Rationale: Rhinoviruses are the major cause of asthma exacerbations; however, its underlying mechanisms are poorly understood. We hypothesized that the epithelial cell-derived cytokine IL-33 plays a central role in exacerbation pathogenesis through augmentation of type 2 inflammation.Objectives: To assess whether rhinovirus induces a type 2 inflammatory response in asthma in vivo and to define a role for IL-33 in this pathway.Methods: We used a human experimental model of rhinovirus infection and novel airway sampling techniques to measure IL-4, IL-5, IL-13, and IL-33 levels in the asthmatic and healthy airways during a rhinovirus infection. Additionally, we cultured human T cells and type 2 innate lymphoid cells (ILC2s) with the supernatants of rhinovirusinfected bronchial epithelial cells (BECs) to assess type 2 cytokine production in the presence or absence of IL-33 receptor blockade.

Although growth factors naturally exert their morphogenetic influences within the context of the extracellular matrix microenvironment, the interactions among growth factors, their receptors, and other extracellular matrix components are typically ignored in clinical delivery of growth factors. We present an approach for engineering the cellular microenvironment to greatly accentuate the effects of vascular endothelial growth factor-A (VEGF-A) and platelet-derived growth factor-BB (PDGF-BB) for skin repair, and of bone morphogenetic protein-2 (BMP-2) and PDGF-BB for bone repair. A multifunctional recombinant fragment of fibronectin (FN) was engineered to comprise (i) a factor XIIIa substrate fibrin-binding sequence, (ii) the 9th to 10th type III FN repeat (FN III9-10) containing the major integrin-binding domain, and (iii) the 12th to 14th type III FN repeat (FN III12-14), which binds growth factors promiscuously, including VEGF-A165, PDGF-BB, and BMP-2. We show potent synergistic signaling and morphogenesis between α5β1 integrin and the growth factor receptors, but only when FN III9-10 and FN III12-14 are proximally presented in the same polypeptide chain (FN III9-10/12-14). The multifunctional FN III9-10/12-14 greatly enhanced the regenerative effects of the growth factors in vivo in a diabetic mouse model of chronic wounds (primarily through an angiogenic mechanism) and in a rat model of critical-size bone defects (through a mesenchymal stem cell recruitment mechanism) at doses where the growth factors delivered within fibrin only had no significant effects.

TLRs play an essential role in the induction of immune responses by detecting conserved molecular products of microorganisms. However, the function of TLR8 is largely unknown. In the current study, we investigated the role of TLR8 signaling in immunity in mice. We found that Tlr8 -/-DCs overexpressed TLR7, were hyperresponsive to various TLR7 ligands, and showed stronger and faster NF-κB activation upon stimulation with the TLR7 ligand R848. Tlr8 -/-mice showed splenomegaly, defective development of marginal zone (MZ) and B1 B cells, and increased serum levels of IgM and IgG2a. Furthermore, Tlr8 -/-mice exhibited increased serum levels of autoantibodies against small nuclear ribonucleoproteins, ribonucleoprotein, and dsDNA and developed glomerulonephritis, whereas neither Tlr7 -/-nor Tlr8 -/-Tlr7 -/-mice showed any of the phenotypes observed in Tlr8 -/-mice. These data provide evidence for a pivotal role for mouse TLR8 in the regulation of mouse TLR7 expression and prevention of spontaneous autoimmunity. IntroductionTLRs, mammalian homologs of the Drosophila receptor Toll, detect evolutionarily conserved structures expressed by different groups of microbes and play a major role in the elimination of infections by coactivation of the immune system (1). TLRs are composed of an ectodomain of leucine-rich repeats, which are involved in ligand binding, a transmembrane domain, and a cytoplasmic Toll/IL-1 receptor (TIR) domain that interacts with TIR domain-containing adaptor molecules. The signaling pathways activated by different TLRs involve a family of 5 adaptor proteins, which couple to downstream protein kinases and ultimately lead to the activation of transcription factors such as NF-κB, MAPKs, and members of the IFN-regulatory factor family (2).The family of TLRs consists of 10 members in humans (TLR1-TLR10) and 12 members in mice (TLR1-TLR9 and TLR11-TLR13). The mammalian TLRs that are located in the plasma membrane recognize bacterial membrane components, whereas the TLRs that detect nucleic acid-based ligands are predominately located within endosomal compartments (3). The nucleic acid-sensing TLRs include TLR3, TLR7, TLR8, and TLR9. TLR3 senses viral and synthetic double-stranded RNA, TLR7 recognizes viral single-stranded RNA (ssRNA) and synthetic imidazoquinoline compounds, and TLR9 detects unmethylated CpG containing DNA motifs, found in bacterial and viral DNA (3). Although TLR7 and TLR8 are phylogenetically very close, their natural ligand viral ssRNA stimulates human TLR7 and TLR8 and mouse TLR7, but not mouse TLR8, leading to the belief that TLR8 is biologically inactive in mice (4). However, recent studies have shown that TLR8 is dynamically expressed during mouse brain development and functions as a negative regulator of neurite outgrowth and an inducer of neuronal apoptosis (5). Moreover, stimulation of murine TLR8-transfected HEK293 cells with a combination of imidazoquinoline immune response modifiers and polyT oligonucleotides leads to NF-κB activation, which suggests that mouse