Impairment of regulatory T cells in patients with neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a life-threatening condition that can occur in about 7% of pre-term infants, and approximately 20% to 30% of the cases will end in death. An overactive immune response is thought to be a primary instigator of many symptoms during NEC. Hence, we hypothesized that NEC patients might present impairment in regulatory T (Treg) cells that limited their capacity to contain the excessive inflammation-induced damage. To investigate this, peripheral blood mononuclear cells were collected from NEC and non-NEC infants with matching age and weight. Treg cells, identified as CD3+CD4+CD25+/hiFoxp3+ T cells, were present at significantly lower frequency in NEC infants than in non-NEC infants. We also observed that the frequency of IL‑17+ CD4+ T cells was significantly higher in NEC infants, while the frequencies of IL‑10+ and TGF‑β+ CD4+ T cells were significantly lower in NEC infants. The CD4+CD25+/hi Treg cells from NEC infants were capable of suppressing CD4+CD25− T conventional cell proliferation, but with significantly reduced potency than the CD4+CD25+/hi Treg cells from non-NEC infants. In addition, the CD4+CD25+/hi Treg cells from non-NEC infants, but not those from NEC infants, were capable of suppressing IL‑17 expression. Furthermore, the CD4+CD25+/hi Treg cells from NEC infants displayed reduced expression of CTLA‑4, LAG‑3, and Helios, compared to those from non-NEC infants. Overall, these results demonstrated that Treg cells from NEC infants displayed a multitude of functional impairments, and suggested that Treg cells might serve as a treatment target in NEC. •Frequency of Tregs was significantly lower in NEC infants than in non-NEC infants.•IL‑17+ CD4+ T cells were higher while TGF-β+ CD4+ T cells were lower in NEC infants.•Tregs from NEC were less capable to suppressing CD4+CD25− Tconv proliferation.•Tregs from NEC infants were incapable of suppressing IL‑17 expression.•Tregs from NEC infants displayed reduced expression of CTLA‑4, LAG‑3, and Helios.