Protective Effect of Dexmedetomidine on Acute Lung Injury via the Upregulation of Tumour Necrosis Factor-α-Induced Protein-8-like 2 in Septic Mice

Dexmedetomidine administration is associated with reduced mortality in patients with sepsis-induced acute respiratory distress syndrome: a retrospective study

BACKGROUND

Although studies have revealed the benefits of using dexmedetomidine (DEX) in treating rodent models of acute lung injury (ALI) by improving their survival rates, clinical investigation on the effect of DEX on patients with acute respiratory distress syndrome (ARDS) remains scarce. Through this retrospective study, we aim to better understand the underlying mechanism of sepsis-induced ARDS and the effect of DEX on patients' standard treatment.

METHODS

A total of 208 patients with sepsis-induced ARDS, admitted to the intensive care unit (ICU) at Affiliated Hospital of Jiangsu University, China, from January 2017 to December 2019, were included. The patients were divided into the control group (n = 102) and the DEX group (n = 106). Both groups of patients received mechanical ventilation and standard care; however, the DEX group was additionally treated with DEX as a sedative. Demographic information, baseline characteristics, laboratory parameters, arterial blood gas (ABG) analyses, and inflammatory indicators were compared between the two groups to evaluate the therapeutic outcomes of different treatment approaches.

RESULTS

Age and male gender constituted risk factors for high ARDS incidence, and hypertension led in the list of patients' comorbidities. The baseline characteristics including primary diagnosis and ARDS causes, and prognostic values such as the Acute Physiology and Chronic Health Evaluation (APACHE) II score and predicted mortality, were comparable between the two groups of patients. However, the multiple organ dysfunction syndrome (MODS) incidence and actual mortality rate were significantly lower in the DEX group compared to the control group. Additionally, the DEX group demonstrated improved ABG metrics, representing better acid-base balance and oxygenation, and enhanced inflammatory responses.

CONCLUSIONS

Intravenous administration of DEX was associated with reduced in-hospital mortality, at least in part, by ameliorating ABG indices and inflammatory mediators.

The effects of dexmedetomidine on liver injury in rats with experimental sepsis: A histopathological and immunohistochemical study

BACKGROUND

In the rat sepsis model, the protective effect of dexmedetomidine (Dex) in sepsis-induced tissue injuries by reducing inflammation is still unclear, and research is ongoing to determine whether Dex modulates sepsis-induced tissue injury. To investigate the effect of Dex on liver injury in sepsis rats histopathologically and immunohistochemically.

METHODS

In this study, sepsis was induced in rats by 10 ml/kg E. coli injection and the protective efficacy of Dex against liver damage was investigated with histopathological and immunohistochemical findings by intraperitoneal administration of 100 mcg/kg Dex.

RESULTS

In our results, the most striking and basic morphological changes in the liver tissues of sepsis group rats were neutrophil leukocyte infiltrations in and around the vessels. In Dex-treated groups, neutrophil leucocyte infiltrations were more prominent and marked dilatations were observed in the vessels. The fact that inflammatory reactions were more prominent in the Dex-treated groups was thought to be related to the increase in vascular permeability due to Dex's vasodilation effect.

CONCLUSION

according to the histopathological and immunohistochemical findings obtained in the present study, we conclude that Dex did not alleviate sepsis-induced liver inflammation in a rat sepsis model.

Using the sympathetic system, beta blockers and alpha-2 agonists, to address acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) manifests as an acute inflammatory lung injury characterized by persistent hypoxemia, featuring a swift onset, high mortality, and predominantly supportive care as the current therapeutic approach, while effective treatments remain an area of active investigation. Adrenergic receptors (AR) play a pivotal role as stress hormone receptors, extensively participating in various inflammatory processes by initiating downstream signaling pathways. Advancements in molecular biology and pharmacology continually unveil the physiological significance of distinct AR subtypes. Interventions targeting these subtypes have the potential to induce specific alterations in cellular and organismal functions, presenting a promising avenue as a therapeutic target for managing ARDS. This article elucidates the pathogenesis of ARDS and the basic structure and function of AR. It also explores the relationship between AR and ARDS from the perspective of different AR subtypes, aiming to provide new insights for the improvement of ARDS.

Songorine inhibits oxidative stress-related inflammation through PI3K/AKT/NRF2 signaling pathway to alleviate lipopolysaccharide-induced septic acute lung injury

OBJECTIVE

The present study aimed to investigate the protective action and mechanism of songorine on sepsis-induced acute lung injury (ALI).

METHODS

The sepsis-induced ALI mouse and cell models were established by lipopolysaccharide (LPS) induction. Lung injury was assayed by hematoxylin and eosin staining, lung injury score, and lung wet-to-dry (W/D) weight ratio. Apoptosis in lung tissues was evaluated by TUNEL assay, and the expression of apoptosis-related markers (Bcl2, Bax, and caspase-3) was measured by western blotting. Levels of pro-inflammatory factors and oxidative stress markers in the bronchoalveolar lavage fluid (BALF) of mice were measured by ELISA and RT-qPCR. The expression of PI3K/AKT/NRF2 pathway-related proteins was analyzed by western blotting.

RESULTS

Songorine treatment at 40 mg/kg mitigated sepsis-induced ALI, characterized by improved histopathology, lung injury score, and lung W/D weight ratio (p < 0.05). Moreover, songorine markedly attenuated sepsis-induced apoptosis in lung tissues; this was evidenced by an increase in Bcl2 levels and a decrease in Bax and caspase-3 levels (p < 0.01). Also, songorine reduced levels of proinflammatory cytokines (TNF-α, IL-6, IL-1β and MPO) and oxidative stress regulators (SOD and GSH) in the BALF of LPS-induced sepsis mice and RAW264.7 cells (p < 0.05). In addition, songorine upregulated the PI3K/AKT/NRF2 pathway-related proteins in LPS-induced sepsis mice and RAW264.7 cells (p < 0.05). Furthermore, LY294002 (a PI3K inhibitor) treatment reversed the protective effect of songorine on sepsis-induced ALI.

CONCLUSION

Songorine inhibits oxidative stress-related inflammation in sepsis-induced ALI via the activation of the PI3K/AKT/NRF2 signaling pathway.

Dexmedetomidine activates the PKA/CREB pathway and inhibits proinflammatory factor expression through β2 adrenergic receptors

INTRODUCTION

Dexmedetomidine (DEX) is primarily utilized for sedation in the context of general anesthesia or intensive care. However, the exact regulatory mechanism by which DEX affects cytokines remains unclear. This study aims to investigate the underlying mechanism by which DEX inhibits proinflammatory factors through activation of the β2 adrenergic receptor (β2 AR).

METHODS

The inflammatory cell model of human mononuclear macrophage (THP-1) cells induced by lipopolysaccharide (LPS) was established to study the effect of DEX on the expression of cell-related inflammatory factors. ADRA2A gene knockout THP-1 cells (THP-1KO ) were constructed by CRISPR technology, and the effect of DEX on the expression of inflammatory factors of THP-1KO cells was detected. The target sites of DEX on β2 AR were screened by molecular docking. Reversion experiments were performed using ADRB2-siRNA. Western blot was used to detect the activation of β2 AR/PKA/CREB pathway and NF-κB, and ELISA was used to detect the release level of inflammatory factors.

RESULTS

The results demonstrated a significant reduction in the expression levels of MCP-1, interleukin-06, and IL-8 in both THP-1 and THP-1KO cells when induced by LPS following treatment with DEX. Additionally, DEX treatment led to an increase in IL-10 expression. Immunofluorescence analysis revealed an upregulation of β2 AR expression after DEX treatment. Western blot results indicated that DEX notably enhanced the activation of the β2 AR and PKA/CREB pathways, while concurrently suppressing the activation of NF-κB. Notably, the use of ADRB2 siRNA reversed the effects of DEX treatment and promoted the release of inflammatory cytokines.

CONCLUSION

DEX initiates the activation of the PKA/CREB pathway through the activation of β2 AR. Simultaneously, it exerts an inhibitory effect on the activation of NF-κB, consequently reducing the transcription of proinflammatory factors while increasing the transcription of anti-inflammatory factors.

Tumor Necrosis Factor-α-Induced Protein-8-like 2 Transfected Adipose-Derived Stem Cells Regulated the Dysfunction of Monocrotaline Pyrrole-Induced Pulmonary Arterial Smooth Muscle Cells and Pulmonary Arterial Endothelial Cells

ABSTRACT

Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial endothelial cell (PAEC) dysfunction and pulmonary arterial smooth muscle cell (PASMC) activation. For decades, the therapies for PAH based on stem cells have been shown to be effective. Meanwhile, tumor necrosis factor-α-induced protein-8-like 2 (TIPE2) promote the viability of human amniotic mesenchymal stem cells. Therefore, we aimed to explore the role of TIPE2 in adipose-derived stem cells (ADSCs) and the function of TIPE2-transfected ADSCs in the regulation of PAH. We first explored the role and underlying molecular mechanism of TIPE2 in viability and migration of ADSCs. Moreover, the ADSCs transfected with TIPE2 were cocultured with monocrotaline pyrrole (MCTP)-stimulated PASMCs or PAECs. The effects and mechanisms of TIPE2-transfected ADSCs on MCTP-induced PASMCs and PAECs were further investigated. The results showed that TIPE2 overexpression promoted viability and migration of ADSCs by activating the TLR4-ERK1/2 pathway. In addition, TIPE2-transfected ADSCs inhibited the abnormal proliferation and the impaired apoptosis of PASMCs via NF-κB signaling and promoted the conversion of PASMCs from synthetic to contractile. Meanwhile, TIPE2-transfected ADSCs reduced the apoptosis, endothelial-to-mesenchymal transition, and migration of PAECs via PI3K/AKT signaling after MCTP treatment. MCTP-induced oxidative stress and inflammation of PAECs were significantly decreased by TIPE2-transfected ADSCs. In rat model, TIPE2-ADSCs administration further decreased the monocrotaline-induced increase in the right ventricular systolic pressure and ratio of right ventricle weight/left ventricle and septa weight (L + S) and right ventricle weight/body weight compared with the ADSCs group. In conclusion, TIPE2-transfected ADSCs dramatically attenuated the PAH via inhibiting the dysfunction of PASMCs and PAECs.

Synthesis and protective effect of pyrazole conjugated imidazo[1,2-a]pyrazine derivatives against acute lung injury in sepsis rats via attenuation of NF-κB, oxidative stress, and apoptosis

The current work was conducted to elucidate the pharmacological effect of pyrazole-conjugated imidazo[1,2-a]pyrazine derivatives against acute lung injury in rats in sepsis and their mechanism of action. Various pyrazole-conjugated imidazo[1,2-a]-pyrazine derivatives have been synthesized in a straightforward synthetic route. They exhibited a diverse range of inhibitory activity against NF-ĸB with IC 50 ranging from 1 to 94 µmol L-1. Among them, compound 3h [(4-(4-((4-hydroxyphenyl)sulfonyl) phenyl)-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl) (8-(methylamino)imidazo[1,2-a]pyrazin-2-yl)methanone] was identified as the most potent NF-κB inhibitor with IC 50 of 1.02 µmol L-1. None of the synthesized compounds was found cytotoxic to normal cell-line MCF-12A. The pharmacological activity of the most potent NF-ĸB inhibitor 3h was also investigated in cecal ligation and puncture (CLP)-induced sepsis injury of the lung in rats. Compound 3h was administered to rats after induc tion of lung sepsis, and various biochemical parameters were measured. Results suggested that compound 3h significantly reduced lung inflammation and membrane permeability, as evidenced by H&E staining of lung tissues. It substantially reduced the generation of pro-inflammatory cytokines (TNF-α, IL-1B, IL-6) and oxidative stress (MPO, MDA, SOD). It showed attenuation of NF-ĸB and apoptosis in Western blot and annexin--PI assay, resp. Compound 3h also reduced the production of bronchoalveolar lavage fluid from the lung and provided a protective effect against lung injury. Our study showed the pharmacological significance of pyrazole-conjugated imidazo[1,2-a] pyrazine derivative 3h against acute lung injury in sepsis rats.

Resolving neutrophils due to TRAM deletion renders protection against experimental sepsis

OBJECTIVE

Proper inflammation resolution is crucial to prevent runaway inflammation during sepsis and reduce sepsis-related mortality/morbidity. Previous studies suggest that deleting TRAM, a key TLR4 signaling adaptor, can reprogram the first inflammatory responder cell-neutrophil from an inflammatory state to a resolving state. In this study, we aim to examine the therapeutic potential of TRAM-deficient neutrophils in vivo with recipient mice undergoing experimental sepsis.

MATERIAL AND METHODS

Wild-type or Tram-/- mice were intraperitoneally injected with cecal slurry to induce either severe or mild sepsis. Phenotypic examinations of sepsis and neutrophil characteristics were examined in vivo and ex vivo. The propagations of resolution from donor neutrophils to recipient cells such as monocytes, T cells, and endothelial cells were examined through co-culture assays in vitro. The efficacies of Tram-/- neutrophils in reducing inflammation were studied by transfusing either wild-type or Tram-/- neutrophils into septic recipient mice.

RESULTS

Tram-/- septic mice had improved survival and attenuated injuries within the lung and kidney tissues as compared to wild-type septic mice. Wild-type septic mice transfused with Tram-/- resolving neutrophils exhibited reduced multi-organ damages and improved cellular homeostasis. In vitro co-culture studies revealed that donor Tram-/- neutrophils can effectively propagate cellular homeostasis to co-cultured neighboring monocytes, neutrophils, T cells as well as endothelial cells.

CONCLUSIONS

Neutrophils with TRAM deletion render effective reprogramming into a resolving state beneficial for ameliorating experimental sepsis, with therapeutic potential in propagating cellular and tissue homeostasis as well as treating sepsis.

Research progress of TIPE2 in immune-related diseases

The tumor necrosis factor α-induced protein 8 (TNFAIP8) family, which consists of TNFAIP8 (TIPE), TNFAIP8L1 (TIPE1), TNFAIP8L2 (TIPE2) and TNFAIP8L3 (TIPE3), has recently emerged as a regulatory factor involved in immune response and tumorigenesis. Among its members, TIPE2 acts as a negative regulator of both innate and adaptive immunity, playing a crucial role in maintaining immune homeostasis by negatively regulating T cell receptor (TCR) and toll-like receptor (TLR) signal transduction. Immune homeostasis is an indispensable characteristic of the immune system, which prevents harmful inflammatory reactions and ensures the proper functioning of the body. A large number of studies have shown that abnormal TIPE2 expression exists in a variety of inflammation-related diseases such as asthma, colitis, and systemic lupus erythematosus, highlighting the importance of comprehending its function for the prevention and treatment of immune-related conditions. This review aims to provide an overview of the in vivo distribution and expression of TIPE2, its regulatory role in central and peripheral immune-related diseases, and the underlying mechanisms that govern its function in the inflammatory response. By delving into these aspects, a deeper understanding of the role and functionality of TIPE2 in inflammatory responses can be achieved.

Dexmedetomidine alleviates acute lung injury by promoting Tregs differentiation via activation of AMPK/SIRT1 pathway

OBJECTIVES

To explore the anti-inflammatory effect and the potential mechanism of dexmedetomidine in ARDS/ALI.

MATERIALS AND METHODS

C57BL/6 mice and EL-4 cells were used in this research. The ALI model was established by CLP. The level of inflammatory cytokines in the lung and blood, the severity of lung injury, the expression of Foxp3, and the proportion of Tregs were detected before and after dexmedetomidine treatment. The expression of the AMPK/SIRT1 after dexmedetomidine treatment was detected in vivo and in vitro. After blocking the AMPK/SIRT1 pathway or depleting Tregs in vivo, the level of the inflammatory response, tissue injury, and Tregs differentiation were detected again to clarify the effect of dexmedetomidine.

RESULTS

Dexmedetomidine significantly reduced systemic inflammation and lung injury in CLP mice. Dexmedetomidine enhanced the Foxp3 expression in the lungs and the frequency of Tregs in the spleen. Dexmedetomidine up-regulated the protein expression of p-AMPK and SIRT1 in lungs and EL-4 cells and facilitated the differentiation of naïve CD4⁺ T cells into Tregs in vitro. Meanwhile, DEX also increased the expression of Helios in Treg cells.

CONCLUSIONS

DEX could improve ARDS/ALI by facilitating the differentiation of Tregs from naïve CD4⁺ T cells via activating the AMPK/SIRT1 pathway.

TIPE2 May Target the Nrf2/HO-1 Pathway to Inhibit M1 Macrophage-Related Neutrophilic Inflammation in Asthma

Purpose

Although recent studies have highlighted the link of TIPE2 and asthma airway inflammation, its roles and molecular mechanisms in different asthma inflammatory phenotypes remain largely unknown. We evaluated sputum TIPE2 expression level and its correlation with different asthma phenotypes. Additionally, we explored the roles and mechanism of TIPE2 in M1 polarization of macrophages.

Methods

A total of 102 asthma patients who underwent sputum induction were enrolled to evaluate the expression level of TIPE2 and its association with different asthma phenotypes. To explore the roles and mechanism of TIPE2 in M1 polarization of macrophages, THP-1 monocytes stimulated with phorbol-12-myristate-13-acetate, were used as a model of undifferentiated (M0) macrophages, and M0 macrophages were treated with lipopolysaccharide to induce M1 macrophages.

Results

The sputum TIPE2 level was significantly lower in patients with neutrophilic asthma (NA) and higher in patients with eosinophilic asthma (EA) compared with patients with paucigranulocytic asthma. The levels of IL-1β, TNF-α and IL-6 were highest in NA compared with other groups. TIPE2 levels in sputum negatively correlated with IL-1β and TNF-α levels but positively correlated with IL-4, IL-5, IL-13, and IL-10 levels (P < 0.05). In vitro, TIPE2 enhanced Nrf2/HO-1 pathway activation in macrophages and inhibited LPS-induced M1 macrophage differentiation and related cytokine release. Further analysis showed that the Nrf2 inhibitor ML385 weakened TIPE2-induced activation of the Nrf2/HO-1 pathway, as well as TIPE2-induced suppression in M1 polarization of macrophage and inflammatory cytokines secretion.

Conclusions

TIPE2 expression level was highly down-regulated in NA and was negatively correlated with inflammatory factors (IL-1β and TNF-α). Aberrant expression of TIPE2 may target the Nrf2/HO-1 pathway to inhibit M1 macrophage–related neutrophilic inflammation in asthma.

Dexmedetomidine protects against acute lung injury in mice via the DUSP1/MAPK/NF-κB axis by inhibiting miR-152-3p

OBJECTIVE

Acute lung injury (ALI) is a debilitating condition in clinics. Dexmedetomidine (Dex) is known for its anti-apoptotic and anti-inflammatory properties. This study attempted to investigate the protective mechanism of Dex in ALI mice.

METHODS

Mice were pretreated with Dex before model establishment by tracheal injection of lipopolysaccharide (LPS). Pulmonary function indexes and wet-to-dry (W/D) ratio were measured. Pulmonary pathological changes were observed through HE staining, CD31+-positive mouse pulmonary microvascular endothelial cells (MPMVECs) were counted through immunofluorescence staining, and apoptosis was detected through TUNEL staining. miR-152-3p mimic, sh-DUSP1, or p38 MAPK inhibitor was delivered into MPMVECs, followed by combined treatment of Dex and LPS. miR-152-3p expression, apoptosis, levels of apoptosis- and MAPK/NF-κB pathway-associated proteins, and inflammatory factors were measured through RT-qPCR, flow cytometry, Western blot, and ELISA. The binding relationship of miR-152-3p and DUSP1 was verified through bioinformatics software and dual-luciferase assay. ALI mouse model was established after injection of miR-152-3p antagomir.

RESULTS

Dex improved ALI mouse pulmonary function and mitigated injury in mice and MPMVECs. miR-125-3p overexpression or sh-DUSP1 partially abolished the protection of Dex on MPMVECs. miR-152-3p targeted DUSP1. sh-DUSP1 partially averted the protection of Dex on MPMVECs. Dex inhibited the activation of the MAPK/NF-κB pathway in MPMVECs mediated by LPS, which was partially reversed by sh-DUSP1. The p38 MAPK inhibitor SB203580 antagonized the protective effect of Dex on MPMVECs mediated by sh-DUSP1. Similarly, downregulation of miR-152-3p mitigated ALI via the DUSP1/MAPK/NF-κB axis in vivo.

CONCLUSION

Dex relieved ALI in mice via the DUSP1/MAPK/NF-κB axis by down-regulating miR-152-3p.

RETRACTED: Exosomal microRNA-16-5p from adipose mesenchymal stem cells promotes TLR4-mediated M2 macrophage polarization in septic lung injury

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). The authors have requested that this paper be retracted as they were unable to replicate the experimental data reported in Figure 1A. The authors posit that changes in reagents or experimental conditions might be the source of their inability to do so. Additional concerns were raised about the reliability of the Western blot results in Figure 1E, Figure 4B and F, Figure 5B, and Figure 6B, as regarding ‘morphology space’ similarities contained within a series of papers with distinctive eyebrow blots, tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0 [nam11.safelinks.protection.outlook.com] [nam11.safelinks.protection.outlook.com]). The journal requested the authors comment on these concerns and provide raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Rosmarinic acid ameliorates septic-associated mortality and lung injury in mice via GRP78/IRE1α/JNK pathway

OBJECTIVES

Acute lung injury (ALI) is the major complication of sepsis, and no effective treatment is available now. Recently, rosmarinic acid (RA), a water-soluble polyphenolic phytochemical, exerts a potential role on ALI with anti-inflammation, and antioxidant properties. However, there is still no evidence on its protective effect on cell apoptosis in sepsis. Here, we investigated the protective effect of RA in septic-associated mortality and lung injury based on apoptosis.

METHODS

Male C57BL/6 mice were administered with lipopolysaccharide (LPS) (15 mg/kg, ip) to establish ALI mice model. Preteatment of RA (20 or 40 mg/kg, ip) was performed once daily for five consecutive days. The mortality was monitored for seven days after injection of LPS.

KEY FINDINGS

RA (40 mg/kg) significantly decreased mortality and alleviated septic-associated lung injury. Meanwhile, RA significantly reversed LPS induced decrease in serum T-aoc level and superoxide dismutase (SOD) activity, and increase in malondialdehyde (MDA) activity. Furthermore, RA pretreatment significantly inhibited lung cell apoptosis, as well as decreased p53 level in sepsis mice. Finally, the LPS induced activation of GRP78/IRE1α/JNK pathway was suppressed by RA pretreatment.

CONCLUSIONS

These findings indicated that RA could be beneficial to septic-associated lung injury through anti-apoptosis effect.

Tumor Necrosis Factor-α-Induced Protein 8-Like 2 Negatively Regulates Innate Immunity Against RNA Virus by Targeting RIG-I in Macrophages

A systematic and flexible immunoregulatory network is required to ensure the proper outcome of antiviral immune signaling and maintain homeostasis during viral infection. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2), a novel immunoregulatory protein, has been extensively studied in inflammatory response, apoptosis, and cancer. However, the function of TIPE2 in antiviral innate immunity is poorly clarified. In this study, we reported that the expression of TIPE2 declined at the early period and then climbed up in macrophages under RNA virus stimulation. Knockout of TIPE2 in the macrophages enhanced the antiviral capacity and facilitated type I interferon (IFN) signaling after RNA viral infection both in vitro and in vivo. Consistently, overexpression of TIPE2 inhibited the production of type I IFNs and pro-inflammatory cytokines, and thus promoted the viral infection. Moreover, TIPE2 restrained the activation of TBK1 and IRF3 in the retinoic acid inducible gene-I (RIG-I)-like receptors (RLR) signaling pathway by directly interacting with retinoic acid inducible gene-I (RIG-I). Taken together, our results suggested that TIPE2 suppresses the type I IFN response induced by RNA virus by targeting RIG-I and blocking the activation of downstream signaling. These findings will provide new insights to reveal the immunological function of TIPE2 and may help to develop new strategies for the clinical treatment of RNA viral infections.

Dexmedetomidine at a dose of 1 µM attenuates H9c2 cardiomyocyte injury under 3 h of hypoxia exposure and 3 h of reoxygenation through the inhibition of endoplasmic reticulum stress

Myocardial ischemia-reperfusion injury (MIRI) has been confirmed to induce endoplasmic reticulum stress (ERS) during downstream cascade reactions after the sufficient deterioration of cardiomyocyte function. However, clinically outcomes have been inconsistent with experimental findings because the mechanism has not been entirely elucidated. Dexmedetomidine (DEX), an α² adrenergic receptor agonist with anti-inflammatory and organ-protective activity, has been shown to attenuate IRI in the heart. The present study aimed to determine whether DEX is able to protect injured cardiomyocytes under in vitro hypoxia/reoxygenation (H/R) conditions and evaluate the conditions under which ERS is efficiently ameliorated. The cytotoxicity of DEX in H9c2 cells was evaluated 24 h after treatment with several different concentrations of DEX. The most appropriate H/R model parameters were determined by the assessment of cell viability and injury with Cell Counting Kit-8 and lactate dehydrogenase (LDH) release assays after incubation under hypoxic conditions for 3 h and reoxygenation conditions for 3, 6, 12 and 24 h. Additionally, the aforementioned methods were used to assess cardiomyocytes cultured with various concentrations of DEX under H/R conditions. Furthermore, the degree of apoptosis and the mRNA and protein expression levels of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12 were evaluated in all groups. The addition of 1, 5 and 10 µM DEX to the cell culture significantly increased the proliferation of H9c2 cells by >80% under normal culture conditions. In the H/R model assessment, following 3 h of anoxia exposure, H9c2 cell viability decreased to 62.67% with 3 h of reoxygenation and to 36% with 6 h of reoxygenation compared with the control. The viability of H9c2 cells subjected to hypoxia for 3 h and reoxygenation for 3 h increased by 61.3% when pretreated with 1 µM DEX, and the LDH concentration in the supernatant was effectively decreased by 13.7%. H/R significantly increased the percentage of apoptotic cells, as detected by flow cytometry, and increased the expression levels of GRP78, CHOP and caspase-12, while treatment with either DEX or 4-phenylbutyric acid (4-PBA) significantly attenuated these effects. Additionally, despite the protective effect of DEX against H/R injury, 4-PBA attenuated the changes induced by DEX and H/R. In conclusion, treatment with 1 µM DEX alleviated cell injury, apoptosis and the increases in GRP78, CHOP and caspase-12 expression levels in H9c2 cells induced by 3 h of hypoxia and 3 h of reoxygenation.

Dexmedetomidine Attenuates Cellular Injury and Apoptosis in H9c2 Cardiomyocytes by Regulating p-38MAPK and Endoplasmic Reticulum Stress

Background

Myocardial ischaemia-reperfusion injury (IRI) has been confirmed to induce endoplasmic reticulum stress (ERS) when myocardial cell function continues to deteriorate to a certain degree. The clinical applications of effective tested strategies are sometimes inconsistent with the applications evaluated in experiments, although reasonable mechanisms and diverse signalling pathways have been broadly explored. Dexmedetomidine (DEX) has been shown to attenuate IRI of the heart in animal studies. This study aimed to determine whether DEX can protect injured cardiomyocytes under hypoxia/reoxygenation (H/R) at the cellular level and whether the mechanism is related to ERS and the p38 MAPK pathway.

Methods

H9c2 cells were subjected to H/R or thapsigargin (TG) to build a model. DEX or 4-PBA was added to the medium either 1 h or 24 h before modelling, respectively. Model parameters were determined by assessing cell viability and injury, which were measured by assessing cell counting kit-8 (CCK8), lactate dehydrogenase (LDH) release and flow cytometry results, and the expression of GRP78, CHOP and caspase-12. In addition, the protein expression of p38MAPK and p-p38MAPK was examined, and SB202190, a negative regulator, was also preincubated in medium.

Results

Compared to that of cells in the control group, the activity of cells in the H/R and TG groups was decreased dramatically, and the LDH concentration and proportion of apoptotic cells were increased. DEX could correspondingly reverse the changes induced by H/R or TG. Additionally, DEX effectively attenuated ERS defined as increased expression of GRP78, CHOP and caspase-12. Additionally, DEX could obviously depress the P38 MAPK phosphorylation and high p-p38 MAPK expression in the TG group, indicating DEX has a function similar to that of SB202190.

Conclusion

H/R injury in H9c2 cells can lead to abnormal ERS and apoptosis, as well as activation of the p38MAPK signalling pathway. DEX can protect cardiomyocytes by intervening in ERS, regulating p38MAPK and the downstream apoptotic signalling pathway.

Dexmedetomidine alleviates non-ventilation associated lung injury via modulating immunology phenotypes of macrophages

AIMS

We aimed to evaluate the effect of Dexmedetomidine (Dex) on immunology function of macrophages and inflammatory reactions in non-ventilated lung tissues from both humans and rats.

MAIN METHODS

Patients scheduled for lung lobectomy were randomly assigned to traditional anesthesia group or Dex anesthesia group, 15 subjects in each group. CD68, CD86 and CD206 were used to mark activate and polarized macrophages using immunofluorescence staining in human lung tissues. Sprague-Dawley rats were used to set lung injury model and randomly divided into Control group, one-lung ventilation group (CLI group) and CLI + Dex group. Lung tissues and bronchoalveolar lavage fluid (BALF) from non-ventilated lungs were collected. The acquired lung tissues were subjected to hematoxylin-eosin (H&E) staining and the inflammatory cells in BALF were calculated. Levels of cytokines and chemokines were detected by enzyme-linked immunosorbent assays (ELISA).

KEY FINDINGS

Results from humans showed that anesthesia with Dex decreased the number of both CD68 positive cells and CD86 positive cells and down-regulated level of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and monocyte chemotactic protein 1 (MCP-1) in human lung. Results from rats demonstrated that treatment with Dex reversed the increased inflammatory cells in lung and the increased levels of TNF-α, interleukin-1β (IL-β), MCP-1 and chemokine (C-X-C motif) ligand 1 (CXCL1) resulted from non-ventilation; Dex increased the anti-inflammatory cytokine interleukin-10 (IL-10) in BALF from non-ventilated lung.

SIGNIFICANCE

This study showed that Dex modulated the activation and immunological function of macrophages in non-ventilated lung and revealed a protective role in collapsed lung injury.

The enigmatic role of TIPE2 in asthma

Unlike other members of the tumor necrosis factor (TNF)-α-induced protein 8 (TNFAIP8/TIPE) family that play a carcinogenic role and regulate apoptosis, TNFAIP8-like 2 (TIPE2) can not only maintain immune homeostasis but also regulate inflammation. TIPE2 mainly restrains the activation of T cell receptor (TCR) and Toll-like receptors (TLR), regulating its downstream signaling pathways, thereby regulating inflammation. Interestingly, TIPE2 is abnormally expressed in many inflammatory diseases and may promote or inhibit inflammation in different diseases. This review summarizes the molecular target and cellular function of TIPE2 in immune cells and inflammatory diseases and the underlying mechanism by which TIPE2 regulates inflammation. The function and mechanism of TIPE2 in asthma is also explained in detail. TIPE2 is abnormally expressed in asthma and participates in the pathogenesis of different phenotypes of asthma through regulating multiple inflammatory cells' activity and function. Considering the indispensable role of TIPE2 in asthma, TIPE2 may be an effective therapeutic target in asthma. However, the available data are insufficient to provide a full understanding of the complex role of TIPE2 in human asthma. Further study is still necessary to explore the possible mechanism and functions of TIPE2 in different asthma phenotypes.