Effects of polyunsaturated fatty acids on isolated canine peripheral blood mononuclear cells and cytokine expression (IL-4, IFN-γ, TGF-β) in healthy and atopic dogs

A placebo-controlled, double-blind study evaluating the effect of orally administered polyunsaturated fatty acids on the oclacitinib dose for atopic dogs

BACKGROUND

Supplementation of polyunsaturated fatty acids (PUFA) enables dose reduction of prednisolone and ciclosporin in canine atopic dermatitis (cAD).

OBJECTIVE

To determine if oral administration of PUFA reduces the dose of oclacitinib in cAD.

ANIMALS

Twenty-two client-owned dogs with cAD receiving oclacitinib.

MATERIALS AND METHODS

Dogs received a fish oil product (PUFA) or paraffin oil (placebo) for 16 weeks. Owners adjusted the oclacitinib dose according to daily pruritus assessments. On Day (D)0, D56 and D112, Canine Atopic Dermatitis Extent and Severity Index, fourth iteration (CADESI-04), pruritus Visual Analog Scale (PVAS), quality-of-life score (QoL), Global Assessment (GA), quality-of-coat (QoC) and adverse events were recorded.

RESULTS

Mean daily oclacitinib dose was significantly reduced in the PUFA group from 0.51 ± 0.20 mg/kg/24 h (D0) to 0.19 ± 0.14 mg/kg/24 h (D85-112; p < 0.00001) and not in the placebo group (D0: 0.70 ± 0.33 mg/kg/24 h; D85-112: 0.53 ± 0.35 mg/kg/24 h, p = 0.5422). CADESI-04 did not change over time or differ between groups. PVAS was significantly lower in the PUFA group (2.8 ± 1.5) compared to placebo (4.2 ± 1.6) at D112 (p = 0.0375). QoL and QoC improved only in the PUFA group (QoL: D0: 20 ± 7, D112: 12 ± 5, p = 0.0057; QoC: D0: 0 ± 0.5, D112: 1 ± 0.5, p = 0.0410). GA on D112 was higher in the PUFA group (p = 0.008). No adverse events were observed.

CONCLUSION

Oral supplementation of PUFA allowed dose reduction of oclacitinib and improved PVAS, QoL, QoC and GA. The use of PUFA is recommended and was safe in the atopic study dogs receiving oclacitinib.

Dietary Betaine and Fatty Acids Change Circulating Single-Carbon Metabolites and Fatty Acids in the Dog

In order to evaluate the interaction of betaine and n-3 PUFA in foods consumed by the dog, six extruded dry foods were formulated. The control food had no specific source of added betaine or n-3 fatty acids, while the test foods were supplemented with betaine, flax or fish oil in a 2 × 3 factorial design (no added n-3 source, added flax, added menhaden fish oil, and all with or without added betaine). Forty eight adult dogs were used in this study. All dogs were assigned to one of the six dietary treatments and consumed that food for the length of the 60-day study. Blood was analyzed for metabolomics (plasma), fatty acids and selected health-related analytes (serum) at the beginning and the end of the study. Added dietary betaine increased single-carbon metabolites (betaine, dimethyl glycine, methionine and N-methylalanine), decreased xenobiotics (stachydrine, N-acetyl-S-allyl-L-cysteine, 4-vinylguaiacol sulfate, pyrraline, 3-indoleglyoxylic acid, N-methylpipecolate and ectoine) and enhanced the production of eicosapentaenoic acid (EPA). Dietary betaine also decreased the concentration of circulating carnitine and a number of carnitine-containing moieties. The addition of the n-3 fatty acids alpha-linolenic, EPA and docosahexaenoic acid (DHA) increased their respective circulating concentrations as well as those of many subsequent moieties containing these fatty acids. The addition of alpha-linolenic acid increased the concentration of EPA when expressed as a ratio of EPA consumed.

Expression and biological functions of Ancylostoma ceylanicum saposin-like protein

Ancylostoma ceylanicum is a common zoonotic nematode that inhabits the small intestine of humans, dogs, and cats. Saposin-like proteins (SLPs) have hemolytic and antibacterial activities and could be used as diagnostic or vaccine candidates. To explore the biological functions of Ancylostoma ceylanicum SLP (Ace-SLP-1), cDNA-encoding Ace-SLP-1 mature peptide was cloned into prokaryotic expression vector pET-28a and transformed into Escherichia coli BL21 (DE3) to induce expression. After incubation of canine red blood cell suspension with different concentrations of recombinant Ace-SLP-1, the supernatant was separated to measure OD value and calculate the hemolysis rate. The different concentrations of recombinant protein were co-cultured with E. coli and Enterococcus faecalis, and colony-forming units (CFU) were determined by the plate counting method. Peripheral blood mononuclear cells (PBMCs) from healthy dogs were incubated with different concentrations of recombinant Ace-SLP-1, and the cytokine expression was evaluated by relative quantitative PCR. Our results showed that the hemolytic activity of Ace-SLP-1 increased with the increase in protein concentration from 25 to 100 μg/mL. The recombinant protein had no antibacterial activity against the two kinds of bacteria but could stimulate the secretion of cytokines (IL-4, IL-10, IL-12, and IL-13) in canine PBMCs. These data suggest that Ace-SLP-1 is involved in hookworm blood-feeding and survival and has good immunogenicity, supporting its potential as a diagnostic and vaccine target molecule.

Effect of Ancylostoma ceylanicum hookworm platelet inhibitor on platelet adhesion and peripheral blood mononuclear cell proliferation

Ancylostoma ceylanicum is a zoonotic parasitic nematode that can cause iron-deficiency anemia and malnutrition in humans. A. ceylanicum hookworm platelet inhibitor (Ace-HPI) can inhibit platelet aggregation in the host to facilitate blood sucking, but whether it possesses platelet adhesion inhibitory activity or immunomodulatory role is yet unknown. To explore the effect of Ace-HPI on platelet adhesion, we expressed the recombinant protein in two competent cells, BL21 (DE3) and Rosetta-gami2 (DE3), and incubated this protein with canine platelets in a 96-well microplate. Ace-HPI was used to stimulate peripheral blood mononuclear cells (PBMC) in vitro to investigate the effect on PBMC proliferation and cytokine expression. Results showed that Ace-HPI expressed in Rosetta-gami2 (DE3) strain was mostly soluble. The inhibitory effect of this protein on platelet adhesion was relatively weak (7-8%). This protein stimulated the proliferation of PBMC and promoted the expression of Treg and Th2 cytokines, such as IL-10 and IL-13. These results lay a foundation for exploring the role of Ace-HPI in hookworm disease pathogenesis and as a candidate molecule for hookworm vaccines.

Non-controlled, open-label clinical trial to assess the effectiveness of a dietetic food on pruritus and dermatologic scoring in atopic dogs

BACKGROUND

Canine atopic dermatitis (AD) is a common skin disease. The goal of this study was to evaluate food designed to improve skin barrier function and lower inflammation to reduce pruritus and clinical severity in client-owned atopic dogs. The food contained an antioxidant blend to reduce oxidative stress, plant polyphenols to stabilize mast cells, and polyunsaturated fatty acids to improve skin health and reduce inflammation.

RESULTS

Seventeen dogs were included in the analysis. Initially 48 adult atopic dogs were enrolled and exclusively fed a dermatologic food for 8 weeks in a non-controlled, open-label study. Thirty-one dogs were excluded for the following reasons: oral and topical medication changes (n = 17), missing data (n = 4), fatty acid supplementation (n = 3), food refusal (n = 3), dropped out (n = 3), and owner concerns (n = 1). Using a scale from 0 (normal) - 4 (severe), veterinarians evaluated the presence and severity of clinical signs of atopy at weeks 0, 4, and 8. Pet owners also rated their pet's clinical signs of atopy on a scale from 0 (not present) - 10 (present continuously) at weeks 0, 4, and 8. Compared with initial baseline scores (median 19, range 3-69), the total veterinarian scores were significantly lower at weeks 4 (median 11, range 1-15) and 8 (median 7, range 3-46) (p < 0.05). Similarly, owner assessments showed significant improvements in the least squares mean (LSM) from baseline to 4 weeks (itching, redness, licking, and scratching) continuing to 8 weeks (itching, redness, and scratching) (p < 0.05).

CONCLUSIONS

In this open, non-controlled study evaluating a dermatologic diet in seventeen client-owned dogs, owner and veterinarian assessments showed statistically significant reductions in clinical scores designed to measure severity of atopic dermatitis. While these results show promise for the management of canine atopic dermatitis, controlled clinical trials are also needed to affirm our findings.

An update on the treatment of canine atopic dermatitis

Canine atopic dermatitis is a common skin disease seen in veterinary clinical practice. Several factors appear to contribute to the cutaneous inflammation and pruritus. The therapeutic strategy should focus on control of those factors that can be identified and for which interventional measures are feasible; these include ectoparasites, bacterial/fungal infection and dietary hypersensitivity. Ectoparasites, particularly fleas, are not the cause of atopic dermatitis, but they are a confounding factor, which can exacerbate pruritus, and preventative measures are therefore indicated. Bacterial and yeast infections are frequently associated with atopic dermatitis and initial systemic and/or topical therapy should be considered, followed by regular topical treatment for preventing relapse. Concurrent dietary hypersensitivity should be investigated by undertaking an elimination/provocation trial, followed by feeding of a hypoallergenic diet where appropriate. Depending on the severity of the clinical signs of atopic dermatitis and the willingness and expectations of owners, symptomatic treatment and/or specific interventional therapy for environmental allergy (allergen avoidance, allergen-specific immunotherapy) may be implemented. Symptomatic treatment includes use of glucocorticoids (systemically or topically), ciclosporin and oclacitinib. Other treatment modalities of lower or less proven efficacy include antihistamines, dextromethorphan, fatty acids, feline interferon-omega, misoprostol, pentoxifylline, specific serotonin re-uptake inhibitors and tricyclic antidepressant drugs. The therapeutic approach should be reviewed at regular intervals and tailored to the individual's needs. A successful long-term outcome can usually be achieved by combining the various treatment approaches in a way that maximises their benefits and minimises their drawbacks.

Allergen-induced production of IL-31 by canine Th2 cells and identification of immune, skin, and neuronal target cells

The canine cytokine IL-31 induces pruritus in dogs and can be detected in dogs with atopic dermatitis; however very little is understood around its interactions with specific canine cells. We hypothesize that IL-31 is involved in the progression of allergic skin disease by coordinating the interaction between the immune system with skin and neuronal systems. The goal of the following work was to identify cells that produce IL-31 as well as cells that may respond to this cytokine. Peripheral blood mononuclear cells (PBMCs) were collected from naïve and house dust mite (HDM) allergen-sensitized beagle dogs and used for ex vivo characterization of cytokine production assessed using ELISpot and quantitative immunoassay. Sensitization to HDM allergen induced a T-helper type 2 (Th2) cell phenotype characterized by an increase in the production of IL-4 protein. Interestingly, repeated allergen challenge over time also resulted in an increase in IFN-γ. Further evaluation showed that co-stimulation of Th2 polarized cells with antigen and the bacterial component Staphylococcus enterotoxin B (SEB) produced higher levels of IL-31 compared to either stimulant alone. Production of IL-31 when PBMCs were stimulated by T cell mitogens suggests T cells as a source of IL-31. Quantitative real-time PCR was utilized to determine expression of the IL-31 receptor alpha chain in canine cell lines and tissue. Canine monocytic cells, keratinocytes, and dorsal root ganglia were shown to express the IL-31 receptor alpha chain mRNA. In a multifaceted disease such as canine atopic dermatitis, the combination of Th2 polarization and microbial presence may lead to IL-31 mediated effects driving inflammation and pruritus by immune cells, keratinocytes, and direct neuronal stimulation.

In vitro effects of CpG oligodeoxynucleotides delivered by gelatin nanoparticles on canine peripheral blood mononuclear cells of atopic and healthy dogs - a pilot study

BACKGROUND

Cytosine-phosphate-guanine (CpG) oligodeoxynucleotides offer a novel promising immunotherapeutic approach for atopic dermatitis (AD) both in humans and animals. Gelatin nanoparticles (GNP) enhance and prolong CpG-associated immunomodulatory effects and minimize adverse effects both in vitro and in vivo. Information about the effects of this combination in dogs is lacking.

HYPOTHESIS/OBJECTIVES

The aim of this study was to evaluate immunological effects of CpG coupled to GNP on canine peripheral blood mononuclear cells (PBMCs) in vitro.

ANIMALS

Eight dogs with AD, diagnosed by standard criteria and with a concurrent immediate hypersensitivity to house dust mites were included. Control samples were taken from eight healthy, age-matched control dogs without history or evidence of cutaneous or systemic illness.

METHODS

Peripheral blood mononuclear cells of healthy and allergic dogs were incubated with CpG-GNP and the uptake of CpG-GNP was demonstrated using confocal laser scanning microscopy. Cell culture supernatant concentrations of interferon gamma (IFN-γ), interleukin (IL)-4, IL-6 and IL-10 were measured by Canine Cytokine Milliplex.

RESULTS

No significant changes in IFN-γ and IL-4 were found when comparing PBMCs incubated with CpG and CpG-GNP with the negative controls in atopic and healthy dogs. Interleukin-6 was not detected in any of the groups. However, a statistically significant increase in IL-10 concentration was found after 24 h stimulation with CpG-GNP compared with CpG alone both in atopic and healthy dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

As IL-10 is considered an immunosuppressive cytokine playing a key role in peripheral tolerance; the reported CpG-GNP formulation could be a new approach in allergy treatment.

Supplementation with long chain polyunsaturated fatty acids in treatment of atopic dermatitis in children

Some recent studies indicate that unsaturated fatty acids, components of cellular membranes and precursors of immunomodulators, play a significant role in the pathogenesis of some symptoms of atopic dermatitis. Since they cannot be synthesized by the human body, they must be provided with nutrition as the so called exogenous fatty acids: linoleic (a precursor of arachidonic acid) and α-linolenic acid (a precursor of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)). Their deficiency facilitates the development of some disorders, e.g. of the cardiovascular system or of the nervous system, or becomes the cause of intensification of ailments in their course e.g. pruritus and dryness in atopic dermatitis. Though clinical examinations to date confirm the efficacy of fatty acid supplementation in treatment of atopic dermatitis, their results are not explicit.

Double-blinded, placebo-controlled study to evaluate an antipruritic shampoo for dogs with allergic pruritus

Shampoo therapy is frequently used on pruritic dogs. However, there are few double-blinded, placebo-controlled studies of this form of therapy. This randomised, double-blinded, placebo-controlled study evaluated the efficacy of a commercial medicated shampoo (DermaTopic; Almapharm) containing chlorhexidine, lactoferrin, piroctone olamine, chitosan and essential fatty acids in 27 dogs with mild to moderate allergic pruritus without secondary skin infections. All dogs received shampoo therapy with either DermaTopic or a shampoo vehicle as placebo twice weekly for four weeks. The extent of pruritus was evaluated before the study and then on a daily basis by the owners using a visual analogue scale. Before beginning the treatment and after four weeks, the skin lesions were evaluated by an experienced clinician with a validated lesion score (Canine Atopic Dermatitis Extent and Severity Index - CADESI). The pruritus was reduced significantly by both DermaTopic and placebo. However, there was no significant difference between both groups. There was no statistically significant difference in the CADESI scores pre- and post-treatment in either group or between the two types of treatment. This study provides further evidence of the benefit of shampoo therapy for pruritic dogs.

The Influence of Topical Unsaturated Fatty Acids and Essential Oils on Normal and Atopic Dogs

Seven dogs with atopic dermatitis and six normal dogs were treated with a spot-on product containing essential oils and unsaturated fatty acids q 7 days for 8 wk. Seven additional atopic dogs received a daily spray containing similar ingredients to the spot-on. In all dogs, transepidermal water loss (TEWL) was measured before and after treatment using a closed chamber device. In atopic dogs, a validated lesion score (canine atopic dermatitis extent and severity index, CADESI) was determined and pruritus was assessed with a visual analog scale before and after treatment. The mean CADESI scores in atopic dogs decreased with the spot-on (P=0.0043) and with the spray (P=0.0366). Similarly, the pruritus scores decreased with the spot-on (P=0.266) and with the spray (P=0.0177). There was a significant difference between the TEWL values of healthy and atopic dogs on the abdomen (P=0.0181) and back (P=0.0123). TEWL decreased significantly on the back after treatment with the spray (P=0.016), but not on the abdomen (P=0.078). Adverse effects were not observed. The results of this pilot study indicate that topical fatty acids and essential oils are a useful treatment option for canine atopic dermatitis.