Toll-like receptor 4 deficiency increases resistance in sepsis-induced immune dysfunction

Toll-like receptor 4 (TLR4) deficiency impedes Toxoplasma gondii excreted-secreted antigens (ESA)-induced abortion

INTRODUCTION

Toxoplasma gondii is an opportunistic intracellular parasite that is a major pathogenic factor in miscarriage, especially when it occurs early in pregnancy. We have previously demonstrated that the regulation of forkhead box transcription factor (Foxp3) is associated with abortion in early pregnancy caused by excretory-secretory antigen (ESA) of strain China 1. We aimed to reveal the underlying mechanism of miscarriage caused by ESA.

METHODS

A TLR4-/- pregnant mouse model was successfully constructed. Pregnant mice at gestational day 5 (G5) were injected with ESA. All animals were sacrificed on G13, pregnancy outcomes were observed, and abortion rates were calculated. Placental status observed by Hematoxylin-eosin staining; gene expression was measured by IHC; flow cytometry analysis was used to determine the number and function of regulatory T cells. In EL4 cells, real-time PCR and Western blot were used to evaluate gene expression and cytokines assay.

RESULTS

In vivo studies revealed that ESA injection caused 83% abortion in pregnant mice but only 35% abortion in TLR4-/- pregnant mice. In addition, ESA attenuated the number and function of regulatory T cells, further suppressed Foxp3, FOXO1 levels, and upregulated CD127 expression. TLR4-/- mice partially reversed this inhibitory effect on regulatory T cells. Furthermore, in vitro studies revealed that ESA inhibited TLR4/NF-κB signaling pathway expression and that TLR4 agonists significantly restored the ESA-induced decrease in Foxp3.

DISCUSSION

These findings suggest that ESA suppresses Foxp3 expression by blocking TLR4/NF-κB signaling, resulting in miscarriage. More importantly, the results indicated that miscarriage caused by ESA is TLR4 dependent.

Advances and Challenges in Sepsis Management: Modern Tools and Future Directions

Sepsis, a critical condition marked by systemic inflammation, profoundly impacts both innate and adaptive immunity, often resulting in lymphopenia. This immune alteration can spare regulatory T cells (Tregs) but significantly affects other lymphocyte subsets, leading to diminished effector functions, altered cytokine profiles, and metabolic changes. The complexity of sepsis stems not only from its pathophysiology but also from the heterogeneity of patient responses, posing significant challenges in developing universally effective therapies. This review emphasizes the importance of phenotyping in sepsis to enhance patient-specific diagnostic and therapeutic strategies. Phenotyping immune cells, which categorizes patients based on clinical and immunological characteristics, is pivotal for tailoring treatment approaches. Flow cytometry emerges as a crucial tool in this endeavor, offering rapid, low cost and detailed analysis of immune cell populations and their functional states. Indeed, this technology facilitates the understanding of immune dysfunctions in sepsis and contributes to the identification of novel biomarkers. Our review underscores the potential of integrating flow cytometry with omics data, machine learning and clinical observations to refine sepsis management, highlighting the shift towards personalized medicine in critical care. This approach could lead to more precise interventions, improving outcomes in this heterogeneously affected patient population.

Regulatory effects of mangiferin on LPS-induced inflammatory responses and intestinal flora imbalance during sepsis

Studies suggest that mangiferin (MAF) has good therapeutic effects on chronic bronchitis and hepatitis. Also, it is one of the antiviral ingredients in Anemarrhena asphodeloides Bunge. However, its effect on the LPS-induced inflammation and intestinal flora during sepsis remains unclear yet. In the present study, LPS-stimulated inflammation RAW264.7 cells and LPS-induced sepsis mice were used to evaluate the efficacy of MAF in vitro and in vivo. 16S rDNA sequencing was performed to analyze the characteristics of intestinal flora of the sepsis mice. It has been demonstrated that MAF (12.5 and 25 μg/mL) significantly inhibited protein expressions of TLR4, MyD88, NF-κB, and TNF-α in the LPS-treated cells and reduced the supernatant TNF-α and IL-6 levels. In vivo, MAF (20 mg/kg) markedly protected the sepsis mice and reduced the serum TNF-α and IL-6 levels. Also, MAF significantly downregulated the protein expressions of TLR4, NF-κB, and MyD88 in the livers. Importantly, MAF significantly attenuated the pathological injuries of the livers and small intestines. Further, MAF significantly increased proportion of Bacteroidota and decreased the proportions of Firmicutes, Desulfobacterota, Actinobacteriota, and Proteobacteria at phylum level, and it markedly reduced the proportions of Escherichia-Shigella, Pseudoalteromonas, Staphylococcus at genus level. Moreover, MAF affects some metabolism-related pathways such as citrate cycle (TCA cycle), lipoic acid metabolism, oxidative phosphorylation, bacterial chemotaxis, fatty acid biosynthesis, and peptidoglycan biosynthesis of the intestinal flora. Thus, it can be concluded that MAF as a treatment reduces the inflammatory responses in vitro and in vivo by inhibiting the TLR4/ MyD88/NF-κB pathway, and corrects intestinal flora imbalance during sepsis to some degree.

YBX-1 alleviates sepsis-stimulated lung epithelial cell injury

OBJECTIVE

To explore the role of Y-box binding protein 1 (YBX-1) in the lipopolysaccharide (LPS)-stimulated inflammation and oxidative stress of BEAS-2B cell line and clarify the underlying mechanism.

METHODS

LPS-stimulated BEAS-2B cells were used as a cell model of sepsis-stimulated acute lung injury (ALI). Immunoblot and quantitative polymerase chain reaction assays were used to detect the expression of YBX-1 in LPS-stimulated BEAS-2B cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, TdT-mediated dUTP nick end labeling, and immunoblot assays were conducted to determine the effects of YBX-1 on cell survival. JC-1 staining and adenosine triphosphate production were used to detect the effects of YBX-1 on mitochondrial function. Immunostaining and enzyme-linked immunosorbent serologic assay were performed to examine the effects of YBX-1 on the inflammation and oxidative stress of cells. Immunoblot assay was conducted to confirm the mechanism.

RESULTS

YBX-1 was lowly expressed in LPS-stimulated BEAS-2B cells and enhanced the survival of LPS-stimulated lung epithelial cells. In addition, YBX-1 improved mitochondrial function of LPS-stimulated BEAS-2B cells. YBX-1 inhibited the inflammation and oxidative stress of LPS-stimulated BEAS-2B cells. Mechanically, YBX-1 inhibited mitogen-activated protein kinase (MAPK) axis, thereby alleviating sepsis-stimulated ALI.

CONCLUSION

YBX-1 alleviated inflammation and oxidative stress of LPS-stimulated BEAS-2B cells via MAPK axis.

BACTERIOPHAGE M13 MODULATES THE SEPSIS-RELATED INFLAMMATORY RESPONSES AND ORGAN DAMAGE IN A CLP MODEL

ABSTRACT

Background: Sepsis is a life-threatening disorder that leads to the induction of inflammatory responses and organ failure. Phage therapy is a new approach to controlling infections resistant to common treatments, including sepsis. Several studies have shown the effect of lytic bacteriophages on infection control by reducing the bacterial load. The present study deals with lysogenic bacteriophage M13 on the inflammatory responses caused by cecal ligation and puncture (CLP)-induced sepsis in a mouse model. Methods Bacteriophage M13 harvested from ER2738, titrated, and confirmed by transmission electron microscopy analysis. In vitro toxicity and immunomodulatory effect of bacteriophage M13 were assessed on splenocytes by measurement of cell viability and the production level of cytokines, nitric oxide, and reactive oxygen species. For in vivo experiments, 8-weeks-old male C57BL/6 mice were randomly divided into the following three groups: CLP + NS (treated with normal saline), CLP + M13 (treated with an intraperitoneal injection of 10 9 PFU/mL of bacteriophage M13), and sham + NS (induced surgery but without ligation and puncture, treated with NS). The mice were killed at different time points after surgery (6, 24, 48, and 72, n = 10 for each time point of each group). The kidney, liver, and lungs were harvested for histopathological analysis, and blood was obtained for cytokine and liver enzyme assay. The spleen was used to assess the bacterial load using colony-forming unit assay. The rectal temperature and survival were evaluated during the study. Results According to the in vitro results, 10 9 PFU/mL of bacteriophage M13 was not toxic and did not affect the level of cytokine, nitric oxide, and reactive oxygen species production by splenocytes, but it reduced the inflammatory response of splenocytes in responses to LPS. In vivo studies indicated that the amount of proinflammatory cytokines, liver enzymes, bacterial load, and organ failure were decreased in the CLP + M13 group compared with CLP + NS, whereas the survival rate was increased. Conclusions These experiments demonstrated that bacteriophage M13 could lessen the consequences related to sepsis in CLP mice and can be considered a therapeutic approach in sepsis.

Network pharmacology- and molecular simulation-based exploration of therapeutic targets and mechanisms of heparin for the treatment of sepsis/COVID-19

Critically infected patients with COVID-19 (coronavirus disease 2019) are prone to develop sepsis-related coagulopathy as a result of a robust immune response. The mechanism underlying the relationship between sepsis and COVID-19 is largely unknown. LMWH (low molecular weight heparin) exhibits both anti-inflammatory and anti-coagulating properties that result in a better prognosis of severely ill patients with COVID-19 co-associated with sepsis-induced coagulopathy or with a higher D-dimer value. Heparin-associated molecular targets and their mechanism of action in sepsis/COVID-19 are not well understood. In this work, we characterize the pharmacological targets, biological functions and therapeutic actions of heparin in sepsis/COVID-19 from the perspective of network pharmacology. A total of 38 potential targets for heparin action against sepsis/COVID-19 and 8 core pharmacological targets were identified, including IL6, KNG1, CXCL8, ALB, VEGFA, F2, IL10 and TNF. Moreover, enrichment analysis showed that heparin could help in treating sepsis/COVID-19 through immunomodulation, inhibition of the inflammatory response, regulation of angiogenesis and antiviral activity. The pharmacological effects of heparin against these targets were further confirmed by molecular docking and simulation analysis, suggesting that heparin exerts effective binding capacity by targeting the essential residues in sepsis/COVID-19. Prospective clinical practice evaluations may consider the use of these key prognostic indicators for the treatment of sepsis/COVID-19.Communicated by Ramaswamy H. Sarma.

Gentamicin promoted the production of CD4+CD25+ Tregs via the STAT5 signaling pathway in mice sepsis

Background

Increasing studies have reported that gentamicin (GNT) plays an essential role in sepsis; however, its underlying mechanism is still unclear. In this study, we investigated the mechanism of GNT in sepsis.

Results

We observed that GNT enhanced survival and alleviated inflammatory injuries of the lungs, liver, kidneys, and intestines in mice with sepsis. Furthermore, regulatory T cells (Tregs) showed enhanced inhibitory function, and pro-inflammatory cytokines IL-1β, TNF-α, and IL-2 and anti-inflammatory cytokine IL-10 showed decreased and increased peritoneal fluid levels, respectively, after treatment with GNT. GNT showed enhanced phosphorylation of signal transducer and activator of transcription 5 (p-STAT5) in Tregs in vivo and in vitro. The STAT5 inhibitor restrained the increased functional changes of Tregs and reduced inflammatory responses induced by GNT in vitro. Moreover, the STAT5 inhibitor reversed GNT-mediated impacts on survival and inflammation, and the percentage, apoptosis, and phenotypic and functional changes of Tregs in neonatal sepsis.

Conclusions

Our study revealed that GNT regulates the function of Tregs via the STAT5 signaling pathway, alleviating inflammatory injuries, and provides novel evidence in the treatment of neonatal sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00521-4.

Effects of the interaction of Notch and TLR4 pathways on inflammation and heart function in septic heart

We investigated the role of the interaction between the Notch and Toll-like receptor 4 (TLR4) pathways in septic myocardial injury. The sepsis model was induced in rats with lipopolysaccharide (LPS). Rats were divided into control, LPS, LPS + TAK242 ((6R)-6-[N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate) and LPS + DAPT (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-s-phenylglycinetbutylester) groups. Heart function was evaluated with a Cardiac Doppler ultrasound. Myocardial morphological changes were detected by hematoxylin-eosin staining (H&E). Apoptosis was assessed by a TUNEL assay. The mRNA and protein levels were detected with real-time PCR, Western blot, and immunohistochemistry analysis. We found that heart function in the LPS + TAK242 group was significantly improved, but not in the LPS + DAPT group. LPS + TAK242 had a lower level of degeneration and necrosis of cardiomyocytes and inflammatory cell infiltration, as well as lower apoptosis and caspase-3 expression than the LPS group. Compared with the LPS group, the inflammatory cell infiltration was reduced in the LPS + DAPT group, while the degeneration and necrosis of cardiomyocytes were not obviously improved. Additionally, the expression levels of tumor necrosis factor-α and Interleukin-6, the protein contents of Notch intracellular domain and Hes1, and the P65 nuclear factor kappa-B (NF-κB) to P-P65 NF-κB ratio in LPS + TAK242 group and LPS + DAPT group were significantly lower than those in LPS group. Conclusively, the interaction between TLR4 and Notch signaling pathways enhances the inflammatory response in the septic heart by activating NF-κB. Blocking the TLR4 pathway with TAK242 can improve heart dysfunction and myocardial damage in sepsis, while blocking the Notch pathway with DAPT cannot effectively prevent heart dysfunction and myocardial damage in sepsis.

TLR4-SIRT3 Mechanism Modulates Mitochondrial and Redox Homeostasis and Promotes EPCs Recruitment and Survival

The low survival rate of endothelial progenitor cells (EPCs) in vivo which are susceptible to adverse microenvironments including inflammation and oxidative stress has become one primary challenge of EPCs transplantation for regenerative therapy. Recent studies reported functional expression of toll-like receptor (TLR) 4 on EPCs and dose-dependent effects of lipopolysaccharide (LPS) on cellular oxidative stress and angiogenic properties. However, the involved mechanism has not yet been elucidated well, and the influence of TLR4 signaling on EPCs survival and function in vivo is unknown. In the present study, we observed the effects of LPS and TLR4/SIRT3 on EPCs mitochondrial permeability and intracellular mitochondrial superoxide. We employed the monocrotaline-induced pulmonary arteriolar injury model to observe the effects of TLR4/SIRT3 on the recruitment and survival of transplanted EPCs. We found the destructive effects of 10 μg/mL LPS on mitochondrial homeostasis, and cellular viability was mediated by TLR4/SIRT3 signals at least partially, and the TLR4 mediates the early-stage recruitment of transplanted EPCs in pulmonary arteriolar inflammation injury; however, SIRT3 has more contribution to the survival of incorporated EPCs and ameliorated arteriolar remodeling in lung vascular tissue. The study provides insights for the critical role of TLR4/SIRT3 in LPS-induced oxidative stress and mitochondrial disorder in EPCs in vitro and in vivo. The TLR4/SIRT3 signaling is important for EPCs resistance against inflammation and oxidative stress and may represent a new manipulating target for developing efficient cell therapy strategy.

miR-21 Regulates Immune Balance Mediated by Th17/Treg in Peripheral Blood of Septic Rats during the Early Phase through Apoptosis Pathway

Objective

To study the mechanism by which miR-21 regulates the differentiation and function of Th17/Treg cells in sepsis.

Methods

A rat model with sepsis was made by cecal ligation and puncture (CLP). Then, some of the septic rats were transfected with miR-21 mimic or inhibitor by liposome. At 48 hours, lymphocytes and plasma from septic rats were isolated for further experimental detection. The expression of miR-21 in lymphocytes was detected by Polymerase Chain Reaction (PCR); the differentiation of Th17/Treg cells was counted by flow cytometry; lymphocyte apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. The caspase-3/9 proteins were tested by Western blot; IL-10 and IL-17 were detected by enzyme-linked immunosorbent assay (ELISA).

Results

Compared with the sepsis group (SP group), the Th17 cells increased significantly, the Treg cells decreased significantly, the apoptosis rate of lymphocytes decreased significantly, the mRNA and proteins of caspase-3/9 decreased significantly, the IL-17 decreased, and the IL-10 increased in the sepsis group transfected with miR-21 (SP + miR-21 mimic group). After transfection of miR-21 inhibitor, the results were almost opposite to those of SP + miR-21 mimic group.

Conclusions

The differentiation and function of Th17/Treg cells were regulated by miR-21 in sepsis through caspase pathway.

Lipopolysaccharide increases exosomes secretion from endothelial progenitor cells by toll-like receptor 4 dependent mechanism

Endothelial progenitor cells (EPCs) can exert angiogenic effects by a paracrine mechanism, where exosomes work as an important mediator. Recent studies reported functional expression of toll-like receptor (TLR) 4 on human EPCs and dose-dependent effects of lipopolysaccharide (LPS) on EPC angiogenic properties. To study on the effects of TLR4/LPS signaling on EPC-derived exosomes (Exo) and involved mechanisms, we investigated the effect of LPS on exosomes secretion from human EPC and tested Exo functions by senescence-associated β-galactosidase activity assay and reactive oxygen species (ROS) related H₂ DCF-DA assay. To clarify the mechanism, we examined the changes in intracellular calcium levels and multivesicular bodies (MVBs) development in EPC. We employed the inhibitors of the plasma membrane Ca ²⁺ -ATPase (PMCA), endoplasmic reticulum Ca ²⁺ -ATPase (ERCA), PLC-IP₃ pathway and store-operated calcium entry to assess the effects of LPS on calcium signalings which critical for exosome secretion. LPS induced the release of Exo in a TLR4-dependent manner in vitro, which effect can be partly abrogated by the membrane-permeable IP ₃ R antagonist, 2-aminoethyl diphenylborinate (2-APB), but not PLC inhibitor, U-73122. The LPS can significantly delay the fallback of [Ca ²⁺ ]_i after isolating the cellular PMCA activity, and disturb PMCA 1/4 expression. The distribution of elevated intracellular calcium seemed coincident with the development of MVBs. Furthermore, the LPS-induced Exo maintained valid anti-oxidation/senescence properties. The PMCA and ER Ca ²⁺ release mechanism may contribute to the pro-exosomal effects of LPS on EPC, which is valuable for potential pro-regenerative application in future. This article is protected by copyright. All rights reserved.

Regulatory T Cells: Angels or Demons in the Pathophysiology of Sepsis?

Sepsis is a syndrome characterized by life-threatening organ dysfunction caused by the dysregulated host response to an infection. Sepsis, especially septic shock and multiple organ dysfunction is a medical emergency associated with high morbidity, high mortality, and prolonged after-effects. Over the past 20 years, regulatory T cells (Tregs) have been a key topic of focus in all stages of sepsis research. Tregs play a controversial role in sepsis based on their heterogeneous characteristics, complex organ/tissue-specific patterns in the host, the multi-dimensional heterogeneous syndrome of sepsis, the different types of pathogenic microbiology, and even different types of laboratory research models and clinical research methods. In the context of sepsis, Tregs may be considered both angels and demons. We propose that the symptoms and signs of sepsis can be attenuated by regulating Tregs. This review summarizes the controversial roles and Treg checkpoints in sepsis.

Inflammation and Cell Death of the Innate and Adaptive Immune System during Sepsis

Sepsis is a life-threatening medical condition that occurs when the host has an uncontrolled or abnormal immune response to overwhelming infection. It is now widely accepted that sepsis occurs in two concurrent phases, which consist of an initial immune activation phase followed by a chronic immunosuppressive phase, leading to immune cell death. Depending on the severity of the disease and the pathogen involved, the hosts immune system may not fully recover, leading to ongoing complications proceeding the initial infection. As such, sepsis remains one of the leading causes of morbidity and mortality world-wide, with treatment options limited to general treatment in intensive care units (ICU). Lack of specific treatments available for sepsis is mostly due to our limited knowledge of the immuno-physiology associated with the disease. This review will provide a comprehensive overview of the mechanisms and cell types involved in eliciting infection-induced immune activation from both the innate and adaptive immune system during sepsis. In addition, the mechanisms leading to immune cell death following hyperactivation of immune cells will be explored. The evaluation and better understanding of the cellular and systemic responses leading to disease onset could eventuate into the development of much needed therapies to combat this unrelenting disease.

BCG vaccination-induced emergency granulopoiesis provides rapid protection from neonatal sepsis

Death from sepsis in the neonatal period remains a serious threat for millions. Within 3 days of administration, bacille Calmette-Guérin (BCG) vaccination can reduce mortality from neonatal sepsis in human newborns, but the underlying mechanism for this rapid protection is unknown. We found that BCG was also protective in a mouse model of neonatal polymicrobial sepsis, where it induced granulocyte colony-stimulating factor (G-CSF) within hours of administration. This was necessary and sufficient to drive emergency granulopoiesis (EG), resulting in a marked increase in neutrophils. This increase in neutrophils was directly and quantitatively responsible for protection from sepsis. Rapid induction of EG after BCG administration also occurred in three independent cohorts of human neonates.

Targeting STAT3: A crucial modulator of sepsis

Signal transducer and activator of transcription 3 (STAT3) is a cellular signal transcription factor that has recently attracted a great deal of attention. It can trigger a variety of genes transcription in response to cytokines and growth factors stimulation, which plays an important role in many cellular biological processes involved in anti/proinflammatory responses. Sepsis is a life-threatening organ dysfunction resulting from dysregulated host responses to infection. As a converging point of multiple inflammatory responses pathways, accumulating studies have presented the elaborate network of STAT3 in sepsis pathophysiology; these results generally indicate a promising therapeutic application for targeting STAT3 in the treatment of sepsis. In the present review, we evaluated the published literature describing the use of STAT3 in the treatment of experimental and clinical sepsis. The information presented here may be useful for the design of future studies and may highlight the potential of STAT3 as a future biomarker and therapeutic target for sepsis.

Loss of Nucleobindin-2/Nesfatin-1 increases lipopolysaccharide-induced murine acute lung inflammation

NUCB2/nesfatin-1 is expressed in variety of tissues. Treatment with nesfatin-1 reduces inflammation in rat models of subarachnoid hemorrhage-induced oxidative brain damage and traumatic brain injury as well as myocardial injury. There is only one study showing anti-inflammatory actions of nesfatin-1 on acute lung inflammation. To more precisely determine the role of NUCB2/nesfatin-1 in acute lung inflammation, we conducted a study using NUCB2/nesfatin-1 knockout (NKO) mice as well as neutrophils isolated from the bone marrows of WT and NKO mice. Our findings suggest that the absence of NUCB2/nesfatin-1 significantly increases the accumulation of adherent neutrophils by approximately 3 times compared with WT within LPS-treated lungs. Integrating this with observations from both BALF and neutrophil cytokine expression, we propose that although neutrophils lacking NUCB2/nesfatin-1 individually secrete less pro-inflammatory cytokines compared with stimulated WT cells, the result of knocking out NUCB2/nesfatin-1 is net pro-inflammatory. No change was found in NUCB2/nesfatin-1 mRNA or protein expression comparing WT LPS and PBS-treated samples. Taken together, our results show that NUCB2/nesfatin-1 is constitutively expressed in mouse lungs and neutrophils and demonstrates anti-inflammatory properties in mouse lungs during acute lung injury, by inhibiting adherent neutrophil accumulation and inflammatory cytokine expression.

MicroRNA-23a-5p regulates cell proliferation, migration and inflammation of TNF-α-stimulated human fibroblast-like MH7A synoviocytes by targeting TLR4 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial joint inflammation. RA synovial fibroblasts (RASFs) constitute a major cell subset of the RA synovia. MicroRNAs (miRNAs/miRs) have been reported to serve a role in the activation and proliferation of RASFs. The present study aimed to investigate the effects and underlying mechanisms of miR-23a-5p on RA progression. Peripheral blood was collected from patients with RA (n=20) to analyze the expression levels of miR-23a-5p. The effects of miR-23a-5p on cell apoptosis, proliferation and migration in MH7A cells were determined in TNF-α-treated human fibroblast-like synoviocytes (MH7A cells) by flow cytometry, colony formation assay and Transwell assay, respectively. The cell cycle distribution was evaluated using flow cytometry. The binding relationship between miR-23a-5p and toll-like receptor (TLR) 4 was analyzed using a dual luciferase reporter gene assay. ELISA and reverse transcription-quantitative PCR assays were used to detect the levels of the inflammatory factors IL-6, IL-1β and IL-10. The expression levels of apoptosis- and migration-related proteins were analyzed using western blotting. The results of the present study revealed that the expression levels of miR-23a-5p were significantly downregulated in the plasma of patients with RA and in MH7A cells. In addition, the TNF-α-induced increase in the cell proliferative and migratory rates and the production of IL-6 and IL-1β were markedly inhibited following miR-23a-5p overexpression. The TNF-α-induced decreases in MH7A cell apoptosis were also reversed following miR-23a-5p overexpression. Additionally, transfection with miR-23a-5p mimics significantly inhibited the activation of the TLR4/NF-κB signaling pathway in TNF-α-treated MH7A cells by targeting TLR4. Notably, TLR4 overexpression weakened the effects of miR-23a-5p mimic on cell proliferation, apoptosis, migration, inflammation and the TLR4/NF-κB signaling pathway in TNF-α-induced MH7A cells. In conclusion, the findings of the present study indicated that the miR-23a-5p/TLR4/NF-κB axis may serve as a promising target for RA diagnosis and treatment.

KLF4 down-regulation resulting from TLR4 promotion of ERK1/2 phosphorylation underpins inflammatory response in sepsis

Sepsis is a systemic inflammatory response to invading pathogens, leading to high mortality rates in intensive care units worldwide. Krüppel-like factor 4 (KLF4) is an important anti-inflammatory transcription factor. In this study, we investigate the anti-inflammatory role of KLF4 in caecal ligation and puncture (CLP)-induced septic mice and lipopolysaccharide (LPS)-induced RAW264.7 cells and its potential mechanism. We found that KLF4 was down-regulated in CLP-induced septic mice and in LPS-induced RAW264.7 cells, and that its overexpression led to increased survival rates of septic mice along with inhibited inflammatory response in vivo and in vitro. ITGA2B was up-regulated in the setting of sepsis and was inhibited by KLF4 overexpression. ITGA2B knock-down mimicked the effects of KLF4 overexpression on septic mice and LPS-induced RAW264.7 cells. TLR4 promoted the phosphorylation of ERK1/2 and then up-regulated the ubiquitination and the degradation of KLF4, thereby elevating the expression of ITGA2B. Moreover, TLR4 knock-down or treatment with PD98059 (a MEK inhibitor) inhibited inflammatory response in the setting of sepsis in vivo and in vitro. Furthermore, this effect of PD98059 treatment was lost upon KLF4 knock-down. Collectively, these results explain the down-regulation of KLF4 in sepsis, namely via TLR4 promotion of ERK1/2 phosphorylation, and identify ITGA2B as the downstream gene of KLF4, thus highlighting the anti-inflammatory role of KLF4 in sepsis.

Role of the adaptive immune response in sepsis

Sepsis is a syndrome of shock and dysfunction of multiple vital organs that is caused by an uncontrolled immune response to infection and has a high mortality rate. There are no therapies for sepsis, and it has become a global cause for concern. Advances in patient care and management now mean that most patients survive the initial hyper-inflammatory phase of sepsis but progress to a later immunosuppressed phase, where 30% of patients die due to secondary infection. Deficits in the adaptive immune response may play a major role in sepsis patient mortality. The adaptive immune response involves a number of cell types including T cells, B cells and dendritic cells, all with immunoregulatory roles aimed at limiting damage and returning immune homeostasis after infection or insult. However, in sepsis, adaptive immune cells experience cell death or exhaustion, meaning that they have defective effector and memory responses ultimately resulting in an ineffective or suppressed immune defence. CD4+ T cells seem to be the most susceptible to cell death during sepsis and have ensuing defective secretory profiles and functions. Regulatory T cells seem to evade apoptosis and contribute to the immune suppression observed with sepsis. Preclinical studies have identified a number of new targets for therapy in sepsis including anti-apoptotic agents and monoclonal antibodies aimed at reducing cell death, exhaustion and maintaining/restoring adaptive immune cell functions. While early phase clinical trials have demonstrated safety and encouraging signals for biologic effect, larger scale clinical trial testing is required to determine whether these strategies will prove effective in improving outcomes from sepsis.

Atezolizumab alleviates the immunosuppression induced by PD‑L1‑positive neutrophils and improves the survival of mice during sepsis

Atezolizumab can reduce immunosuppression caused by T lymphocyte apoptosis in various cancer types. The current study aimed to investigate whether this drug can also alleviate immunosuppression during sepsis. For that purpose, a C57BL/6 mouse sepsis model was generated. Mice were randomly assigned to three groups: Sham, cecal ligation and puncture (CLP) and atezolizumab groups. Atezolizumab was administered <em>in vivo</em> by intraperitoneal injection. The expression of programmed death ligand‑1 (PD‑L1) on neutrophils and programmed death‑1 (PD‑1) on T lymphocytes was evaluated, and endotoxin concentration, intestinal permeability, ileum histopathological score and tight junction protein expression were assessed to determine the extent of disease in each group. The rate of T lymphocyte apoptosis was determined to assess the effects of atezolizumab on T lymphocyte apoptosis <em>in vivo</em> and <em>in vitro</em>. Survival times were also recorded to compare mouse prognosis during sepsis. In the CLP group, the proportion of PD‑L1+ neutrophils was significantly higher at 48, 72 and 96 h in blood, and at 24, 48, 72 and 96 h in bone marrow, compared with those of the sham group (P&lt;0.05). The proportion of PD‑1+ T lymphocytes was also upregulated at 72 h in blood. In the atezolizumab group, endotoxin concentration, intestinal permeability and ileum histopathological score were lower compared with those in the CLP group (P&lt;0.05), whereas the expression of claudin‑1 and occludin proteins on ileum was higher compared with that in the CLP group (P&lt;0.05). Both <em>in vivo</em> and <em>in vitro</em> experiments indicated that the rate of T lymphocyte apoptosis following atezolizumab treatment was lower compared with that in the CLP group (P&lt;0.05). Survival analysis demonstrated that mice in the atezolizumab group survived longer compared with those in the CLP group (P&lt;0.05). The current study demonstrated that treatment with atezolizumab may be an effective method for treating immunosuppression induced by sepsis.

Phosphorylated Heat Shock Protein 27 Inhibits Lipopolysaccharide-Induced Inflammation in Thp1 Cells by Promoting TLR4 Endocytosis, Ubiquitination, and Degradation

The aims of this study were to investigate the effect of Hsp27 on LPS-induced inflammation and identify the precise mechanisms about how Hsp27 regulates LPS-induced TLR4 signaling in Thp1 cells. Thp1 cells were transfected with Flag-Hsp27 or pcDNA3.1, and then treated with LPS for indicated time. TNF-α, IL-1β, and IL-6 were determined by ELISA. The protein levels of Hsp27, p-Hsp27 (Ser15, Ser78, and Ser82), and TLR4 were measured by Western blotting. In vitro study showed that over-expression of Hsp27 downregulated the release of TNF-α, IL-1β, and IL-6 and suppressed the activation of TLR4 signals after stimulated by LPS. The location of TLR4 and RAB5 was detected by confocal microscopy. Immunoprecipitation was used to determine the ubiquitination and degradation of TLR4 and interaction between Hsp27 and TLR4. Results showed that Hsp27 could promote TLR4 endocytosis and ubiquitination and degradation. Further research revealed that Hsp27 was phosphorylated after LPS, only phosphorylated Hsp27 can interact with TLR4 and inhibit the activation of TLR4 signaling, which was demonstrated by inhibition of Hsp27 phosphorylation with inhibitors or transfection of Hsp27 mutants into Thp1 cells. Phosphorylated Hsp27 reduced the release of TNF-α, IL-1β, and IL-6, and suppressed the activation of TLR4 signaling by promoting TLR4 endocytosis, ubiquitination, and degradation.

Loss of tissue-nonspecific alkaline phosphatase (TNAP) enzyme activity in cerebral microvessels is coupled to persistent neuroinflammation and behavioral deficits in late sepsis

Sepsis is a host response to systemic inflammation and infection that may lead to multi-organ dysfunction and eventual death. While acute brain dysfunction is common among all sepsis patients, chronic neurological impairment is prevalent among sepsis survivors. The brain microvasculature has emerged as a major determinant of sepsis-associated brain dysfunction, yet the mechanisms that underlie its associated neuroimmune perturbations and behavioral deficits are not well understood. An emerging body of data suggests that inhibition of tissue-nonspecific alkaline phosphatase (TNAP) enzyme activity in cerebral microvessels may be associated with changes in endothelial cell barrier integrity. The objective of this study was to elucidate the connection between alterations in cerebrovascular TNAP enzyme activity and brain microvascular dysfunction in late sepsis. We hypothesized that the disruption of TNAP enzymatic activity in cerebral microvessels would be coupled to the sustained loss of brain microvascular integrity, elevated neuroinflammatory responses, and behavioral deficits. Male mice were subjected to cecal ligation and puncture (CLP), a model of experimental sepsis, and assessed up to seven days post-sepsis. All mice were observed daily for sickness behavior and underwent behavioral testing. Our results showed a significant decrease in brain microvascular TNAP enzyme activity in the somatosensory cortex and spinal cord of septic mice but not in the CA1 and CA3 hippocampal regions. Furthermore, we showed that loss of cerebrovascular TNAP enzyme activity was coupled to a loss of claudin-5 and increased perivascular IgG infiltration in the somatosensory cortex. Analyses of whole brain myeloid and T-lymphoid cell populations also revealed a persistent elevation of infiltrating leukocytes, which included both neutrophil and monocyte myeloid derived suppressor cells (MDSCs). Regional analyses of the somatosensory cortex, hippocampus, and spinal cord revealed significant astrogliosis and microgliosis in the cortex and spinal cord of septic mice that was accompanied by significant microgliosis in the CA1 and CA3 hippocampal regions. Assessment of behavioral deficits revealed no changes in learning and memory or evoked locomotion. However, the hot plate test uncovered a novel anti-nociceptive phenotype in our septic mice, and we speculate that this phenotype may be a consequence of sustained GFAP astrogliosis and loss of TNAP activity in the somatosensory cortex and spinal cord of septic mice. Taken together, these results demonstrate that the loss of TNAP enzyme activity in cerebral microvessels during late sepsis is coupled to sustained neuroimmune dysfunction which may underlie, in part, the chronic neurological impairments observed in sepsis survivors.

NEAT1 Promotes LPS-induced Inflammatory Injury in Macrophages by Regulating MiR-17-5p/TLR4

Background

The inflammatory response of macrophages is responsible for sepsis. Long noncoding RNA nuclear enriched abundant transcript 1 (NEAT1) has been reported to be involved in sepsis development. However, its underlying mechanism remains largely unclear. This study aims to investigate the effect of NEAT1 on inflammatory response of macrophages and explore the regulatory network of NEAT1/microRNA-17-5p (miR-17-5p)/Toll-like receptor 4 (TLR4).

Methods

The serum samples of 68 sepsis patients and 32 heathy controls were collected. THP-1 macrophages were treated with lipopolysaccharide (LPS) to induce inflammatory injury model of sepsis. The expressions of NEAT1, miR-17-5p and TLR4 were measured by quantitative real-time polymerase chain reaction or western blot. The inflammatory response was investigated by levels of inflammatory cytokines, tumor necrosis factor-alpha (TNF-ɑ), interleukin-1beta (IL-1β) and IL-6 as well as nitric oxide (NO) production. The interaction among NEAT1, miR-17-5p and TLR4 were investigated by bioinformatics analysis, luciferase reporter assay and RNA pull-down.

Results

NEAT1 expression was enhanced in patient serum and associated with severity of sepsis. Knockdown of NEAT1 inhibited levels of TNF-ɑ, IL-1β, IL-6 and NO release in LPS-treated macrophages. miR-17-5p is bound to NEAT1 and its abrogation reversed NEAT1 knockdown-mediated inhibition of inflammatory response in LPS-treated macrophages. Overexpression of miR-17-5p weakened LPS-induced inflammatory response. TLR4 as a target of miR-17-5p was regulated by NEAT1 and miR-17-5p. TLR4 res-to ration alleviated silencing NEAT1-induced inflammatory suppression.

Conclusion

Silence of NEAT1 suppressed LPS-induced inflammatory response of macrophages by mediating miR-17-5p and TLR4, indicating that NEAT1 might be a promising target for sepsis treatment.

Porphyran isolated from Pyropia yezoensis inhibits lipopolysaccharide-induced activation of dendritic cells in mice

We previously demonstrated that porphyran, a sulfated polysaccharide extracted from Pyropia yezoensis, shows protective effects on LPS-induced septic shock in the mouse. However, the immune cell-mediated inhibitory effect of porphyran in LPS-induced activation of immune cells has not been well investigated. In this study, we found that treatment of porphyran suppressed LPS-induced upregulation of costimulatory molecule and C-C chemokine receptor type 7 (CCR7) expression in bone marrow-derived dendritic cells (BMDCs) in vitro and spleen DCs in vivo. Moreover, the LPS-induced expression of IL-6, IL-12, and TNF-α in the culture medium of BMDCs and serum dose-dependently decreased by porphyran treatment, which contributed to the inhibition of the intracellular cytokine production in spleen DCs. In addition, LPS-induced differentiation of helper T1 (Th1) and cytotoxic T1 (Tc1) cells was effectively suppressed by porphyran treatment in mice. The inhibitory effect of porphyran in LPS-induced immune activation was mediated by competitive binding of porphyran with LPS in spleen DCs. Thus, these results suggest that porphyran is a promising potential therapeutic agent in endotoxin-mediated inflammatory disease and septic shock.

Pathological alteration and therapeutic implications of sepsis-induced immune cell apoptosis

Sepsis is a life-threatening organ dysfunction syndrome caused by dysregulated host response to infection that leads to uncontrolled inflammatory response followed by immunosuppression. However, despite the high mortality rate, no specific treatment modality or drugs with high efficacy is available for sepsis to date. Although improved treatment strategies have increased the survival rate during the initial state of excessive inflammatory response, recent trends in sepsis show that mortality occurs at a period of continuous immunosuppressive state in which patients succumb to secondary infections within a few weeks or months due to post-sepsis “immune paralysis.” Immune cell alteration induced by uncontrolled apoptosis has been considered a major cause of significant immunosuppression. Particularly, apoptosis of lymphocytes, including innate immune cells and adaptive immune cells, is associated with a higher risk of secondary infections and poor outcomes. Multiple postmortem studies have confirmed that sepsis-induced immune cell apoptosis occurs in all age groups, including neonates, pediatric, and adult patients, and it is considered to be a primary contributing factor to the immunosuppressive pathophysiology of sepsis. Therapeutic perspectives targeting apoptosis through various strategies could improve survival in sepsis. In this review article, we will focus on describing the major apoptosis process of immune cells with respect to physiologic and molecular mechanisms. Further, advances in apoptosis-targeted treatment modalities for sepsis will also be discussed.

Ulinastatin Protects Against LPS-Induced Acute Lung Injury By Attenuating TLR4/NF-κB Pathway Activation and Reducing Inflammatory Mediators

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, remain the leading causes of morbidity and mortality in intensive care units. Ulinastatin (UTI), a serine protease inhibitor, possesses anti-inflammatory properties and has been suggested to modulate lipopolysaccharide (LPS)-induced sepsis; thus, it is now widely used in the treatment of pancreatitis, sepsis, and septic shock. Toll-like receptor 4 (TLR4), an essential LPS signaling receptor, plays a critical role in the activation of innate immunity. The aim of this study was to investigate whether UTI alleviates ALI by attenuating TLR4 expression and to explore the underlying molecular mechanisms involved. Male C56BL/6 mice were administered UTI intravenously 1 h before and 6 h after exposure to LPS by intratracheal instillation. Human lung epithelial (BEAS-2B) cells were incubated with LPS in the presence or absence of UTI. An enzyme-linked immunosorbent assay was used to detect levels of inflammatory cytokines. Western blot analysis was performed to detect changes in TLR4 expression and nuclear factor-κB (NF-κB) activation. UTI significantly protected animals from LPS-induced ALI, decreasing the lung wet/dry weight ratio, ALI score, total cells, neutrophils, macrophages, myeloperoxidase activity, and malondialdehyde content, factors associated with lung histological damage. UTI treatment also markedly attenuated levels of TLR4 and other proinflammatory cytokines. Furthermore, UTI significantly attenuated LPS-induced increases in TLR4 protein expression and NF-κB activation in lung tissues. Similarly, UTI markedly attenuated TLR4 expression and NF-κB activation in LPS-stimulated BEAS-2B cells. These findings indicate that UTI ameliorates LPS-induced ALI by attenuating the TLR4/NF-κB pathway activation.

Effects of resveratrol on intestinal oxidative status and inflammation in heat-stressed rats

Heat stress, experienced by humans and animals under high ambient temperatures, is known to induce oxidative stress and inflammation, which endangers human health as well as animal welfare and production. The gastrointestinal tract is predominantly responsive to heat stress and compromised intestinal functions can contribute to multi-organ injury under heat environment. Resveratrol (RSV) has significant antioxidant and anti-inflammatory activities. The aim of this study was to investigate the potential effects of RSV on intestinal function (digestion and barrier), oxidative stress and inflammation in heat-stressed rats. Male Sprague-Dawley rats were orally fed with 100 mg RSV/kg body weight/day prior to daily heat stress (40 °C per day for 1.5 h) exposure for 3 consecutive days. The results showed that RSV reversed the increased serum cortisol level and diamine oxidase activity, the altered jejunal morphology, the decreased jejunal disaccharidase activities, the elevated malondialdehyde and tumor necrosis factor alpha concentrations and antioxidant enzymes activities in the jejunum, as well as the increased jejunal mRNA expression of toll-like receptor 4, cytokines, antioxidant enzymes and tight junction proteins in heat-stressed rats, to various degrees. In conclusion, RSV could alleviate intestinal injury and dysfunctions by improving oxidative status and suppressing inflammation in heat-stressed rats.

Identification of key miRNA‑mRNA pairs in septic mice by bioinformatics analysis

Sepsis is one of the most common causes of death among critically ill patients in intensive care units worldwide; however, the microRNAs (miRNAs/miRs) involved in the sepsis process (and their target genes) are largely unknown. The present study integrated miRNA and mRNA datasets to elucidate key sepsis-related miRNA-mRNA pairs. The datasets, GSE74952 and GSE55238 were downloaded from the Gene Expression Omnibus. By performing bioinformatics analysis such as GEO2R, miRNA target gene prediction, Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis and miRNA-mRNA network analysis, a total of four sepsis-related miRNA-mRNA pairs were successfully obtained. Mmu-miR-370-3p, cluster of differentiation (CD)8a, CD247, Zap70 and inhibitor of nuclear factor κ B kinase subunit β (Ikbkb) were identified as the components involved in these pairs, and these genes were enriched in the T-cell receptor signaling pathway. Finally, reverse transcription-quantitative PCR results validated that the expression levels of the four genes (CD8a, CD247, Zap70 and Ikbkb) in the sepsis model mice were consistent with the microarray analysis. In conclusion, the present study identified four sepsis-related miRNA-mRNA pairs using bioinformatics analysis. These results indicated that the candidate miRNA-mRNA pairs may be involved in the regulation of immunity in sepsis, which may in turn act as indicators or therapeutic targets for sepsis.

Ethanol Extract of Illicium henryi Attenuates LPS-Induced Acute Kidney Injury in Mice via Regulating Inflammation and Oxidative Stress

The root bark of Illicium henryi has been used in traditional Chinese medicine to treat various diseases. Its ethanol extract (EEIH) was found to contain a large number of phenols and possess in vitro antioxidant activities. The present study aimed to investigate its protective effect against lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice. BALB/c mice were intraperitoneally pretreated with EEIH for five days, and then LPS injection was applied to induce AKI. Blood samples and kidney tissues were collected and used for histopathology, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH not only significantly dose-dependently attenuated histological damage and reduced renal myeloperoxidase (MPO) activity (from 9.77 ± 0.73 to 0.84 ± 0.30 U/g tissue) but also decreased serum creatinine (from 55.60 ± 2.70 to 27.20 ± 2.39 µmol/L) and blood urea nitrogen (BUN) (from 29.95 ± 1.96 to 16.12 ± 1.24 mmol/L) levels in LPS-treated mice. EEIH also markedly dose-dependently inhibited mRNA expression and production of TNF-α (from 140.40 ± 5.15 to 84.74 ± 5.65 pg/mg), IL-1β (from 135.54 ± 8.20 to 77.15 ± 5.34 pg/mg), IL-6 (from 168.74 ± 7.23 to 119.16 ± 9.35 pg/mg), and COX-2 in renal tissue of LPS-treated mice via downregulating mRNA and protein expressions of toll-like receptor 4 (TLR4) and phosphorylation of nuclear factor-κB (NF-κB) p65. Moreover, EEIH significantly dose-dependently reduced malondialdehyde (MDA) (from 5.43 ± 0.43 to 2.80 ± 0.25 nmol/mg prot) and NO (from 1.01 ± 0.05 to 0.24 ± 0.05 µmol/g prot) levels and increased superoxide dismutase (SOD) (from 22.32 ± 2.92 to 47.59 ± 3.79 U/mg prot) and glutathione (GSH) (from 6.57 ± 0.53 to 16.89 ± 0.68 µmol/g prot) levels in renal tissue induced by LPS through upregulating mRNA expression of nuclear factor erythroid 2 related factor 2 (Nrf2). Furthermore, EEIH inhibited LPS-induced intracellular reactive oxygen species (ROS) production from RAW264.7 cells in a concentration-dependent manner. These results suggest that EEIH has protective effects against AKI in mice through regulating inflammation and oxidative stress.

Tolerizing CTL by Sustained Hepatic PD-L1 Expression Provides a New Therapy Approach in Mouse Sepsis

Cytotoxic T lymphocyte (CTL) activation contributes to liver damage during sepsis, but the mechanisms involved are largely unknown. Understanding the underlying principle will permit interference with CTL activation and thus, provide a new therapeutic option. Methods: To elucidate the mechanism leading to CTL activation we used the Hepa1-6 cell line in vitro and the mouse model of in vivo polymicrobial sepsis, following cecal-ligation and -puncture (CLP) in wildtype, myeloid specific NOX-2, global NOX2 and NOX4 knockout mice, and their survival as a final readout. In this in vivo setting, we also determined hepatic mRNA and protein expression as well as clinical parameters of liver damage - aspartate- and alanine amino-transaminases. Hepatocyte specific overexpression of PD-L1 was achieved in vivo by adenoviral infection and transposon-based gene transfer using hydrodynamic injection. Results: We observed downregulation of PD-L1 on hepatocytes in the murine sepsis model. Adenoviral and transposon-based gene transfer to restore PD-L1 expression, significantly improved survival and reduced the release of liver damage, as PD-L1 is a co-receptor that negatively regulates T cell function. Similar protection was observed during pharmacological intervention using recombinant PD-L1-Fc. N-acetylcysteine blocked the downregulation of PD-L1 suggesting the involvement of reactive oxygen species. This was confirmed in vivo, as we observed significant upregulation of PD-L1 expression in NOX4 knockout mice, following sham operation, whereas its expression in global as well as myeloid lineage NOX2 knockout mice was comparable to that in the wild type animals. PD-L1 expression remained high following CLP only in total NOX2 knockouts, resulting in significantly reduced release of liver damage markers. Conclusion: These results suggest that, contrary to common assumption, maintaining PD-L1 expression on hepatocytes improves liver damage and survival of mice during sepsis. We conclude that administering recombinant PD-L1 or inhibiting NOX2 activity might offer a new therapeutic option in sepsis.

Monomethyl fumarate alleviates sepsis-induced hepatic dysfunction by regulating TLR-4/NF-κB signalling pathway

AIMS

Sepsis is a potentially fatal illness that can lead to impairment of multiple organs such as liver. The condition is deeply associated with oxidative stress and inflammation. Monomethyl fumarate (MMF) has manifested antioxidant and immunomodulatory properties. The aim of current study was to evaluate protective effects of MMF in sepsis-induced hepatic dysfunction.

MAIN METHODS

Sepsis was induced by cecal ligation and puncture (CLP). Wistar rats were assigned to one of sham, CLP, CLP + dexamethasone (as positive control of inflammation) and CLP + MMF groups. Levels of serum IL-1β, IL-6, IL-10, AST, ALT and γ‑GT were quantified. Furthermore, Hepatic levels of GSH and MDA and mRNA expression of TNF and NFKBIA along with hepatic protein level of TLR-4 were assessed. Also, histopathological study of liver was carried out to evaluate hepatic injuries.

KEY FINDINGS

Septic rats demonstrated risen levels of IL-1β, IL-6, IL-10, AST, ALT and γ‑GT, while treatment with dexamethasone or MMF attenuated these levels. Moreover, enhancements in protein level of TLR-4 and mRNA levels of TNF and NFKBIA were observed in CLP rats. These elevations were mitigated in CLP-induced rats that were treated with either dexamethasone or MMF. Treatment with dexamethasone or MMF also shifted sepsis-induced disturbance in the levels of GSH and MDA towards sham levels. Hepato-protective effects of dexamethasone and MMF were further confirmed by histopathological observations.

SIGNIFICANCE

Our findings imply that MMF alleviates sepsis-induced hepatic dysfunction by mitigating the inflammatory and oxidative state and this effect is at least partly mediated by the inhibition of TLR-4/NF-κB signalling pathway.

Ulinastatin mediates suppression of regulatory T cells through TLR4/NF-κB signaling pathway in murine sepsis

CD4⁺CD25⁺ regulatory T cells (Tregs) play an essential role in the suppression of the immune response and prevention of autoimmune reactions. The activation of TLR4, which provides a critical link between the innate and adaptive immune systems, has been implicated in regulating the function of Tregs. Ulinastatin (UTI) is a broad-spectrum protease inhibitor that has been shown to modulate innate immunity and pro-inflammatory signaling in sepsis. In addition, there are reports that UTI may modulate the functional activity of Tregs to influence the inflammatory response in infectious disease. In the present study, we investigated the effect of UTI on the activity of Tregs, which was assessed by measuring the survival and inflammatory responses of mice with cecal ligation and puncture (CLP)-induced sepsis. In addition, we further explored the cellular and molecular mechanisms involved in these effects. The results showed that UTI could enhance survival and attenuate inflammatory responses during CLP-induced sepsis. Moreover, sepsis-induced increases in the quantity and activity of Tregs were attenuated under UTI treatment, but not in TLR4^-/- mice. We also found that the functional changes in Tregs could be attributed to the TLR4/NF-κB signaling pathway. Collectively, our results indicated that UTI could ameliorate inflammatory damage by modulating the quantity and function of Tregs via the TLR4/NF-κB signaling pathway. Our study provides theoretical and experimental evidence for the administration of UTI in the treatment of sepsis and other acute critical illnesses.

Toll-Like Receptors -2, -3, -4 and -7 Expression Patterns in the Liver of a CLP-Induced Sepsis Mouse Model

Objective: To investigate the expression of toll-like receptors (TLRs) in the liver of septic mouse model. Materials and methods: For this study seventy-two C57BL/6J mice were utilized. Sepsis was induced by cecal ligation and puncture (CLP) in the mice of the three septic (S) groups (euthanized at 24 hours, 48 hours and 72 hours). Sham (laparotomy)- operated mice constituted the control (C) groups (euthanized at 24, 48 and 72 hours). Blood samples were drawn and liver tissues were extracted and examined histologically. The expression of TLRs 2, 3, 4 and 7 was assessed via immunohistochemistry (IHC) and qrt-PCR (quantitative- Polymerase Chain Reaction). Results: Liver function tests were elevated in all S-groups in contrast to their time-equivalent control groups (S24 versus C24, S48 versus C48 and S72 versus C72) (p < 0.05). Liver histology displayed progressive deterioration in the septic groups. IHC and qrt-PCR both showed an increased expression of all TLRs in the septic mice in comparison to their analogous control ones (p < 0.05). Analysis of livers and intestines of the septic animals proved that all TLRs were significantly expressed in higher levels in the intestinal tissues at 24h and 48h (p < 0.05) except for TLR 3 in S48 (p > 0.05); whereas at 72 hours only TLR 4 levels were significantly elevated in the intestine (p < 0.05). Conclusion: TLRs seem to be expressed in significant levels in the livers of septic rodents, indicating that they have a possible role in the pathophysiology of liver damage in septic conditions.

The Potential of Phage Therapy in Sepsis

Sepsis remains a difficult clinical challenge, since our understanding of its immunopathology is incomplete and no efficacious treatment currently exists. Its earlier stage results from an uncontrolled inflammatory response to bacteria while in the later stage disturbed immune response with immunodeficiency syndrome develops. More than a hundred of clinical trials have not provided an efficient therapy which could ascertain an improvement or cure. Recent advancements in immunobiology of bacterial viruses (phages) indicate that in addition to their well-known antibacterial action phages have potent immunomodulating properties. Those data along with preliminary observations in experimental animals and the clinic strongly suggest that clinical trials on the efficacy of phages in sepsis are urgently needed.