Deregulation of intestinal immune responses seems to have a principal function in the pathogenesis of inflammatory bowel disease. The gut epithelium is critically involved in the maintenance of ...intestinal immune homeostasis-acting as a physical barrier separating luminal bacteria and immune cells, and also expressing antimicrobial peptides. However, the molecular mechanisms that control this function of gut epithelial cells are poorly understood. Here we show that the transcription factor NF- B, a master regulator of pro-inflammatory responses, functions in gut epithelial cells to control epithelial integrity and the interaction between the mucosal immune system and gut microflora. Intestinal epithelial-cell-specific inhibition of NF- B through conditional ablation of NEMO (also called I B kinase- (IKK )) or both IKK1 (IKK ) and IKK2 (IKK )-IKK subunits essential for NF- B activation-spontaneously caused severe chronic intestinal inflammation in mice. NF- B deficiency led to apoptosis of colonic epithelial cells, impaired expression of antimicrobial peptides and translocation of bacteria into the mucosa. Concurrently, this epithelial defect triggered a chronic inflammatory response in the colon, initially dominated by innate immune cells but later also involving T lymphocytes. Deficiency of the gene encoding the adaptor protein MyD88 prevented the development of intestinal inflammation, demonstrating that Toll-like receptor activation by intestinal bacteria is essential for disease pathogenesis in this mouse model. Furthermore, NEMO deficiency sensitized epithelial cells to tumour-necrosis factor (TNF)-induced apoptosis, whereas TNF receptor-1 inactivation inhibited intestinal inflammation, demonstrating that TNF receptor-1 signalling is crucial for disease induction. These findings demonstrate that a primary NF- B signalling defect in intestinal epithelial cells disrupts immune homeostasis in the gastrointestinal tract, causing an inflammatory-bowel-disease-like phenotype. Our results identify NF- B signalling in the gut epithelium as a critical regulator of epithelial integrity and intestinal immune homeostasis, and have important implications for understanding the mechanisms controlling the pathogenesis of human inflammatory bowel disease.
Interleukin (IL)-17A is regarded as an important cytokine to drive psoriasis, an inflammatory skin disease marked by increased cardiovascular mortality. We aimed to test the hypothesis that ...overproduction of IL-17A in the skin leading to dermal inflammation may systemically cause vascular dysfunction in psoriasis-like skin disease.
Conditional overexpression of IL-17A in keratinocytes caused severe psoriasis-like skin inflammation in mice (K14-IL-17A(ind/+) mice), associated with increased reactive oxygen species formation and circulating CD11b(+) inflammatory leukocytes in blood, with endothelial dysfunction, increased systolic blood pressure, left ventricular hypertrophy, and reduced survival compared with controls. In K14-IL-17A(ind/+) mice, immunohistochemistry and flow cytometry revealed increased vascular production of the nitric oxide/superoxide reaction product peroxynitrite and infiltration of the vasculature with myeloperoxidase(+)CD11b(+)GR1(+)F4/80(-) cells accompanied by increased expression of the inducible nitric oxide synthase and the nicotinamide dinucleotide phosphate (NADPH) oxidase, nox2. Neutrophil depletion by anti-GR-1 antibody injections reduced oxidative stress in blood and vessels. Neutralization of tumor necrosis factor-α and IL-6 (both downstream of IL-17A) reduced skin lesions, attenuated oxidative stress in heart and blood, and partially improved endothelial dysfunction in K14-IL-17A(ind/+) mice.
Dermal overexpression of IL-17A induces systemic endothelial dysfunction, vascular oxidative stress, arterial hypertension, and increases mortality mainly driven by myeloperoxidase(+)CD11b(+)GR1(+)F4/80(-) inflammatory cells. Depletion of the GR-1(+) immune cells or neutralization of IL-17A downstream cytokines by biologicals attenuates the vascular phenotype in K14-IL-17A(ind/+) mice.
Interleukin-17A- (IL-17A) and IL-17F-producing CD4
T helper cells (T
17 cells) are implicated in the development of chronic inflammatory diseases, such as multiple sclerosis and its animal model, ...experimental autoimmune encephalomyelitis (EAE). T
17 cells also orchestrate leukocyte invasion of the central nervous system (CNS) and subsequent tissue damage. However, the role of IL-17A and IL-17F as effector cytokines is still confused with the encephalitogenic function of the cells that produce these cytokines, namely, T
17 cells, fueling a long-standing debate in the neuroimmunology field. Here, we demonstrated that mice deficient for IL-17A/F lose their susceptibility to EAE, which correlated with an altered composition of their gut microbiota. However, loss of IL-17A/F in T
cells did not diminish their encephalitogenic capacity. Reconstitution of a wild-type-like intestinal microbiota or reintroduction of IL-17A specifically into the gut epithelium of IL-17A/F-deficient mice reestablished their susceptibility to EAE. Thus, our data demonstrated that IL-17A and IL-17F are not encephalitogenic mediators but rather modulators of intestinal homeostasis that indirectly alter CNS-directed autoimmunity.
A20/TNFAIP3 is an ubiquitin-editing enzyme, important for the regulation of the NF-κB pathway. Mutations in the TNFAIP3 gene have been linked to different human autoimmune disorders. In human B-cell ...lymphomas, the inactivation of A20 results in constitutive NF-κB activation. Recent studies demonstrate that in mice the germline inactivation of A20 leads to early lethality, due to inflammation in multiple organs of the body. In this report, we describe a new mouse strain allowing for the tissue-specific deletion of A20. We show that B-cell-specific deletion of A20 results in a dramatic reduction in marginal zone B cells. Furthermore, A20-deficient B cells display a hyperactive phenotype represented by enhanced proliferation upon activation. Finally, these mice develop higher levels of serum immunoglobulins, resulting in an excessive production of self-reactive autoantibodies.
Organ fibrosis is characterized by a chronic wound-healing response, with excess deposition of extracellular matrix components. Here, collagen type I represents the most abundant scar component and a ...primary target for antifibrotic therapies. Liver fibrosis can progress to cirrhosis and primary liver cancer, which are the major causes of liver related morbidity and mortality. However, a (pro-)collagen type I specific therapy remains difficult and its therapeutic abrogation may incur unwanted side effects. We therefore designed tetracycline-regulated procollagen alpha1(I) short hairpin (sh)RNA expressing mice that permit a highly efficient inducible knockdown of the procollagen alpha1(I) gene in activated (myo-)fibroblasts, to study the effect of induced procollagen type I deficiency. Transgenic mice were generated using recombinase-mediated integration in embryonic stem cells or zinc-finger nuclease-aided genomic targeting combined with miR30-shRNA technology. Liver fibrosis was induced in transgenic mice by carbon tetrachloride, either without or with doxycycline supplementation. Doxycycline treated mice showed an 80–90% suppression of procollagen alpha1(I) transcription and a 40–50% reduction in hepatic collagen accumulation. Procollagen alpha1(I) knockdown also downregulated procollagens type III, IV and VI and other fibrosis related parameters. Moreover, this was associated with an attenuation of chronic inflammation, suggesting that collagen type I serves not only as major scar component, but also as modulator of other collagens and promoter of chronic inflammation.
•Fibrosis is characterized by excess deposition of extracellular matrix components, especially collagen type I.•Mice were engineered to express tetracycline-regulated procollagen alpha1(I) short hairpin RNA.•In experimental liver fibrosis induced procollagen alpha1(I) knockdown suppressed procollagen alpha1(I) mRNA by up to 90%.•This resulted in a 40–50% reduction in hepatic collagen accumulation and downregulation of Procollagens type III, IV, VI were downregulated and chronic inflammation attenuated.
Bcl-3 is an atypical NF-κB family member that regulates NF-κB-dependent gene expression in effector T cells, but a cell-intrinsic function in regulatory T (Treg) cells and colitis is not clear. Here ...we show that Bcl-3 expression levels in colonic T cells correlate with disease manifestation in patients with inflammatory bowel disease. Mice with T-cell-specific overexpression of Bcl-3 develop severe colitis that can be attributed to defective Treg cell development and function, leading to the infiltration of immune cells such as pro-inflammatory γδT cells, but not αβ T cells. In Treg cells, Bcl-3 associates directly with NF-κB p50 to inhibit DNA binding of p50/p50 and p50/p65 NF-κB dimers, thereby regulating NF-κB-mediated gene expression. This study thus reveals intrinsic functions of Bcl-3 in Treg cells, identifies Bcl-3 as a potential prognostic marker for colitis and illustrates the mechanism by which Bcl-3 regulates NF-κB activity in Tregs to prevent colitis.
Interleukin-1 (IL-1) plays a crucial role in numerous inflammatory diseases via action on its only known signaling IL-1 receptor type 1 (IL-1R1). To investigate the role of IL-1 signaling in selected ...cell types, we generated a new mouse strain in which exon 5 of the Il1r1 gene is flanked by loxP sites. Crossing of these mice with CD4-Cre transgenic mice resulted in IL-1R1 loss of function specifically in T cells. These mice, termed IL-1R1ΔT, displayed normal development under steady state conditions. Importantly, isolated CD4 positive T cells retained their capacity to differentiate toward Th1 or Th17 cell lineages in vitro, and strongly proliferated in cultures supplemented with either anti-CD3/CD28 or Concanavalin A, but, as predicted, were completely unresponsive to IL-1β administration. Furthermore, IL-1R1ΔT mice were protected from gut inflammation in the anti-CD3 treatment model, due to dramatically reduced frequencies and absolute numbers of IL-17A and interferon (IFN)-γ producing cells. Taken together, our data shows the necessity of intact IL-1 signaling for survival and expansion of CD4 T cells that were developed in an otherwise IL-1 sufficient environment.
Rotationally resolved electronic spectra of several low frequency vibrational bands that appear in the S1 ← S0 transition of 4-fluorobenzyl alcohol (4FBA) in the collision-free environment of a ...molecular beam have been observed and assigned. Each transition is split into two or more components by the tunneling motion of the attached −CH2OH group. A similar splitting is observed in the microwave spectrum of 4FBA. Analyses of these data show that 4FBA has a gauche structure in both electronic states, but that the ground state C1C2–C7O dihedral angle of ∼60° changes by ∼30° when the photon is absorbed. The barriers to the torsional motion of the attached −CH2OH group are also quite different in the two electronic states; V 2 ∼ 300 cm–1 high and ∼60° wide in the S0 state, and V 2 ∼ 300 cm–1 high and ∼120° wide (or V 2 ∼ 1200 cm–1 high and ∼60° wide) in the S1 state. Possible reasons for these behaviors are discussed.
The transcription factor Bcl‐3 functions as a proto‐oncogene via regulation of cell proliferation and apoptosis. Bcl‐3 is an atypical member of the IκB family and plays a central role in the immune ...response through interactions with the NF‐κB subunits p50 and p52. To investigate the impact of Bcl‐3 on B‐cell maturation and regulation, we generated mice that overexpress Bcl‐3 specifically in B cells. Interestingly, these mice lack marginal zone B cells and exhibit a significant reduction in the number of B‐1 B cells. Further, B cells from these mice are impaired in their proliferative capacity. Our data demonstrate that the overexpression of the transcription factor Bcl‐3 inhibits germinal center formation, marginal zone B‐cell development, and affects the B‐1 B‐cell compartment.
Wheat has become a main staple globally. We studied the effect of defined pro-inflammatory dietary proteins, wheat amylase trypsin inhibitors (ATI), activating intestinal myeloid cells via toll-like ...receptor 4, in experimental autoimmune encephalitis (EAE), a model of multiple sclerosis (MS).
EAE was induced in C57BL/6J mice on standardised dietary regimes with defined content of gluten/ATI. Mice received a gluten and ATI-free diet with defined carbohydrate and protein (casein/zein) content, supplemented with: (a) 25% of gluten and 0.75% ATI; (b) 25% gluten and 0.19% ATI or (c) 1.5% purified ATI. The effect of dietary ATI on clinical EAE severity, on intestinal, mesenteric lymph node, splenic and central nervous system (CNS) subsets of myeloid cells and lymphocytes was analysed. Activation of peripheral blood mononuclear cells from patients with MS and healthy controls was compared.
Dietary ATI dose-dependently caused significantly higher EAE clinical scores compared with mice on other dietary regimes, including on gluten alone. This was mediated by increased numbers and activation of pro-inflammatory intestinal, lymph node, splenic and CNS myeloid cells and of CNS-infiltrating encephalitogenic T-lymphocytes. Expectedly, ATI activated peripheral blood monocytes from both patients with MS and healthy controls.
Dietary wheat ATI activate murine and human myeloid cells. The amount of ATI present in an average human wheat-based diet caused mild intestinal inflammation, which was propagated to extraintestinal sites, leading to exacerbation of CNS inflammation and worsening of clinical symptoms in EAE. These results support the importance of the gut-brain axis in inflammatory CNS disease.
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