Parallel Self-Induction of TNF-α and Apoptosis in the Thymus of Mice after Burn Injury

Dietary α-ketoglutarate alleviates glycinin and β-conglycinin induced damage in the intestine of mirror carp (Cyprinus carpio)

This study investigated the glycinin and β-conglycinin induced intestinal damage and α-ketoglutarate alleviating the damage of glycinin and β-conglycinin in intestine. Carp were randomly divided into six dietary groups: containing fish meal (FM) as the protein source, soybean meal (SM), glycinin (FMG), β-conglycinin (FMc), glycinin+1.0% α-ketoglutarate (AKG) (FMGA), β-conglycinin+1.0% AKG (FMcA). The intestines were collected on 7^th, and the hepatopancreas and intestines were collected on 56^th. Fish treated with SM and FMc displayed reduced weight gain, specific growth rate, and protein efficiency. On 56^th day, Fish fed on SM, FMG and FMc presented lower superoxide dismutase (SOD) activities. FMGA and FMcA had higher SOD activity than those fed on the FMG and FMc, respectively. In intestine, fish fed on the SM diets collected on 7^th presented upregulated the expression of transforming growth factor beta (TGFβ1), AMP-activated protein kinase beta (AMPKβ), AMPKγ, and acetyl-CoA carboxylase (ACC). Fish fed FMG presented upregulated expression of tumor necrosis factor alpha (TNF-α), caspase9, and AMPKγ, while downregulated the expression of claudin7 and AMPKα. FMc group presented upregulated expression of TGFβ1, caspase3, caspase8, and ACC. Fish fed FMGA showed upregulated expression of TGFβ1, claudin3c, claudin7, while downregulating the expression of TNF-α and AMPKγ when compared to fish fed FMG diet. FMcA upregulated the expression of TGFβ1, claudin3c than fed on the FMc. In intestine, the villus height and mucosal thickness of the proximal intestine (PI) and the distal intestine (DI) were decreased and crypt depth of the PI and mid intestine (MI) were increased in SM, FMG and FMc. In addition, fish fed on SM, FMG and FMc presented lower citrate synthase (CS), isocitrate dehydrogenase (ICD), α-ketoglutarate dehydrogenase complex (α-KGDHC) Na⁺/K⁺-ATPase activity in DI. FMGA had higher CS, ICD, α-KGDHC, and Na⁺/K⁺-ATPase activity in PI and MI than those fed on the FMG. FMcA had higher Na⁺/K⁺-ATPase activity in MI. In conclusion, dietary soybean meal destroys the intestine's health, the adverse effects are related to the presence of β-conglycinin and glycinin, especially glycinin. AKG may regulate intestinal energy via tricarboxylic acid cycle, thereby alleviating the damage intestinal morphology caused by the dietary soybean antigen proteins.

Comparison of Thermal Burn-Induced and Excisional-Induced Scarring in Animal Models: A Review of the Literature

Significance: Scar formation is a natural result of mammalian wound healing. In humans and other mammals, however, deep dermal wounds and thermal injuries often result in formation of hypertrophic scars, leading to substantial morbidity and lending great importance to development of therapeutic modalities for burn scars. Clinical Issues: Thus, preclinical burn wound models that adequately simulate processes underlying human burn-induced wound healing, particularly those processes leading to chronic inflammation and development of hypertrophic scars, are critical to developing further treatment paradigms for clinical use. Approach: In this study, we review literature describing various burn models, focusing on their characteristics and the functional readouts that lead to generation of useful data. We also briefly discuss recent work using human ex vivo skin culture as an alternative to animal models, as well as our own development of rabbit ear wound models for burn scars, and assess the pros and cons of these models compared to other models. Future Direction: Understanding of the strengths and weaknesses of preclinical burn wound models will enable choice of the most appropriate wound model to answer particular clinically relevant questions, furthering research aimed at treating burn scars.

A narrative review of changes in microvascular permeability after burn

Objective

We aimed to review and discuss some of the latest research results related to post-burn pathophysiological changes and provide some clues for future study.

Background

Burns are one of the most common and serious traumas and consist of a series of pathophysiological changes of thermal injury. Accompanied by thermal damage to skin and soft tissues, inflammatory mediators are released in large quantities. Changes in histamine, bradykinin, and cytokines such as vascular endothelial growth factor (VEGF), metabolic factors such as adenosine triphosphate (ATP), and activated neutrophils all affect the body’s vascular permeability.

Methods

We searched articles with subject words “microvascular permeability”, “burn” “endothelium”, and “endothelial barrier” in PubMed in English published from the beginning of database to Dec, 2020.

Conclusions

The essence of burn shock is the rapid and extensive fluid transfer in burn and non-burn tissue. After severe burns, the local and systemic vascular permeability increase, causing intravascular fluid extravasation, leading to a progressive decrease in effective circulation volume, an increase in systemic vascular resistance, a decrease in cardiac output, peripheral tissue edema, multiple organ failure, and even death. There are many cells, tissues, mediators and structures involved in the pathophysiological process of the damage to vascular permeability. Ulinastatin is a promising agent for this problem.

Effects of dietary anthocyanin on innate immune parameters, gene expression responses, and ammonia resistance of Nile tilapia (Oreochromis niloticus)

The present study investigated the effects of dietary anthocyanin on the growth performance, haematological, non-specific immune, and spleen gene expression responses of Nile tilapia, Oreochromis niloticus. Five experimental groups of fish with mean weights of 8.24 ± 0.64 g were used in the study; four of these were fed with diets incorporating anthocyanin (20 mg kg -¹, 40 mg kg^-1, 80 mg kg^-1 and 160 mg kg^-1), while the fifth was a control group without dietary anthocyanin. Growth performance and haematological parameters of tilapia were not affected by anthocyanin-supplemented diets (p > 0.05). Dietary anthocyanin significantly increased respiratory burst activity, phagocytic activity, phagocytic index, lysozyme activity, myeloperoxidase activity, serum total superoxide dismutase (T.SOD) activity, and serum catalase (CAT) activity (p < 0.05). The total immunoglobulin level was highest in the 80 mg kg^-1 group compared with the other groups (p < 0.05). In addition, with the anthocyanin-containing diets, the gene levels of interleukin 1, beta (IL-1β), interleukin 8 (IL-8), tumor necrosis factor (TNF-α), heat shock protein 70 (HSP70), and interferon gamma (IFN-γ) were increased in the fish spleen, and the gene levels of CAT, GPx, and SOD were also increased in fish liver (p < 0.05). At the end of the experiment, the fish were subjected to ammonia stress. The groups fed with 20 and 40 mg kg^-1 anthocyanin exhibited higher survival rates than the other groups. In summary, feeding Nile tilapia with anthocyanin-containing diets caused increases in the innate immune parameters, gene expression responses, and the survival rate of the fish subjected to ammonia stress.

Effect of a probiotic fermented milk on the thymus in Balb/c mice under non-severe protein-energy malnutrition

Protein–energy malnutrition (PEM) causes a significant impairment of the immune system, the thymus being one of the most affected organs. It has been demonstrated that the administration of probiotic fermented milk (PFM) recovered the intestinal barrier, histological alterations and mucosal and systemic immune functions in a non-severe malnutrition model using BALB/c mice. The aim of the present study was to evaluate, in the same model of malnutrition, the effect of a PFM added to a re-nutrition diet on the recovery of the thymus, analysing histological and functional alterations caused by malnutrition. Mice were undernourished and divided into three groups according to the dietary supplement received during re-nutrition: milk, PFM or its bacterial-free supernatant (BFS). They were compared with well-nourished and malnourished mice. PFM was the most effective re-nutrition supplement to improve the histology of the thymus, decreasing cellular apoptosis in this organ and recovering the percentage of CD4þ/CD82 single-positive thymocytes. Immature doublepositive thymocytes were increased in the malnourished control (MC). The production of different cytokines in the thymus was increased in mice given PFM, compared with the mice that received other dietary supplements and MC. Mice given the BFS presented an improvement in the thymus similar to those that received milk. We demonstrated the importance of the whole PFM supplementation on the histological and functional recovery of the thymus in a non-severe PEM model.

Tropism, cytotoxicity, and inflammatory properties of two envelope genes of murine leukemia virus type-endogenous retroviruses of C57BL/6J mice

Envelope (env) proteins of certain endogenous retroviruses (ERVs) participate in various pathophysiological processes. In this study, we characterized pathophysiologic properties of two murine leukemia virus-type ERV (MuLV-ERV) env genes cloned from the ovary of C57BL/6J mice. The two env genes (named ENV_OV1 and ENV_OV2), with 1,926 bp coding region, originated from two MuLV-ERV loci on chromosomes 8 and 18, respectively. ENV_OV1 and ENV_OV2 were ~75 kDa and predominantly expressed on the cell membrane. They were capable of producing pseudotype murine leukemia virus virions. Tropism trait and infectivity of ENV_OV2 were similar to the polytropic env; however, ENV_OV1 had very low level of infectivity. Overexpression of ENV_OV2, but not ENV_OV1, exerted cytotoxic effects and induced expression of COX-2, IL-1β, IL-6, and iNOS. These findings suggest that the ENV_OV1 and ENV_OV2 are capable of serving as an env protein for virion assembly, and they exert differential cytotoxicity and modulation of inflammatory mediators.

Second hit post burn increased proximal gut mucosa epithelial cells damage

Secondary infections after burn are common and are a major contributor to morbidity and mortality. We previously showed that burn disrupted proximal gut mucosal homeostasis through increased epithelial cell apoptosis. In the present study, we sought to determine whether proximal gut mucosal disruption is additively affected by secondary endotoxemia after a severe burn. C57BL/6 mice received 30% total body surface area full-thickness scald burns and were randomized to receive saline or LPS 1 mg/kg body weight given intraperitoneally 72 h after burn. Proximal small bowel was harvested 12 h after LPS injection. Mucosal height and epithelial cell number were assessed on hematoxylin-eosin sections, intestinal epithelial cell apoptosis was identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and cell proliferation by immunohistochemical staining for proliferating cell nuclear antigen. Results showed that proximal gut mucosa impairment occurred 12 h after injury, including significantly decreased proximal gut wet weight, gut mucosal height, and epithelial cell number associated with increased proximal gut epithelial apoptosis (P < 0.05). This impairment diminished 72 h after burn. Second-hit endotoxemia caused additional proximal gut mucosa damage with decreased proximal gut weight, cell number, and mucosal height (P < 0.05) and significantly increased small intestinal epithelial apoptosis and mucosal atrophy, even after the first event, indicating a second detrimental effect of endotoxemia after the initial injury.

“Systemic apoptotic response” after thermal burns

The systemic pathophysiologic changes following thermal injuries affect multiple organs and body systems leading to clinical manifestations including shock, intestinal alterations, respiratory and renal failure, immunosuppression and others. Recent advances in the comprehension of mechanisms underlying systemic complications of thermal injuries have contributed to uncover part of the cellular and molecular basis that underlie such changes. Recently, programmed cell death (apoptosis) has been considered playing an important role in the development of such pathological events. Therefore, investigators utilizing animal models and clinical studies involving human primates have produced a large body of information suggesting that apoptosis is associated with most of the tissue damages triggered by severe thermal injuries. In order to draw the attention on the important role of apoptosis on systemic complications of thermal injuries, in this review we describe most of these studies, discuss possible cellular and molecular mechanisms and indicate ways to utilize them for the development of therapeutic strategies by which apoptosis may be prevented or counteracted.

The effects of propofol and ketamine on gut mucosal epithelial apoptosis in rats after burn injury

BACKGROUND AND OBJECTIVES

Apoptosis occurs after thermal injury and may result from either ischaemic intestinal insult or inflammatory mediators released after burn injury. The aim of the study was to investigate the effects of propofol and ketamine on gut epithelium apoptosis after burn injury.

METHODS

Sixty male Wistar Albino rats were randomly assigned into four groups. Anaesthesia was induced and maintained with propofol in Groups 1 and 2, and ketamine in Groups 3 and 4 over 12 h. Groups 2 and 4 received 30% total body surface area burn. Groups 1 and 3 had no burn injury. Mean arterial pressure was maintained within 10% of baseline levels in all animals. At 12 h postburn, animals were sacrificed and tissue samples were taken from small intestine for determination of lipid peroxidation, apoptosis and proliferation. Also blood samples were taken for measurement of serum tumor necrosis factor-alpha (TNF-alpha) levels.

RESULTS

Ileal malondialdehyde (MDA) concentration (extent of lipid peroxidation) increased significantly in Group 4 (112.4 +/- 10.2 nmol g-1) compared to Group 3 (48.4 +/- 5.6 nmol g-1) and Group 2 (59.8 +/- 3.2 nmol g-1). The mean TNF-alpha level in Group 4 (118.9 +/- 10.5 pg mL-1) at 12 h postburn was significantly higher than the mean in Group 2 (56.4 +/- 4.3 pg mL-1). Group 4 had the highest mean TUNEL index (terminal deoxyuridine nick-end labelling--an index of extent of apoptosis) of all the groups (265/10). Also the mean TUNEL index value in Group 2 (53/10) was higher than that of Group 1 (3/10) and Group 3 (5/10). The proliferating cell nuclear antigen index (extent of proliferation) remained unchanged among groups.

CONCLUSIONS

Propofol could offer a protection against apoptosis of enterocytes with a stable tissue MDA and serum TNF-alpha level compared to ketamine anaesthesia in an animal model of burn injury.

Corticosterone binding globulin regulation and thymus changes after thermal injury in mice

Thermal injury is extremely stressful, and data characterizing the systemic endocrine stress response to this injury are sparse. The objective of this study was to measure the effects of thermal injury on mice on corticosterone (Cort) levels in relation with corticosteroid-binding globulin (CBG) and thymus cell populations. The endocrine stress response was determined by measuring total Cort, free Cort, CBG binding capacity, liver CBG mRNA, and circulating CBG levels at 1, 2, 5, and 10 days postburn. Thymus cell populations were also analyzed. After thermal injury, a rapid increase of total Cort was observed in the first 48 h. This was associated with a decrease of hepatic CBG mRNA, protein levels, and binding capacity. Percentage of free Cort in the burn group peaked at day 2 postburn with a dramatic (+500%) increase. This correlated with a significant decrease of thymus cellularity (50% less). Phenotypic analyses showed that corticosensitive cells were significantly altered. After treatment (5 days), both endocrine and immune parameters returned to control levels. Our results demonstrate that, after a thermal injury, CBG is mainly responsible for Cort's action on corticosensitive immune cells.

The effect of shock resuscitation fluids on apoptosis

BACKGROUND

Recent data suggest that the type of resuscitation fluid used to treat hemorrhagic shock contributes to cellular dysfunction

METHODS

Rats were hemorrhaged, exposed to a hypovolemic shock period for 75 minutes, and then resuscitated for 1 hour. Treatment animals were assigned randomly to lactate Ringer's solution, normal saline solution, bicarbonate Ringer's solution, hypertonic saline solution, rat plasma solution, ketone Ringer's solution, or nonresuscitation. After resuscitation, lung and liver samples were collected and evaluated for apoptosis by using ligation-mediated polymerase chain reaction.

RESULTS

Nonresuscitated shock rats had significantly higher levels of apoptosis in lung and liver. Rats treated with normal saline solution, bicarbonate Ringer's solution, ketone Ringer's solution, and hypertonic saline solution had significantly lower levels of apoptosis in lung compared with nonresuscitated animals. Rats treated with bicarbonate Ringer's solution and ketone Ringer's solution had significantly lower levels of apoptosis in liver tissue when compared with nonresuscitated animals.

CONCLUSIONS

Cellular damage results from hemorrhagic shock. The use of resuscitation fluids decreases apoptosis during shock.

Alterations in the Levels of Metallothionein and Metals in the Liver, and Unique Serum Liver Enzyme Response in Metallothionein Knock-Out Mice after Burn Injury

OBJECTIVES

Metallothionein (MT) is a small cysteine-rich protein that sequesters and distributes metal ions. Its overexpression stimulates cell proliferation and inhibits apoptosis. We investigated the effects of burn injury on MT expression and metal localization. We also sought to determine roles of MT in the pathophysiologic alterations in the liver after injury.

METHODS

Mice (C57BLKS/J, MT-I/II knock-out, KO, and wild-type control mice) were subjected to an 18% burn. Liver tissues harvested after injury were analyzed for the MT expression and the levels of zinc, copper, manganese, and iron. Levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were measured in serum samples from MT-I/MT-II KO mice and controls after injury.

RESULTS

Transient induction of MT-I and MT-II mRNAs was observed 3-6 h after injury, while MT-I/MT-II protein peaked on day 1. The induction was localized to hepatocytic nuclei. The intrahepatic levels of zinc, copper, and iron were transiently elevated on day 1, when a downregulation of manganese was evident. Interestingly, only the serum levels of aspartate aminotransferase were significantly augmented in MT-I/MT-II KO mice compared to controls after injury.

CONCLUSIONS

These data suggest that MT and metals may participate in the pathogenesis of the liver after burn injury.

The role of γδ T cells in the regulation of neutrophil-mediated tissue damage after thermal injury

Thermal injury induces an inflammatory response that contributes to the development of secondary tissue damage. Neutrophil recruitment and activation are in part responsible for this tissue damage. Although gammadelta T cells have been shown to regulate the inflammatory responses in tissues that are prone to neutrophil-mediated injury post-burn, their role in the induction of secondary tissue injury post-burn remains unknown. To study this, gammadelta T cell-deficient (gammadelta TCR-/-) and wild-type (WT) mice were subjected to thermal injury or sham procedure, and tissue samples were isolated 1-24 h thereafter. Burn injury induced neutrophil accumulation in the lung and small intestines of WT mice at 1-3 h post-injury. No such increase in neutrophil tissue content was observed in gammadelta TCR-/- mice. An increase in tissue wet/dry weight ratios was also observed in these organs at 3 h post-burn in WT but not in gammadelta TCR-/- mice. A parallel increase in plasma and small intestine levels of the chemokines macrophage-inflammatory protein-1beta (chemokine ligand 4) and keratinocyte-derived chemokine (CXC chemokine ligand 1) were observed in injured WT mice but not in injured gammadelta TCR-/- mice. Increased activation (CD120b expression) of the circulating gammadelta T cell population was also observed at 3 h post-burn in WT mice. These results indicate the gammadelta T cells, through the production of chemokines, play a central role in the initiation of neutrophil-mediated tissue damage post-burn.

Injury-associated differential regulation of histone expression and modification in the thymus of mice

One of the key events in the regulation of gene expression is chromatin remodeling involving histone regulation. We investigated the effects of burns on the expression of histone that might be associated with altered molecular and pathological profiles in the thymus. A markedly decreased expression of histone variant H2A.1 mRNA was identified in the thymus after burn during a differential display experiment. Subsequently, we examined the histone expression (mRNA and protein) and posttranslational modification in the thymus after burn. Also, changes in proliferating cell nuclear antigen (PCNA), a central molecule in chromatin assembly, was examined. Reverse-transcription polymerase chain reaction analysis revealed a transient decrease in the expression of several histone variants (H2A.1, H1(r1), H3-B, H3-1, and H4-D) mRNAs in the thymus at 1 day after burn. A decrease in histone subtypes H2A, H2B, H3, and H4, but not H1, was demonstrated 1 and 3 days after burn according to the results of Western blot. Furthermore, there were different levels of decreases in acetylated and dimethylated forms of histone H3 1 and 3 days after burn. In addition, decreased levels of PCNA were evident in the thymus 1 day after burn. Changes in the expression of histones and PCNA may reflect mere decrease in proliferating cells and/or a reorganization of the chromatin structure associated with altered transcriptional activities, eventually contributing to the phenotypic changes in the thymus after burn.

Burn injury-mediated alterations in cell cycle progression in lymphoid organs of mice

A key event in the cellular and molecular pathogenesis of multiple organ failure (MOF) after burn injury may be the change in profiles of the cell cycle progression in affected organs. We investigated the effects of burn injury on cell cycle progression in immune organs. Cell cycle analysis in the lymphoid tissues of mice after 18% burn injury revealed that S phase entry was temporarily arrested in the thymus 1 day after injury, whereas the spleen had substantially increased S phase entry at day 8. This mode of cell cycle regulation was reproduced in different age groups and strains of mice. Furthermore, the reactivity to the Ki-67 antibody (indicative of proliferation) was markedly reduced in the thymic cortex at day 1. There was a distinct pattern of hematopoietic foci formation and increased reactivities to the Ki-67 antibody in myelogenous cells in the red pulp of spleen at day 7, consistent with the elevated S phase entry. These data suggest that differential regulation of cell cycle progression may play a crucial role in the phenotypic changes in immune organs after burn injury.

Nitric oxide inhibits spleen cell proliferative response after burn injury by inducing cytostasis, apoptosis, and necrosis of activated T lymphocytes: role of the guanylate cyclase

We previously showed that an overproduction of nitric oxide (NO) by macrophages was responsible for the collapse of lymphoproliferative responses after burn injury in rats. First, we demonstrate here that 10 days post-burn, the inhibition of splenocyte response to concanavalin-A results from cytostatic, apoptotic, and necrotic effects of NO on activated T cells. This was evidenced by various criteria at the levels of DNA, mitochondria, and plasma membrane. Inhibition of NO synthase by S-methylisothiourea (10 microM) normalized all the parameters. Second, we show that two soluble guanylate cyclase (sGC) inhibitors, LY83583 and ODQ, restored the proliferative response in a concentration-dependent manner. LY83583 (0.5 microM) rescued T cells from apoptosis. Similar results were obtained with KT5823 (5 microM) a specific inhibitor of protein kinase G (PKG). In contrast, neither LY83583 nor KT5823 inhibited NO-induced necrosis. These results suggest that NO blocked T cells in the G1 phase and induced apoptosis through a sGC-PKG-dependent pathway and necrosis through an independent one.

Identification of truncated form of mouse HAX-1s gene (HAX-1xs) and characterization of its expression in small intestine and thymus of mice after burn injury

Burn injury often leads to distant organ injury such as acute respiratory distress syndrome. We hypothesize that the pathophysiologic changes in distant organs result from orchestrated regulation of multiple genes in response to bum injury. Differential display was performed to identify genes regulated in distant organs in response to burn injury. Initial characterization of differentially amplified products demonstrated that HAX-1s mRNA was regulated in several distant organs after 18% total body surface area (TBSA) full-thickness flame burn injury in mice. Further characterization of HAX-1s mRNA revealed a novel transcript variant, which is rapidly and transiently induced in multiple tissues of mice within 6 h after burn injury. This novel HAX-1s transcript variant, called HAX-1xs, has an internal deletion of 252 nucleotides and single point mutation, resulting in reading frame intact. Western blot and immunohistochemical analyses of multiple tissues of mice using rabbit antibody raised against a 15-mer synthetic peptide clearly revealed the presence of HAX-1xs protein in the duodenum, and suggested that expression of HAX-1xs and/or HAX-1s was tissue- and cell type-specific. The expression of HAX-1xs and/or HAX-1s was distinctively regulated in Paneth cells of the duodenum and macrophages of the thymus after burn injury. These findings suggest that HAX-1xs has a different biological activity from HAX-1s and participates in a cascade of immediate-early cellular events in response to burn injury.

Induction of murine AIDS virus-related sequences after burn injury

To better understand the molecular signaling events leading to systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF), changes in gene expression profiles after burn injury were investigated by differential display. C57BLKS/J mice were subjected to 18% total body surface area (TBSA) full-thickness burn and various tissues were harvested at multiple time points after injury. Initial differential display revealed that retroviral transcripts similar to the envelope sequence of murine AIDS (MAIDS) virus were rapidly and transiently up-regulated after injury. Subsequent RT-PCR and DNA sequencing analyses confirmed the transient up-regulation of retroviral sequences similar to those of the MAIDS virus. In addition, the presence and induction of the subgenomic envelope transcripts of these MAIDS virus-related sequences, including a novel double spliced message, were identified after burn injury. These data suggest that the transcriptional efficiency of the integrated retroviral DNA and reactivation of defective MAIDS virus-related sequences may be affected by pathophysiological signals, such as burn injury. The elevated expression of these MAIDS virus-related retroviral sequences may affect the transcriptional activities of the flanking genes at the integration sites and may be a cause of altered local and systemic immune responses to burn-related stress.