In Vitro Influence of Mycophenolic Acid on Selected Parameters of Stimulated Peripheral Canine Lymphocytes.

Mycophenolic acid (MPA) is an active metabolite of mycophenolate mofetil, a new immunosuppressive drug effective in the treatment of canine autoimmune diseases. The impact of MPA on immunity is ambiguous and its influence on the canine immune system is unknown. The aim of the study was to determine markers of changes in stimulated peripheral canine lymphocytes after treatment with MPA in vitro. Twenty nine healthy dogs were studied. Phenotypic and functional analysis of lymphocytes was performed on peripheral blood mononuclear cells cultured with mitogens and different MPA concentrations- 1 μM (10(-3) mol/m(3)), 10 μM or 100 μM. Apoptotic cells were detected by Annexin V and 7-aminoactinomycin D (7-AAD). The expression of antigens (CD3, CD4, CD8, CD21, CD25, forkhead box P3 [FoxP3] and proliferating cell nuclear antigen [PCNA]) was assessed with monoclonal antibodies. The proliferation indices were analyzed in carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled cells. All analyses were performed using flow cytometry. The influence of MPA on apoptosis was dependent on the mechanism of cell activation and MPA concentration. MPA caused a decrease in the expression of lymphocyte surface antigens, CD3, CD8 and CD25. Its impact on the expression of CD4 and CD21 was negligible. Its negative influence on the expression of FoxP3 was dependent on cell stimulation. MPA inhibited lymphocyte proliferation. In conclusion, MPA inhibited the activity of stimulated canine lymphocytes by blocking lymphocyte activation and proliferation. The influence of MPA on the development of immune tolerance-expansion of Treg cells and lymphocyte apoptosis-was ambiguous and was dependent on the mechanism of cellular activation. The concentration that MPA reaches in the blood may lead to inhibition of the functions of the canine immune system. The applied panel of markers can be used for evaluation of the effects of immunosuppressive compounds in the dog

T cells and immunomodulation in canine atopic dermatitis

Atopic dermatitis (AD) in dogs is defined as “a genetically-predisposed inflammatory and pruritic allergic skin disease with characteristic clinical features.” It is associated most commonly with IgE antibodies specific for common environmental allergens such as house dust mites, grass and plant pollens. The etiology of cAD is considered as multifactorial. An epidermal barrier dysfunction combined with dysregulation of the immune system leads to the development of clinical disease in dogs with a suggested genetic background for AD. T-lymphocytes (T cells) with effector functions play a dominant role in the development of atopic skin lesions. T cells with regulatory functions (Tregs) also exist. However, whether absence or reduction in number and function of Tregs may contribute to the development of canine AD skin lesions, was unknown. The only disease-modifying treatment available is the allergen-specific immunotherapy (ASIT). Success of ASIT in atopic dogs is currently only achieved in 50-80%, hence, potentiation of ASIT in order to improve its efficacy would be beneficial for future therapeutic interventions of cAD. A better understanding of immunoregulatory mechanisms may be at the basis for more successful ASIT. Tregs are thought to contribute to the beneficial effects of ASIT in AD. For that reason, the research questions addressed in this thesis focussed on the dysbalance of T cell responsiveness, with emphasis on the possible roles of Tregs and CD8+ T cells within the etiology of cAD.In addition, the effects of two different immunomodulatory compounds (Hsp and CpG ODN), potentially capable of restoring the dysbalance in T cell responsiveness in cAD, were evaluated. This thesis shows that cells of not only the subpopulation of CD4+ T cells, but also the subpopulation of CD8+ T cells likely contribute to the disease by producing inflammatory cytokines. First evidence for presence of allergen-specific CD8+ T cells was found in the peripheral blood of AD dogs. In addition to a role as effector T cell, CD8+ T cells may also have a regulatory function. Presence of T cells of both CD4+ and CD8+ lineages with regulatory markers (CD25+FoxP3+) have been found in the peripheral blood and skin of AD dogs. However, at this moment, we don’t know their role in the immunopathogenesis of cAD, since their numbers were largely similar to those in healthy dogs. The Treg function could be diminished or Tregs could have been functionally overruled by the high numbers or activation status of effector T cells in lesional atopic skin. Future functional studies, including suppression assays, need to be performed to determine the relevance of the T cells with regulatory markers and their usefulness as targets in new immunomodulatory strategies for dogs with AD

Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides

Vet Dermatol. 2009 Feb;20(1):67-71. Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides. Jassies-van der Lee A, van Zeeland Y, Kik M, Schoemaker N. Department of Clinical Sciences of Companion Animals, Utrecht University, The Netherlands. [email protected] A 4-year-old rabbit was presented with a chronic exfoliative dermatitis and patchy alopecia. General physical examination revealed no abnormalities. Skin scrapings and fungal culture were negative. A blood sample was obtained for a complete blood cell count and biochemical profile, and yielded results that were within normal limits. Radiographic examination of the thorax excluded the presence of a thymoma. Histopathology of the skin showed orthokeratotic hyperkeratosis, absence of sebaceous glands and mural lymphocytic folliculitis, consistent with sebaceous adenitis. Oral treatment was started with ciclosporin dissolved in a medium-chain triglyceride solution (Miglyol 812), combined with essential fatty acids and topical propylene glycol sprays. Within 2 months of treatment, complete regression of skin lesions and regrowth of hair was observed. Serum chemistry values including kidney and liver function tests remained within reference range during the course of treatment. Histopathological examination of control biopsies of the skin showed presence of normal sebaceous glands and active hair follicles. Treatment was changed to a different pharmaceutical formulation of ciclosporin without Miglyol and deterioration of clinical signs was noticed. Using pure Miglyol 812, however, resulted in a gradual improvement of 60%. A nearly complete response was again observed after re-administration of the combination ciclosporin/Miglyol. It is hypothesized that sebaceous adenitis in the rabbit is most likely due to an autoimmune reaction directed at the sebaceous glands and a defect in lipid metabolism. The outcome indicates that a combination of ciclosporin and Miglyol 812 is a promising new treatment for sebaceous adenitis in rabbits. PMID: 19152589 [PubMed - indexed for MEDLINE

Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides

Vet Dermatol. 2009 Feb;20(1):67-71. Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides. Jassies-van der Lee A, van Zeeland Y, Kik M, Schoemaker N. Department of Clinical Sciences of Companion Animals, Utrecht University, The Netherlands. [email protected] A 4-year-old rabbit was presented with a chronic exfoliative dermatitis and patchy alopecia. General physical examination revealed no abnormalities. Skin scrapings and fungal culture were negative. A blood sample was obtained for a complete blood cell count and biochemical profile, and yielded results that were within normal limits. Radiographic examination of the thorax excluded the presence of a thymoma. Histopathology of the skin showed orthokeratotic hyperkeratosis, absence of sebaceous glands and mural lymphocytic folliculitis, consistent with sebaceous adenitis. Oral treatment was started with ciclosporin dissolved in a medium-chain triglyceride solution (Miglyol 812), combined with essential fatty acids and topical propylene glycol sprays. Within 2 months of treatment, complete regression of skin lesions and regrowth of hair was observed. Serum chemistry values including kidney and liver function tests remained within reference range during the course of treatment. Histopathological examination of control biopsies of the skin showed presence of normal sebaceous glands and active hair follicles. Treatment was changed to a different pharmaceutical formulation of ciclosporin without Miglyol and deterioration of clinical signs was noticed. Using pure Miglyol 812, however, resulted in a gradual improvement of 60%. A nearly complete response was again observed after re-administration of the combination ciclosporin/Miglyol. It is hypothesized that sebaceous adenitis in the rabbit is most likely due to an autoimmune reaction directed at the sebaceous glands and a defect in lipid metabolism. The outcome indicates that a combination of ciclosporin and Miglyol 812 is a promising new treatment for sebaceous adenitis in rabbits. PMID: 19152589 [PubMed - indexed for MEDLINE