Adrenaline Attenuates the Acute Lung Injury After Intratracheal Lipopolysaccharide Instillation: an Experimental Study

Anti-inflammatory action of Athyrium multidentatum extract suppresses the LPS-induced TLR4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial part of Athyrium multidentatum (Doll.) Ching (AM) is widely used in the northeastern region of China as an edible wild herb, but its medicinal value, especially its anti-inflammatory effect, has not been fully explored.

AIM OF THE STUDY

To investigate the anti-inflammatory activity of AM and clarify the anti-inflammatory mechanism involving the TLR4 signaling pathway using a lipopolysaccharide (LPS)-induced inflammatory model.

MATERIALS AND METHODS

AM ethanol extract was used as the experimental material to investigate the effect that the extract has on the production of pro-inflammatory mediators (NO, PGE_2, TNF-α, IL-1β and IL-6); changes in LPS-induced peritoneal macrophages (PMs); and TLR4-mediated intracellular events, including MAPKs (ERK, JNK, and p38) and IκB-α in the MyD88-dependant pathway and IRF3, STAT1, and STAT3 in the TRIF-dependent pathway. In in vivo experiments, we established an LPS-induced acute lung injury (ALI) model and investigated the cell count and cytokine (TNF-α, IL-1β and IL-6) levels in bronchoalvelar lavage fluid (BALF) of C57BL6 mice. Histological changes in the lung tissues were observed with H&E staining.

RESULTS

AM extract inhibited NO and PGE₂ by suppressing their synthetase (iNOS and COX-2) gene expression in LPS-induced PMs; the secretion of IL-6, IL-1β, and TNF-α also deceased via the down-regulation of mRNA levels. Furthermore, the TLR4-mediated intracellular events involved the phosphorylated forms of MAPKs (ERK, JNK) and IκB-α in the MyD88-dependent pathway and the TRIF-dependent pathway (IRF3, STAT1, STAT3), and the relevant proteins were expressed at low levels in the AM extract groups. In in vivo experiments, the cell count and cytokine (TNF-α, IL-1β and IL-6) levels in BALF decreased significantly in a dose-dependent manner in the AM extract groups. The lung tissue structure exhibited dramatic damage in the LPS group, and the damaged area decreased in the AM extract groups; in particular, the effect of 10 mg/kg extract was similar to that of the positive control dexamethasone (DEX).

CONCLUSION

The findings demonstrate that AM protects against LPS-induced acute lung injury by suppressing TLR4 signaling, provide scientific evidence to support further study of the safety of anti-inflammatory drugs and indicate that AM can be used as an anti-inflammatory and anti-injury agent to prevent pneumonia caused by microbial infection.

EFhd2/swiprosin-1 regulates LPS-induced macrophage recruitment via enhancing actin polymerization and cell migration

Macrophage motility is vital in innate immunity, which contributes strategically to the defensive inflammation process. During bacterial infection, lipopolysaccharide (LPS) potently activates the migration of macrophages via the NF-κB/iNOS/c-Src signaling pathway. However, the downstream region of c-Src that participates in macrophage migration is unclear. EFhd2, a novel actin bundling protein, was evaluated for its role in LPS-stimulated macrophage migration in this study. We found that LPS stimulated the up-regulation, tyrosine phosphorylation and membrane translocation of EFhd2 in macrophages. The absence of EFhd2 inhibited the recruitment of macrophages in the lungs of LPS-induced septic mice. LPS-induced macrophage migration was neutralized by the deletion of EFhd2. EFhd2-mediated up-regulation of NFPs (including Rac1/Cdc42, N-WASP/WAVE2 and Arp2/3 complex) induced by LPS could be used to explain the role of EFhd2 in promoting actin polymerization. Furthermore, the purified EFhd2 could directly promote actin polymerization in vitro. Dasatinib, a c-Src specific inhibitor, inhibited the up-regulation of EFhd2 stimulated by LPS. Therefore, our study demonstrated that EFhd2 might be involved in LPS-stimulated macrophage migration, which provides a potential target for LPS-activated c-Src during macrophage mobilization.

Acanthopanax trifoliatus inhibits lipopolysaccharide-induced inflammatory response in vitro and in vivo

Acanthopanax trifoliatus is a well-known herb that is used for the treatment of bruising, neuralgia, impotence, and gout in Taiwan. This herb exhibits multifunctional activities, including anticancer, anti-inflammation, and antioxidant effects. This paper investigated the in vitro and in vivo anti-inflammatory effect of A. trifoliatus. High-performance liquid chromatography analysis established the fingerprint chromatogram of the ethyl acetate fraction of A. trifoliatus (EAAT). The anti-inflammatory effect of EAAT was detected using lipopolysaccharide (LPS) stimulation of the mouse macrophage cell line RAW264.7 in vitro and LPS-induced lung injury in vivo. The effects of EAAT on LPS-induced production of inflammatory mediators in RAW264.7 murine macrophages and the mouse model were measured using enzyme-linked immunosorbent assay and Western blot. EAAT attenuated the production of LPS-induced nitric oxide (NO), tumor necrosis factor-alpha, interleukin-1β (IL-1β), and IL-6 in vitro and in vivo. Pretreatment with EAAT markedly reduced LPS-induced histological alterations in lung tissues. Furthermore, EAAT significantly reduced the number of total cells and protein concentration levels in the bronchoalveolar lavage fluid. Western blotting test results revealed that EAAT blocked protein expression of inducible NO synthase, cyclooxygenase-2, phosphorylation of Nuclear factor-kappa-B Inhibitor alpha (IκB-α) protein, and mitogen-activated protein kinases in LPS-stimulated RAW264.7 cells as well as LPS-induced lung injury. This study suggests that A. trifoliatus may be a potential therapeutic candidate for the treatment of inflammatory diseases.

Epinephrine enhances the response of macrophages under LPS stimulation

Trauma associated with infection may directly trigger a neuroendocrine reaction in vivo while the hormone epinephrine is known to mediate immune responses to inflammation after injury. However, the role of epinephrine during the earliest stage of trauma still remains unclear. We therefore explored the role of epinephrine on activated macrophages under LPS stimulation in vitro as well as the mechanisms underlying its effect. Dose- and time-dependent effects of epinephrine on macrophage immune function were assessed after LPS activation. We also employed CD14 siRNA interference to investigate whether CD14 played a role in the mechanism underlying the effect of epinephrine on LPS-induced macrophage responses. Our results showed that epinephrine pretreatment (10 ng/mL) significantly promoted immune responses from LPS stimulated macrophages, including phagocytic rate, phagocytic index, TNFα/IL-1β/IL-10 secretion, and CD14 expression (P < 0.05). Moreover, TNFα/IL-1β/IL-10 levels attained their peak value 1 hour after incubation with 10 ng/mL epinephrine (P < 0.05), and CD14 siRNA transfection dramatically decreased phagocytosis and cytokine secretion by LPS-activated macrophages (P < 0.05). We therefore conclude that 10 ng/mL epinephrine enhances immune responses from macrophages under LPS stimulation and that the underlying mechanism may relate to CD14 upregulation on the surface of macrophages.

Methanol extract of Antrodia camphorata protects against lipopolysaccharide-induced acute lung injury by suppressing NF-κB and MAPK pathways in mice

Antrodia camphorata (AC) has been used as a herbal medicine for drug intoxication for the treatment of inflammation syndromes and liver-related diseases in Taiwan. This study demonstrates the protective effect of the methanol extract of AC (MAC) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. Mice were treated with MAC 1 h before the intratracheal (I.T.) instillation of LPS challenge model. Lung injury was evaluated 6 h after LPS induction. Pretreatment with MAC markedly improved LPS-induced histological alterations and edema in lung tissues. Moreover, MAC also inhibited the release of pro-inflammatory mediators such as nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6 at 6 h in the bronchoalveolar lavage fluid (BALF) during LPS-induced lung injury. Furthermore, MAC reduced total cell number and protein concentrations in the BALF the pulmonary wet/dry weight (W/D) ratio, and myeloperoxidase activity and enhanced superoxide dismutase (SOD) activity in lung tissues. MAC also efficiently blocked protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and phosphorylation of mitogen-activated protein kinases (MAPKs) and inhibited the degradation of nuclear factor-kappa B (NF-κB) and IκBα. This is the first investigation in which MAC inhibited acute lung edema effectively, which may provide a potential target for treating ALI. MAC may utilize the NF-κB and MAPKs pathways and the regulation of SOD activity to attenuate LPS-induced nonspecific pulmonary inflammation.

Lysimachia clethroides Duby extract attenuates inflammatory response in Raw 264.7 macrophages stimulated with lipopolysaccharide and in acute lung injury mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Lysimachia clethroides Duby (LC) is a traditional medicinal herb used to treat edema, hepatitis and inflammatory diseases in China and other Asian countries. In this study, the anti-inflammatory effects of LC extract and the mechanisms underlying were explored in both in vitro cell lines and acute lung injury (ALI) animal model of inflammation in vivo.

MATERIALS AND METHODS

Lipopolysaccharide (LPS)-stimulated Raw 264.7 murine macrophages were used to study the regulatory effects of LC extract on inflammatory mediators such as nitric oxide (NO) and proinflammatory cytokine expression. Western blotting or ELISA techniques were employed to estimate protein levels. RT-PCR was used for analyzing the interferon (IFN)-β production. LPS-induced ALI mouse model in vivo was employed to study the effect of LC extract. Further high-performance liquid chromatography (HPLC) fingerprinting technique was used to evaluate the active constituents present in LC extract, compared with reference standards.

RESULTS

Pre-treatment with LC extract inhibited the LPS-stimulated NO release, interleukin (IL)-1β and IL-6 production in Raw 264.7 cells dose dependently. LC extract inhibited the LPS-stimulated IRF3 and STAT1 phosphorylation. Further, in vivo experiments revealed that LC extract suppressed the infiltration of immune cells into the lung and proinflammatory cytokine production in broncho-alveolar lavage fluid (BALF) in the LPS-induced ALI mouse model.

CONCLUSIONS

Our results indicate that LC extract attenuates LPS-stimulated inflammatory responses in macrophages via regulating the key inflammatory mechanisms, providing a scientific support for its traditional use in treating various inflammatory diseases.

Indole-3-carbinol inhibits LPS-induced inflammatory response by blocking TRIF-dependent signaling pathway in macrophages

Indole-3-carbinol (I3C), a natural hydrolysis product of glucobrassicin, is a member of the Brassica family of vegetables and is known to have various anti-cancer activities. In the present study, we assessed in vitro and in vivo anti-inflammatory effects of I3C and its molecular mechanisms. I3C attenuated the production of pro-inflammatory mediators such as NO, IL-6, and IL-1β in LPS-induced Raw264.7 cells and THP-1 cells through attenuation of the TRIF-dependent signaling pathway. Furthermore, I3C suppressed the infiltration of immune cells into the lung and pro-inflammatory cytokine production such as IL-6, TNF-α in broncho-alveolar lavage fluid (BALF) in the LPS-induced acute lung injury mouse model. I3C also suppressed IL-1β secretion in nigericin treated in vivo model. I3C has potent anti-inflammatory effects through regulating TRIF-dependent signaling pathways, suggesting that I3C may provide a valuable therapeutic strategy in treating various inflammatory diseases.

T cell pathways involving CTLA4 contribute to a model of acute lung injury

Acute lung injury (ALI) is a frequent pulmonary complication in critically ill patients. We characterized a murine model of LPS-induced ALI, focusing on Th cells. Following LPS administration, bronchoalveolar lavage lymphocytes, neutrophils, IL-6, TNF-alpha, and albumin were increased. Analysis of LPS-induced T cells revealed increased Th cell-associated cytokines (IL-17A, -17F, and -22), as well as increased expression of CD69 (a cell activation marker), Foxp3, and CTLA4 in CD4(+) T cells. Administration of anti-CTLA4 Ab decreased LPS-induced bronchoalveolar lavage albumin and IL-17A, while increasing CD4(+)Foxp3(+) cell number and Foxp3 expression in CD4(+)Foxp3(+) cells. These data suggest that pulmonary LPS administration promotes CD4(+) T cells and that T cell pathways involving CTLA4 contribute to ALI.

Propagation prevention: a complementary mechanism for "lung protective" ventilation in acute respiratory distress syndrome

OBJECTIVE

To describe the clinical implications of an often neglected mechanism through which localized acute lung injury may be propagated and intensified.

DATA EXTRACTION AND SYNTHESIS

Experimental and clinical evidence from the medical literature relevant to the airway propagation hypothesis and its consequences.

CONCLUSIONS

The diffuse injury that characterizes acute respiratory distress syndrome is often considered a process that begins synchronously throughout the lung, mediated by inhaled or blood-borne noxious agents. Relatively little attention has been paid to possibility that inflammatory lung injury may also begin focally and propagate sequentially via the airway network, proceeding mouth-ward from distal to proximal. Were this true, modifications of ventilatory pattern and position aimed at geographic containment of the injury process could help prevent its generalization and limit disease severity. The purposes of this communication are to call attention to this seldom considered mechanism for extending lung injury that might further justify implementation of low tidal volume/high positive end-expiratory pressure ventilatory strategies for lung protection and to suggest additional therapeutic measures implied by this broadened conceptual paradigm.