Cecal Ligation Perforation Research Articles

STING-Mediated Intestinal Barrier Dysfunction Contributes to Lethal Sepsis

Gut integrity is compromised in abdominal sepsis with increased cellular apoptosis and altered barrier permeability. Intestinal epithelial cells (IEC) form a physiochemical barrier that separates the intestinal lumen from the host's internal milieu and is strongly involved in the mucosal inflammatory response and immune response. Recent research indicates the involvement of the stimulator of interferons genes (STING) pathway in uncontrolled inflammation and gut mucosal immune response. We investigated the role of STING signaling in sepsis and intestinal barrier function using intestinal biopsies from human patients with abdominal sepsis and with an established model of abdominal sepsis in mice. In human abdominal sepsis, STING expression was elevated in peripheral blood mononuclear cells and intestinal biopsies compared with healthy controls, and the degree of STING expression in the human intestinal lamina propria correlated with the intestinal inflammation in septic patients. Moreover, elevated STING expression was associated with high levels of serum intestinal fatty acid binding protein that served as a marker of enterocyte damage. In mice, the intestinal STING signaling pathway was markedly activated following the induction of sepsis induced by cecal ligation perforation (CLP). STING knockout mice showed an alleviated inflammatory response, attenuated gut permeability, and decreased bacterial translocation. Whereas mice treated with a STING agonist (DMXAA) developed greater intestinal apoptosis and a more severe systemic inflammatory response. We also showed that blocking TNF or type I interferon signaling suppressed DMXAA-induced systemic shock and IEC apoptosis. In addition, we demonstrated that mitochondrial DNA (mtDNA) was released during sepsis, inducing the intestinal inflammatory response through activating the STING pathway. We finally investigated DNase I administration at 5 hours post CLP surgery, showing that it reduced systemic mtDNA and inflammatory cytokines levels, organ damage, and bacterial translocation, suggesting that inhibition of mtDNA-STING signaling pathway protects against CLP-induced intestinal barrier dysfunction. Our results indicate that the STING signaling pathway can contribute to lethal sepsis by promoting IEC apoptosis and through disrupting the intestinal barrier. Our findings suggest that regulation of the mtDNA-STING pathway may be a promising therapeutic strategy to promote mucosal healing and protect the intestinal barrier in septic patients. Funding Statement: This study was supported by National Natural Science Foundation of China (81571881, 81772052 and 81801971), and Medical Research Program of Jiangsu Commission of Health (H2018058). Declaration of Interests: We declare no potential conflicts of interest concerning the research, authorship, and/or publication of this article. Ethics Approval Statement: This study was carried out according to the Recommendations of Guidelines for Clinical Trials by the Ethics Committee of Jinling Hospital. All animal experiments in our study were carried out according to the principles of the Declaration of Helsinki, and were approved by the Animal Ethical Committee of Jinling Hospital. The protocol was approved by the Ethics Committee of Jinling Hospital. All patients provided written informed consent before any study-related procedure was performed.

Effect of early fluid resuscitation combined with low dose cyclophosphamide on intestinal barrier function in severe sepsis rats.

To investigate the effect of early fluid resuscitation on intestinal microecology in rats with severe sepsis. The severe sepsis model used was mainly cecal ligation perforation (CLP) model. Male SD rats were randomly divided into five groups: sham, CLP, CLP + normal saline (NS), CLP + cyclophosphamide (CTX), and CLP + NS + CTX. (1) The levels of IL-6, IL-10, and TNF-α in peripheral blood were measured by ELISA. (2) The expression of occludin/β-action in colonic tissue of mice was examined by Western Blot. (3) The intestinal permeability was measured by FD70 detection. (4) The length of the chorionic membrane was measured by colon histopathological staining. (5) The intestinal epithelial cell apoptosis was measured with the apoptosis index. (1) The rat model of severe sepsis was successfully replicated, and the 7-day survival rate of sepsis mice in each group was analyzed. (2) The expression level of splenic junction protein and the pathological damage in colonic tissue of the severe sepsis mice was significantly different between sham, CLP, CTX, NS, and NS + CTX (P < 0.05). The expression of tight junction protein in the NS + CTX mice was the highest, and the pathological damage was the smallest. (3) The colonic tissue apoptosis and intestinal permeability in the severe sepsis mice were compared with those of the colon tissues (P < 0.05). (4) The expression levels of IL-6, IL-10, and TNF-α in peripheral blood were significantly increased after severe sepsis (P < 0.01). The expression of IL-6 and TNF-alpha in each treatment group decreased (P < 0.05), while the expression of IL-10 in NS + CTX group increased significantly (P < 0.01). (1) We successfully replicated the rat model of severe sepsis. (2) Early fluid intervention and cyclophosphamide treatment can significantly improve the 7-day survival rate of the sepsis mice. (3) The fluid resuscitation and cyclophosphamide can delay intestinal damage to the intestinal tract barrier function and play a protective role.

The NRF2‑PGC‑1β pathway activates kynurenine aminotransferase 4 via attenuation of an E3 ubiquitin ligase, synoviolin, in a cecal ligation/perforation‑induced septic mouse model.

Sepsis‑associated encephalopathy (SAE) is a systemic inflammatory response syndrome of which the precise associated mechanisms remain unclear. Synoviolin (Syvn1) is an E3 ubiquitin ligase involved in conditions associated with chronic inflammation, including rheumatoid arthritis, obesity, fibrosis and liver cirrhosis. However, the role of Syvn1 in acute inflammation is not clear. The aim of the present study was to investigate the role of Syvn1 in a septic mouse model induced by cecal ligation/perforation (CLP). Metabolome analysis revealed that kynurenine (KYN), a key factor for the development of neuroinflammation, was increased in CLP‑induced septic mice. Notably, KYN was not detected in CLP‑induced septic Syvn1‑deficient mice. KYN is converted to kynurenic acid (KYNA) by kynurenine aminotransferases (KATs), which has a neuroprotective effect. The expression of KAT4 was significantly increased in Syvn1‑deficient mice compared to that in wild‑type mice. Promoter analysis demonstrated that Syvn1 knockdown induced the KAT4 promoter activity, as assessed by luciferase reporter activity, whereas Syvn1 overexpression repressed this activity in a dose‑dependent manner. Furthermore, the KAT4 promoter was significantly activated by the transcriptional factors, NF‑E2‑related factor2 and peroxisome proliferator‑activated receptor coactivator1β, which are targets of Syvn1‑induced degradation. In conclusion, the results of the current study demonstrates that the repression of Syvn1 expression induces the conversion of neurotoxic KYN to neuroprotective KYNA in a CLP‑induced mouse model of sepsis, and that Syvn1 is a potential novel target for the treatment of SAE.

Comparison of two different models of sepsis induced by cecal ligation and puncture in rats

BackgroundThe present study was designed to explore the difference between two rat models of sepsis and to establish a more stable rat model. Materials and methodsSprague–Dawley rats were randomly divided into three groups: sham operation group, simple cecal ligation and perforation group (SCLP), and cecal ligation perforation plus drainage group (CLP-DS). The general condition of the rats was observed, and the time of death and survival rate at 72 h were recorded. The arterial blood and lung tissue were obtained 9 h after the operation. ResultsThe mortality of the CLP-DS group was significantly higher than that of the SCLP group. The limitation package, intestinal adhesion, and poor drainage were detected in the SCLP rats, whereas intestinal edema and hyperemia, bloody water in the abdominal cavity, but no inflammatory package were observed 24 h after the operation in the CLP-DS rats by autopsy. There were significant differences in interleukin-6 and tumor necrosis factor-alpha levels between the SCLP group and the CLP-DS group. Severe pulmonary septal thickening, alveolar wall vascular congestion, and protein debris deposition in the alveolar cavity were observed in the SCLP group, whereas pulmonary bullae were observed in the CLP-DS group using light microscopy, and there were significant difference among groups in Smith lung injury score. ConclusionsThese results suggested that the cecal ligation combined with puncture drainage model of sepsis is more stable than that of the simple cecal ligation and puncture model of sepsis in the rat, which resolved the problem of puncture wrapped in the traditional CLP model of sepsis in rat.

Nesfatin-1 ameliorates sepsis-induced remote organ injury: The role of oxidant-antioxidant status and neutrophils

Purpose: Protective effects of nesfatin-1 was studied in sepsis-induced injury of remote organs. Methods: Male rats were randomly divided as control and sepsis (cecal ligationperforation) groups, treated with either saline or nesfatin-1 (10 μg/kg). At 16 h following surgery, samples of brain, kidney, liver and lung tissues were removed and myeloperoxidase (MPO) activity, glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) levels were measured in these tissues. Results: In saline-treated septic rats, elevated MDA and MPO activities were accompanied with depleted CAT, SOD and GSH levels in the brain, kidney, liver and lung tissues, implicating extensive oxidative damage in all remote organs. Nesfatin-1 reduced MDA levels (brain, lung) and MPO activities (brain, kidney), and preserved antioxidant GSH (brain, lung), CAT (brain) and SOD (kidney) levels. Severe hepatocyte degeneration, neuronal damage, glomerulotubular degeneration and alveolar disturbance in saline-treated septic rats were replaced with regular tissue morphologies in nesfatin-1-treated rats. Conclusion: Nesfatin-1 alleviates oxidative damage by enhancing endogenous antioxidant systems and inhibiting recruitment of neutrophils, suggesting that nesfatin-1 may be have a potential therapeutic impact on the treatment of septic shock to reduce subsequent remote organ failure.

Neuroprotective effects of intravenous immunoglobulin are mediated through inhibition of complement activation and apoptosis in a rat model of sepsis

BackgroundIntravenous (IV) immunoglobulin (Ig) treatment is known to alleviate behavioral deficits and increase survival in the experimentally induced model of sepsis. To delineate the mechanisms by which IVIg treatment prevents neuronal dysfunction, an array of immunological and apoptosis markers was investigated.MethodsSepsis was induced by cecal ligation perforation (CLP) in rats. The animals were divided into five groups: sham, control, CLP + saline, CLP + immunoglobulin G (IgG) (250 mg/kg, iv), and CLP + immunoglobulins enriched with immunoglobulin M (IgGAM) (250 mg/kg, iv). Blood and brain samples were taken in two sets of experiments to see the early (24 h) and late (10 days) effects of treatment. Total complement activity, complement 3 (C3), and soluble complement C5b-9 levels were measured in the sera of rats using ELISA-based methods. Cerebral complement, complement receptor, NF-κB, Bax, and Bcl-2 expressions were analyzed by western blot and/or RT-PCR methods. Immune cell infiltration and gliosis were examined by immunohistochemistry using CD3, CD4, CD8, CD11b, CD19, and glial fibrillary acidic protein antibodies. Apoptotic neuronal death was investigated by TUNEL staining.ResultsIVIgG and IgGAM administration significantly reduced systemic complement activity and cerebral C5a and C5a receptor expression. Likewise, both treatment methods reduced proapoptotic NF-κB and Bax expressions in the brain. IVIgG and IgGAM treatment induced considerable amelioration in glial cell proliferation and neuronal apoptosis which were increased in non-treated septic rats.ConclusionsWe suggest that IVIgG and IgGAM administration ameliorates neuronal dysfunction and behavioral deficits by reducing apoptotic cell death and glial cell proliferation. In both treatment methods, these beneficial effects might be mediated through reduction of anaphylatoxic C5a activity and subsequent inhibition of inflammation and apoptosis pathways.

Neuroinflammation-Induced Downregulation of Hippocampacal Neuregulin 1-ErbB4 Signaling in the Parvalbumin Interneurons Might Contribute to Cognitive Impairment in a Mouse Model of Sepsis-Associated Encephalopathy.

Sepsis-associated encephalopathy (SAE) is a common complication associated with poor prognosis in septic patients, but the underlying mechanism remains unclear. We hypothesized that disturbed neuregulin 1 (NRG1)-ErbB4 signaling in the parvalbumin interneurons was involved in sepsis-induced cognitive impairment in a mouse model of SAE. The SAE model was induced by cecal ligation/perforation (CLP). Animals were randomly divided into the following six groups: sham + vehicle group, sham + NRG1 group, CLP + vehicle group, CLP + NRG1 group, CLP + NRG1 + AG1478 (ErbB4 inhibitor) group, and CLP + minocycline group. Behavioral tests and in vivo electrophysiology were performed at the indicated time points. The brain tissues were harvested to determine the levels of hippocampcal cytokines, IBA1-positive cells, NRG1, ErbB4, and parvalbumin. In the present study, sepsis induced the anxiety-like behavior and hippocampal-dependent cognitive impairment, as reflected by significantly increased distance spent in the open field test and decreased freezing time to context in the fear conditioning test. The abnormal behavioral changes co-occurred with significant increases in hippocampal IBA1-positive cells, IL-1β and IL-6 levels, and decreased NRG1, ErbB4, parvalbumin expressions, and evoked gamma activity. NRG1 treatment attenuated the sepsis-induced cognitive impairment and the associated biochemical markers, which were abolished by AG1478 administration. Notably, minocycline treatment attenuated neuroinflammation and mimicked the beneficial effects of NRG1 treatment. In summary, we provided additional evidence that the disruption of NRG1-ErbB4 signaling in the parvalbumin interneurons mediated by neuroinflammation might lead to abnormal gamma oscillations and thus contribute to cognitive impairment in a mouse model of SAE.

Tissue inhibitor of metalloproteinases 3-dependent microvascular endothelial cell barrier function is disrupted under septic conditions.

Sepsis is associated with dysfunction of microvascular endothelial cells (MVEC) leading to tissue edema and multiple organ dysfunction. Metalloproteinases can regulate MVEC function through processing of cell surface proteins, and tissue inhibitor of metalloproteinases 3 (TIMP3) regulates metalloproteinase activity in the lung following injury. We hypothesize that TIMP3 promotes normal pulmonary MVEC barrier function through inhibition of metalloproteinase activity. Naive Timp3(-/-) mice had significantly higher basal pulmonary microvascular Evans blue (EB) dye-labeled albumin leak vs. wild-type (WT) mice. Additionally, cecal-ligation/perforation (CLP)-induced sepsis significantly increased pulmonary microvascular EB-labeled albumin leak in WT but not Timp3(-/-) mice. Similarly, PBS-treated isolated MVEC monolayers from Timp3(-/-) mice displayed permeability barrier dysfunction vs. WT MVEC, evidenced by lower transendothelial electrical resistance and greater trans-MVEC flux of fluorescein-dextran and EB-albumin. Cytomix (equimolar interferon γ, tumor necrosis factor α, and interleukin 1β) treatment of WT MVEC induced significant barrier dysfunction (by all three methods), and was associated with a time-dependent decrease in TIMP3 mRNA and protein levels. Additionally, basal Timp3(-/-) MVEC barrier dysfunction was associated with disrupted MVEC surface VE-cadherin localization, and both barrier dysfunction and VE-cadherin localization were rescued by treatment with GM6001, a synthetic metalloproteinase inhibitor. TIMP3 promotes normal MVEC barrier function, at least partially, through inhibition of metalloproteinase-dependent disruption of adherens junctions, and septic downregulation of TIMP3 may contribute to septic MVEC barrier dysfunction.

Disrupted Tryptophan Metabolism Induced Cognitive Impairment in a Mouse Model of Sepsis-associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a common complication in critically ill patients and is associated with a poor prognosis. However, the precise mechanisms underlying sepsis-induced cognitive impairment remain largely to be elucidated. The aim of the present study was to investigate whether indoleamine 2, 3-dioxygenase (IDO) activation-mediated neurotoxicity is involved in the pathophysiology of sepsis-induced cognitive impairment. Sepsis was induced by cecal ligation/perforation (CLP). The animals were randomly divided into the following five groups: Sham + vehicle group; Sham + 1-methyl-D, L-tryptophan group; Sham + L-Kynurenine group; CLP + vehicle group; or CLP + 1-methyl-D, L-tryptophan group. The survival rate was estimated by the Kaplan-Meier method. Behavioral tests were performed by the open field and fear conditioning tests at days 13 and 14 after operation. In the present study, we demonstrated that sepsis induced a deficit in hippocampus-dependent cognitive impairment in a mouse model of SAE. Furthermore, a single peripheral kynurenine administration, the metabolic product of IDO, induced a deficit in the cognitive impairment in the sham mice. However, mice treated with IDO inhibitor 1-methyl-D, L-tryptophan were protected from sepsis-induced cognitive impairment. In conclusion, our study implicates IDO-dependent neurotoxic kynurenine metabolism as a critical factor responsible for the sepsis-induced cognitive impairment and a potential novel target for the treatment of SAE.

Role of pulmonary microvascular endothelial cell apoptosis in murine sepsis-induced lung injury in vivo.

BackgroundSepsis remains a common and serious condition with significant morbidity and mortality due to multiple organ dysfunction, especially acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Sepsis-induced ALI is characterized by injury and dysfunction of the pulmonary microvasculature and pulmonary microvascular endothelial cells (PMVEC), resulting in enhanced pulmonary microvascular sequestration and pulmonary infiltration of polymorphonuclear leukocytes (PMN) as well as disruption of the normal alveolo-capillary permeability barrier with leak of albumin-rich edema fluid into pulmonary interstitium and alveoli. The role of PMVEC death and specifically apoptosis in septic pulmonary microvascular dysfunction in vivo has not been established.MethodsIn a murine cecal ligation/perforation (CLP) model of sepsis, we quantified and correlated time-dependent changes in pulmonary microvascular Evans blue (EB)-labeled albumin permeability with (1) PMVEC death (propidium iodide [PI]-staining) by both fluorescent intravital videomicroscopy (IVVM) and histology, and (2) PMVEC apoptosis using histologic fluorescent microscopic assessment of a panel of 3 markers: cell surface phosphatidylserine (detected by Annexin V binding), caspase activation (detected by FLIVO labeling), and DNA fragmentation (TUNEL labeling).ResultsCompared to sham mice, CLP-sepsis resulted in pulmonary microvascular barrier dysfunction, quantified by increased EB-albumin leak, and PMVEC death (PI+ staining) as early as 2 h and more marked by 4 h after CLP. Septic PMVEC also exhibited increased presence of all 3 markers of apoptosis (Annexin V+, FLIVO+, TUNEL+) as early as 30 mins – 1 h after CLP-sepsis, which all similarly increased markedly until 4 h. The time-dependent changes in septic pulmonary microvascular albumin-permeability barrier dysfunction were highly correlated with PMVEC death (PI+; r = 0.976, p < 0.01) and PMVEC apoptosis (FLIVO+; r = 0.991, p < 0.01). Treatment with the pan-caspase inhibitor Q-VD prior to CLP reduced PMVEC death/apoptosis and attenuated septic pulmonary microvascular dysfunction, including both albumin-permeability barrier dysfunction and pulmonary microvascular PMN sequestration (p < 0.05). Septic PMVEC apoptosis and pulmonary microvascular dysfunction were also abrogated following CLP-sepsis in mice deficient in iNOS (Nos2−/−) or NADPH oxidase (p47phox−/− or gp91phox−/−) and in wild-type mice treated with the NADPH oxidase inhibitor, apocynin.ConclusionsSeptic murine pulmonary microvascular dysfunction in vivo is due to PMVEC death, which is mediated through caspase-dependent apoptosis and iNOS/NADPH-oxidase dependent signaling.

Effect of coenzyme Q10 on organ damage in sepsis.

Investigating the effects of coenzyme Q10 on organ damage and survival on mice in cecal ligation perforation (CLP) model in sepsis. Coenzyme Q10 is an antioxidant molecule playing an important role in mitochondria. Mitochondrial dysfunction is an important mechanism in sepsis pathophysiology. Nintyfour Swiss Albino male mice were divided into 8 groups. CLP was performed in Group I. Coenzyme Q10, 100 mg/kg subcutaneously, was given 5 hours after CLP to Group II and 20 hours after CLP to Group III. Sham operation was performed in Group IV, 100 mg/kg coenzyme Q10 subcutaneously was given 5 hours after sham operation to Group V and 20 hours after sham operation to Group VI. No operation was performed in Group VII; coenzyme Q10, 100 mg/kg subcutaneously, was given to Group VIII. Antibiotics and fluid replacement were applied for 3 days. The mice still living were sacrificed at 576th hour. The organ damages were scored under light microscopy. The survival of Group I and Group II was lower than that of the control groups, but the survival in the Group III was similar to control groups. It was established that spleen, kidney, heart damage and total organ damage were decreased when compared to CLP group. Coenzyme Q10 is effective in decreasing histological organ damage in sepsis (Tab. 3. Fig. 1, Ref. 30).

Effect of Melilotus extract on lung injury via the upregulation of tumor necrosis factor-α-induced protein-8-like 2 in septic mice.

As a Traditional Chinese Medicine, Melilotus extracts have been reported to function as an anti-inflammatory agent, antioxidant and inhibitor of capillary permeability. The present study aimed to identify the mechanisms by which Melilotus interferes with inflammation-associated and oxidative stress pathways during sepsis. An animal model of cecal ligation-perforation (CLP)-induced sepsis was established. Two hours prior to surgery, animals in the treatment group were administered 25 mg/kg Melilotus extract tablets and subsequently every 8 h. At 24 h post-administration, pathological modifications in lung tissue and expression levels of tumor necrosis factor-α-induced protein-8-like 2 (TIPE2) expression, nuclear factor (NF)-κB, toll-like receptor 4 (TLR4), heme oxygenase-1 (HO-1), inhibitor of κB kinase (IκB), pro-inflammatory mediators (interleukin-6 and tumor necrosis factor-α), myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD), were examined. The results showed that Melilotus extract had a marked effect on the pathological manifestation of lung tissue and lung inflammatory response, the upregulation of TIPE2, HO-1 and IκB expression, and the inhibition of TLR4 and NF-κB activities. In addition, following treatment with Melilotus extract, the model animals demonstrated decreased levels of MPO and MDA as well as increased levels of SOD. In conclusion, these results indicated that Melilotus extract may be a potential therapeutic agent for the treatment of CLP-induced lung injury, the mechanism of which proceeded via inflammation- and oxidation-associated pathways by increasing TIPE2 expression.

Pulmonary Microvascular Albumin Leak Is Associated with Endothelial Cell Death in Murine Sepsis-Induced Lung Injury In Vivo

Sepsis is a systemic inflammatory response that targets multiple components of the cardiovascular system including the microvasculature. Microvascular endothelial cells (MVEC) are central to normal microvascular function, including maintenance of the microvascular permeability barrier. Microvascular/MVEC dysfunction during sepsis is associated with barrier dysfunction, resulting in the leak of protein-rich edema fluid into organs, especially the lung. The specific role of MVEC apoptosis in septic microvascular/MVEC dysfunction in vivo remains to be determined. To examine pulmonary MVEC death in vivo under septic conditions, we used a murine cecal ligation/perforation (CLP) model of sepsis and identified non-viable pulmonary cells with propidium iodide (PI) by intravital videomicroscopy (IVVM), and confirmed this by histology. Septic pulmonary microvascular Evans blue (EB)-labeled albumin leak was associated with an increased number of PI-positive cells, which were confirmed to be predominantly MVEC based on specific labeling with three markers, anti-CD31 (PECAM), anti-CD34, and lectin binding. Furthermore, this septic death of pulmonary MVEC was markedly attenuated by cyclophosphamide-mediated depletion of neutrophils (PMN) or use of an anti-CD18 antibody developed for immunohistochemistry but shown to block CD18-dependent signaling. Additionally, septic pulmonary MVEC death was iNOS-dependent as mice lacking iNOS had markedly fewer PI-positive MVEC. Septic PI-positive pulmonary cell death was confirmed to be due to apoptosis by three independent markers: caspase activation by FLIVO, translocation of phosphatidylserine to the cell surface by Annexin V binding, and DNA fragmentation by TUNEL. Collectively, these findings indicate that septic pulmonary MVEC death, putatively apoptosis, is a result of leukocyte activation and iNOS-dependent signaling, and in turn, may contribute to pulmonary microvascular barrier dysfunction and albumin hyper-permeability during sepsis.

Effects of intraperitoneal immunoglobulin therapy on behavior and cognitive functions in CLP-induced sepsis model in rats

The present study investigated the effects of a single dose of intraperitoneal (i.p.) IgG and IgGAM administration on various behavioral alterations in a cecal ligation perforation (CLP)-induced sepsis model in rats.

The effects of carnosine in an experimental rat model of septic shock

BackgroundTo examine the effect of carnosine on liver function and histological findings in experimental septic shock model, 24 Sprague-Dawley rats were used.Material/MethodsRats were divided into control, septic shock, and carnosine-treated septic shock groups. Femoral vein and artery catheterization were performed on all rats. Rats in the control group underwent laparotomy and catheterization; in the test groups, cecal ligation-perforation and bladder cannulation were added. Rats in the treatment group received a single intraperitoneal (IP) injection of 250 mg/kg carnosine 60 minutes after cecal ligation-perforation. Rats were monitored for blood pressure, heart rate, and body temperature to assess the postoperative septic response, and body fluids were replaced as necessary. At the end of 24 hours, rats were sacrificed and liver samples were collected.ResultsStatistically significant improvements were observed in liver function, tissue and serum MDA levels, and histological findings in rats treated with carnosine, compared to rats with untreated sepsis. HB and HCT values did not change significantly during the course of the experiment. Rats exposed to septic shock and treated with carnosine exhibited decreased sinusoidal dilatation and cellular inflammation into the portal region, compared to the sepsis group; the livers of rats in this group had near-normal histological structure.ConclusionsWe conclude that carnosine may be an effective treatment for oxidative damage due to liver tissue perfusion defects in cases of septic shock.

Polymicrobial sepsis and endotoxemia promote microvascular thrombosis via distinct mechanisms.

We reported recently that endotoxemia promotes microvascular thrombosis in cremaster venules of wild-type mice, but not in mice deficient in toll-like receptor 4 (TLR4) or von Willebrand factor (VWF). To determine whether the clinically relevant model of polymicrobial sepsis induced by cecal ligation/perforation (CLP) induces similar responses via the same mechanisms as endotoxemia. We used a light/dye-injury model of thrombosis in the cremaster microcirculation of wild-type mice and mice deficient in toll-like receptor-4 (C57BL/10ScNJ), toll-like receptor 2 (TLR2), or VWF. Mice underwent CLP or sham surgery, or an intraperitoneal injection of endotoxin (LPS) or saline. In the CLP model, we assessed the influence of fluid replacement on thrombotic responses. Both CLP and LPS enhanced thrombotic occlusion in wild-type mice. In contrast to LPS, CLP enhanced thrombosis in TLR4- and VWF-deficient strains. While TLR2-deficient mice did not demonstrate enhanced thrombosis following CLP, LPS enhanced thrombosis in these mice. LPS, but not CLP, increased plasma VWF antigen relative to controls. Septic mice, particularly those undergoing CLP, developed significant hemoconcentration. Intravenous fluid replacement with isotonic saline prevented the hemoconcentration and prothrombotic responses to CLP, though fluids did not prevent the prothrombotic response to LPS. Polymicrobial sepsis induced by CLP and endotoxemia promote microvascular thrombosis via distinct mechanisms; enhanced thrombosis induced by CLP requires TLR2 but not TLR4 or VWF. The salutary effects of intravenous fluid replacement on microvascular thrombosis in polymicrobial sepsis remain to be characterized.

Polymicrobial sepsis and endotoxemia promote microvascular thrombosis via distinct mechanisms

ObjectiveTo determine whether the clinically relevant model of polymicrobial sepsis induced by cecal ligation/perforation (CLP) induces similar responses via the same mechanisms as endotoxemia.MethodsWe used a light/dye injury model in the cremaster microcirculation of C57BL/6 (wild type), and mice deficient in either toll‐like receptor‐4 (C57BL/10ScNJ) or vWF. Mice underwent CLP or sham surgery (six hours prior to experiments); in other groups, mice received an intraperitoneal injection of endotoxin (LPS) or saline (four hours prior to experiments).ResultsBoth CLP and LPS enhanced thrombotic occlusion in wild type mice; however, in contrast to LPS, CLP also enhanced thrombosis in TLR4‐ and vWF‐deficient strains. LPS, but not CLP, increased plasma vWF antigen relative to controls. Septic mice, particularly those undergoing CLP, developed significant hemoconcentration. Intravenous fluid replacement with isotonic saline prevented the hemoconcentration and the prothrombotic responses to CLP, though fluids did not prevent the prothrombotic response to LPS.ConclusionsPolymicrobial sepsis induced by CLP and endotoxemia promote microvascular thrombosis via distinct mechanisms; enhanced thrombosis induced by CLP is independent of TLR4 and vWF. The salutary effects of intravenous fluid replacement on microvascular thrombosis in polymicrobial sepsis remain to be characterized.

Caspase and calpain activation both contribute to sepsis-induced diaphragmatic weakness.

The cecal ligation perforation (CLP) model of sepsis is known to induce severe diaphragm dysfunction, but the cellular mechanisms by which this occurs remain unknown. We hypothesized that CLP induces diaphragm caspase-3 and calpain activation, and that these two enzymes act at the level of the contractile proteins to reduce muscle force generation. Rats (n = 4/group) were subjected to 1) sham surgery plus saline (intraperitoneal); 2) CLP; 3) CLP plus administration of calpain inhibitor peptide III (12 mg/kg ip); or 4) CLP plus administration of a caspase inhibitor, zVAD-fmk (3 mg/kg). At 24 h, diaphragms were removed, and the following were determined: 1) calpain and caspase-3 activities by fluorogenic assay; 2) caspase-3 and calpain I protein levels; 3) the intact diaphragm force-frequency relationship; and 4) the force generated by contractile proteins of single, permeabilized diaphragm fibers in response to exogenous calcium. CLP significantly increased diaphragm calpain activity (P < 0.02), caspase-3 activity (P < 0.02), active calpain I protein levels (P < 0.02), and active caspase-3 protein (P < 0.02). CLP also reduced the force generated by intact diaphragm muscle (P < 0.001) and the force generated by single-fiber contractile proteins (P < 0.001). Administration of either calpain inhibitor III or zVAD-fmk markedly improved force generation of both intact diaphragm muscle (P < 0.01) and single-fiber contractile proteins (P < 0.001). CLP induces significant reductions in diaphragm contractile protein force-generating capacity. This force reduction is mediated by the combined effects of activated caspase and calpain. Inhibition of these pathways may prevent diaphragm weakness in infected patients.

Abstract 6255: Adiponectin Deficiency Profoundly Exacerbates Sepsis-Related Mortality through Endothelial Activation: A Novel Mechanistic Link between Adiposity and Sepsis

INTRODUCTION: Sepsis is a multifactorial, and often fatal disorder, characterized by widespread inflammation with resultant endothelial activation. Adiposity and diabetes are strong negative predictors of sepsis related cardiovascular dysregulation and mortality, however, the mechanisms remain unclear. We postulated that alterations in adipokine biology, particularly adiponectin, are essential modulators of survival and endothelial activation in sepsis. METHODS AND RESULTS: We evaluated both loss-of-function (adiponectin gene-deficient mice) and subsequent gain-of-function (recombinant adiponectin reconstitution) strategies in two well-established inflammatory models, cecal ligation perforation (CLP) and thioglyocollate-induced peritonitis. Adipoq −/− mice, subjected to CLP, exhibited a profound (~8 fold) reduction in survival compared to their wild-type Adipoq −/− littermates after 48 hours. Furthermore, compared to wild-type controls, thioglycollate challenge resulted in a markedly greater influx of peritoneal neutrophils in Adipoq −/− mice accompanied by an excess production of key chemoattractant cytokines (IL-12p70, TNFalpha, MCP-1 and IL-6) and upregulation of aortic endothelial adhesion molecule expression, VCAM-1 and ICAM-1. Importantly, all of these effects were blunted by recombinant total adiponectin administration given three days prior to thioglycollate challenge. The protective effects of adiponectin were largely ascribed to higher order adiponectin oligomers, since administration of recombinant trimeric adiponectin did not attenuate endothelial adhesion molecule expression in thioglycollate-challenged Adipoq −/− mice. CONCLUSIONS: These data suggest a critical role of adiponectin as a modulator of survival and endothelial inflammation in experimental sepsis and suggest one of the first mechanistic links between adiposity and sepsis related death.

Adiponectin deficiency promotes endothelial activation and profoundly exacerbates sepsis-related mortality.

Sepsis is a multifactorial, and often fatal, disorder typically characterized by widespread inflammation and immune activation with resultant endothelial activation. In the present study, we postulated that the adipokine adiponectin serves as a critical modulator of survival and endothelial activation in sepsis. To this aim, we evaluated both loss-of-function (adiponectin gene-deficient mice) and subsequent gain-of-function (recombinant adiponectin reconstitution) strategies in two well-established inflammatory models, cecal ligation perforation (CLP) and thioglyocollate-induced peritonitis. Adipoq(-/-) mice, subjected to CLP, exhibited a profound ( approximately 8-fold) reduction in survival compared with their wild-type Adipoq(+/+) littermates after 48 h. Furthermore, compared with wild-type controls, thioglycollate challenge resulted in a markedly greater influx of peritoneal neutrophils in Adipoq(-/-) mice accompanied by an excess production of key chemoattractant cytokines (IL-12p70, TNFalpha, MCP-1, and IL-6) and upregulation of aortic endothelial adhesion molecule VCAM-1 and ICAM-1 expressions. Importantly, all of these effects were blunted by recombinant total adiponectin administration given 3 days prior to thioglycollate challenge. The protective effects of adiponectin were ascribed largely to higher-order adiponectin oligomers, since administration of recombinant C39A trimeric adiponectin did not attenuate endothelial adhesion molecule expression in thioglycollate-challenged Adipoq(-/-) mice. These data suggest a critical role of adiponectin as a modulator of survival and endothelial inflammation in experimental sepsis and a potential mechanistic link between adiposity and increased sepsis.