Effects of various applications of lipopolysaccharides on blood parameters of pigs

Berberine Ameliorates Inflammation in Acute Lung Injury via NF-κB/Nlrp3 Signaling Pathway

The inflammatory response is the key pathophysiological character of acute lung injury (ALI). Berberine (BBR), a natural quaternary ammonium alkaloid, plays a functional role in anti-inflammation both in vitro and in vivo. However, the underlying mechanism between BBR and ALI has not been expounded. Here, we found that BBR improved the permeability of pulmonary and repressed the inflammatory factors in the lipopolysaccharides (LPSs)-induced ALI model. We demonstrated that BBR could suppress the expression of phosphorylated nuclear factor-kappa B (NF-κB) and further restrain the downstream gene nucleotide-binding domain and leucine-rich repeat protein-3 (Nlrp3). Moreover, we also revealed that BBR could directly interact with Nlrp3 protein. After knocked down of Nlrp3 by using siRNA, the protective role of BBR was abrogated in vitro. The expression of IL-1β and IL-18 was downregulated by BBR via the two signaling pathways. Notably, in Nlrp3 deficient mice, the protective effect of BBR was abolished. These findings demonstrate that BBR has a depressant effect on inflammatory response caused by LPS via regulating NF-κB/Nlrp3 signaling pathway, providing a potential therapeutic strategy in ALI.

Intrabronchial application of extracellular histones shows no proinflammatory effects in swine in a translational pilot study

Objective

Extracellular histones have been identified as one molecular factor that can cause and sustain alveolar damage and were linked to high mortality rates in critically ill patients. In this pilot study, we wanted to validate the proinflammatory in vivo effects of local histone application in a prospective translational porcine model. This was combined with the evaluation of an experimental acute lung injury model using intrabronchial lipopolysaccharides, which has been published previously.

Results

The targeted application of histones was successful in all animals. Animals showed decreased oxygenation after instillation, but no differences could be detected between the sham and histone treatments. The histologic analyses and inflammatory responses indicated that there were no differences in tissue damage between the groups.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05704-7.

Targeted fibre-optical intrabronchial lipopolysaccharide administration in pigs - a methodical refinement for improved accuracy in respiratory research

OBJECTIVE

To establish and evaluate a standardized method of targeted, intrabronchial drug delivery in pigs.

STUDY DESIGN

Randomized controlled trial.

ANIMALS

A total of 16 German Landrace pigs (Sus scrofa), age range 12‒16 weeks, and weighing 28‒35 kg.

METHODS

The animals were anaesthetized, intubated, and instrumented with extended cardiovascular monitoring. Lung injury was induced by administering via a flexible fibre-optic endoscope using 100 mL saline solution containing either 20 mg of Escherichia coli lipopolysaccharide (E. coli LPS) (n = 8) or no additive (sham, n = 8) into the two distal mainstem bronchi. The animals were monitored for 8 hours and arterial oxygenation, inspiratory pressure and arterial blood pressure were measured repeatedly. Post-mortem, lung tissue was prepared for histologic damage scoring and determination of proinflammatory cytokines Interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFα). Statistical analyses were performed using inter-group analysis of variance and Student's t tests. Data are presented as mean ± standard deviation. A p value <0.05 was considered significant.

RESULTS

The targeted application of LPS led to significant deterioration of oxygenation consistent with mild-to-moderate acute respiratory distress syndrome (ARDS) and hypotension (Horowitz ratio: sham 2 hour, 300 ± 39; LPS 2 hour, 193.7 ± 52; p < 0.001). Histologic analyses identified increased inflammation and oedema in the tissues of the animals in the LPS group IL-6 sham: 6.4 ± 4.4 × 10^-5 pg mL^-1; IL-6 LPS: 2.8 ± 2.4 × 10^-4 pg mL^-1, p = 0.015.

CONCLUSIONS

The targeted application of agents via flexible fibre-optic endoscopy is a valid, reliable method of causing controlled lung damage in a porcine model. The data presented suggest the feasibility and possible advantages of controlled application and could expand the array of techniques used to help understand the critical condition of ARDS. In addition, a targeted approach could help reduce animal numbers used for this purpose.

Hydrogen-Rich Saline Inhibits Lipopolysaccharide-Induced Acute Lung Injury and Endothelial Dysfunction by Regulating Autophagy through mTOR/TFEB Signaling Pathway

Background

Hydrogen-rich saline (HRS) has strong anti-inflammatory, antioxidative stress, and antiapoptotic properties. The study focused on the protection of HRS on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rat models and the relationship with autophagic regulation and mTOR/TFEB signaling pathway. Material and Methods. The LPS-induced ALI rats' model was established. Pathohistological change in lung tissue was detected by hematoxylin-eosin staining. The inflammatory cytokines were examined by enzyme-linked immunosorbent assay (ELISA). The key apoptosis proteins and autophagy-relevant proteins were analyzed by western blotting. In vitro, HPMEC models of ALI were treated with LPS. The inflammatory cytokines were detected. Apoptosis rate was determined by flow cytometry. The autophagy and mTOR/TFEB signaling pathway-related proteins were detected by western blot and immunohistochemical staining.

Results

HRS attenuated LPS-induced ALI and apoptosis both in vivo and in vitro. HRS attenuated inflammatory response, inhibited apoptosis, induced and activated autophagy in LPS-induced ALI model, and downregulated mTOR/TFEB signaling pathway. The protection of HRS can be blocked by autophagy inhibitor. Moreover, mTOR activator reversed HRS protection and mTOR inhibitor enhanced HRS protection in LPS-induced model and HRS activated autophagy via mTOR/TFEB signaling pathway.

Conclusion

The results confirmed the protection of HRS in LPS-induced ALI by regulating apoptosis through inhibiting the mTOR/TFEB signaling pathway.

LPS-RS attenuation of lipopolysaccharide-induced acute lung injury involves NF-κB inhibition

In this study, we studied the effect of lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS), an inhibitor of Toll-like receptor 4 (TLR4), in LPS-induced acute lung injury (ALI). Male Sprague-Dawley rats were treated with LPS-RS (0.1 mg/kg body mass, by intraperitoneal (i.p.) injection) 1 h before LPS injection (10 mg/kg, i.p.). Bronchoalveolar lavage fluid (BALF) and lung tissues were collected 24 h later to determine total and differential cell count, total protein content, levels of lactate dehydrogenase (LDH), histopathological changes, markers of oxidative stress, and mRNA expression of the inhibitory protein nuclear factor kappaB-α (NFκBIA) and TLR4. Additionally, rings of pulmonary artery were isolated for measuring vascular reactivity. LPS-induced ALI was indicated by increases in total and differential cell count, total protein, and LDH in BALF, and increased lung levels of malondialdehyde (MDA), as well as decreased activity of reduced glutathione (GSH) and superoxide dismutase (SOD). Moreover, LPS increased pulmonary artery contraction in response to phenylephrine (PE). Additionally, LPS downregulated mRNA expression of NFκBIA and upregulated mRNA expression of TLR4. LPS caused a marked inflammation in the lung tissue, with tubercular granuloma and numerous neutrophils. Pretreatment with LPS-RS protected against LPS-induced ALI by decreasing total and differential cell count, total protein, and LDH in BALF, and increased pulmonary GSH content and SOD activity without affecting MDA content. Additionally, it decreased the elevated PE-induced pulmonary artery contraction. LPS-RS upregulated mRNA expression of NFκBIA and downregulated mRNA expression of TLR4. Moreover, LPS-RS prevented inflammation in lung tissues. In conclusion, pretreatment with LPS-RS protects against LPS-induced ALI in rats through its anti-inflammatory effects, possibly by decreasing the mRNA expression of TLR4 and increasing that of NFκBIA.

In vivo porcine lipopolysaccharide inflammation models to study immunomodulation of drugs

Lipopolysaccharide (LPS), a structural part of the outer membrane of Gram-negative bacteria, is one of the most effective stimulators of the immune system and has been widely applied in pigs as an experimental model for bacterial infection. For this purpose, a variety of Escherichia coli serotypes, LPS doses, routes and duration of administration have been used. LPS administration induces the acute phase response (APR) and is associated with dramatic hemodynamic, clinical and behavioral changes in pigs. Pro-inflammatory cytokines, including tumor necrosis factor α (TNF-α), interleukin (IL)-1 and IL-6 are involved in the induction of the eicosanoid pathway and the hepatic production of acute phase proteins, including C-reactive protein (CRP), haptoglobin (Hp) and pig major acute phase protein (pig-MAP). Prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) play a major role in the development of fever and pulmonary hypertension in LPS-challenged pigs, respectively. The LPS-induced APR can be modulated by drugs. Steroidal and nonsteroidal anti-inflammatory drugs ((N)SAIDs) possess anti-inflammatory, antipyretic and analgesic properties through (non)-selective central and peripheral cyclooxygenase (COX) inhibition. Antimicrobial drugs, especially macrolide antibiotics, which are commonly used in veterinary medicine for the treatment of bacterial respiratory diseases, have been recurrently reported to exert clinically important immunomodulatory effects in human and murine research. To investigate the influence of these drugs on the clinical response, production of pro-inflammatory cytokines, acute phase proteins (APP) and the course of the febrile response in pigs, in vivo LPS inflammation models can be applied. Yet, to date, in vivo research on the immunomodulatory properties of antimicrobial drugs in these models in pigs is largely lacking. This review provides acritical overview of the use of in vivo porcine E. coli LPS inflammation models for the study of the APR, as well as the potential immunomodulatory properties of anti-inflammatory and antimicrobial drugs in pigs.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) prevents lipopolysaccharide (LPS)-induced, sepsis-related severe acute lung injury in mice

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an energy metabolism-related enzyme in the glycolytic pathway. Recently, it has been reported that GAPDH has other physiological functions, such as apoptosis, DNA repair and autophagy. Some in vitro studies have indicated immunological aspects of GAPDH function, although there is no definite study discussing the advantage of GAPDH as a therapeutic target. Here, we show that GAPDH has an anti-inflammatory function by using a lipopolysaccharide (LPS)-induced, sepsis-related severe acute lung injury (ALI) mouse model, which is referred to as acute respiratory distress syndrome (ARDS) in humans. GAPDH pre-injected mice were protected from septic death, and their serum levels of proinflammatory cytokines were significantly suppressed. In lung tissue, LPS-induced acute injury and neutrophil accumulation were strongly inhibited by GAPDH pre-injection. Pulmonary, proinflammatory cytokine gene expression and serum chemokine expression in GAPDH pre-injected mice were also reduced. These data suggest the therapeutic potential of GAPDH for sepsis-related ALI/ARDS.

Lipopolysaccharide impaired the functional activity of endothelial colony-forming cells

BACKGROUND

Recent studies have shown that endothelial progenitor cells (EPCs) contribute to lung repair after lipopolysaccharide (LPS)-induced lung injury and infusion of LPS decreased early EPCs in human peripheral blood. However, the effects of LPS on endothelial colony-forming cells (ECFCs) remain to be determined.

OBJECTIVE

To investigate possible effects of LPS on the functional activity of ECFCs.

METHODS

ECFCs were isolated from human umbilical cord blood and characterized. ECFCs at passages 3-5 were treated for 24 h with either LPS or vehicle control. Their viability, migration and in vitro vasculogenesis activity were assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, modified Boyden chamber and in vitro angiogenesis assays, respectively. ECFC adhesion was assessed by replating cells on fibronectin-coated dishes and subsequent counting of adherent cells.

RESULTS

Incubation with LPS dose-dependently inhibited the viable, migratory, adhesive and in vitro vasculogenesis capacity of ECFCs.

CONCLUSION

LPS impaired the functional activity of ECFCs.

Resveratrol reduces acute lung injury in a LPS‑induced sepsis mouse model via activation of Sirt1

The development of acute lung injury (ALI) during sepsis almost doubles the mortality rate of patients. The efficacy of current treatment strategies is low as treatment is usually initiated following the onset of symptoms. Inflammation is one of the main mechanisms of autoimmune disorders and is a common feature of sepsis. The suppression of inflammation is therefore an important mechanism for the treatment of sepsis. Sirtuin 1 (Sirt1) has been demonstrated to play a role in the regulation of inflammation. Resveratrol, a potent Sirt1 activator, exhibits anti‑inflammatory properties. However, the role of resveratrol for the treatment of ALI during sepsis is not fully understood. In the present study, the anti‑inflammatory role of Sirt1 in the lipopolysaccharide (LPS)‑induced TC‑1 cell line and its therapeutic role in ALI was investigated in a mouse model of sepsis. The upregulation of matrix metalloproteinase-9, interleukin (IL)‑1β, IL‑6 and inducible nitric oxide synthase was induced by LPS in the mouse model of sepsis and the TC‑1 cell line, and resveratrol suppressed the overexpression of these proinflammatory molecules in a dose‑dependent manner. Resveratrol decreased pulmonary edema in the mouse model of sepsis induced by LPS. In addition, resveratrol improved lung function and reduced pathological alterations in the mouse model of sepsis. Knockdown of Sirt1 by RNA interference resulted in an increased susceptibility of TC‑1 cells to LPS stimulation and diminished the anti‑inflammatory effect of resveratrol. These results demonstrated that resveratrol inhibits LPS‑induced ALI and inflammation via Sirt1, and indicated that Sirt1 is an efficient target for the regulation of LPS‑induced ALI and inflammation. The present study provides insights into the treatment of ALI during sepsis.

Endotoxin-induced lung injury in mice: structural, functional, and biochemical responses

Acute lung injury is usually a complication of sepsis, and endotoxin treatment of mice is a frequently used experimental model. To define this model and to clarify pathogenesis of the lung injury, we injected with 1 mg/kg endotoxin ip and measured pulmonary function, pulmonary edema, serum concentrations of cytokines and growth factors, and lung histology over 48 h. During the first 6 h, tidal volume and minute volume increased and respiratory frequency decreased. Serum concentrations of cytokines showed three patterns: 10 cytokines peaked at 2 h and declined rapidly, two peaked at 6 h and declined, and two had biphasic peaks at 2 and 24 h. Growth factors increased later and remained elevated longer. Both collagen and fibronectin were deposited in the lungs beginning within hours of endotoxin and resolving over 48 h. Histologically, lungs showed increased cellularity at 6 h with minimal persistent inflammation at 48 h. Lung water peaked at 6 h and gradually decreased over 48 h. We conclude that intraperitoneal administration of endotoxin to mice causes a transient systemic inflammatory response and transient lung injury and dysfunction. The response is characterized by successive waves of cytokine release into the circulation, early evidence of lung fibrogenesis, and prolonged increases in growth factors that may participate in lung repair.

L-lysine decreases nitric oxide production and increases vascular resistance in lungs isolated from lipopolysaccharide-treated neonatal pigs

Nitric oxide (NO) production may depend on the uptake of L-arginine (L-arg), the substrate for NO synthase in inflammatory lung diseases. The cellular transport of L-arg occurs via the cationic amino acid transporters (CAT), and L-lysine (L-lys) competitively inhibits CAT. Neonatal pigs were treated with lipopolysaccharide (LPS) or vehicle for 4 h. LPS increased exhaled NO (exNO; 0.026 +/- 0.003 to 0.046 +/- 0.003 nmol. kg(-1). min(-1); p < 0.005) and decreased mean systemic arterial blood pressure (89 +/- 4 to 67 +/- 4 mm Hg; p < 0.05), whereas vehicle did not affect exNO or mean systemic arterial blood pressure. The lungs were then isolated and perfused; exNO was greater in lungs from LPS-treated animals (0.08 +/- 0.01 nmol/kg/min) than in lungs from vehicle-treated animals (0.05 +/- 0.01 nmol. kg(-1). min(-1); p < 0.05). The addition of L-arg (0.3 mM) significantly (p < 0.05) increased exNO production in both groups of lungs (mean increase 0.04 +/- 0.01 nmol. kg(-1). min(-1) LPS-treated lungs, p < 0.05; mean increase 0.02 +/- 0.01 nmol. kg(-1). min(-1) vehicle-treated lungs); however, L-arg decreased pulmonary vascular resistance (PVR) only in LPS-treated lungs (mean decrease 0.03 +/- 0.01 mm Hg. ml(-1). kg(-1). min(-1), p < 0.05). L-lys caused a dose-dependent decrease in exNO production and a dose-dependent increase in PVR in LPS-treated lungs. L-lys decreased exNO only at 30 mM and had no effect on PVR in vehicle-treated lungs. In four lungs each from vehicle- and LPS-treated animals, reverse transcriptase-PCR demonstrated CAT-2 mRNA only in LPS-treated animals. These results suggest that the increased NO production in the lungs from LPS-treated animals depends on the uptake of vascular L-arg.