Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Identification of biomarkers in breastmilk associated with risk of lactational mastitis (128434)

Amna Ghith 1 2 , Reza Maleki 1 2 , Luke E. Grzeskowiak 3 4 , Lisa H. Amir 5 6 , Wendy V. Ingman 1 2
  1. Discipline of Surgical Specialties, Adelaide Medical School, University of Adelaide, The Queen Elizabeth Hospital, Woodville South, SA 5011, Australia
  2. Robinson Research Institute, University of Adelaide, Adelaide, SA 5006, Australia
  3. College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, SA 5042, Australia
  4. SAHMRI Women and Kids, South Australian Health and Medical Research Institute, Women’s and Children’s Hospital, North Adelaide, SA 5006, Australia
  5. Judith Lumley Centre, School of Nursing and Midwifery, La Trobe University, Bundoora, VIC 3086, Australia
  6. Breastfeeding Service, The Royal Women’s Hospital, Parkville, VIC 3050, Australia

Aims

Lactational mastitis is a common inflammatory breast condition affecting 1 in 5 women within the first six months postpartum [1]. Although the presence of pathogenic bacteria can be a feature of mastitis, research suggests the host inflammatory response is a key determinant of disease [2]. Women with a past history of mastitis are at increased risk of experiencing another episode, and we hypothesised that there may be factors in breastmilk that increases risk of inflammation [3]. This research aimed to identify proteins in breastmilk associated with mastitis risk and investigate how these might affect immune signalling.

Methods

Breastmilk samples were collected from multiparous healthy women with full-term infants, stratified into high-risk (n=20) and low-risk (n=20) of mastitis based on past history of mastitis whilst feeding a previous infant. Samples were collected at week 2 and week 8 postpartum, proteins were identified and quantified using mass spectrometry and validated with ELISA. The impact of breastmilk on immune cell activity was investigated using the RAW264.7 mouse macrophage cell line.

Results

Using data-independent acquisition proteomic analysis, 36 proteins were differentially expressed between the high- and low-risk mastitis groups. Several upregulated proteins are associated with immune regulation. Macrophage migration inhibitory factor is a pleiotropic proinflammatory cytokine and was validated by ELISA to be upregulated 1.6-fold in breastmilk from high-risk mastitis breastmilk (p=0.035). Immunoglobulin kappa was also significantly upregulated (3.6-fold) and confirmed by ELISA (p=0.039). Breastmilk from high-risk women upregulated expression of proinflammatory chemokine C-C motif ligand 2 (CCL2) in macrophages compared to low-risk breastmilk (p=0.049).

Conclusion

Increased abundance of proteins associated with inflammation in the breastmilk of healthy women with a past history of mastitis suggests that host factors could in part be responsible for mastitis. This research provides new opportunities to identify women at risk of mastitis and develop new treatment options.