Tumour necrosis factor-α induces C-C motif chemokine ligand 5 production in canine keratinocytes.

BACKGROUND: C-C motif chemokine ligand (CCL)5 induces skin inflammation in healthy dogs. In addition, CCL5 is overexpressed in the skin of experimental models of canine atopic dermatitis (cAD). Tumour necrosis factor (TNF)-α has been shown to be upregulated in cAD. However, it remains unclear whether TNF-α induces CCL5 production in canine keratinocytes. HYPOTHESIS/OBJECTIVES: To determine the effect of TNF-α on CCL5 production in canine keratinocyte culture and investigate possible synergy with interferon (IFN)-γ and interleukin (IL)-4. MATERIALS AND METHODS: CCL5 protein concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in the culture supernatant of a cell line of canine progenitor epidermal keratinocyte (CPEK) cells stimulated with TNF-α with or without inhibitors of the TNF receptor signalling pathway. CCL5 protein concentrations also were measured in CPEK cells stimulated with TNF-α in the absence or presence of IFN-γ, a T-helper (Th)1-type cytokine, and/or IL-4, a Th2-type cytokine. RESULTS: TNF-α increased CCL5 production in CPEK cells in time- and dose-dependent manners. Inhibitors of the TNF receptor signalling pathway diminished CCL5 production. Although neither IFN-γ nor IL-4 alone induced CCL5 production in CPEK cells, the combination of TNF-α and IFN-γ, and not IL-4, synergistically enhanced CCL5 production in these cells. CONCLUSIONS AND CLINICAL RELEVANCE: TNF-α may be involved in skin inflammation in dogs by promoting CCL5 production in keratinocytes. Furthermore, the synergistic effect of TNF-α and IFN-γ suggests that the local Th1-type milieu may aggravate skin inflammation. Further studies are required to elucidate the role of TNF-α-induced CCL5 production of keratinocytes in the pathogenesis of cAD.

Expression of genes encoding interleukin 15 and its receptor subunits in the duodenal and colonic mucosae of dogs with chronic enteropathy.

A pro-inflammatory role of interleukin (IL)-15 and IL-15 receptor (R) in chronic intestinal inflammation, such as inflammatory bowel disease, has been reported in humans. However, the contribution of IL-15 signaling in the pathogenesis of canine chronic enteropathy (CE) remains unclear. Therefore, as a first step in elucidating the importance of IL-15 signaling in canine CE, we measured the mRNA expression of IL-15 and IL-15R subunits, including IL-15Rα, IL-15Rß, and IL-15Rγ, in the duodenal and colonic mucosae of healthy dogs and those with CE, including food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE). Real-time PCR analysis revealed significantly lower IL-15Rα mRNA expression levels in the duodenal mucosa of dogs with IRE compared to healthy dogs. In contrast, the mRNA expression levels of IL-15, IL-15Rß, and IL-15Rγ in the duodenal mucosa and IL-15, IL-15Rα, IL-15Rß, and IL-15Rγ in the colonic mucosa did not differ among healthy dogs and those with FRE, ARE, or IRE. These findings suggest that decreased mRNA expression of IL-15Rα might be involved in the pathogenesis of duodenitis in dogs with IRE. Moreover, even in canine CE, IL-15 signaling appears to play different roles in duodenitis and colitis in dogs with FRE, ARE, and IRE. However, there were no correlations between the gene expression levels of IL-15Rα and clinical severity or histopathological scores in the duodenum of dogs with IRE. Further studies are necessary to investigate the IL-15Rα protein localization and to determine how impaired IL-15Rα expression contributes to the development of duodenitis in dogs with IRE.

Clinical characteristics of dogs presenting with vomiting as a gastrointestinal sign of chronic enteropathy.

Vomiting is a major gastrointestinal (GI) sign of chronic enteropathy (CE) in dogs. Previous studies have reported clinical characteristics of dogs with CE, who developed diarrhea with or without vomiting as GI signs. However, to characterize clinical features of dogs with CE appropriately, dogs presenting with vomiting without diarrhea should be included in the analysis. Thus, this study aimed to characterize clinical features and outcomes of dogs that presented with vomiting without diarrhea. Based on their presenting GI signs, we retrospectively classified 66 dogs with CE into "Vomiting", "Diarrhea", or "Vomiting and diarrhea" groups and compared clinical and histological characteristics of each group. We found that 18 of the 66 dogs with CE (27%) presented with vomiting without diarrhea as a GI sign. Compared to the other 2 groups, the Vomiting group was significantly associated with food-responsive enteropathy (FRE), Beagle, lower clinical severity scores, higher plasma albumin levels, and higher histological scores for eosinophils in the duodenal lamina propria according to the univariate analysis. The multivariate analysis revealed that FRE and higher histological scores for eosinophils in the duodenal lamina propria were significant variables in the Vomiting group. Moreover, the survival time was the longest in the Vomiting group among dogs with CE. These findings are of clinical significance as they indicate that presenting with vomiting without diarrhea may not only be helpful in differentiating FRE from the other types of CE, but also in predicting the prognosis.

The complete genomic sequence of Mycoplasma penetrans, an intracellular bacterial pathogen in humans.

The complete genomic sequence of an intracellular bacterial pathogen, Mycoplasma penetrans HF-2 strain, was determined. The HF-2 genome consists of a 1 358 633 bp single circular chromosome containing 1038 predicted coding sequences (CDSs), one set of rRNA genes and 30 tRNA genes. Among the 1038 CDSs, 264 predicted proteins are common to the Mycoplasmataceae sequenced thus far and 463 are M.penetrans specific. The genome contains the two-component system but lacks the essential cellular gene, uridine kinase. The relatively large genome of M.penetrans HF-2 among mycoplasma species may be accounted for by both its rich core proteome and the presence of a number of paralog families corresponding to 25.4% of all CDSs. The largest paralog family is the p35 family, which encodes surface lipoproteins including the major antigen, P35. A total of 44 genes for p35 and p35 homologs were identified and 30 of them form one large cluster in the chromosome. The genetic tree of p35 paralogs suggests the occurrence of dynamic chromosomal rearrangement in paralog formation during evolution. Thus, M.penetrans HF-2 may have acquired diverse repertoires of antigenic variation-related genes to allow its persistent infection in humans.