Teruaki Kimura

Double‐stranded RNA activates RANTES gene transcription through co‐operation of nuclear factor‐κB and interferon regulatory factors in human airway epithelial cells

Background Regulated on activation, normal T cells expressed and secreted (RANTES) is a member of the CC chemokine family and contributes to viral‐induced airway inflammation including exacerbations of asthma. Double‐stranded RNA (dsRNA) is known to be synthesized during replication of many viruses and a ligand of Toll‐like receptor 3. We hypothesized that dsRNA may mimic viral infection and induce RANTES expression in airway epithelial cells.

Tyrosine phosphorylation of the linker for activator of T cells in mast cells by stimulation with the high affinity IgE receptor.

Aggregation of the high affinity IgE receptors (FcepsilonRI) on basophils and mast cells, members of the immune receptor family, initiates a cascade of events that results in the release of inflammatory mediators. This pathway involves the activation of several protein-tyrosine kinases, including Lyn, Syk, Btk, and Fak that induce the tyrosine phosphorylation of various proteins. The linker for activation of T cells (LAT), was originally found as a ZAP-70 tyrosine kinase substrate that linked T cell receptors to cellular activation, and was expressed in T cells, NK cells and mast cells. Here we show that LAT expressed in the RBL-2H3 rat mast cell line is tyrosine-phosphorylated after aggregation of FcepsilonRI. The tyrosine phosphorylation of the LAT was dramatically enhanced after receptor aggregation. Furthermore, a tyrosine-phosphorylated 80-kDa protein associated with LAT transiently after receptor aggregation. GST fusion proteins containing parts of PLCgamma or PI3 kinase can bind LAT. These results suggest that LAT plays an important role not only in T cell, but also in mast cell activation, and that the association among these signaling molecules is critical for FcepsilonRI-mediated intracellular signal transduction in mast cells.

Eosinophilic Gastroenteritis due to Cow’s Milk Allergy Presenting with Acute Pancreatitis

Eosinophilic gastroenteritis (EGE) is characterized by eosinophilic infiltration of the digestive organs, most commonly of the stomach and the duodenum. Symptoms of EGE are nonspecific and include nausea, vomiting, abdominal pain, dyspepsia, malabsorption, ascites and weight loss. The various symptoms of EGE depend on its location and the depth of gastrointestinal eosinophil infiltration. We report a case presenting with acute pancreatitis caused by a milk allergy. The patient’s symptoms rapidly improved after treatment with corticosteroids, and he remained symptom-free for more than 20 months by the elimination of cow’s milk from his diet. Serum titers of pancreatic enzymes and total bilirubin simultaneously recovered and blood eosinophil counts normalized. The causative allergens of EGE are too various to detect; however, allergologic exams revealed that a cow’s milk allergy had provoked EGE in our case. Adult-onset cow’s milk allergies are rare; when seen, however, they may present severe complications such as anaphylaxis, gastroenteritis and pancreatitis. When unaccountable gastrointestinal symptoms are observed, EGE caused by food allergies should be included in the differential diagnosis.

Cooperative Activation of CCL5 Expression by TLR3 and Tumor Necrosis Factor-α or Interferon-γ through Nuclear Factor-κB or STAT-1 in Airway Epithelial Cells

Background: CCL5/RANTES contributes to prolonged eosinophilic inflammation and asthma exacerbation after a viral infection. We studied the mechanism of CCL5 expression using viral product double-stranded RNA (dsRNA), a ligand of Toll-like receptor 3 (TLR3), and inflammatory cytokines in airway epithelial cells. Methods: The airway epithelial cell line BEAS-2B was used in our in vitro study, and the levels of CCL5 mRNA and CCL5 protein expression were determined using real-time PCR and ELISA. The activity of the CCL5 promoter region and nuclear factor (NF)-ĸB was assessed by dual luciferase assay using specific luciferase reporter plasmids. We used actinomycin D to assess the stability of mRNA. Phosphorylation of signal transducer and activator of transcription 1 (STAT-1) was analyzed by Western blot. Results: Synthetic dsRNA up-regulated the expression of CCL5 mRNA and CCL5 protein. Adding TNF-α or IFN-γ to dsRNA further increased the expression of CCL5. The combination of TNF-α and dsRNA cooperatively activated the CCL5 promoter region and the NF-ĸB-specific reporter. IFN-γ did not activate these reporters. However, it increased the stability of CCL5 mRNA induced by dsRNA. IFN-γ phosphorylated STAT-1, but dsRNA did not. The effects of IFN-γ were not evident in the cells transfected with short interfering RNA for STAT-1. Conclusions: Cross-talk between TLR3 signaling and inflammatory cytokines regulates the expression of CCL5 in airway epithelial cells. In this mechanism, TNF-α may activate NF-ĸB, in cooperation with TLR3 signaling. IFN-γ may stabilize CCL5 mRNA up-regulated by TLR3. This mechanism may depend on STAT-1.