precise measurement of changes that take place during ALI/ARDS. The main objective of this study was to clarify the regulation of NEP activity and its expression during ALI/ARDS.

Methods

In a clinical study, we measured plasma NEP activity in patients who developed postoperative ALI/ARDS, using a HPLC fluorometric system. In an experimental study, we induced ALI by intratracheal instillation of hydrochloric acid (HCl) or lipopolysaccharide (LPS) in mice, and similarly measured NEP activity in plasma, lung tissue, and broncho-alveolar lavage fluid (BALF). We also studied the distribution and measured the amounts of NEP protein, using immuno-histochemical and immunoblot analyses, and measured the levels of NEP mRNA, using real-time reverse transcription-polymerase chain reaction, in the lungs of mice with ALI.

Results

The plasma NEP activity was significantly lower in patients presenting with ALI/ARDS than in controls. Similarly, the NEP activity in plasma and lung tissue was markedly lower, and lung injuries more severe in LPS- than in HCl-treated mice. In contrast, the activity of NEP in the BALF of LPS-treated mice was increased. The intratracheal instillation of LPS decreased the gene expression of NEP in the lung. Immuno-histochemical and Western immunoblot studies in mice confirmed a) the presence of NEP in the alveolar wall, a critical target in ALI/ARDS, and b) a decrease in its expression in HCl- and LPS-induced ALI.

Conclusion

In this experimental and clinical study of ALI/ARDS, the activity of NEP was significantly decreased in plasma and increased in the alveolar air space.

Role of hydrogen sulfide in severe burn injury-induced inflammation in mice

Endogenous hydrogen sulfide (H(2)S) is naturally synthesized in many types of mammalian cells from L-cysteine in the reactions catalyzed by cystathionine-β-synthase and cystathionine-γ-lyase (CSE). H(2)S has been demonstrated to play a proinflammatory role in various animal models of hindpaw edema, acute pancreatitis, lipopolysaccharide-induced endotoxemia and cecal ligation, and puncture-induced sepsis. Full-thickness burns that exceed 25% of the total body surface area (TBSA) produce a profound systemic inflammatory reaction characterized by leukocyte activation and plasma leakage in the microvasculature of tissues and organs remote from the wound. The aim of this study was to investigate the effect of local burn injury on induced distant organ endogenous H(2)S release and expression of CSE. Male BALB/c mice were subjected to 30% TBSA full-thickness burn and treated with saline (administered intraperitoneally [i.p.]); DL-propargylglycine (PAG, 50 mg/kg i.p.), which is a CSE inhibitor; or sodium hydrosulfide (NaHS, 10 mg/kg i.p.), which is an H(2)S donor. PAG was administered either 1 h before or 1 h after the burn injury, whereas NaHS was given at the same time as the burn injury. Measurements of liver myeloperoxidase (MPO) activities, liver H(2)S-synthesizing activity, plasma H(2)S level and liver and lung CSE mRNA expression and histological examination of tissues were performed after burn injury. Burn injury significantly increased the plasma H(2)S level and liver H(2)S synthesis 8 h after burn compared with the sham group. Burn injury also resulted in a significant upregulation of CSE mRNA in liver and lung. Prophylactic as well as therapeutic administration of PAG significantly reduced burn-associated systemic inflammation, as evidenced by MPO activity and histological changes in liver and lung. Injection of NaHS significantly aggravated burn-associated systemic inflammation. Therefore, our findings show for the first time the role of H(2)S in contributing to inflammatory damage after burn injury.