Inflammatory cytokines in human milk are inter‐correlated and may be related to infant growth characteristics and maternal weight status

Abstract

This ongoing study aims to longitudinally characterize inflammatory cytokines in human milk (HM) and investigate associations with maternal weight and infant growth characteristics. Morning HM samples from 9 normal weight (NW) and 9 overweight (OW) mothers (BMI range: 21.0 – 30.0 kg/m2) and anthropometry measures of their healthy term infants were obtained at 2‐weeks (T1: 2.1 ± 0.4 wks) and 4‐months (T2: 16.7 ± 1.2 wks) post‐partum. HM % fat was measured by creamatocrit; IL‐6, IL‐8, and TNF‐α concentrations by multiplex. The inflammatory load of HM was calculated as the standardized sum of cytokine concentrations. Infant length for age, weight for age, and weight for length Z‐scores (LAZ, WAZ, WLZ) did not significantly change from T1 to T2. IL‐8, TNF‐α, and inflammatory load at T1 were positively correlated with those at T2 (p < 0.01, R2≥ 0.39). IL‐6 and TNF‐α decreased from T1 to T2 (p < 0.05). IL‐6, TNF‐α, and % fat did not differ between NW and OW mothers. HM IL‐8 and inflammatory load decreased from T1 to T2 in NW (p = 0.03) but tended to increase in OW mothers (p = 0.07). By T2, all 3 cytokines were positively inter‐correlated (p < 0.02, R2≥ 0.33). Infant growth results were inconclusive: HM inflammatory load at T1 inversely correlated with ΔWAZ from T1 to T2 (p = 0.04, R2= 0.26) but not ΔLAZ (p = 0.76) or ΔWLZ (p = 0.05). Maternal BMI status may impact inflammatory cytokines in early HM.Grant Funding Source: NIH T32DK007658–21, 5K24DK083772‐08, P01HD13021