Mechanical ventilation enhances extrapulmonary sepsis-induced lung injury: role of WISP1–αvβ5 integrin pathway in TLR4-mediated inflammation and injury

Abstract

BackgroundHigh tidal volume ventilation of healthy lungs or exacerbation of existing acute lung injury (ALI) by more moderate mechanical ventilation (MTV) produces ventilator-induced lung injury. It is less clear whether extrapulmonary sepsis sensitizes the lung to MTV.MethodsWe used a two-hit model of cecal ligation and puncture (CLP) followed 12 h later by MTV (10 ml/kg; 6 h) to determine whether otherwise noninjurious MTV enhances CLP-induced ALI by contrasting wildtype and TLR4−/− mice with respect to: alveolar-capillary permeability, histopathology and intrapulmonary levels of WNT-inducible secreted protein 1 (WISP1) and integrin β5; plasma levels of cytokines and chemokines (TNF-α, IL-6, MIP-2, MCP-1) and intrapulmonary neutrophil infiltration; and other inflammatory signaling via intrapulmonary activation of JNK, p38 and ERK. A separate cohort of mice was pretreated with intratracheal neutralizing antibodies to WISP1, integrin β5 or IgG as control and the presented phenotyping repeated in a two-hit model; there were 10 mice per group in these first three experiments. Also, isolated peritoneal macrophages (PM) from wildtype and TLR4−/−, MyD88−/− and TRIF−/− mice were used to identify a WISP1–TLR4–integrin β5 pathway; and the requisite role of integrin β5 in WISP1-induced cytokine and chemokine production in LPS-primed PM was examined by siRNA treatment.ResultsMTV, that in itself did not cause ALI, exacerbated increases in alveolar-capillary permeability, histopathologic scoring and indices of pulmonary inflammation in mice that previously underwent CLP; the effects of this two-hit model were abrogated in TLR4−/− mice. Attendant with these findings was a significant increase in intrapulmonary WISP1 and integrin β5 in the two-hit model. Anti-WISP1 or anti-integrin β5 antibodies partially inhibited the two-hit phenotype. In PM, activation of TLR4 led to an increase in integrin β5 expression that was MyD88 and NF-κB dependent. Recombinant WISP1 increased LPS-induced cytokine release in PM that was inhibited by silencing either TLR4 or integrin β5.ConclusionsThese data show for the first time that otherwise noninjurious mechanical ventilation can exacerbate ALI due to extrapulmonary sepsis underscoring a potential interactive contribution of common events (sepsis and mechanical ventilation) in critical care, and that a WISP1–TLR4–integrin β5 pathway contributes to this phenomenon.Electronic supplementary materialThe online version of this article (10.1186/s13054-018-2237-0) contains supplementary material, which is available to authorized users.

WISP1 and TLR4 on Macrophages Contribute to Ventilator-Induced Lung Injury

“…In addition, we also found that pure over-distension on healthy mice lung could only raise WISP1 level, while it could not upregulate cytokine levels (the results were not shown in this paper). Reports about WISP1 mainly concentrated on WISP1/β-catenin signaling pathway [30], like our previous study about WISP1 interacting with β6 [19,31] or with β3 [32,33], which was related to alveolarcapillary permeability in VILI or ALI/ARDS.…”

Mechanical Ventilation Exacerbates Poly (I:C) Induced Acute Lung Injury: Central Role for Caspase-11 and Gut-Lung Axis

“…2 (and consistent with the above ndings ( Fig. 1) and our previous ndings [18][19][20]), MTV alone for 4 h had no impact on indices of lung injury including leakage of Evans blue dye into the lung ( Fig. 2A), accumulation of protein into the BAL uid (BALF; Fig.…”

“…Nonetheless, otherwise non-injurious lower tidal volume ventilation may exacerbate preexisting acute lung injury due to bacterial [5,6] or viral [11] infection, intratracheal endotoxin [7][8][9][10] or sterile injury such as hyperoxia [14] or acid instillation [12,13]. Sensitization of VILI to events originating at distal sites or plasma space including exogenous endotoxin [16,17] or polymicrobial sepsis [18,19] has also been documented. We con rmed [20] that MTV exacerbated modest acute lung injury secondary to intratracheal instillation of Poly(I:C).…”

“…For Hematoxylin & Eosin (H & E) staining, the left upper lobe was in ated with 4% paraformaldehyde, embedded in para n and assessed via semiquantitative histopathology at light microscopic level including following features: edema, hyperemia and congestion, neutrophil margination and tissue in ltration, intra-alveolar hemorrhage and debris, and cellular hyperplasia [18]. Each feature was graded as absent, mild, moderate, or severe, with a score of 0-3.…”

“…In preclinical studies, sensitization of VILI to preexisting acute lung injury (ALI) secondary to pneumonia [5,6], intratracheal endotoxin [7][8][9][10], viral [11] and sterile injury [12][13][14] is apparent. Although preclinical outcomes vary as a function of magnitude of extrapulmonary septic condition and the nature of mechanical ventilation parameters (tidal volume, onset and duration; positive end expiratory pressure; [15]), sensitization of VILI to events originating in distal site and plasma space including exogenous endotoxin [16,17] and polymicrobial sepsis [18,19] has also been documented.…”