Elevated SOX1, miR-155, and miR-21 in Breast Milk After COVID Pregnancy: Lublin's Nature Study Breakthrough

A groundbreaking study published today in Scientific Reports, a Nature portfolio journal, has uncovered significant molecular alterations in the colostrum—the first milk produced by mothers immediately after birth—of women who contracted COVID-19 during pregnancy. Researchers from the Medical University of Lublin in Poland found elevated levels of key regulatory molecules: SOX1 (SRY-box transcription factor 1), miR-155 (microRNA-155), and miR-21 (microRNA-21). These changes suggest that breast milk adapts dynamically to provide enhanced protection and regenerative support to newborns exposed to maternal SARS-CoV-2 infection in utero.

This discovery highlights how human milk serves not just as nutrition but as a sophisticated biochemical communicator, potentially bolstering infant immunity and resilience against the lingering effects of maternal viral exposure. For higher education institutions specializing in clinical genetics and maternal-fetal medicine, such findings underscore the critical role of interdisciplinary research in unraveling post-pandemic health challenges.

🔬 The Groundbreaking Research from Medical University of Lublin

The study, titled "Higher expression of SOX1, miR-155, and miR-21 in the colostrum of SARS-CoV-2-infected mothers," involved 19 mothers who had confirmed COVID-19 during their pregnancies and a control group of 21 healthy mothers. Colostrum samples were collected shortly after birth, and expression levels of the target molecules were quantified using quantitative polymerase chain reaction (qPCR), a highly sensitive technique for measuring gene and microRNA activity.

Lead author Paulina Gil-Kulik and her team from the Department of Clinical Genetics at Medical University of Lublin demonstrated statistically significant elevations in all three molecules in the COVID-affected group. This Polish university, renowned for its contributions to genetic research, exemplifies how regional higher education hubs drive global health insights, particularly in reproductive and neonatal sciences.

Decoding the Key Molecules: SOX1, miR-155, and miR-21

To grasp the significance, it's essential to understand these molecules fully. MicroRNAs (miRNAs) are small, non-coding RNA strands, typically 20-25 nucleotides long, that regulate gene expression post-transcriptionally by binding to messenger RNA (mRNA), leading to degradation or translational repression. They fine-tune nearly 60% of human genes, playing pivotal roles in development, immunity, and disease.

miR-21, often dubbed an "oncomiR" due to its overexpression in cancers, also promotes cell proliferation, survival, and tissue repair. In the context of breast milk, its elevation post-COVID suggests regenerative signaling to help repair potential inflammation-induced damage in the newborn's developing systems.

miR-155, another immunomodulatory miRNA, enhances inflammatory responses by targeting genes involved in immune cell differentiation, such as SHIP1 (SH2-containing inositol phosphatase 1). It activates T-cells and macrophages, potentially priming the infant's immune system against viral threats.

SOX1, a transcription factor from the SOX (SRY-related HMG-box) family, is crucial for neural development and stem cell pluripotency. Encoded by the SOX1 gene on chromosome 13, it binds DNA to regulate neurogenesis and epithelial-mesenchymal transitions. Its upregulation indicates a push toward regenerative processes, possibly countering hypoxia or stress from maternal infection.

These molecules' synergy in colostrum positions breast milk as a targeted delivery system for epigenetic programming, a concept increasingly explored in university labs worldwide.

Step-by-Step Methodology: Rigorous Science at Play

The researchers followed a meticulous protocol. Mothers provided informed consent, with COVID status verified via PCR tests during pregnancy. Colostrum (within 48 hours postpartum) was collected, total RNA extracted using standard kits, and reverse-transcribed for qPCR analysis with specific primers for miR-21, miR-155, SOX1, and housekeeping genes like U6 snRNA for normalization.

• RNA isolation: TRIzol method for high purity.
• qPCR: SYBR Green detection, Ct values calculated via 2^-ΔΔCt method.
• Clinical correlations: Analyzed cord blood parameters (CRP, lactate, glucose) using Spearman's rank correlation.

This gold-standard approach ensures reproducibility, a hallmark of research from institutions like Medical University of Lublin.

Key Results: Quantifiable Elevations and Correlations

Results revealed markedly higher expression: miR-21, miR-155, and SOX1 were significantly upregulated in the COVID group (p < 0.05, exact folds not detailed but strong differences noted). Notably, SOX1 showed robust correlations:

• Positive with C-reactive protein (CRP, inflammation marker) in arterial cord blood (r = positive, p < 0.05).
• Positive with lactate (LAC, hypoxia indicator).
• Negative with glucose levels, suggesting metabolic shifts.

These links imply SOX1 responds to intrauterine stress, signaling via milk to the infant.

Photo by NighthawStudio on Unsplash

Clinical Correlations: Insights into Newborn Health

The negative glucose correlation hints at adaptive metabolic programming, where elevated SOX1 might enhance glucose uptake in stressed tissues. CRP and lactate ties reflect inflammation resolution, crucial as maternal COVID can elevate newborn infection risks by 20-30% per meta-analyses from other universities.

Real-world case: In Poland, post-pandemic cohorts show lower respiratory issues in breastfed infants of COVID mothers, aligning with this molecular boost.

Implications for Infant Immunity and Regeneration

Post-COVID breast milk acts as an "active immunomodulator," per the study. miR-155 ramps up innate immunity, miR-21 aids epithelial repair, SOX1 supports neural protection—vital against potential long-COVID effects like neurodevelopmental delays reported in 5-10% of exposed infants.

For read more on the full study, visit the original publication.

Echoes from Global Higher Ed: University of Cincinnati's Parallel Findings

Complementing Lublin's work, a 2025 University of Cincinnati study on human milk extracellular vesicles (HMEVs) post-prenatal Delta variant COVID found 52 altered proteins, enhancing metabolic reprogramming, mucosal development, and B-cell immunity. No miRNA changes there, but protein shifts (e.g., PIGR for IgA transport) synergize with miRNA effects.

Explore their insights via PMC article. Such cross-institutional collaborations highlight higher education's role in maternal health advancement.

Medical University of Lublin: A Hub for Genetic Innovation

Home to the Doctoral School and Student Scientific Society, this university fosters talents like Dominika Przywara and Michał Mitrus. Their work builds on Poland's strong biomedical tradition, with implications for funding and careers in clinical genetics research.

Broader Academic Impacts and Future Research Trajectories

This study opens doors for longitudinal trials tracking infant outcomes, miRNA therapeutics, and personalized lactation support. Universities could integrate such findings into obstetrics curricula, training future experts.

Challenges include larger cohorts and variant-specific analyses (e.g., Omicron vs. earlier strains). Solutions: international consortia via EU grants.

Photo by Zahraa Hassan on Unsplash

In summary, this Nature study from Medical University of Lublin illuminates breast milk's adaptive power post-COVID pregnancy, with elevated SOX1, miR-155, and miR-21 poised to enhance infant resilience. As higher education drives these discoveries, they promise healthier futures for post-pandemic generations.