Amphiregulin Derived from Multiple Sources Is Important for Barrier Function of the Intestine Following Hematopoietic Stem Cell Transplantation

Abstract

Conditioning therapy prior to allogeneic hematopoietic stem cell transplantation (allo-SCT) causes damage to the intestinal epithelia, leading to the loss of barrier function. Amphiregulin (AREG), a member of the epidermal growth factor (EGF) family. The EGF family plays an important role in the proliferation and differentiation of the intestinal epithelia1. We have previously shown that co-transplantation of activated type 2 innate lymphoid cells (ILC2) reduced mortality in murine acute GvHD, improved intestinal barrier function following allo-SCT and that ILC2 production of AREG was critical for intestinal repair and restoration of intestinal barrier2. Here we show that isolated intestinal stem cell crypts (ISC) grow and expand significantly when co-cultured with activated ILC2s compared to untreated. We see similar growth in cultures containing media that was conditioned with ILC2 cells for 48 hours prior to use in the organoid cultures. However, both ILC2 culture conditions as well as cultures containing EGF itself. In other experiments ISC co-cultures containing media conditioned with AREG deficient ILC2, IL-13 deficient ILC2 and AREG / IL-13 deficient ILC2 there is significant reduction of organoid growth. These findings further support the role of ILC2 cells during intestinal repair following allo-SCT. ILC2 cells are not the only source of AREG along the GI tract. Intestinal subepithelial myofibroblasts (ISEMF) have been shown to produce AREG in response to radiation treatment in mice.1 To investigate the role of AREG derived from ISEMFs we used a conditional knockout Myh11Cre+/Aregfl/fl strain3 in a B10.BR in to B6 model of acute GvHD. While Myh11Cre+/Aregfl/fl recipients of bone marrow alone all survived long term, Myh11Cre+/Aregfl/fl recipients that also received T cells had significantly increased mortality compared to WT B6 following allo-SCT with a median survival of 10 days and 21 days respectively. Myh11Cre+/Aregfl/fl BM+T recipients also had significantly higher clinical scores than WT B6 controls. Even though Myh11Cre+/Aregfl/fl recipients of BM only did survive long term they did have significantly increased clinical scores in the first 15 days when compared to WT B6. These findings indicate that ISEMF derived AREG is extremely important for early tissue repair following conditioning therapy and allo-SCT. In summary, ILC2s represent a cell population that produce AREG and are required for recovery of GI tract homeostasis following allo-SCT. ISEMFs are also an important source of AREG following transplantation. Additional investigation is needed to fully understand the role of AREG in intestinal health and recovery following allo-SCT.