Long-term survivors of murine sepsis are predisposed to enhanced LPS-induced lung injury and pro-inflammatory immune reprogramming

Millions of people who survive sepsis each year are rehospitalized and die due to late pulmonary complications. In order to prevent and treat these complications, biomarkers and molecular mediators must be identified. Persistent immune reprogramming in the form of immunoparalysis and impaired host defense is proposed to mediate late pulmonary complications after sepsis, particularly new pulmonary infections. However, immune reprogramming may also involve enhanced/primed responses to secondary stimuli, although their contribution to long-term sepsis complications remains understudied. We hypothesize that enhanced/primed immune responses in the lungs of sepsis survivors are associated with late pulmonary complications. To this end, we developed a murine sepsis model using cecal ligation and puncture (CLP) followed 3 weeks later by administration of intranasal lipopolysaccharide to induce inflammatory lung injury. Mice surviving sepsis exhibit enhanced lung injury with increased alveolar permeability, neutrophil recruitment, and enhanced Ly6Chi monocyte Tnf expression. To determine the mediators of enhanced lung injury, we performed flow cytometry and RNA sequencing of lungs 3 weeks after CLP, prior to lipopolysaccharide. Sepsis survivor mice showed expanded Ly6Chi monocytes populations and increased expression of many inflammatory genes. Of these, S100A8/A9 was also elevated in the circulation of human sepsis survivors for months after sepsis, validating our model and identifying S100A8/A9 as a potential biomarker and therapeutic target for long-term pulmonary complications after sepsis. These data provide new insight into the importance of enhanced/primed immune responses in survivors of sepsis and establish a foundation for additional investigation into the mechanisms mediating this response.

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Trained Innate Immunity by Repeated Low-Dose Lipopolysaccharide Injections Displays Long-Term Neuroprotective Effects

Mediators of Inflammation ◽

10.1155/2020/8191079 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Xiao-yan Zhou ◽

Rong Gao ◽

Jian Hu ◽

Da-peng Gao ◽

Yan-ling Liao ◽

...

Keyword(s):

Immune Response ◽

Low Dose ◽

Neurological Diseases ◽

Cecal Ligation ◽

Immune Memory ◽

Sham Operation ◽

Neuroprotective Effects ◽

Neurobehavioral Outcomes ◽

Sepsis Survivors

Disrupted immune response is an important feature of many neurodegenerative conditions, including sepsis-associated cognitive impairment. Accumulating evidence has demonstrated that immune memory occurs in microglia, which has a significant impact on pathological hallmarks of neurological diseases. However, it remains unclear whether immune memory can cause subsequent alterations in the brain immune response and affect neurobehavioral outcomes in sepsis survivors. In the present study, mice received daily intraperitoneal injection of low-dose lipopolysaccharide (LPS, 0.1 mg/kg) for three consecutive days to induce immune memory (immune tolerance) and then were subjected to sham operation or cecal ligation and puncture (CLP) 9 months later, followed by a battery of neurobehavioral and biochemical studies. Here, we showed that repeated low-dose LPS injection-induced immune memory protected mice from sepsis-induced cognitive and affective impairments, which were accompanied by significantly decreased brain proinflammatory cytokines and immune response. In conclusion, our study suggests that modulation of brain immune responses by repeated LPS injections confers neuroprotective effects by preventing overactivated immune response in response to subsequent septic insult.

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DNA Vaccination and All-Trans Retinoic Acid Treatment-Induced Long Term Survival Requires CD4+ and CD8+ T-Cell Activation in An APL Mouse Model.

Blood ◽

10.1182/blood.v112.11.962.962 ◽

2008 ◽

Vol 112 (11) ◽

pp. 962-962

Author(s):

Rose Ann Padua ◽

Kouichi Furugaki ◽

Helene Moins-Teisserenc ◽

Katerina Pokorna ◽

Carole Le Pogam ◽

...

Keyword(s):

T Cells ◽

Immune Responses ◽

Antibody Production ◽

Dna Vaccination ◽

Activated T Cells ◽

Cd8 Cells ◽

Trans Retinoic Acid ◽

All Trans Retinoic Acid ◽

Long Term Survivors

Abstract OBJECTIVES: DNA vaccines can be effective in the acquisition of humoral and cellmediated immune responses. Our studies on an acute promyelocytic leukemia (APL) mouse model show that DNA vaccination combined with all-trans retinoic acid (ATRA) results in a survival advantage with a significant increase in the Th1 cytokine IFNg. ATRA alone can act as an adjuvant to induce immune responses as measured by an increase in anti-RARa antibody production, which correlated with improved survival in mice. Similar increases in antibody production have been observed in our patients after maintenance therapy. The aim of this study is to use immunomonitoring and functional assays to evaluate the presence of activated T-cells and to demonstrate APL-specific killing and to determine if the protective effect of DNA vaccination is CD4+ and CD8+ mediated. METHODS: Using an APL transplant model in FVB/N mice, CD107a, expressed on the surface of lytic granules of activated T-cells, was measured by flow cytometry. A flow based CFSE assay was used to measure APL specific cell killing by cytotoxic T-cells (CTLs). As FVB/N mice have H2q haplotyes, blocking anti-H2q antibodies were used to determine if the cytotoxic activity was MHC restricted. Immunophenotyping by measuring CD4+ and CD8+ absolute counts were conducted. Mice injected with APL cells were depleted of CD4+ or CD8+ cells with anti-CD4 or anti-CD8+ antibody treatment initiated the day after DNA vaccination (early) and continued every 5 days and assayed for efficacy of the DNA+ATRA combined therapy or CD4+ or CD8+ cells were depleted in long term survivors (>100 days, late). RESULTS: Th1 cytokines TNFa and IFNg were increased indicative of DNA effects and specific activated CD3/CD8 T cells were detected and observed to release cytotoxic granules in the presence of APL cells in long term survivors. A dose dependent decrease in CFSE positive cells was observed assaying effectors from spleens of ATRA alone, ATRA+DNA treated mice and CD107a+ sorted cells from the latter using APL cells as targets. This effect was MHC restricted as anti-H2q antibodies reduced the specific cytotoxic activity. CD4+ absolute numbers measured on day 38 significantly correlated with survival (p=0.005). Although not significant a similar trend was observed for CD8+ counts. The CD4+ or CD8+ depleted mice treated with DNA + ATRA died earlier compared with the undepleted animals. When DNA + ATRA treated long term survivors were depleted of CD4+ or CD8+ cells, the CD4+ depleted mice relapsed and died in 3 months whereas the CD8+ depleted mice survived for a further 3 months when the experiment was terminated. These data are consistent with an increase in anti-RARa antibody production previously measured in other protocols. Interestingly the late depletions show that CD4+ cells are required for the maintenance of the remissions and show that memory T-cells are required. CONCLUSION: Therefore we have been able to detect protective cellular and humoral responses in mice with the combined treatment of DNA+ATRA, which correlates with outcome.

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Mitochondrial dysfunction is associated with long-term cognitive impairment in an animal sepsis model

Clinical Science ◽

10.1042/cs20190351 ◽

2019 ◽

Vol 133 (18) ◽

pp. 1993-2004 ◽

Cited By ~ 8

Author(s):

Andressa Manfredini ◽

Larissa Constantino ◽

Milton Castro Pinto ◽

Monique Michels ◽

Henrique Burger ◽

...

Keyword(s):

Cognitive Impairment ◽

Mitochondrial Dysfunction ◽

Mitochondrial Biogenesis ◽

Mitochondrial Function ◽

Ex Vivo ◽

Mitochondrial Dynamics ◽

Cecal Ligation ◽

Inhibitory Avoidance ◽

Sepsis Survivors

Abstract Background: Several different mechanisms have been proposed to explain long-term cognitive impairment in sepsis survivors. The role of persisting mitochondrial dysfunction is not known. We thus sought to determine whether stimulation of mitochondrial dynamics improves mitochondrial function and long-term cognitive impairment in an experimental model of sepsis. Methods: Sepsis was induced in adult Wistar rats by cecal ligation and perforation (CLP). Animals received intracerebroventricular injections of either rosiglitazone (biogenesis activator), rilmenidine, rapamycin (autophagy activators), or n-saline (sham control) once a day on days 7–9 after the septic insult. Cognitive impairment was assessed by inhibitory avoidance and object recognition tests. Animals were killed 24 h, 3 and 10 days after sepsis with the hippocampus and prefrontal cortex removed to determine mitochondrial function. Results: Sepsis was associated with both acute (24 h) and late (10 days) brain mitochondrial dysfunction. Markers of mitochondrial biogenesis, autophagy and mitophagy were not up-regulated during these time points. Activation of biogenesis (rosiglitazone) or autophagy (rapamycin and rilmenidine) improved brain ATP levels and ex vivo oxygen consumption and the long-term cognitive impairment observed in sepsis survivors. Conclusion: Long-term impairment of brain function is temporally related to mitochondrial dysfunction. Activators of autophagy and mitochondrial biogenesis could rescue animals from cognitive impairment.

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LOX-1 Deletion Improves Neutrophil Responses, Enhances Bacterial Clearance, and Reduces Lung Injury in a Murine Polymicrobial Sepsis Model

Infection and Immunity ◽

10.1128/iai.01317-10 ◽

2011 ◽

Vol 79 (7) ◽

pp. 2865-2870 ◽

Cited By ~ 35

Author(s):

Zhuang Wu ◽

Tatsuya Sawamura ◽

Anna K. Kurdowska ◽

Hong-Long Ji ◽

Steven Idell ◽

...

Keyword(s):

Lung Injury ◽

Immune Responses ◽

Tissue Injury ◽

Cecal Ligation ◽

Density Lipoprotein ◽

Polymicrobial Sepsis ◽

Lung Edema ◽

Bacterial Clearance ◽

Edema Formation ◽

Study Results

ABSTRACTInflammatory tissue injury and immunosuppression are the major causes of death in sepsis. Novel therapeutic targets that can prevent excessive inflammation and improve immune responses during sepsis could be critical for treatment of this devastating disease. LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1), a membrane protein expressed in endothelial cells, has been known to mediate vascular inflammation. In the present study, we demonstrated that LOX-1 deletion markedly improved the survival rate in a murine model of polymicrobial sepsis. Wild-type (LOX-1+/+) and LOX-1 knockout (LOX-1−/−) mice were subjected to cecal ligation and puncture (CLP) to induce sepsis. LOX-1 deletion significantly reduced systemic inflammation and inflammatory lung injury during sepsis, together with decreased production of proinflammatory cytokines and reduced lung edema formation. Furthermore, LOX-1 deletion improved host immune responses after the induction of sepsis, as indicated by enhanced bacterial clearance. Interestingly, we were able to demonstrate that LOX-1 is expressed in neutrophils. LOX-1 deletion prevented neutrophil overreaction and increased neutrophil recruitment to infection sites after sepsis induction, contributing at least partly to increased immune responses in LOX-1 knockout mice. Our study results indicate that LOX-1 is an important mediator of inflammation and neutrophil dysfunction in sepsis.

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Moesin Is a Novel Biomarker of Endothelial Injury in Sepsis

Journal of Immunology Research ◽

10.1155/2021/6695679 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Yikun Chen ◽

Jiajia Wang ◽

Lei Zhang ◽

Jianjie Zhu ◽

Yuanyuan Zeng ◽

...

Keyword(s):

Lung Injury ◽

Cecal Ligation ◽

Lavage Fluid ◽

Endothelial Injury ◽

Inflammatory Factors ◽

Inflammatory Factor ◽

Protein Levels ◽

Potential Biomarker ◽

The Impact

Objective. Increased vascular permeability and inflammation are principal hallmark of sepsis. Moesin (MSN) is a membrane-associated cytoskeleton protein and crucial for the vascular endothelial function. This study is aimed at evaluating the role of MSN in endothelial injury during the process of sepsis. Methods. Serum MSN in septic patients was measured by ELISA. BALB/c mice were injected with different doses of lipopolysaccharide (LPS) or underwent cecal ligation and single or double puncture (CLP) to mimic sublethal and lethal sepsis. After treatment, their serum MSN and PCT levels, wet to dry lung weights (W/D ratio), bronchoalveolar lavage fluid (BALF) protein concentrations, and lung injury scores were measured. The impact of MSN silencing on LPS-altered Rock1/myosin light chain (MLC), NF-κB, and inflammatory factors in human microvascular endothelial cells (HMECs), as well as monolayer HMEC permeability, was tested in vitro. Results. Compared with healthy controls, serum MSN increased in septic patients and was positively correlated with SOFA scores and serum PCT levels in septic patients. LPS injection significantly increased serum the MSN and PCT expression, BALF protein levels, and W/D ratio, and the serum MSN levels were positively correlated with serum PCT, lung W/D ratio, and lung injury scores in mice. Similar results were obtained in the way of CLP modelling. LPS enhanced MSN, MLC, NF-κB phosphorylation, increased Rock1 expression, and inflammatory factors release in the cultured HMECs, while MSN silencing significantly mitigated the LPS-induced Rock1 and inflammatory factor expression, NF-κB, and MLC phosphorylation as well as the monolayer hyperpermeability in HMECs. Conclusions. Increased serum MSN contributes to the sepsis-related endothelium damages by activating the Rock1/MLC and NF-κB signaling and may be a potential biomarker for evaluating the severity of sepsis.

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