The response to an innate immune challenge is conditioned by the time of day, but the molecular basis for this remains unclear. In myeloid cells, there is a temporal regulation to induction by lipopolysaccharide (LPS) of the proinflammatory microRNA miR-155 that correlates inversely with levels of BMAL1. BMAL1 in the myeloid lineage inhibits activation of NF-κB and miR-155 induction and protects mice from LPS-induced sepsis. Bmal1 has two miR-155-binding sites in its 3′-UTR, and, in response to LPS, miR-155 binds to these two target sites, leading to suppression of Bmal1 mRNA and protein in mice and humans. miR-155 deletion perturbs circadian function, gives rise to a shorter circadian day, and ablates the circadian effect on cytokine responses to LPS. Thus, the molecular clock controls miR-155 induction that can repress BMAL1 directly. This leads to an innate immune response that is variably responsive to challenges across the circadian day.inflammation | sepsis | circadian clock | miR-155 | Bmal1

Toll-like receptors (TLRs) are a family of proteins that act as the primary sensors of microbial products. Many TLRs require accessory molecules in order to recognize these microbial products and initiate signal transduction cascades. We have identified TRIL (TLR4 interactor with leucine-rich repeats) as a novel modulator of TLR4 signaling showing high expression in the brain. We now show that TRIL also plays a role in TLR3 signaling. TRIL is expressed intracellularly in the astrocytoma cell line U373 and in the monocytic cell line THP1. TRIL co-localizes with the endosomal compartment. These data are consistent with a role for TRIL in TLR3 signaling and endosomal TLR4 signaling. TRIL was induced by the TLR3 ligand poly(I:C). Overexpression of TRIL enhanced cytokine production and interferon-stimulated response element (ISRE) luciferase activity following poly(I:C) stimulation in U373. TRIL interacted with TLR3, and this interaction was enhanced following poly(I:C) stimulation. Transient knockdown of TRIL with siRNA or stable knockdown using shRNA in U373 cells inhibited TLR3 signaling, reducing ISRE luciferase, RANTES, and type I interferon production. Knockdown of TRIL did not affect TLR2 signaling. Most accessory molecules identified to date, such as CD14, gp96, PRAT4a, and Unc93B, all play roles in multiple TLR signaling pathways, and we now show that this is also the case for TRIL. Toll-like receptors (TLRs)3 are pattern recognition receptors essential for the recognition of a wide range of microbial products (2). TLR4, -1, -2, and -6 are expressed on the surface of cells and recognize microbial products, such as LPS and lipopeptides, whereas TLR3, -7, -8, and -9 are expressed intracellularly and are involved in the recognition of nucleic acids (3). The subcellular localization of TLRs is optimized for recognition of microbial products and results in the activation of a specific type of transcriptional response. TLRs activated at the plasma membrane engage MyD88, leading to the activation of NFB, resulting in the production of proinflammatory cytokines. In contrast, the intracellular TLRs (TLR7, -8, and -9) all associate with MyD88 and lead to the activation of IRF7, resulting in the production of type I interferons. TLR3 engages the adaptor molecule TRIF in order to activate the production of type I interferons (4). In addition, TLR4 has been found to traffic to the early endosome. At the plasma membrane, TLR4 engages with MyD88 and signals to activate NFB. When TLR4 is endocytosed, it binds TRIF, resulting in the production of type 1 interferons (5).In order for the TLR signaling complexes to function, they require a number of accessory molecules (6). Some accessory proteins function at the level of regulation at the cell surface, such as MD-2. Both MD-2 and TLR4 bind to LPS and initiate signaling (7). MD-2 knock-out mice fail to respond to LPS, further emphasizing the important role MD-2 plays in this response (8). RP-105 also functions at the cell surface, where it appears to have contrasting roles, whi...

TLR4 interactor with leucine-rich repeats (TRIL) is a brain-enriched accessory protein important in Toll-like receptor 3 and 4 signalling. Here we generated TRIL-deficient mice and examined TLR responses in vitro and in vivo. We found a role for TRIL in both TLR4 and TLR3 signalling in mixed glial cells, consistent with the high level of expression of TRIL in these cells. We also found that TRIL is a modulator of the innate immune response to LPS challenge and E.coli infection in vivo. TRIL-deficient mice produce lower levels of multiple proinflammatory cytokines and chemokines specifically within the brain following E.coli and LPS challenge. Collectively these data uncover TRIL as a mediator of innate immune responses within the brain, where it enhances neuronal cytokine responses to infection.

Myeloproliferative neoplasms (MPNs) are associated with a high disease burden, reduced quality of life and shortened survival. The aim of this questionnaire was to gain patients' and caregivers' perspectives on the impact of living with an MPN in the Republic of Ireland. An Irish adaptation of the ‘Global MPN Landmark survey’ was conducted. Fifty-one patients and 44 caregivers completed the questionnaire. Patients reported a wide variety of symptoms at the time of questionnaire completion; fatigue, bone pain and pruritus being most frequently reported. Approximately one-third of respondents from each of the groups (patients and caregivers) reported a negative impact of MPNs on their emotional wellbeing and daily lives. The study findings revealed that, despite treatment, symptom burden remains high, and several unmet needs exist, including educational, emotional and peer group support. Interventions that focus on reducing symptom burden and addressing these unmet needs, may improve the quality of life for patients with MPNs and their caregivers.