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IL-22 promotes tumor progression in pre-clinical models of CRC, but its importance in human CRC remains unclear. Using a rigorous discovery/verification analysis of tumor gene expression from over 1,000 patients, we have discovered that among CRC patients with high expression of either or both subunits of the heterodimeric IL-22 receptor, KRAS mutation confers poor prognosis. Functional studies revealed that this association is due to an interaction between IL-22 signaling and oncogenic KRAS that enhances tumor cell proliferation through induction of the Myc pathway. These findings demonstrate that cell-intrinsic drivers of CRC can interact with cell-extrinsic factors from the inflammatory microenvironment to influence disease progression.Our data further justify the assessment of KRAS mutations in CRC patients, which has until now been clinically beneficial only for prediction of cetuximab responsiveness, and suggest that for KRAS mutant CRCs with high IL-22 receptor expression, closer monitoring and more aggressive or alternative therapeutic strategies (e.g. antibody-based blockade of IL-22) could be beneficial.Research.

The intestinal immune system must maintain tolerance to commensal microbiota and self antigens whilst defending against invading pathogens. Recognising how homeostasis is established and maintained in a complex immune environment such as the gut is critical to understanding how to re-establish tolerance once broken in inflammatory disorders. Peripherally induced regulatory T cells (Tregs) play a key role in homeostasis. In intestinal tissue, Tregs work in concert with a diverse network of cells but which cellular interactions occur to instruct Treg adaptation and acquisition of distinct Treg suppressor function is not clear. We used two-photon in vivo live imaging and NICHE-seq to deep phenotype Helicobacter hepaticus (Hh)- specific Tregs with shared specificity but distinct spatially compartmentalised functions in the tissue. We show transcriptionally distinct central Treg (cTreg) and effector Treg (eTreg) populations in lymphoid versus gut tissue. The lamina propria (LP), and not embedded lymphoid aggregates (LA), is the key location of acquired immune suppressor eTreg function. Tregs recruited to the LP compartment are the dominant interacting cell type and acquired a more effector Treg profile with upregulation of Areg, Gzmb, Icos, Tigit, Tnfrsf4 (OX40), and Tnfrsf18 (GITR). We identify IL-1B+ macrophages, CD206+ macrophages, and ILC2 in the LP niche as the key players governing Treg survival and function. In contrast, LA, dominated by interactions with ILC3s and populations of IL-6+ DCs, are equipped to tip the balance towards a pro- inflammatory response. By functionally isolating the gut tissue from secondary lymphoid organs, we show that eTregs maintain their phenotype in the context of inflammatory insult. Blocking their key effector molecule, IL-10, results in locally differentiated Th17 cell proliferation without overt inflammation due to local IL-10 independent mechanisms that constrain inflammation. Our results reveal a previously unrecognised spatial mechanism of tolerance, and demonstrate how knowledge of local interactions can guide cell function and potentially be manipulated for the next generation of tolerance-inducing therapies.

No abstract

Although intestinal epithelial cells (IECs) can express major histocompatibility complex class II (MHC II), especially during intestinal inflammation, it remains unclear if antigen presentation by IECs favours pro- or anti-inflammatory CD4+ T cell responses. Using selective gene ablation of MHC II in IECs and IEC organoid cultures, we assessed the impact of MHC II expression by IECs on CD4+ T cell responses and disease outcomes in response to enteric bacterial pathogens. We found that intestinal bacterial infections elicit inflammatory cues that greatly increase expression of MHC II processing and presentation molecules in colonic IECs. Whilst IEC MHC II expression had little impact on disease severity following Citrobacter rodentium or Helicobacter hepaticus infection, using a colonic IEC organoid-CD4+ T cell co-culture system, we demonstrate that IECs can activate antigen-specific CD4+ T cells in an MHC II-dependent manner, modulating both regulatory and effector Th cell subsets. Furthermore, we assessed adoptively transferred H. hepaticus-specific CD4+ T cells during intestinal inflammation in vivo and report that IEC MHC II expression dampens pro-inflammatory effector Th cells. Our findings indicate that IECs can function as non-conventional antigen presenting cells and that IEC MHC II expression fine-tunes local effector CD4+ T cell responses during intestinal inflammation.

<div>AbstractPurpose:<p>The cytokine IL22 promotes tumor progression in murine models of colorectal cancer. However, the clinical significance of IL22 in human colorectal cancer remains unclear. We sought to determine whether the IL22 pathway is associated with prognosis in human colorectal cancer, and to identify mechanisms by which IL22 can influence disease progression.</p>Experimental Design:<p>Transcriptomic data from stage II/III colon cancers in independent discovery (GSE39582 population-based cohort, <i>N</i> = 566) and verification (PETACC3 clinical trial, <i>N</i> = 752) datasets were used to investigate the association between IL22 receptor expression (encoded by the genes <i>IL22RA1</i> and <i>IL10RB</i>), tumor mutation status, and clinical outcome using Cox proportional hazard models. Functional interactions between IL22 and mutant KRAS were elucidated using human colorectal cancer cell lines and primary tumor organoids.</p>Results:<p>Transcriptomic analysis revealed a poor-prognosis subset of tumors characterized by high expression of <i>IL22RA1</i>, the alpha subunit of the heterodimeric IL22 receptor, and <i>KRAS</i> mutation [relapse-free survival (RFS): HR = 2.93, <i>P</i> = 0.0006; overall survival (OS): HR = 2.45, <i>P</i> = 0.0023]. <i>KRAS</i> mutations showed a similar interaction with <i>IL10RB</i> and conferred the worst prognosis in tumors with high expression of both <i>IL22RA1</i> and <i>IL10RB</i> (RFS: HR = 3.81, <i>P</i> = 0.0036; OS: HR = 3.90, <i>P</i> = 0.0050). Analysis of human colorectal cancer cell lines and primary tumor organoids, including an isogenic cell line pair that differed only in <i>KRAS</i> mutation status, showed that IL22 and mutant KRAS cooperatively enhance cancer cell proliferation, in part through augmentation of the Myc pathway.</p>Conclusions:<p>Interactions between KRAS and IL22 signaling may underlie a previously unrecognized subset of clinically aggressive colorectal cancer that could benefit from therapeutic modulation of the IL22 pathway.</p></div>

<div>AbstractPurpose:<p>The cytokine IL22 promotes tumor progression in murine models of colorectal cancer. However, the clinical significance of IL22 in human colorectal cancer remains unclear. We sought to determine whether the IL22 pathway is associated with prognosis in human colorectal cancer, and to identify mechanisms by which IL22 can influence disease progression.</p>Experimental Design:<p>Transcriptomic data from stage II/III colon cancers in independent discovery (GSE39582 population-based cohort, <i>N</i> = 566) and verification (PETACC3 clinical trial, <i>N</i> = 752) datasets were used to investigate the association between IL22 receptor expression (encoded by the genes <i>IL22RA1</i> and <i>IL10RB</i>), tumor mutation status, and clinical outcome using Cox proportional hazard models. Functional interactions between IL22 and mutant KRAS were elucidated using human colorectal cancer cell lines and primary tumor organoids.</p>Results:<p>Transcriptomic analysis revealed a poor-prognosis subset of tumors characterized by high expression of <i>IL22RA1</i>, the alpha subunit of the heterodimeric IL22 receptor, and <i>KRAS</i> mutation [relapse-free survival (RFS): HR = 2.93, <i>P</i> = 0.0006; overall survival (OS): HR = 2.45, <i>P</i> = 0.0023]. <i>KRAS</i> mutations showed a similar interaction with <i>IL10RB</i> and conferred the worst prognosis in tumors with high expression of both <i>IL22RA1</i> and <i>IL10RB</i> (RFS: HR = 3.81, <i>P</i> = 0.0036; OS: HR = 3.90, <i>P</i> = 0.0050). Analysis of human colorectal cancer cell lines and primary tumor organoids, including an isogenic cell line pair that differed only in <i>KRAS</i> mutation status, showed that IL22 and mutant KRAS cooperatively enhance cancer cell proliferation, in part through augmentation of the Myc pathway.</p>Conclusions:<p>Interactions between KRAS and IL22 signaling may underlie a previously unrecognized subset of clinically aggressive colorectal cancer that could benefit from therapeutic modulation of the IL22 pathway.</p></div>

<p>Supplementary data to accompany manuscript</p>