Placental small humanin-like peptides (SHLP1-6) are reduced in gestational diabetes mellitus
Background
Gestational diabetes mellitus (GDM) is a prevalent pregnancy complication marked by maternal insulin resistance and hyperglycemia, often associated with placental mitochondrial alterations. Small humanin-like peptides (SHLP1-6) are mitochondria-derived peptides (MDPs) encoded within the mitochondrial 16S rRNA region, known for their cytoprotective and metabolic effects in experimental models. Despite their potential, the expression of these crucial MDPs in placental tissues from pregnancies complicated by GDM has remained unexplored, representing a significant knowledge gap in understanding GDM pathophysiology.
Study Design
Researchers obtained placental tissues from women with GDM and normoglycemic controls following cesarean delivery. Maternal metabolic parameters, including fasting glucose, fasting insulin, glycated hemoglobin A1c (HbA1c), and homeostatic model assessment for insulin resistance (HOMA-IR), were recorded. Total RNA was isolated from placental samples, and the mRNA expression levels of SHLP1-6 were quantified using quantitative real-time polymerase chain reaction (qPCR). Additionally, Humanin and SHLP2 peptide levels were measured at the protein level in both serum and placental samples. Group comparisons and correlation analyses assessed associations between placental SHLP expression and maternal metabolic status.
Results
Placental mRNA expression levels of all six SHLP transcripts were significantly reduced in the GDM group compared with controls. This reduction was consistent across all SHLPs. Lower placental SHLP expression was significantly associated with higher HOMA-IR values and elevated HbA1c levels, indicating a strong link to maternal metabolic dysfunction. Furthermore, reduced SHLP transcript levels correlated with an increased neonatal birth weight. Consistently, protein levels of both Humanin and SHLP2 were significantly reduced in both maternal serum and placental samples from the GDM group. This integrated transcriptional and proteomic evidence supports a direct link between altered placental SHLP expression and metabolic disturbances in GDM.
Placental expression of all six SHLP transcripts was significantly reduced in the GDM group, correlating with higher HOMA-IR and HbA1c.
Key Findings
- All six SHLP mRNA transcripts were significantly reduced in GDM placentas.
- Lower placental SHLP expression correlated with higher maternal HOMA-IR and HbA1c.
- Reduced SHLP levels were associated with increased neonatal birth weight.
- Humanin and SHLP2 protein levels were significantly reduced in GDM serum and placentas.
Why It Matters
Reduced placental SHLP levels highlight a potential new biomarker for GDM severity and progression, offering a novel avenue for early detection or risk stratification. Given the reported cytoprotective and metabolic roles of SHLPs, this finding suggests that restoring SHLP levels or mimicking their actions could be a future therapeutic strategy for GDM, potentially mitigating both maternal insulin resistance and adverse fetal outcomes. While this study is observational, it lays the groundwork for future interventional studies to explore SHLPs or their mimetics as novel agents to support placental health and improve glucose homeostasis in GDM. This could eventually influence how GDM is managed, moving beyond glucose control to addressing underlying mitochondrial dysfunction.
gestational-diabetes
gdm
shlp
humanin
mitochondrial-peptide
insulin-resistance