Characterization of the pathoimmunology of necrotizing enterocolitis reveals novel therapeutic opportunities

Steven Cho ,Philip J Berger,Christine B Bui,Kai König,Alex Veldman,Merrin A Pang,L Larivière ,Georg Tiefenthaler,Hortense Slevogt,Andrew M Ellisdon,Magdalena Stock,Niamh E Mangan,James C Whisstock,Stefan Gfroerer,Atul Malhotra,Rimma Goldberg,Manjeet K Sandhu ,Friederike Beker,Felix F Schumacher ,Claudia A Nold-Petry,Jason C Lao,Tilman E Klassert,Ina Rudloff,Devi Ngo,Alexander Bujotzek,Wei Cheng,Kenneth Tan,C Collins ,Catriona Mclean ,Christiane Theda,Doris Fischer,C Omar F Kamlin,Marcel F Nold

doi:10.1038/s41467-020-19400-w

Abstract

Necrotizing enterocolitis (NEC) is a severe, currently untreatable intestinal disease that predominantly affects preterm infants and is driven by poorly characterized inflammatory pathways. Here, human and murine NEC intestines exhibit an unexpected predominance of type 3/TH17 polarization. In murine NEC, pro-inflammatory type 3 NKp46−RORγt+Tbet+ innate lymphoid cells (ILC3) are 5-fold increased, whereas ILC1 and protective NKp46+RORγt+ ILC3 are obliterated. Both species exhibit dysregulation of intestinal TLR repertoires, with TLR4 and TLR8 increased, but TLR5-7 and TLR9-12 reduced. Transgenic IL-37 effectively protects mice from intestinal injury and mortality, whilst exogenous IL-37 is only modestly efficacious. Mechanistically, IL-37 favorably modulates immune homeostasis, TLR repertoires and microbial diversity. Moreover, IL-37 and its receptor IL-1R8 are reduced in human NEC epithelia, and IL-37 is lower in blood monocytes from infants with NEC and/or lower birthweight. Our results on NEC pathomechanisms thus implicate type 3 cytokines, TLRs and IL-37 as potential targets for novel NEC therapies.

Highlights

Necrotizing enterocolitis (NEC) is a severe, currently untreatable intestinal disease that predominantly affects preterm infants and is driven by poorly characterized inflammatory pathways
Just 10% of IL-37 transgenic (IL-37tg) mouse pups died by the experimental endpoint at 72 h, whereas mortality was sixfold higher in WT pups (63%; i.e., mortality was 84% lower in IL-37tg pups, Fig. 2a)
Whereas the difference in Tlr[4] (Fig. 3h) and a decrease in jejunal Tlr[2] (−53%, Supplementary Fig. 3i) were the only significant changes conferred by IL-37 when we compared the two NEC groups, we unexpectedly found that the presence of IL-37 altered Toll-like receptor (TLR) expression in the intestines of control mice: There was an up to 3.4-fold increase in Tlr[5,6,7], Tlr[9], and Tlr[11,12,13] mRNA abundance (Fig. 3i–o, significant for Tlr[5], Tlr[7], Tlr[9], and Tlr13) in IL-37tg compared to WT dam-fed mice

Summary

Introduction

Necrotizing enterocolitis (NEC) is a severe, currently untreatable intestinal disease that predominantly affects preterm infants and is driven by poorly characterized inflammatory pathways. Existing literature points to intestinal dysbiosis in NEC that results from an imbalance between proinflammatory mediators such as Toll-like receptor (TLR)[4], interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF) and IL-18 on the one hand, and protective anti-inflammatory mediators such as TLR9, IL-1 receptor antagonist (IL-1Ra), IL-10 and transforming growth factor (TGF)β2 on the other[12]. This imbalance leads to a vicious cycle in which excessive pro-inflammatory signaling and intestinal injury reinforce one another and perpetuate disease activity[12]

Methods

Results

Conclusion