The Roles Of Histone Deacetylase Inhibitors On Ventilator-Induced Lung Injury

PART ⅠTo establish the animal model of mechanical ventilation-induced lung injuryObjectiveTo establish a rat model of mechanical ventilation induced lung injury (VILI), and to study the pathophysiological changes and its possible mechanism of VILI.MethodsRat VILI animal model is divided into two parts:the first part was grouped according to the duration time of mechanical ventilation:40healthy male SD rats, weighing between240-290were randomly divided into A1, A2, A3, A4four groups, n=10. A1group was the control group; A2group was tidal volume ventilationlh group; A3group was tidal volume ventilation2h group; A4group was tidal volume ventilation4h group. The set tidal volume (VT) of A2-A4was42ml/kg, respiratory rate was40beats/min. Positive end expiratory pressure (PEEP) was set to0. Four groups of animals on mechanical ventilation or spontaneous breathing were sacrificed, the lung tissue was collected and the lung wet/dry weight ratio (W/D) was calculated, the lung injury score light was detected by microscope observations and pathological changes. The neutrophil myeloperoxidase (MPO) activity was simultaneous detected. Bronchoalveolar lavage fluid (BALF), the expression levels of TNF-α, IL-1β and IL-6were detected. The ICAM-1expression level in lung tissue was detected. The second part was grouped according to tidal volume of mechanical ventilation:40healthy male SD rats, weighing between240-290were randomly divided into B1, B2, B3, B4four groups of10each. B1group was the control group; B2group was set low tidal volume ventilation, tidal volume (VT) was7ml/kg, end-expiratory pressure (PEEP) was set to3cm H2O; B3group was the middle tidal volume ventilation group, tidal volume (VT) was20ml/kg; B4group was high tidal volume ventilation, tidal volume (VT) was42ml/kg. B2, B3, B4group ventilatory frequency was40beats/min. Four groups of animals on mechanical ventilation or spontaneous breathing were sacrificed, the lung tissue was collected and the lung wet/dry weight ratio (W/D) was calculated, the lung injury score light was detected by microscope observations and pathological changes. The neutrophil myeloperoxidase (MPO) activity was simultaneous detected. Bronchoalveolar lavage fluid (BALF), the expression levels of TNF-α, IL-1β and IL-6were detected. Real-time PCR and Western blot were used to detect the ICAM-1expression level in lung tissues.Results1. light microscope:A1lung tissue without significant changes in the histological injury; A2had obvious pathological changes in lung tissue, such as:lung capillary congestion, swelling and thickening of alveolar septa, alveolar over number of inflammatory cell infiltration, alveolar exudate visible liquid, some alveolar atrophy atelectasis; A3had increased pathological changes in lung tissue; A4had serious pathological changes in lung tissue. In comparison with A1group, The ALI scores of A2, A3, A4Groups was significantly higher (P<0.01); In comparison with A2group, the ALI score of A3, A4groups was significantly higher (P<0.01); In comparison with A3group, the ALI score of A4group was significantly higher (P<0.01).2.in comparison with A1group, the wet to dry weight (W/D) ratio, MPO activity, TNF-α, IL-1β and IL-6levels, ICAM-1gene and protein expression of A2, A3, A4groups were significantly increased (P<0.01); In comparison with A2group, these indicators of A3, A4group were increased significantly (P<0.01); In comparison with A3group, these index values of A4group were significantly increased (P<0.01).3.In B1, B2group, no significant pathological changes of lung tissue were observed, the alveolar septa was normal, a small amount of inflammatory cells and macrophages were occasionally observed, no alveolar was exudate; In B3group, obvious pathological changes were observed, alveolar septal was thickening, alveolar inflammatory cells were more visible, some bloody alveolar exudate was observed; In B4group, pathological changes in lung tissue were significantly increased, alveolar septa was thickened, alveolar inflammatory cells were significantly increased and bloody exudate was clearly observed in alveolar cavity.4.In comparison with B1, B2group, the ALI score of B3, B4groups was significantly higher (P<0.01); In comparison with group B3, the ALI score of B4group was significantly higher (P<0.01).(Four) In comparison with B1, B2group, the W/D and MPO values, TNF-a, IL-1(3and IL-6levels, ICAM-1gene and protein expression of B3, B4were significantly higher (P<0.01); In comparison with B3, the W/D and MPO values, TNF-α, IL-1β and IL-6levels, ICAM-1gene and protein expression of B4group was significantly increased (P<0.01).ConclusionsHigh tidal volume ventilation produced a significant acute lung injury; the extent of acute lung injury was increased with the increased-extension of time. PART IIThe protective effect of VILI by histone deacetylase inhibitorsObjectiveTo explore the potential roles of histone deacetylase inhibitor on mechanical ventilation-induced acute lung injury and to explore the possible mechanisms.Methods40SD rats were randomly divided into four groups (n=10):low tidal volume mechanical ventilation group (LV group); high tidal volume mechanical ventilation group (HV group); TSA treatment group (HV+TSA group); SAHA treatment group (HV+SAHA group). LV group underwent low tidal volume (VT7ml/kg, RR40times/min), the remaining three groups were high tidal volume (VT42ml/kg, RR40times/min), four groups were mechanically ventilated for4h. HV+TSA, HV+SAHA group were injected intraperitoneally TSA (2mg/kg), or SAHA (200mg/kg), Rats from LV group and HV group were intraperitoneal injection of equal PBS in30mins before mechanical ventilation. After30minutes, these rats were given mechanical ventilation. Four groups of animals on mechanical ventilation or spontaneous breathing were sacrificed, the lung tissue was collected and the lung wet/dry weight ratio (W/D) was calculated, the lung injury score light was detected by microscope observations and pathological changes. The neutrophil myeloperoxidase (MPO) activity was simultaneous detected. Bronchoalveolar lavage fluid (BALF), the expression levels of TNF-α, IL-1β and IL-6were detected. Real-time PCR and Western blot were used to detect the ICAM-1expression level in lung tissues.Results1.LV group had no significant pathological changes in lung tissue, alveolar septa was thin and uniform, and a small amount of inflammatory cells and macrophages were occasionally observed, no exudate in alveolar. High tidal volume group (HV group) had significantly increased lung pathology changes, alveolar septa was thicken, alveolar inflammatory cells were significantly increased in alveolar with obvious visible bloody exudate, some alveolar atrophy atelectasis. In Histone deacetylase inhibitors groups (HV+TSA group and HV+SAHA group):In compared with the high tidal volume group, alveolar compression was significantly reduced, alveolar septum was significantly reduced, pulmonary interstitial edema was reduced significantly, alveolar exudate was significantly reduced. In compared with the HV group, the ALI scores of HV+TSA group and HV+SAHA group were significantly higher (P<0.01).2.1n compared with the HV group, the lung tissue W/D ratio and MPO activity, TNF-α, IL-1β and IL-6levels, ICAM-1gene and protein expression of HV+TSA group and HV+SAHA were significantly decreased (P<0.01).ConclusionsHistone deacetylase inhibitors could significantly relief ventilator-associated lung injury, mainly through the anti-inflammatory and anti-oxidant roles, suggesting a protective role of histone deacetylase inhibitors for tidal volume-induced lung injury.