Tuftsin-derived T-peptide prevents cellular immunosuppression and improves survival rate in septic mice

Potential roles of vitamin D binding protein in attenuating liver injury in sepsis

BACKGROUND

In sepsis, vitamin D binding protein (VDBP) has been shown to be low-expressed. The current study examined the relationship between serum VDBP level and liver injury in sepsis patients, as well as in a mouse model for sepsis and in cultured liver epithelial cell line exposed to lipopolysaccharide (LPS).

METHODS

The human study included 78 sepsis patients and 50 healthy volunteers. Sepsis patients were categorized into sepsis survivor group (n = 43) and sepsis non-survivor group (n = 35) based on 28-day mortality for data analysis. Adult male C57BL/6 mice were subjected to cecal ligation and puncture (CLP). Serum samples were collected on day 1, 3, 5 and 7 to determine the levels of VDBP, 25-hydroxyvitamin D [25(OH)D₃], 1,25-dihydroxyvitamin D [1,25(OH)₂D₃], interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α). Potential protective effects of VDBP overexpression against LPS-induced liver damage were examined in cultured THLE2 cells.

RESULTS

Serum levels of VDBP, 25(OH)D₃, and 1,25(OH)₂D₃ were significantly lower in sepsis patients vs. the healthy control (P < 0.001), as well as in the sepsis non-survivor group vs. the sepsis survivor group (P < 0.001, P = 0.0338, or P = 0.0013, respectively). Lower serum VDBP level was associated with higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (r = - 0.2565, P = 0.0234) and Sequential Organ Failure Assessment score (r = - 0.3522, P = 0.0016), but lower serum albumin (ALB, r = 0.4628, P < 0.001) and total protein (TP, r = 0.263, P = 0.02). In CLP mice, there was a 5-day period of serum VDBP reduction, followed by return towards the baseline on day 7. VDBP was also decreased in LPS-treated THLE2 cells (P < 0.001). VDBP overexpression reduced LPS-induced THLE2 damage. Reduced damage was associated with decreased oxidative stress and inactivation of the c-Jun N-terminal kinase signaling pathway.

CONCLUSION

VDBP may be protective against sepsis-induced liver injury.

The contribution of neuropilin-1 in the stability of CD4+ CD25+ regulatory T cells through the TGF-β1/Smads signaling pathway in the presence of lipopolysaccharides

Introduction

This study investigates the synergistic effect of TGF‐β1 and Nrp‐1 on CD4⁺CD25⁺ T_regs' stabilization, and the associated pathways of signal transduction, in vitro models in the presence of LPS.

Materials and Methods

Spleen CD4⁺CD25⁺ T_regs cells of mice models in the presence of LPS, were transfected with an shRNA targeting Nrp‐1, Smad2, or Smad3, may or may not be treated with recombinant TGF‐β1. Followed by subsequent determination of cellular proliferation, rate of apoptosis, observation of the Foxp3, CTLA‐4, and TGF‐β1^m+ expression levels, foxp3‐TSDR methylation, secretion levels of the inhibitory cytokines IL‐10 and TGF‐β1, and Smad2/3 of CD4⁺CD25⁺ T_regs expression.

Results

A remarkable stimulation in CD4⁺CD25⁺ T_regs' stability is noted after administering recombinant TGF‐β1 in the presence of LPS, and promoted cellular viability, increased Foxp3, CTLA‐4, and TGF‐β1^m+ expression, and elevated secretion of IL‐10 and TGF‐β1. This also inhibited the apoptosis and methylation of foxp3‐ TSDR of CD4⁺CD25⁺ T_regs. The shRNA transfection silenced Nrp‐1 and Smad3, but not Smad2, resulting in the suppression of the recombinant TGF‐β1‐mediated effects in the presence of LPS.

Conclusions

According to the results, Nrp‐1 mediates TGF‐β1 to improve the stability of regulatory CD4⁺CD25⁺ T cells and maybe a possible therapeutic target with the ability to improve the CD4⁺CD25⁺ T_regs associated negative immunoregulation that is related to the TGF‐β1/Smads cell signaling during sepsis.

Protective effect of acute splenic irradiation in rats with traumatic brain injury

OBJECTIVE

To explore the protective effect of acute splenic irradiation against traumatic brain injury (TBI) in rats.

METHODS

A rat model of TBI was established according to Feeney's method. Splenic irradiation was performed by the reverse intensity-modulated radiation therapy (IMRT) source-axis distance (SAD) irradiation technique. Rat brain tissue samples were collected, the water content of the rat brain tissue was determined and the abundance of microglia was detected by immunofluorescence. Spleens were collected to measure the spleen index. Lung, liver, small intestine and kidney tissues were taken for hematoxylin and eosin staining to observe whether there was radiation-induced pathological damage. Peripheral blood was collected to detect tuftsin and the inflammatory factors IL-6 and IL-10.

RESULTS

Compared with the nonirradiated TBI rat group, the 4-h spleen irradiation TBI rat group showed (1) increased behavioral scores at 3 days after TBI (P  < 0.05), (2) reduced water content of the ipsilateral hemisphere at 3 days after TBI, (3) reduced spleen index at 3 and 7 days after TBI, (4) reduced number of microglia cells infiltrating around the lesion at 7 days after TBI, (5) reduced IL-6 levels at 3 days after TBI, (6) increased IL-10 levels at 3 and 5days after TBI and (7) Compared with the nonirradiated TBI rat group, the 8-h spleen irradiation TBI rat group showed reduced tuftsin levels at 3 and 7days after TBI.

CONCLUSIONS

Acute splenic irradiation had a protective effect in rats with TBI.

Semaphorin 3A contributes to sepsis‑induced immunosuppression by impairing CD4+ T cell anergy

Semaphorin 3A (Sema3A), a member of the Sema family of proteins, appears to serve an important role in sepsis and sepsis‑induced immunosuppression and has been regarded as a crucial regulator involved in cellular immune response. However, the role of Sema3A in CD4+ T cell anergy during sepsis remains to be elucidated. In the present study, the cecal ligation and perforation model and lipopolysaccharide (LPS) were used to simulate sepsis and the role of Sema3A in sepsis‑induced CD4+ T cell anergy was investigated in vivo and in vitro. In vivo, the serum concentration of Sema3A was enhanced and exacerbated sepsis‑induced T cell immunosuppression and multiple organ dysfunction syndromes (MODS). Administration of (‑)‑epigallocatechin‑3‑gallate, an inhibitor of Sema3A, markedly improved sepsis‑induced T cell immunosuppression and MODS. In vitro, both lymphoid and myeloid lineages secreted high concentration of Sema3A in LPS‑induced sepsis, especially in the lymphoid lineage. Inhibition of Sema3A alleviated T cell anergy. The NF‑κB signaling pathway was involved in Sema3A‑mediated autocrine loop aggravating T cell immune dysfunction during LPS‑induced sepsis. Inhibiting Sema3A exerted significant improvement of sepsis‑induced immunosuppression and MODS, which was associated with improvement of CD4+ T cells anergy via regulation of the NF‑κB signaling pathway.

Targeting Neuropilin-1 Suppresses the Stability of CD4+ CD25+ Regulatory T Cells via the NF-κB Signaling Pathway in Sepsis

Neuropilin-1 (Nrp-1) contributes to maintaining the stability of CD4⁺ CD25⁺ regulatory T cells (T_regs). We investigated the impact of Nrp-1 on the stability of CD4⁺ CD25⁺ T_regs, and the underlying signaling pathways, in a model of sepsis. Splenic CD4⁺ CD25⁺ T_regs were either treated with anti-Nrp-1, transfected to silence Nrp-1 and inhibitor of NF-κB kinase subunit beta (IKKβ), or administered ammonium pyrrolidine dithiocarbamate (PDTC), followed by recombinant semaphorin 3A (rSema3A), in a simulation of sepsis. After the creation of a sepsis model in mice, anti-Nrp-1 was administered. The expression of the gene encoding forkhead box protein P-3 foxp3-T_reg-specific demethylated region (foxp3-TSDR), the apoptosis rate, the expression of Foxp-3, cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), and transforming growth factor β1 (TGF-β1), interleukin 10 (IL-10) and TGF-β1 secretion, and the NF-κB signaling activity of CD4⁺ CD25⁺ T_regs were determined. Sepsis simulation with or without rSema3A increased the stability of CD4⁺ CD25⁺ T_regs, including an increase in the expression of Foxp-3, CTLA-4, and TGF-β1, decreases in apoptosis and the methylation of foxp3-TSDR, increases in the secretion of TGF-β1 and IL-10, and an increase in the immunosuppressive effect on CD4⁺ T lymphocytes. Silencing of Nrp-1 or anti-Nrp-1 treatment abrogated lipopolysaccharide (LPS) stimulation with or without an rSema3A-mediated effect. Sepsis simulation increased the DNA-binding activity of NF-κB, as well as the ratios of phosphorylated IKKβ (p-IKKβ) to IKKβ and p-P65 to P65 in vitro and vivo Silencing of IKKβ expression or PDTC treatment suppressed the stability of CD4⁺ CD25⁺ T_regs in LPS-induced sepsis. Weakening Nrp-1 reduced the stability of CD4⁺ CD25⁺ T_regs by regulating the NF-κB signaling pathway; thus, Nrp-1 could be a new target for immunoregulation in sepsis.

Increased intestinal permeability exacerbates sepsis through reduced hepatic SCD-1 activity and dysregulated iron recycling

Inflammatory bowel disease is associated with changes in the mucosal barrier, increased intestinal permeability, and increased risk of infections and sepsis, but the underlying mechanisms are incompletely understood. Here, we show how continuous translocation of gut microbial components affects iron homeostasis and facilitates susceptibility to inflammation-associated sepsis. A sub-lethal dose of lipopolysaccharide results in higher mortality in Mucin 2 deficient (Muc2^-/-) mice, and is associated with elevated circulatory iron load and increased bacterial translocation. Translocation of gut microbial components attenuates hepatic stearoyl CoA desaturase-1 activity, a key enzyme in hepatic de novo lipogenesis. The resulting reduction of hepatic saturated and unsaturated fatty acid levels compromises plasma membrane fluidity of red blood cells, thereby significantly reducing their life span. Inflammation in Muc2^-/- mice alters erythrophagocytosis efficiency of splenic macrophages, resulting in an iron-rich milieu that promotes bacterial growth. Our study thus shows that increased intestinal permeability triggers a cascade of events resulting in increased bacterial growth and risk of sepsis.

Tuftsin prevents the negative immunoregulation of neuropilin-1highCD4+CD25+Regulatory T cells and improves survival rate in septic mice

Our previous research showed that neuropilin (Nrp) -1highCD4+CD25+Regulatory T cells (Tregs) exhibited primary negative immunoregulation in sepsis induced immune dysfunction. Tuftsin is the typical ligand of Nrp-1. Herein, we investigated the potential therapeutic value and mechanisms of tuftsin in sepsis. Sepsis per se markedly decreased the serum concentration of tuftsin, administration of tuftsin improved the survival rate of septic mice with cecal ligation and puncture (CLP). In vitro study, tuftsin prevented the negative immunoregulation of Nrp-1highCD4+CD25+Tregs, including weakening the expression of forkhead/winged helix transcription factor (Foxp)- 3/cytotoxic T lymphocyte associated antigen (CTLA)-4, inhibiting the secretion of transforming growth factor (TGF)-β, and weakening the immunosuppressive function of Nrp-1highCD4+CD25+Tregs to conventional CD4+CD25-T cells. Tuftsin markedly inhibited the demethylation of Foxp3-Tregs specific demethylated region (TSDR) of Nrp-1highCD4+CD25+Tregs. Tuftsin could represent a new potential therapeutic agentia to improve the outcome of septic mice, and associate with preventing the negative immunoregulation of Tregs via Nrp-1.

Hydroxysafflor Yellow A Attenuates the Apoptosis of Peripheral Blood CD4+ T Lymphocytes in a Murine Model of Sepsis

Sepsis is generally considered as a severe condition of inflammation that leads to lymphocyte apoptosis and multiple organ dysfunction. Hydroxysafflor yellow A (HSYA) exerts anti-inflammatory and anti-apoptotic effects in infectious diseases. However, the therapeutic effect of HSYA on polymicrobial sepsis remains unknown. This study was undertaken to investigate the therapeutic effects and the mechanisms of action of HSYA on immunosuppression in a murine model of sepsis induced by cecal ligation and puncture (CLP). NIH mice were randomly divided into four groups: control group, sham group, CLP group, and CLP+HSYA group. HSYA (120 mg/kg) was intravenously injected into experimental mice at 12 h before CLP, concurrent with CLP and 12 h after CLP. The levels of circulating inflammatory cytokines, the apoptosis of CD4⁺ and CD8⁺ T lymphocytes, and protein expression of cytochrome C (Cytc), Bax, Bcl-2, cleaved caspase-9, and cleaved caspase-3 were examined. Plasma levels of IL-6, IL-10 and TNF-alpha as well as the apoptosis of CD4⁺ T lymphocytes were increased compared with sham group. These changes were accompanied by increases of pro-apoptotic proteins including Cytc, Bax, cleaved caspase-9, and cleaved caspase-3 and decreases of anti-apoptotic protein Bcl-2 in CD4⁺ T lymphocytes from mice undergoing CLP. In contrast, we fail to observe significant effect of HSYA on the apoptosis of CD8⁺ T lymphocytes in CLP-treated group. Of note, HSYA treatment reversed all above changes observed in CD4⁺ T lymphocytes, and significantly increased the ratio of CD4⁺:CD8⁺ T lymphocytes in CLP-treated mice. In conclusion, HSYA was an effective therapeutic agent in ameliorating sepsis-induced apoptosis of CD4⁺ T lymphocytes probably through its anti-inflammatory and anti-apoptotic effects.

[T-peptide Enhances the Killing Effects of Cisplatinum on Lung Cancer]

背景与目的

T肽是Tuftsin的衍生物，其基本功能是刺激巨噬细胞，提高巨噬细胞吞噬及分泌能力，通过增强效应细胞的细胞杀伤作用而被广泛用于多种恶性肿瘤术后抗肿瘤治疗。本研究旨在探讨T肽与化疗药物顺铂的联合能否提高铂类药物的抗肿瘤疗效及机制。

方法

应用酶联免疫吸附剂测定（enzyme-linked immunosorbent assay, ELISA）T肽和/或顺铂处理人巨噬细胞株U937后肿瘤坏死因子-α（tumor necrosis factor-α, TNF-α）和干扰素-γ（interferon-γ, IFN-γ）分泌水平的变化；应用裸鼠荷瘤动物模型，分析T肽和/或顺铂处理小鼠肿瘤变化情况以及小鼠用药期间外周血中巨噬细胞变化情况。

结果

①应用ELISA检测发现在T肽组和T肽联合顺铂组中，U937细胞培养液中TNF-α水平明显高于对照组和顺铂组；T肽联合顺铂组中IFN-γ水平明显高于对照组、顺铂组和T肽组；②在小鼠荷瘤模型中，T肽联合顺铂组的肿瘤体积明显小于对照组、顺铂组和T肽组，并且小鼠没有明显的体重下降；③在小鼠外周血的检测分析中发现，T肽联合顺铂组中活化巨噬细胞数呈现增长趋势。免疫组化分析各组中肿瘤组织Ki67显示T肽联合顺铂组抑制肿瘤细胞增殖。

结论

T肽能够促进巨噬细胞增殖和促进其分泌肿瘤细胞杀伤因子（TNF-α、IFN-γ）；在体内动物模型中，T肽能够提高化疗药物如顺铂的疗效，使联合组具有更强的肿瘤抑制作用，同时能够减轻化疗药物的毒副作用。

The Parenteral Vitamin C Improves Sepsis and Sepsis-Induced Multiple Organ Dysfunction Syndrome via Preventing Cellular Immunosuppression

Cellular immunosuppression appears to be involved in sepsis and sepsis-induced multiple organ dysfunction syndrome (MODS). Recent evidence showed that parenteral vitamin C (Vit C) had the ability to attenuate sepsis and sepsis-induced MODS. Herein, we investigated the impact of parenteral Vit C on cellular immunosuppression and the therapeutic value in sepsis. Using cecal ligation and puncture (CLP), sepsis was induced in WT and Gulo-/- mice followed with 200 mg/Kg parenteral Vit C administration. The immunologic functions of CD4+CD25+ regulatory T cells (Tregs) and CD4+CD25- T cells, as well as the organ functions, were determined. Administration of parenteral Vit C per se markedly improved the outcome of sepsis and sepsis-induced MODS of WT and Gulo-/- mice. The negative immunoregulation of Tregs was inhibited, mainly including inhibiting the expression of forkhead helix transcription factor- (Foxp-) 3, cytotoxic T lymphocyte associated antigen- (CTLA-) 4, membrane associated transforming growth factor-β (TGF-βm+), and the secretion of inhibitory cytokines [including TGF-β and interleukin- (IL-) 10], as well as CD4+ T cells-mediated cellular immunosuppression which was improved by parenteral Vit C in WT and Gulo-/- septic mice. These results suggested that parenteral Vit C has the ability to improve the outcome of sepsis and sepsis-induced MODS and is associated with improvement in cellular immunosuppression.

Neuropilin-1highCD4⁺CD25⁺ Regulatory T Cells Exhibit Primary Negative Immunoregulation in Sepsis

Regulatory T cells (Tregs) appear to be involved in sepsis-induced immune dysfunction; neuropilin-1 (Nrp-1) was identified as a surface marker for CD4⁺CD25⁺Tregs. In the current study, we investigated the negative immunoregulation of Nrp-1^highCD4⁺CD25⁺Tregs and the potential therapeutic value of Nrp-1 in sepsis. Splenic CD4⁺CD25⁺Tregs from cecal ligation and puncture (CLP) mouse models were further segregated into Nrp-1^highTregs and Nrp-1^lowTregs; they were cocultured with CD4⁺CD25⁻  T cells. The expression of forkhead/winged helix transcription factor-3 (Foxp-3), cytotoxic T-lymphocyte associated antigen-4 (CTLA-4), membrane associated transforming growth factor-β (TGF-β^m+), apoptotic rate, and secretive ability [including TGF-β and interleukin-10 (IL-10)] for various types of Tregs, as well as the immunosuppressive ability of Tregs on CD4⁺CD25⁻  T cells, were determined. Meanwhile, the impact of recombinant Nrp-1 polyclonal antibody on the demethylation of Foxp-3-TSDR (Treg-specific demethylated region) was measured in in vitro study. Sepsis per se markedly promoted the expression of Nrp-1 of CD4⁺CD25⁺Tregs. Foxp-3/CTLA-4/TGF-β^m+ of Nrp-1^highTregs were upregulated by septic challenge. Nrp-1^highTregs showed strong resilience to apoptosis and secretive ability and the strongest immunosuppressive ability on CD4⁺CD25⁻  T cells. In the presence of lipopolysaccharide (LPS), the recombinant Nrp-1 polyclonal antibody reduced the demethylation of Foxp-3-TSDR. Nrp-1^highTregs might reveal primary negative immunoregulation in sepsis; Nrp-1 could represent a new potential therapeutic target for the study of immune regulation in sepsis.