The Protective Effect Of Magnesium Sulfate On Placental Inflammation Via Suppressing The NF-κB/NLRP3 Signaling In A Preeclampsia-like Rat Model

Objective:Abnormal placental inflammation has a role in the pathophysiology of preeclampsia（PE）.Magnesium sulfate（Mg SO₄）has anti-inflammatory properties and is a fetal neuroprotective agent.Mg SO₄ is often used to treat severe preeclampsia;however,the specific mechanisms of action underlying this therapeutic effect remain unclear.The objective of this study was to investigate the effects of Mg SO₄ on placental inflammation in a rat model of lipopolysaccharide（LPS）-induced preeclampsia.Methods:Pregnant SD rats were randomized to four groups:pregnant（P）;preeclampsia（LPS）;Mg SO₄ intervention（LPS+MG）;and preeclampsia control（LPS+NS）.A rat model of preeclampsia was established by LPS（1.0μg/kg,2ml/h,Sigma-Aldrich）injection via the tail vein after anesthesia with intraperitoneal injection sodium pentobarbital（40mg/kg?bw）on GD14.Mg SO₄（270 mg/kg）（LPS+Mg SO₄）or saline（LPS+NS）was administered by daily intraperitoneal injection from GD14 to GD19.Systolic blood pressure（SBP）was recorded in the tail artery on GD13,GD15,GD17 and GD19 of the rat while awake using A non-invasive tail cuff blood pressure measuring system and 24h urine was collected to measure urinary albumin.Pregnant rats were euthanized by intraperitoneal injection of sodium pentobarbital on GD20,the fetuses were removed by cesarean section,fetal-related outcomes were observed and recorded,and placental tissues were then collected.The methods of HE staining,RT-q PCR,immunohistochemistry and western blot were used to detect expression levels of vascular-associated proteins（s Flt-1,CD31+）,cellular inflammatory factors（IL-1β,IL-12,IL-10,APOE）,NLRP3 inflammasome associated proteins（NLRP3,ASC,Caspase-1）and NF-κB in placental tissue.Results:1.In LPS and LPS+NS rats,SBP and 24h urinary albumin levels were significantly increased compared to normal control rats.In this way,it was successful to establish the model of preeclampsia-like rats induced by LPS.In LPS+MG rats,SBP and the 24h urinary albumin levels were reduced and approached to those in normal pregnant rats.2.In LPS and LPS+NS group,fetal crown-rump length,fetal weight,placental weight and the ratio of fetal weight/placental weight were significantly decreased,while FGR and dead pups per litter was significantly increased compared to P group.In LPS+MG group,fetal outcomes were improved to a large extent compared to LPS and LPS+NS group.3.In LPS and LPS+NS groups,placental inflammatory grade was elevated,with increased levels of inflammatory factors and decreased levels of anti-inflammatory factors compared to normal controls.Toμ some extent,Mg SO₄ intervention mitigated placental pathology,reduced placental inflammatory factor levels and increased anti-inflammatory factor levels compared to the LPS and LPS+NS groups.4.In LPS and LPS+NS groups,the expression of placental s Flt-1 was increased and CD31+expression was decreased compared to normal controls.Mg SO₄ intervention inhibited the expression of antiangiogenic factors and significantly improved placental blood supply compared to the LPS and LPS+NS groups.5.In the LPS and LPS+NS groups,placental tissues exhibited increased expression of NLRP3 inflammasome associated proteins（NLRP3,Caspase-1,ASC）and phosphorylation levels of NF-κB essential protein（IκB,p65）compared to normal controls,while increased NF-κB translocations shown by immunohistochemistry.Compared to the LPS and LPS+NS groups,Mg SO₄intervention suppressed the activation of NLRP3 inflammasome and NF-κB signaling pathway.Conclusion:Mg SO₄ may improve placental function by promoting placental angiogenesis and inhibiting excessive activation of NF-κB/NLRP3 signaling pathway to reduce placental inflammatory response,ultimately reducing the occurrence of preeclampsia and improving maternal-fetal outcome.