Two canine CD1a proteins are differentially expressed in skin

Lipid antigens are presented to T cells by the CD1 family of proteins. In this study, we characterize the complete dog (Canis familiaris) CD1 locus, which is located on chromosome 38. The canine locus contains eight CD1A genes (canCD1A), of which five are pseudogenes, one canCD1B, one canCD1C, one canCD1D, and one canCD1E gene. In vivo expression of canine CD1 proteins was shown for canCD1a6, canCD1a8, and canCD1b, using a panel of anti-CD1 monoclonal antibodies (mAbs). CanCD1a6 and canCD1a8 are recognized by two distinct mAbs. Furthermore, we show differential transcription of the three canCD1A genes in canine tissues. In canine skin, the transcription level of canCD1A8 was higher than that of canCD1A6, and no transcription of canCD1A2 was detected. Based on protein modeling and protein sequence alignment, we predict that both canine CD1a proteins can bind different glycolipids in their groove. Besides differences in ectodomain structure, we observed the unique presence of three types of cytoplasmic tails encoded by canCD1A genes. cDNA sequencing and expressed sequence tag sequences confirmed the existence of a short, human CD1a-like cytoplasmic tail of four amino acids, of an intermediate length form of 15 amino acids, and of a long form of 31 amino acids

The efficacy of subcutaneous slow-release melatonin implants in the prevention of canine flank alopecia recurrence is uncertain: A double-blind, randomized, placebo-controlled study

BACKGROUND: Canine flank alopecia (CFA) is characterized by seasonally recurring noninflammatory, occasionally hyperpigmented alopecia predominantly in the thoracolumbar area. Previous studies suggest that reduced production of endogenous melatonin may play a role in the pathogenesis of this condition, and placebo-controlled studies on the efficacy of preventative melatonin treatment are lacking. OBJECTIVE: To evaluate the efficacy of subcutaneous slow-release melatonin implants in the prevention of CFA recurrence. ANIMALS: Twenty-one client-owned dogs with a history of CFA were included in the study. MATERIALS AND METHODS: At time (T)0, a general physical and dermatological examination was performed on each dog, blood was collected for serum biochemistry analysis and two skin biopsies were taken from alopecic areas on the nonsedated affected dogs after subcutaneous injection with 2% lidocaine. Dogs with normal blood work and histological results compatible with CFA were included in the study. Participating dogs were randomly assigned to receive either placebo or 18 mg melatonin subcutaneously in the interscapular area, approximately 2 months before expected CFA onset (T1). CFA recurrence was scored qualitatively as complete, ≤50% recurrence, or no recurrence at 5 and 7 months after the intervention (T2 and T3, respectively). RESULTS: At T3, in dogs treated with placebo (nine of 17), the percentages for complete recurrence, ≤50% recurrence and no recurrence were 44%, 0% and 56%, respectively. In dogs treated with melatonin (eight of 17), these percentages were 25%, 50% and 25%, respectively. There were no statistically significant differences in the scores between melatonin-treated dogs and placebo-treated dogs (p = 0.40). In three of eight melatonin-treated dogs, mild transient swelling was observed at the injection site. CONCLUSIONS: This study did not provide evidence that an 18 mg melatonin implant treatment, although well-tolerated, is efficacious in preventing recurrence of CFA in affected dogs

Disseminated Candidiasis in a Young, Previously Healthy, Dog and Review of Literature

BACKGROUND: The reports on disseminated candidiasis in dogs so far describe at least one predisposing factor. This case report, however, highlights candidiasis in a dog without any known predisposition. PATIENT: A 1.5-year-old intact female Hovawart dog was presented with subcutaneous nodules and polyuria/polydipsia. An excisional biopsy revealed a chronic pyogranulomatous and necrotizing inflammation with mycotic structures. The patient became febrile and lethargic, and developed lameness. METHODS: A physical examination, blood tests, urinalysis, thoracic radiographs, abdominal ultrasonography of the abdomen, fine-needle aspiration biopsies, and a culture of a subcutaneous nodule aspirate were obtained. Selected sections of multiple organs were collected for routine histology postmortem. The isolate and a subcutaneous mass were subjected to molecular identification and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. RESULTS: Clinical, laboratory, and radiological findings were consistent with a granulomatous chronic systemic inflammation. Cytology and histology showed a pyogranulomatous and necrotizing inflammation with myriads of intra- and extra-cellular yeasts and extracellular hyphae. Culture yielded numerous yeast colonies, which appeared Candida albicans-like, but showed a negative serum test and a low identification in API 20 C AUX. Nucleic acid sequences showed homology with the C. albicans-type strain CBS 562. Multilocus sequence typing (MLST) resulted in a new type with designation DST121. The identification of the isolates was confirmed by MALDI-TOF-MS analysis. CONCLUSION AND CLINICAL IMPORTANCE: Future MLST typing and investigation of virulence can provide further evidence whether this MLST-type is associated with clinical cases of disseminated candidiasis without an apparent predisposing condition

Clindamycin resistance of skin derived Staphylococcus pseudintermedius is higher in dogs with a previous antibiotic history

BACKGROUND: In the Netherlands there is a lack of data regarding resistance of Staphylococcus pseudintermedius to the systemic antimicrobial drugs used for the treatment of superficial pyoderma. OBJECTIVES: To assess antimicrobial resistance, with emphasis on resistance to clindamycin and meticillin, in clinical isolates of S. pseudintermedius isolated from dogs with superficial pyoderma. Results were compared between dogs with and without a history of systemic antimicrobial therapy during the previous year. ANIMALS: A retrospective study of 237 referral cases presented to an academic teaching hospital between 2014 and 2019, with the clinical and microbiological diagnosis of superficial pyoderma. METHODS AND MATERIALS: All clinical isolates were identified primarily by MALDI-TOF mass spectrometry. Antimicrobial susceptibility was tested either by an agar diffusion method (2014-2016) or by broth microdilution. Antimicrobial history in the preceding year was obtained from medical records. RESULTS: Meticillin-resistant S. pseudintermedius (MRSP) was isolated from 8% of superficial pyoderma cases. Within the meticillin-susceptible S. pseudintermedius (MSSP) population, clindamycin resistance was significantly more common in isolates derived from dogs with histories of antimicrobial treatment (37.7%) compared to dogs with no histories of exposure (21.7%; P = 0.03). CONCLUSIONS: Given the high prevalence of clindamycin resistance in MSSP isolated from dogs with prior antimicrobial exposure, it is recommended that bacterial culture and susceptibility testing be pursued before prescribing systemic antimicrobials. Clindamycin should be regarded as the preferred treatment option if susceptibility is confirmed, due to its narrow spectrum and reduced selective pressure for MRSP

The bacterial and fungal microbiome of the skin of healthy dogs and dogs with atopic dermatitis and the impact of topical antimicrobial therapy, an exploratory study

Contains fulltext : 201261.pdf (publisher's version ) (Open Access

A canine keratinocyte cell line expresses antimicrobial peptide and cytokine genes upon stimulation with bacteria, microbial ligands and recombinant cytokines

Keratinocytes (KC) are the main cellular components of the stratum corneum that constitutes a solid physical skin barrier representing the first line of defense against pathogens. Moreover, KC are potent producers of inflammatory mediators and antimicrobial peptides (AMP) when activated through their pattern recognition receptors. In atopic dermatitis (AD) the protective skin barrier may be compromised due to barrier disruption, secondary infection and accelerated secretion of inflammatory cytokines which may also affect AMP expression in the skin. In the present study, we addressed the responses of a canine KC cell line upon exposure to Staphylococcus pseudintermedius, typically found on canine atopic skin during secondary infections, and stimulation by individual AD-associated ligands and cytokines. All stimuli induced a significant increase in expression of the pro-inflammatory cytokine genes tumor necrosis factor (TNF)-α and interleukin (IL)-8, but with different kinetics. Limited effects were observed on AMP gene expression except for K9CATH which was significantly upregulated upon bacterial infection but with none of the individual AD-associated ligands. Interestingly, K9CATH possessed antimicrobial activity towards Staphylococcus pseudintermedius, indicating that K9CATH expression is a specific defense reaction towards bacterial infection and not part of a general pro-inflammatory profile of KC

Altered lipid properties of the stratum corneum in Canine Atopic Dermatitis

Skin barrier disruption plays a role in the pathogenesis of atopic dermatitis (AD) in humans. However, little is known about skin barrier (dys-) function in Canine Atopic Dermatitis. The properties of lipids located in the outermost layer of the skin, the stratum corneum (SC) are considered to be important for the barrier. In the present study the lipid composition and lipid organization of the SC of AD dogs and control dogs were examined. The lipid composition of lesional AD skin as compared to control skin, showed a reduced free fatty acid level and a decreased ratio of ceramide[NS] C44/C34, in which C44 and C34 are the total numbers of carbon atoms of the sphingosine (S) and non-hydroxy (N) acyl chains. As a consequence of the observed changes in lipid composition in AD lesional skin the lamellar organization of lipids altered and a shift from orthorhombic to hexagonal lipid packing was monitored. Simultaneously an increased conformational disordering occurred. These changes are expected to compromise the integrity of the skin barrier. The C44/C34 chain length ratio of ceramide[NS] also showed a decreasing nonlinear relationship with the AD severity score (CADESI). Taken together, canine atopic skin showed alterations in SC lipid properties, similar to the changes observed in atopic dermatitis in humans, that correlated with a disruption of the skin barrier. Hence lipids play an important role in the pathogenesis of Canine Atopic Dermatitis

Characterization of T cell phenotypes, cytokines and transcription factors in the skin of dogs with cutaneous adverse food reactions

The immunopathogenesis of cutaneous adverse food reactions (CAFRs) in dogs is unknown. Since the clinical manifestations in the skin are like those found in canine atopic dermatitis (AD), this study investigated the similarity in T cell phenotypes and gene expression of cytokines and transcription factors in CAFRs. In addition, the influence of an elimination diet on these parameters was tested. In the skin of canine CAFRs, a predominant presence of CD8+ T cells and increased expression of the IL- 4, IL-13, Foxp3 and SOCS-3 genes were observed. IFN-c gene expression was increased in lesional compared to non-lesional skin. The predominance of CD8+ T cells indicates that the immunopathogenesis of CAFRs is different from that of canine AD. The elimination diet relieved clinical signs, but did not influence T cell phenotypes or expression of the cytokine and transcription factor genes in the skin of dogs with CAFRs, indicating a continuously pre-activated immune status in dogs sensitised to food constituents

Characterisation of T cell phenotypes, cytokines and transcription factors in the skin of dogs with cutaneous adverse food reactions

The immunopathogenesis of cutaneous adverse food reactions (CAFRs) in dogs is unknown. Since the clinical manifestations in the skin are like those found in canine atopic dermatitis (AD), this study investigated the similarity in T cell phenotypes and gene expression of cytokines and transcription factors in CAFRs. In addition, the influence of an elimination diet on these parameters was tested. In the skin of canine CAFRs, a predominant presence of CD8+ T cells and increased expression of the IL- 4, IL-13, Foxp3 and SOCS-3 genes were observed. IFN-c gene expression was increased in lesional compared to non-lesional skin. The predominance of CD8+ T cells indicates that the immunopathogenesis of CAFRs is different from that of canine AD. The elimination diet relieved clinical signs, but did not influence T cell phenotypes or expression of the cytokine and transcription factor genes in the skin of dogs with CAFRs, indicating a continuously pre-activated immune status in dogs sensitised to food constituents