Meconium Influences Pulmonary Short-Chain Fatty Acid Concentration in Porcine Meconium Aspiration Model
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Published on: March 8, 2024
Harry Ramcharran1, Auyon Ghosh2, Qinghe Meng1
1Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, USA.
Introduction:
The factors influencing meconium aspiration syndrome (MAS) severity remain poorly understood. In a piglet model of MAS, we hypothesized the respiratory microbiome would reflect the bacterial signature of meconium with short-chain fatty acid (SCFA) accumulation as a byproduct of bacterial fermentation.
Methods:
Cesarean section at approximately 115-day term was performed on two sows. Male (9) and female (3) piglets were delivered, instrumented, anesthetized, and randomized into a Control (n = 6) or MAS group (n = 6). MAS received a meconium slurry (3 mL/kg) aspiration injury. Experimental animals were monitored continuously, ventilated, and resuscitated for 24 h. BALF was collected for 16S microbiome sequencing and SCFA analysis by gas chromatography. Effects of SCFAs on A549 alveolar pulmonary epithelial in vitro cell viability and inflammation were assessed.
Results:
The MAS group had significantly higher fluid and vasopressor requirements than the Control group (p < 0.05) though both groups developed lung injury. The meconium microbiome demonstrated a difference in genus proportions as compared with the BALF of the Control and MAS groups. The MAS group had a relative increase in propionic acid-forming bacteria and higher BALF concentrations of propionic acid (0.6 ± 0.2 mmol/kg) than the Control group (0.2 ± 0.2 mmol/kg; p > 0.05). Propionic acid was associated with decreased pulmonary epithelial cell viability and an upregulated pro-inflammatory response.
Conclusions:
Meconium may host a microbiome with byproducts that interact with the pulmonary epithelium and influence lung injury severity in MAS.
Insights
The meconium microbiome may influence meconium aspiration syndrome (MAS) severity. Propionic acid from meconium bacteria can harm lung cells and increase inflammation in MAS.
Area of Science:
- Neonatal research
- Pulmonary medicine
- Microbiome research
Background:
- Meconium aspiration syndrome (MAS) severity factors are unclear.
- The role of the respiratory microbiome in MAS is under investigation.
Purpose of the Study:
- To investigate the link between the meconium microbiome and MAS severity.
- To determine if short-chain fatty acids (SCFAs) produced by meconium bacteria affect lung injury.
Main Methods:
- A piglet model of MAS was established by aspirating meconium.
- Bronchoalveolar lavage fluid (BALF) was analyzed for microbiome and SCFA content.
- In vitro studies assessed SCFA effects on lung epithelial cells.
Main Results:
- MAS piglets required more fluids and vasopressors, indicating lung injury.
- Meconium and BALF microbiomes differed, with increased propionic acid-producing bacteria in MAS.
- Higher propionic acid levels in MAS BALF correlated with reduced cell viability and increased inflammation.
Conclusions:
- Meconium may harbor a microbiome that contributes to MAS severity.
- Bacterial byproducts like propionic acid can negatively impact the pulmonary epithelium.
- Understanding the meconium microbiome is crucial for managing MAS.
