Role of cytokines in the regulation and function of mucosal immune responses in the gut to pathogens and pathobionts
We continue to study the transcriptional regulation of cytokines and T and myeloid cell effector functions in vivo to determine their context-specific roles during immune responses to intracellular pathogens and pathobionts and to identify pathways and targets that contribute to protection and immune control or result in immunopathology. We have published many papers leading up to the current project(s) on the molecular regulation of the immune response with two most relevant examples provided below.
We have discovered that while the transcription factor c-Maf plays a dominant role in regulation of the suppressive cytokine Il10 in CD4+ T effector cells in vitro and in vivo, that c-Maf additionally controls immune responses by regulating disease-specific gene networks and exerting context-specific effects in different experimental mouse models of disease in vivo, through its regulation of additional pathways and molecules. We showed that c-Maf is a positive and negative regulator of the expression of cytokine-encoding genes, with context-specific effects that allow each immune response to occur in a controlled yet effective manner.
We have also published the blood and tissue transcriptional response across various experimental models of disease, including infection in the periphery with the pathogen Toxoplasma gondii, demonstrating both type I and II interferon networks.
Areas of interest
We now wish to compare the immune response to T. gondii, Escherichia coli and Helicobacter hepaticus, in the gut and peripheral tissues, using mouse models based on these recent publications and our more recent exciting findings that different transcriptional regulators control different forms of protective immune responses or gut pathology. Specifically, we have shown that another transcription factor Blimp-1 together with c-Maf promotes the expression of Il10 in T-cells while negatively regulating common and unique gene networks of proinflammatory effector molecules. Mice with T-cell specific deletion of Prdm1 (encoding Blimp1), Maf or both transcription factors, showed no inflammatory pathology by 28 weeks of age, but upon infection with the pathobiont H. hepaticus we discovered that Blimp-1 and c-Maf protect against different levels and forms of colitis resulting from distinct T cell or neutrophil-mediated pathways, via IL-10-dependent and independent mechanisms (L. Cox; M. Alvarez-Martinez; --- A. O’Garra et al., submitted for publication). These pathologies resembled different forms of colitis in humans.
We will study gene expression changes in genetically mutated mice such as those with CD4-targetted deletion of Prdm1 and Maf, together with reporter mice expressing these transcription factors, using genomics technologies including RNA-sequencing, single-cell RNA-sequencing and ATAC-sequencing, complemented with flow cytometry and multiplex immunohistochemistry. This will allow us to dissect pathways dictating the immune response to T. gondii and E. coli in the periphery and the gut, and to H. hepaticus in the gut. Candidate targets and pathways may be tested, using blocking antibodies and/or genetically mutated mice, to define the effector functions resulting in the immune response contributing to different forms of pathology in vivo and to understand pathways of regulation to prevent host damage.
The airway response in TB in mouse models of resistance and susceptibility and in human TB patients and their contacts
Another focus in the lab is the study of gene regulation during infection with Mycobacterium tuberculosis in mouse models and human disease. The immune factors determining why tuberculosis (TB) still kills 1.5 million people per year, while most individuals infected with M. tuberculosis remain healthy, are unclear. We have in 2010 defined a type I interferon (IFN) neutrophil driven blood transcriptional signature in the blood of human TB patients and more recently demonstrated that the blood signature of a susceptible mouse model infected with M. tuberculosis resembles that of human TB. Using antibody blockade of IFNAR signalling we demonstrated the dominance of a type I IFN-driven neutrophil pathology in TB susceptible mice. We continue research on the mechanisms underpinning type I IFN in protection or disease progression. This work follows on from our published work, recent examples of which are provided here:
We are now studying in-depth the early airway events in TB resistant and susceptible mice and in parallel the airways of TB patients and their contacts who remain healthy or progress to develop TB. We aim to identify additional targets and pathways that parallel the host factors associated with outcome in human TB, using complex flow cytometry and histology, complemented with genomics technologies including RNA-sequencing, single-cell RNA-sequencing and ATAC-sequencing. Targets/pathways identified can then be tested to identify their role in protection, chronic infection and/or immunopathology in experimental models of TB resistance or susceptibility, using antibody blockade and/or genetically mutated mice to identify mechanisms determining outcome to infection.
This work is underpinned by basic research in the lab on the role of type I IFN in gene regulation and function in myeloid cells both in vitro and in vivo, in response to LPS and E. coli.