Insights into sepsis therapeutic design based on the apoptotic death pathway

[Molecular mechanisms underlying the pathogenesis of septic multiple organ failure]

Sepsis is defined as the body's overwhelming and life-threatening response to infection that can lead to tissue damage, organ failure, and death. Since bacterial infection is one of the main causes of sepsis, appropriate antimicrobial therapy remains the cornerstone of sepsis and septic shock management. However, since sepsis is a multifaceted chaos involving inflammation and anti-inflammation disbalance leading to the unregulated widespread release of inflammatory mediators, cytokines, and pathogen-related molecules leading to system-wide organ dysfunction, the whole body control to prevent the progression of organ dysfunction is needed. In sepsis and septic shock, pathogen-associated molecular patterns (PAMPs), such as bacterial exotoxins, cause direct cellular damage and/or trigger an immune response in the host. PAMPs are recognized by pattern recognizing receptors (PRRs) expressed on immune-reactive cells. PRRs are also activated by host nuclear, mitochondrial, and cytosolic proteins, known as damage-associated molecular patterns (DAMPs) that are released from cells during sepsis. Thus, most PRRs respond to PAMPs or DAMPs by triggering activation of transcriptional factors, NF-κB, AP1, and STAT-3. On the other hand, sepsis leads to immune (lymphocytes and macrophages) and nonimmune (endothelial and epithelial cells) cell death. Apoptosis has been the major focus of research on cell death in sepsis, but autophagy, necrosis, necroptosis, pyroptosis, NETosis, and ferroptosis may also play an important role in this critical situation. The recent development in our understanding regarding the cellular pathogenesis of sepsis will help in developing new treatment of sepsis.

Investigating the link between miR-34a-5p and TLR6 signaling in sepsis-induced ARDS

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are lung complications diagnosed by impaired gaseous exchanges leading to mortality. From the diverse etiologies, sepsis is a prominent contributor to ALI/ARDS. In the present study, we retrieved sepsis-induced ARDS mRNA expression profile and identified 883 differentially expressed genes (DEGs). Next, we established an ARDS-specific weighted gene co-expression network (WGCN) and picked the blue module as our hub module based on highly correlated network properties. Later we subjected all hub module DEGs to form an ARDS-specific 3-node feed-forward loop (FFL) whose highest-order subnetwork motif revealed one TF (STAT6), one miRNA (miR-34a-5p), and one mRNA (TLR6). Thereafter, we screened a natural product library and identified three lead molecules that showed promising binding affinity against TLR6. We then performed molecular dynamics simulations to evaluate the stability and binding free energy of the TLR6-lead molecule complexes. Our results suggest these lead molecules may be potential therapeutic candidates for treating sepsis-induced ALI/ARDS. In-silico studies on clinical datasets for sepsis-induced ARDS indicate a possible positive interaction between miR-34a and TLR6 and an antagonizing effect on STAT6 to promote inflammation. Also, the translational study on septic mice lungs by IHC staining reveals a hike in the expression of TLR6. We report here that miR-34a actively augments the effect of sepsis on lung epithelial cell apoptosis. This study suggests that miR-34a promotes TLR6 to heighten inflammation in sepsis-induced ALI/ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03700-1.

Review: the role of GSDMD in sepsis

Purpose

Gasdermin D (GSDMD) is a cytoplasmic protein that is encoded by the gasdermin family GSDMD gene and is the ultimate executor of pyroptosis. Pyroptosis is a mode of lysis and inflammation that regulates cell death, ultimately leading to cell swelling and rupture. In sepsis, a dysregulated host response to infection frequently results in hyperinflammatory responses and immunosuppression, eventually leading to multiple organ dysfunction. Pyroptosis regulates innate immune defenses and plays an important role in the process of inflammatory cell death, and the absence of any link in the entire pathway from GSDMD to pyroptosis causes bacterial clearance to be hampered. Under normal conditions, the process of pyroptosis occurs much faster than apoptosis, and the threat to the body is also much greater.

Materials and methods

We conducted a systematic review of relevant reviews and experimental articles using the keywords sepsis, Gasdermin D, and Pyroptosis in the PubMed, Scopus, Google Scholar, and Web of Science databases.

Conclusion

Combined with the pathogenesis of sepsis, it is not difficult to find that pyroptosis plays a key role in bacterial inflammation and sepsis. Therefore, GSDMD inhibitors may be used as targeted drugs to treat sepsis by reducing the occurrence of pyroptosis. This review mainly discusses the key role of GSDMD in sepsis.

Preventive effects of arctigenin from Arctium lappa L against LPS-induced neuroinflammation and cognitive impairments in mice

Arctigenin (Arc) is a phenylpropanoid dibenzylbutyrolactone lignan in Arctium lappa L, which has been widely applied as a traditional Chinese herbal medicine for treating inflammation. In the present study, we explored the neuroprotective effect and the potential mechanisms of arctigenin against LPS-evoked neuroinflammation, neurodegeneration, and memory impairments in the mice hippocampus. Daily administration of arctigenin (50 mg/kg per day, i.g.) for 28 days revealed noticeable improvements in spatial learning and memory deficits after exposure to LPS treatment. Arctigenin prevented LPS-induced neuronal/synaptic injury and inhibited the increases in Abeta (Aβ) generation and the levels of amyloid precursor protein (APP) and β-site amyloid precursor protein cleavage enzyme 1 (BACE1). Moreover, arctigenin treatment also suppressed glial activation and reduced the production of proinflammatory cytokines. In LPS-treated BV-2 microglial cells and mice, activation of the TLR4 mediated NF-κB signaling pathway was significantly suppressed by arctigenin administration. Mechanistically, arctigenin reduced the LPS-induced interaction of adiponectin receptor 1 (AdipoR1) with TLR4 and its coreceptor CD14 and inhibited the TLR4-mediated downstream inflammatory response. The outcomes of the current study indicate that arctigenin mitigates LPS-induced apoptotic neurodegeneration, amyloidogenesis and neuroinflammation as well as cognitive impairments, and suggest that arctigenin may be a potential therapeutic candidate for neuroinflammation/neurodegeneration-related diseases.

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.

Vascular endotheliitis associated with infections: Its pathogenetic role and therapeutic implication

Vascular endothelial cells are major participants in and regulators of immune responses and inflammation. Vascular endotheliitis is regarded as a host immune-inflammatory response of the endothelium forming the inner surface of blood vessels in association with a direct consequence of infectious pathogen invasion. Vascular endotheliitis and consequent endothelial dysfunction can be a principle determinant of microvascular failure, which would favor impaired perfusion, tissue hypoxia, and subsequent organ failure. Emerging evidence suggests the role of vascular endotheliitis in the pathogenesis of coronavirus disease 2019 (COVID-19) and its related complications. Thus, once initiated, vascular endotheliitis and resultant cytokine storm cause systemic hyperinflammation and a thrombotic phenomenon in COVID-19, leading to acute respiratory distress syndrome and widespread organ damage. Vascular endotheliitis also appears to be a contributory factor to vasculopathy and coagulopathy in sepsis that is defined as life-threatening organ dysfunction due to a dysregulated response of the host to infection. Therefore, protecting endothelial cells and reversing vascular endotheliitis may be a leading therapeutic goal for these diseases associated with vascular endotheliitis. In this review, we outline the etiological and pathogenic importance of vascular endotheliitis in infection-related inflammatory diseases, including COVID-19, and possible mechanisms leading to vascular endotheliitis. We also discuss pharmacological agents which may be now considered as potential endotheliitis-based treatment modalities for those diseases.

A long way to go: caspase inhibitors in clinical use

Caspases are an evolutionary conserved family of cysteine-dependent proteases that are involved in many vital cellular processes including apoptosis, proliferation, differentiation and inflammatory response. Dysregulation of caspase-mediated apoptosis and inflammation has been linked to the pathogenesis of various diseases such as inflammatory diseases, neurological disorders, metabolic diseases, and cancer. Multiple caspase inhibitors have been designed and synthesized as a potential therapeutic tool for the treatment of cell death-related pathologies. However, only a few have progressed to clinical trials because of the consistent challenges faced amongst the different types of caspase inhibitors used for the treatment of the various pathologies, namely an inadequate efficacy, poor target specificity, or adverse side effects. Importantly, a large proportion of this failure lies in the lack of understanding various caspase functions. To overcome the current challenges, further studies on understanding caspase function in a disease model is a fundamental requirement to effectively develop their inhibitors as a treatment for the different pathologies. Therefore, the present review focuses on the descriptive properties and characteristics of caspase inhibitors known to date, and their therapeutic application in animal and clinical studies. In addition, a brief discussion on the achievements, and current challenges faced, are presented in support to providing more perspectives for further development of successful therapeutic caspase inhibitors for various diseases.

Endothelial dysfunction: a therapeutic target in bacterial sepsis?

INTRODUCTION

Endothelial cells maintain vascular integrity, tone, and patency and have important roles in hemostasis and inflammatory responses. Although some degree of endothelial dysfunction with increased vascular permeability may be necessary to control local infection, excessive dysfunction plays a central role in the pathogenesis of sepsis-related organ dysfunction and failure as it results in dysregulated inflammation, vascular leakage, and abnormal coagulation. The vascular endothelium has thus been proposed as a potential target for therapeutic intervention in patients with sepsis.

AREAS COVERED

Different mechanisms underlying sepsis-related dysfunction of the vascular endothelium are discussed, including glycocalyx shedding, nitrosative stress, and coagulation factors. Potential therapeutic implications of each mechanism are mentioned.

EXPERT OPINION

Multiple targets to protect or restore endothelial function have been suggested, but endothelium-driven treatments remain a future potential at present. As some endothelial dysfunction and permeability may be necessary to remove infection and repair damaged tissue, targeting the endothelium may be a particular challenge. Ideally, therapies should be guided by biomarkers related to that specific pathway to ensure they are given only to patients most likely to respond. This enrichment based on biological plausibility and theragnostics will increase the likelihood of a beneficial response in individual patients and enable more personalized treatment.

Topiroxostat ameliorates oxidative stress and inflammation in sepsis-induced lung injury

Sepsis-induced lung injury was the most common cause of death in patients. Topiroxostat, a novel xanthine oxidoreductase inhibitors, possessed obvious organ protectives effects. Xanthine oxidase played a vital role in acute lung injury. The study aimed to investigate the roles of Topiroxostat in sepsis-induced lung injury. The sepsis rats were established using cecum ligation and perforation. The lung damage induced by sepsis was evaluated by Hematoxylin and Eosin staining and lung tissue wet to dry ratio. The oxidative stress was detected by measurement of reactive oxygen species, malondialdehyde, myeloperoxidase and superoxide dismutase (SOD). The pro-inflammatory mediators, tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and monocyte chemotactic protein 1, were measured by Enzyme-Linked Immunosorbent Assay. The cell apoptosis in lung was detected by TUNNEL staining and western blot analysis of apoptosis-related proteins including pro-apoptosis proteins, Bax, cleaved caspase9, cleaved caspase3 and anti-apoptosis protein Bcl2. The results showed that Topiroxostat significantly reduced lung damage, along with decreased oxidative stress, inflammation response and apoptosis in sepsis rats. Topiroxostat exerted markedly protective effects in sepsis-induced lung injury and could be an antioxidant in treating sepsis-induced lung injury.

Recombinant human milk fat globule-EGF factor VIII (rhMFG-E8) as a therapy for sepsis after acute exposure to alcohol

BACKGROUND

Alcohol intake predisposes to infections and sepsis. Alcohol and sepsis inhibit the expression of milk fat globule epidermal growth factor-factor VIII (MFG-E8), a glycoprotein essential for optimal efferocytosis, resulting in the release of proinflammatory molecules and increased sepsis severity. We previously reported that recombinant mouse (rm) MFG-E8 attenuates sepsis-induced organ injury in rats with acute alcohol intoxication. In order to develop a therapy that can be safely used in humans, we have produced recombinant human (rh) MFG-E8 and evaluated its efficacy to ameliorate sepsis after acute exposure to alcohol.

METHODS

We induced acute alcohol intoxication with a bolus injection of alcohol (1.75 g/kg BW) followed by an intravenous infusion of 300 mg/kg/h alcohol for 10 h. Sepsis was then induced by cecal ligation and puncture (CLP). At -10, 0, and 10 h relative to CLP, rats received MFG-E8 or vehicle (albumin) intravenously. Animals were euthanized at 20 h after CLP for blood and tissue collection. Additional groups of animals were used for a survival study.

RESULTS

Compared to vehicle, rhMFG-E8 treatment ameliorated blood levels of proinflammatory cytokines (% improvement: TNF-α 49.8%, IL-6 34.7%) and endotoxin (61.7%), as well as of transaminases (AST 36.2%, ALT 40.1%) and lactate (18.4%). Rats treated with rhMFG-E8 also had a significant histological attenuation of the acute lung injury, as well as a reduction in the number of apoptotic cells in the thymus (43.4%) and cleaved caspase 3 (38.7%) in the spleen. In addition, rhMFG-E8 improved the 10-day sepsis survival rate from 45 to 80% CONCLUSION: rhMFG-E8 significantly ameliorated sepsis in rats with acute alcohol exposure, demonstrating rhMFG-E8's potential to be developed as an effective therapy for sepsis in alcohol abusers.

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.

Activator Protein-1 Decoy Oligodeoxynucleotide Transfection Is Beneficial in Reducing Organ Injury and Mortality in Septic Mice

OBJECTIVES

Inflammation and apoptosis are decisive mechanisms for the development of end-organ injury in sepsis. Activator protein-1 may play a key role in regulating expression of harmful genes responsible for the pathophysiology of septic end-organ injury along with the major transcription factor nuclear factor-κB. We investigated whether in vivo introduction of circular dumbbell activator protein-1 decoy oligodeoxynucleotides can provide benefits for reducing septic end-organ injury.

DESIGN

Laboratory and animal/cell research.

SETTINGS

University research laboratory.

SUBJECTS

Male BALB/c mice (8-10 wk old).

INTERVENTIONS

Activator protein-1 decoy oligodeoxynucleotides were effectively delivered into tissues of septic mice in vivo by preparing into a complex with atelocollagen given 1 hour after surgery.

MATERIALS AND MAIN RESULTS

Polymicrobial sepsis was induced by cecal ligation and puncture in mice. Activator protein-1 decoy oligodeoxynucleotide transfection inhibited abnormal production of proinflammatory and chemotactic cytokines after cecal ligation and puncture. Histopathologic changes in lung, liver, and kidney tissues after cecal ligation and puncture were improved by activator protein-1 decoy oligodeoxynucleotide administration. When activator protein-1 decoy oligodeoxynucleotides were given, apoptosis induction was strikingly suppressed in lungs, livers, kidneys, and spleens of cecal ligation and puncture mice. These beneficial effects of activator protein-1 decoy oligodeoxynucleotides led to a significant survival advantage in mice after cecal ligation and puncture. Apoptotic gene profiling indicated that activator protein-1 activation was involved in the up-regulation of many of proapoptotic and antiapoptotic genes in cecal ligation and puncture-induced sepsis.

CONCLUSIONS

Our results indicate a detrimental role of activator protein-1 in the sepsis pathophysiology and the potential usefulness of activator protein-1 decoy oligodeoxynucleotides for the prevention and treatment of septic end-organ failure.

Simvastatin Inhibits Endotoxin-Induced Apoptosis in Liver and Spleen Through Up-Regulation of Survivin/NF-κB/p65 Expression

Endotoxemia is associated by dysregulated apoptosis of immune and non-immune cells. We investigated whether simvastatin has anti-apoptotic effects, and induces hepatocytes and lymphocytes survival signaling in endotoxin-induced liver and spleen injuries. Wistar rats were divided into the groups pretreated with simvastatin (20 or 40 mg/kg, orally) prior to a non-lethal dose of lipopolysaccharide (LPS), the LPS group, and the control. The severity of tissue inflammatory injuries was expressed as hepatic damage scores (HDS) and spleen damage scores (SDS), respectively. The apoptotic cell was detected by TUNEL (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling) and immunohistochemical staining (expression of cleaved caspase-3, and anti-apoptotic Bcl-xL, survivin and NF-κB/p65). Simvastatin dose-dependently abolished HDS and SDS induced by LPS (p < 0.01), respectively. Simvastatin 40 mg/kg significantly decreased apoptotic index and caspase-3 cleavage in hepatocytes and lymphocytes (p < 0.01 vs. LPS group, respectively), while Bcl-XL markedly increased accordingly with simvastatin doses. In the simvastatin, groups were determined markedly increased cytoplasmic expression of survivin associated with nuclear positivity of NF-κB, in both hepatocytes and lymphocytes (p < 0.01 vs. LPS group). Cell-protective effects of simvastatin against LPS seemed to be mediated by up-regulation of survivin, which leads to reduced caspase-3 activation and inhibition of hepatocytes and lymphocytes apoptosis.

Synergistic cytoprotection by co-treatment with dexamethasone and rapamycin against proinflammatory cytokine-induced alveolar epithelial cell injury

Background

One of the main pathophysiological manifestations during the acute phase of sepsis is massive production of proinflammatory mediators. Clinical trials involving direct suppression of inflammatory mediators to relieve organ dysfunction in sepsis have been extensively performed; however, the clinical outcomes of such trials remain far from satisfactory. Given the need for better sepsis treatments, we have screened various agents with anti-inflammatory properties for cytoprotective effects. In this study, we identified dexamethasone and rapamycin as clinically applicable candidates with favorable synergistic effects against inflammatory cytokine-induced cytotoxicity in vitro and further explored the molecular mechanisms underlying the augmented cytoprotective effects exerted by co-treatment with both drugs.

Methods

Human alveolar epithelial cell-derived A549 cells were stimulated with a mixture of inflammatory cytokines, TNF-alpha, IL-1beta, and IFN-gamma, which induce cellular injury, including apoptosis. This in vitro model was designed to simulate acute lung injury (ALI) associated with sepsis. The cells were co-treated with dexamethasone and rapamycin under cytokine stimulation. Conditioned medium and cell lysates were subjected to further analysis.

Results

Either dexamethasone or rapamycin significantly attenuated cytokine-induced cytotoxicity in A549 cells in a dose-dependent manner. In addition, the simultaneous administration of dexamethasone and rapamycin had a synergistic cytoprotective effect. The applied doses of dexamethasone (10 nM) and rapamycin (1 nM) were considerably below the reported plasma concentrations of each drug in clinical setting. Interestingly, distinct augmentation of both of c-Jun inhibition and Akt activation were observed when the cells were co-treated with both drugs under cytokine stimulation.

Conclusions

A synergistic protective effect of dexamethasone and rapamycin was observed against cytokine-induced cytotoxicity in A549 cells. Augmentation of both of c-Jun inhibition and Akt activation were likely responsible for the cytoprotective effect. The combined administration of anti-inflammatory drugs such as dexamethasone and rapamycin offers a promising treatment option for alveolar epithelial injury associated with sepsis.

Nucleic-acid based gene therapy approaches for sepsis

Despite advances in overall medical care, sepsis and its sequelae continue to be an embarrassing clinical entity with an unacceptably high mortality rate. The central reason for high morbidity and high mortality of sepsis and its sequelae is the lack of an effective treatment. Previous clinical trials have largely failed to identify an effective therapeutic target to improve clinical outcomes in sepsis. Thus, the key goal favoring the outcome of septic patients is to devise innovative and evolutionary therapeutic strategies. Gene therapy can be considered as one of the most promising novel therapeutic approaches for nasty disorders. Since a number of transcription factors, such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), play a pivotal role in the pathophysiology of sepsis that can be characterized by the induction of multiple genes and their products, sepsis may be regarded as a gene-related disorder and gene therapy may be considered a promising novel therapeutic approach for treatment of sepsis. In this review article, we provide an up-to-date summary of the gene-targeting approaches, which have been developed in animal models of sepsis. Our review sheds light on the molecular basis of sepsis pathology for the development of novel gene therapy approaches and leads to the conclusion that future research efforts may fully take into account gene therapy for the treatment of sepsis.

Lithium ameliorates lipopolysaccharide-induced neurotoxicity in the cortex and hippocampus of the adult rat brain

Lithium an effective mood stabilizer, primary used in the treatment of bipolar disorders, has been reported as a protective agent in various neurological disorders. In this study, we examined the neuroprotective role of lithium chloride (LiCl) against lipopolysaccharide (LPS) in the cortex and hippocampus of the adult rat brain. We determined that LiCl -attenuated LPS-induced activated toll-like receptor 4 (TLR4) signalling and significantly reduced the nuclear factor-_kB (NF-_KB) translation factor and various other inflammatory mediators such as interleukin-1 beta (IL-1β) and tumour necrosis factor alpha (TNF-α). We also analyzed that LiCl significantly abrogated activated gliosis via attenuation of specific markers for activated microglia, ionized calcium-binding adaptor molecule (Iba-1) and astrocytes, glial fibrillary acidic protein (GFAP) in both the cortex and hippocampus of the adult rat brain. Furthermore, we also observed that LiCl treatment significantly ameliorated the increase expression level of apoptotic neurodegeneration protein markers Bax/Bcl2, activated caspase-3 and poly (ADP-ribose) polymerase-1 (PARP-1) in the cortex and hippocampus regions of the LPS-treated adult rat brain. In addition, the morphological results of the fluoro-jade B (FJB) and Nissl staining showed that LiCl attenuated the neuronal degeneration in the cortex and hippocampus regions of the LPS-treated adult rat brain. Taken together, our Western blot and morphological results indicated that LiCl significantly prevents the LPS-induced neurotoxicity via attenuation of neuroinflammation and apoptotic neurodegeneration in the cortex and hippocampus of the adult rat brain.

Alpha-Lipoic Acid Attenuates Oxidative Damage in Organs After Sepsis

Sepsis progression is linked with the imbalance between reactive oxygen species and antioxidant enzymes. Thus, the aim of this study was to evaluate the effect of alpha-lipoic acid (ALA), a powerful antioxidant, in organs of rats submitted to sepsis. Male Wistar rats were subjected to sepsis by cecal ligation puncture (CLP) and treated with ALA or vehicle. After CLP (12 and 24 h), the myeloperoxidase (MPO) activity, protein and lipid oxidative damage, and antioxidant enzymes in the liver, kidney, heart, and lung were evaluated. ALA was effective in reducing MPO activity, lipid peroxidation in the liver, and protein carbonylation only in the kidney in 12 h after CLP. In 12 h, SOD activity increased in the kidney and CAT activity in the liver and kidney with ALA treatment. Thus, ALA was able to reduce the inflammation and oxidative stress in the liver and kidney after sepsis in rats.

Evidencing the Role of Erythrocytic Apoptosis in Malarial Anemia

In the last decade it has become clear that, similarly to nucleated cells, enucleated red blood cells (RBCs) are susceptible to programmed apoptotic cell death. Erythrocytic apoptosis seems to play a role in physiological clearance of aged RBCs, but it may also be implicated in anemia of different etiological sources including drug therapy and infectious diseases. In malaria, severe anemia is a common complication leading to death of children and pregnant women living in malaria-endemic regions of Africa. The pathogenesis of malarial anemia is multifactorial and involves both ineffective production of RBCs by the bone marrow and premature elimination of non-parasitized RBCs, phenomena potentially associated with apoptosis. In the present overview, we discuss evidences associating erythrocytic apoptosis with the pathogenesis of severe malarial anemia, as well as with regulation of parasite clearance in malaria. Efforts to understand the role of erythrocytic apoptosis in malarial anemia can help to identify potential targets for therapeutic intervention based on apoptotic pathways and consequently, mitigate the harmful impact of malaria in global public health.

Evaluation of neutrophil-to-lymphocyte ratio as a potential biomarker for acute cholecystitis

BACKGROUND

The diagnosis of acute cholecystitis (AC) is frequently associated with an increase in white cell count (WCC) and C-reactive protein (CRP). However, one or both of these inflammatory biomarkers can be normal in AC. The aim of this study was to evaluate and compare the discriminative powers of the neutrophil-to-lymphocyte ratio (NLR) with WCC and CRP in diagnosing AC.

METHODS

This was a retrospective cohort study. For more than a period of 5 y, 1959 patients were identified from the cholecystectomy Registry. Laparoscopic cholecystectomy patients with histologic evidence of AC were included if they also had preoperative WCC and CRP measurements. Eligibility criteria were met by 177 patients. These patients were compared with 45 control subjects who had normal gallbladder histology.

RESULTS

One unit of increase in the NLR was associated with a 2.5 times increase in the odds of AC (odds ratio = 2.48; 95% confidence interval [CI], 1.5-4.1; P < 0.0005). NLR cutoff values of 4.1 (95% CI, 3.42-4.79), 3.25 (95% CI, 1.95-4.54), and 4.17 (95% CI, 3.76-4.58) were diagnostic for the overall AC, mild, and moderate-severe AC, respectively. The NLR areas under the receiver operating characteristic curve in AC, mild, and moderate-severe AC were 94% (95% CI, 91%-97%), 87% (95% CI, 81%-93%), and 98% (95% CI, 96%-100%), respectively. The discriminative power of an NLR was superior to that of the WCC and similar to CRP for diagnosing AC and different grades of severity.

CONCLUSIONS

NLR can be considered as a potential inflammatory biomarker for AC.

Osmotin attenuates LPS-induced neuroinflammation and memory impairments via the TLR4/NFκB signaling pathway

Toll-like receptor 4 (TLR4) signaling in the brain mediates autoimmune responses and induces neuroinflammation that results in neurodegenerative diseases, such as Alzheimer’s disease (AD). The plant hormone osmotin inhibited lipopolysaccharide (LPS)-induced TLR4 downstream signaling, including activation of TLR4, CD14, IKKα/β, and NFκB, and the release of inflammatory mediators, such as COX-2, TNF-α, iNOS, and IL-1β. Immunoprecipitation demonstrated colocalization of TLR4 and AdipoR1 receptors in BV2 microglial cells, which suggests that osmotin binds to AdipoR1 and inhibits downstream TLR4 signaling. Furthermore, osmotin treatment reversed LPS-induced behavioral and memory disturbances and attenuated LPS-induced increases in the expression of AD markers, such as Aβ, APP, BACE-1, and p-Tau. Osmotin improved synaptic functionality via enhancing the activity of pre- and post-synaptic markers, like PSD-95, SNAP-25, and syntaxin-1. Osmotin also prevented LPS-induced apoptotic neurodegeneration via inhibition of PARP-1 and caspase-3. Overall, our studies demonstrated that osmotin prevented neuroinflammation-associated memory impairment and neurodegeneration and suggest AdipoR1 as a therapeutic target for the treatment of neuroinflammation and neurological disorders, such as AD.

Inhibition of MicroRNA 195 Prevents Apoptosis and Multiple-Organ Injury in Mouse Models of Sepsis

BACKGROUND

MicroRNAs (miRs) are a class of short RNA molecules, which negatively regulate gene expression. The levels of circulating miR-15 family members are elevated in septic patients and may be associated with septic death. This study investigated whether inhibition of miR-195, a member of the miR-15 family, provided beneficial effects in sepsis.

METHODS AND RESULTS

Sepsis was induced by injection of feces into the peritoneum in mice. miR-195 was upregulated in the lung and liver of septic mice. Silencing of miR-195 increased the protein levels of BCL-2, Sirt1, and Pim-1; prevented apoptosis; reduced liver and lung injury; and improved the survival in septic mice. Silencing of miR-195 provided similar protection in lipopolysaccharide-induced endotoxemic mice. In endothelial cells, upregulation of miR-195 induced apoptosis, and inhibition of miR-195 prevented lipopolysaccharide-induced apoptosis. miR-195 repressed expression of its protein targets, BCL-2, Sirt1, and Pim-1. Furthermore, overexpression of Pim-1 prevented apoptosis induced by lipopolysaccharide and miR-195 mimic. Inhibition of Pim-1 attenuated the protective effects of miR-195 silencing in septic mice.

CONCLUSIONS

Silencing of miR-195 reduced multiple-organ injury and improved the survival in sepsis, and the protective effects of miR-195 inhibition were associated with upregulation of Bcl-2, Sirt1, and Pim-1. Thus, inhibition of miR-195 may represent a new therapeutic approach for sepsis.

Effect of Regulatory T Cells on Promoting Apoptosis of T Lymphocyte and Its Regulatory Mechanism in Sepsis

With both in vivo and in vitro experiments, the present study was conducted to investigate the effect of regulatory T cell (Treg) on promoting T-lymphocyte apoptosis and its regulatory mechanism through transforming growth factor-beta (TGF-β1) signaling in mice. A murine model of polymicrobial sepsis was reproduced by cecal ligation and puncture (CLP); PC61 and anti-TGF-β antibodies were used to decrease counts of CD4(+)CD25(+) Tregs and inhibit TGF-β activity, respectively. Splenic CD4(+)CD25(+) Tregs and CD4(+)CD25(-) T cells were isolated. Phenotypes, including cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), forkhead/winged helix transcription factor p3 (Foxp3), and TGFβ1(m+), as well as the apoptotic rate of CD4(+)CD25(-) T cell, were analyzed by flow cytometry. Real-time reverse transcription-polymerase chain reaction was performed to determine mRNA expression of TGF-β1, and the expressions of Smad2/Smad3, Bcl-2 superfamily members of Bcl-2/Bim, cytochrome C, the mitochondrial membrane potential, and caspases in CD4(+)CD25(-) T cells were simultaneously determined. After treatment with PC61 or anti-TGF-β antibody, CTLA-4, Foxp3, and TGFβ1(m+) expressions of CD4(+)CD25(+) Tregs were markedly decreased in comparison to that of the CLP group and the apoptosis rate of CD4(+)CD25(-) T cells was significantly positively correlated with the expression of TGF-β1. Meanwhile, levels of P-Smad2/P-Smad3, proapoptotic protein Bim, cytochrome C, and activity of caspase-3, -8, -9 were downregulated, whereas the mitochondrial membrane potential and antiapoptotic protein Bcl-2 expression were restored. Taken together, our data indicated that the TGF-β1 signal could be partly involved in the apoptosis of CD4(+)CD25(-) T cells promoted by CD4(+)CD25(+) Tregs, therefore inhibition of TGF-β1 expression may provide a novel strategy for the improvement of host immunosuppression following sepsis.

Insights into the apoptotic death of immune cells in sepsis

Sepsis with subsequent multiple-organ dysfunction is a distinct systemic inflammatory response to concealed or obvious infection, and it is a leading cause of death in intensive care units. Thus, one of the key goals in critical care medicine is to develop novel therapeutic strategies that will affect favorably on outcome of septic patients. In addition to systemic response to infection, apoptosis is implicated to be an important mechanism of the death of immune cells, including neutrophils, macrophages, T lymphocytes, and dendritic cells, and it is usually followed by the development of multiple-organ failure in sepsis. The implication of apoptosis of immune cells is now highlighted by multiple studies that demonstrate that prevention of cell apoptosis can improve survival in relevant animal models of severe sepsis. In this review, we focus on major apoptotic death pathways and molecular mechanisms that regulate apoptosis of different immune cells, and advances in these areas that may be translated into more promising therapies for the prevention and treatment of severe sepsis.

Adjuvant potential of selegiline in attenuating organ dysfunction in septic rats with peritonitis

Selegiline, an anti-Parkinson drug, has antioxidant and anti-apoptotic effects. To explore the effect of selegiline on sepsis, we used a clinically relevant animal model of polymicrobial sepsis. Cecal ligation and puncture (CLP) or sham operation was performed in male rats under anesthesia. Three hours after surgery, animals were randomized to receive intravenously selegiline (3 mg/kg) or an equivalent volume of saline. The administration of CLP rats with selegiline (i) increased arterial blood pressure and vascular responsiveness to norepinephrine, (ii) reduced plasma liver and kidney dysfunction, (iii) attenuated metabolic acidosis, (iv) decreased neutrophil infiltration in liver and lung, and (v) improved survival rate (from 44% to 65%), compared to those in the CLP alone rats. The CLP-induced increases of plasma interleukin-6, organ superoxide levels, and liver inducible nitric oxide synthase and caspase-3 expressions were ameliorated by selegiline treatment. In addition, the histological changes in liver and lung were significantly attenuated in the selegiline -treated CLP group compared to those in the CLP group. The improvement of organ dysfunction and survival through reducing inflammation, oxidative stress and apoptosis in peritonitis-induced sepsis by selegiline has potential as an adjuvant agent for critical ill.

Erythropoietin prevents lymphoid apoptosis but has no effect on survival in experimental sepsis

BACKGROUND

Lymphoid apoptosis in sepsis is associated with poor outcome, and prevention of apoptosis frequently improves survival in experimental models of sepsis. Recently, erythropoietin (EPO) was shown to protect against lipopolysaccharide (LPS)-induced mortality. As cecal ligation and puncture (CLP) is a clinically more relevant model of sepsis, we evaluated the effect of EPO on CLP-induced lymphoid tissue apoptosis and mortality.

METHODS

Young Wistar rats were subjected to polymicrobial sepsis by CLP. EPO (5,000 U/kg intraperitoneal) was administered 30 min before CLP and then 1 and 4 h after CLP. Spleen, thymus, and small intestine were harvested at 24 h and assessed for apoptosis by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) and caspase-3 staining. A separate group of animals was followed up for mortality.

RESULTS

Splenic, thymic, and intestinal apoptosis was increased after CLP; administration of EPO significantly decreased apoptosis as determined by TUNEL and caspase-3 staining. Final survival in the CLP mortality study was 30% in both saline and EPO groups.

CONCLUSION

Our results provide the first evidence that EPO attenuates lymphoid apoptosis in the CLP model of sepsis. However, EPO is not associated with a survival benefit in the CLP model of sepsis.

Ginsenoside-Rd potentiates apoptosis induced by hydrogen peroxide in basilar artery smooth muscle cells through the mitochondrial pathway

Our previous studies showed that ginsenoside-Rd, a purified component from Panax notoginseng, inhibited cell proliferation and reversed basilar artery remodeling. The aim of this study was to investigate whether ginsenoside- Rd influences H(2)O(2)-induced apoptosis in basilar artery smooth muscle cells (BASMCs). The results showed that ginsenoside-Rd significantly potentiated H(2)O(2)-induced cell death and cell apoptosis. This resulted in a concentration-dependent reduction of the cell viability. Ginsenoside-Rd further increased cytochrome C release and caspase-9/caspase-3 activations, and reduced the stability of mitochondrial membrane potential (MMP) and the ratio of Bcl-2/Bax. Cyclosporine A, an inhibitor of mitochondrial-permeability transition, inhibited alteration of mitochondrial permeability induced by H(2)O(2) and reversed the effect of ginsenoside-Rd on MMP. Our data strongly suggest that ginsenoside-Rd potentiated H(2)O(2)-induced apoptosis of BASMCs through the mitochondria-dependent pathway.

Olprinone and colforsin daropate alleviate septic lung inflammation and apoptosis through CREB-independent activation of the Akt pathway

Olprinone, a specific phosphodiesterase III inhibitor, and corforsin daropate, a direct adenylate cyclase activator, are now being used in critical conditions. We investigated whether their therapeutic use provides protection against septic acute lung injury (ALI) and mortality. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in BALB/c mice. Olprinone or colforsin daropate was continuously given through an osmotic pump that was implanted into the peritoneal cavity immediately following CLP. These treatments prevented the ALI development in CLP mice, as indicated by the findings that severe hypoxemia, increased pulmonary vascular permeability, and histological lung damage were strikingly remedied. Furthermore, continued administration of olprinone or colforsin daropate suppressed apoptosis induction in septic lungs and improved the survival of CLP mice. Olprinone and corforsin daropate enhanced Akt phosphorylation in septic lungs. Wortmannin, which inhibits the Akt upstream regulator phosphatidylinositol 3-kinase, abrogated the protective effects of olprinone and corforsin daropate on sepsis-associated lung inflammation and apoptosis. In vivo transfection of cyclic AMP response element binding protein (CREB) decoy oligodeoxynucleotide failed to negate the abilities of these agents to increase Akt phosphorylation and to inhibit IκBα degradation in septic lungs. These results demonstrate for the first time that CREB-independent Akt-mediated signaling is a critical mechanism contributing to the therapeutic effects of olprinone and corforsin daropate on septic ALI. Moreover, our data also suggest that these cyclic AMP-related agents, by blocking both nuclear factor-κB activation and apoptosis induction, may represent an effective therapeutic approach to the treatment of the septic syndrome.

Protective effect of sodium tanshinone IIA sulfonate on injury of small intestine in rats with sepsis and its mechanism

OBJECTIVE

To explore the protective effect of sodium tanshinone IIA sulfonate (STS) on small: intestine injury in rats with sepsis and its possible mechanism.

METHODS

According to a random number table, 24 Tats were randomly divided into 3 groups: sham operation group (sham group), sepsis model group (model group) and STS treatment group (STS group), with 8 Tats in each group. A rat model of sepsis was induced by cecal ligation and puncture (CLP) for 5 h. STS (1 mg/kg) was slowly injected through the right external jugular vein after CLP. The histopathologic changes in the intestine tissue were observed under a light microscope, and the intestinal epithelial cell apoptosis was evaluated by terminal deoxynucleoddyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) method. The expressions of Bcl-2, Bax and nuclear factor κB (NF-κB) p65 in the intestinal tissue was determined by Western blot. The levels of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in the intestinal tissue were determined using enzyme-linked immuno-sorbent assay (ELISA).

RESULTS

Obvious injuries were observed in the intestinal tissue in the CLP group compared with the sham group. The expression of NF-κB p65 and the levels of TNF-α and IL-6 were up-regulated after CLP, the apoptosis of intestinal epithelial cells was increased after CLP, and the ratio of Bcl-2 to Bax was decreased. STS post-treatment could attenuate the injury on the intestinal tissue induced by CLP, decrease the apoptosis of intestinal treatment epithelial cells and the levels of NF-κB p65, TNF-α and IL-6, and increase the ratio of Bcl-2 to Bax.

CONCLUSION

STS can protect the small intestine in rats with sepsis, and the mechanism may be associated with the inhibition of intestinal epithelial apoptosis and the reduction of activation of inflammatory cytokines.

Detrimental effect of apoptosis of lymphocytes at an early time point of experimental abdominal sepsis

Background

Apoptosis of lymphocytes is considered a late sequelum in the sepsis cascade. The role of apoptosis of lymphocytes as a driver of final outcome was investigated.

Methods

Abdominal sepsis was induced after cecal ligation and puncture (CLP) in 31 rabbits. Blood was sampled at serial time intervals and peripheral blood mononuclear cells (PBMCs) were isolated. Apoptosis of lymphocytes and monocytes was measured through flow cytometric analysis. PBMCs were stimulated with LPS and Pam3Cys for the release of tumor necrosis factor-alpha (TNFα). Tissue bacterial growth was quantitatively measured. In a second set of experiments, CLP was performed in another 40 rabbits; 20 received single intravenous infusions of ciprofloxacin and of metronidazole 4 hours after surgery.

Results

Animals were divided into two groups based on the percentage of lymphocyte apoptosis at 4 hours after surgery; less than or equal to 32% and more than 32%. Survival of the former was shorter than the latter (p: 0.017). Tissue growth was similar between groups. Apoptosis of lymphocytes and of monocytes was lower in the former group over follow-up. Release of ΤNFα did not differ. The above findings on survival were repeated in the second set of experiments. Administration of antimicrobials prolonged survival of the former group (p: 0.039) but not of the latter group (pNS).

Conclusions

Lymphocyte apoptosis at an early time point of experimental peritonitis is a major driver for death. A lower percentage of apoptosis leads earlier to death. Antimicrobials were beneficial even at that disease state.

Early and late effects of bone marrow-derived mononuclear cell therapy on lung and distal organs in experimental sepsis

We tested the hypothesis that bone marrow-derived mononuclear cells (BMDMCs) at an early phase of cecal ligation and puncture (CLP)-induced sepsis may have lasting effects on: (1) lung mechanics and histology, (2) the structural remodelling of lung parenchyma, (3) lung, kidney, and liver cell apoptosis, and (4) pro- and anti-inflammatory cytokines and growth factors. At day 1, BMDMC significantly reduced mortality, as well as caspase-3, interleukin (IL)-6 and IL-1β, vascular endothelial growth factor, platelet-derived growth factor, hepatocyte growth factor, and transforming growth factor-β, but increased IL-10 mRNA expression in lung tissue in septic mice contributing to endothelium and epithelium alveolar repair and improvement of lung mechanics. BMDMC also prevented the increase of apoptotic cells in lung, liver, and kidney. At day 7, these early functional and morphological effects were preserved or further improved. In conclusion, in the present model of sepsis, the beneficial effects of early administration of BMDMCs on lung and distal organs were preserved, possibly by paracrine mechanisms.