Systemic_Lupus_Erythematosus

Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a rare disease that can affect the musculoskeletal, haematopoietic, urinary and cutaneous systems. (Gaudiano, 2005). Animals suffering from SLE produce a variety of autoantibodies which result in a great range of clinical symptoms. In dogs the disease is most commonly seen in Collies, German Sheppards and Shetland sheep dogs. Characteristically the disease presents itself in dogs as a fluctuating fever and non-erosive polyarthritis. Skin disease is another common symptom with skin lesions that can occur anywhere on the body but most commonly on the face ears and distal extremities. Lesions that are characteristic of autoimmune disease are those that occur on the nasal planum, ear pinnae and footpads. Other common symptoms of canine lupus are renal failure and lymphedema. Pneumonitis, blood dycrosis, pleuritis, pericarditis, myocarditis and neuropathy may also be present. SLE is uncommon in cats. Feline lupus usually presents itself as antiglobulin-positive anaemia. The dermatological form can produce various cutaneous lesions including an erythematosus, alopecia, scaling, crusting and scarring dermatitis. Although these lesions can occur anywhere on the body, it is the face, ear pinnae and paws that are most commonly affected. Other common symptoms in cats are fever, polyarthritis, renal failure, neurologic or behavioural abnormalities, hematologic abnormalities and myopathy. In equines, SLE presents itself as generalised skin disease along with antiglobulin-positive anaemia. (Medleau, 2006). The most characteristic autoantibody produced in lupus cases are antinuclear antibodies (ANAs). Affected animals develop autoantibodies against antigens located within the cell nucleus. The ANAs participate in the pathogenesis of the disease by combining with free antigens and forming immune complexes. These complexes localise in glomeruli and cause Type III hypersensitivity reaction and subsequently membranous glomerolonephritis. These complexes may be deposited in joints causing arthritis, or if deposited at the dermal-epidermal joint the dermatological form of the disease occurs. Deposition in the arteriolar walls causes fibrinoid necrosis and fibrosis. (Gershwin, et al., 1995). ANAs also produce hematoxylin bodies in the skin, kidney, lung lymph nodes, spleen and heart by binding to the nuclei of degenerating cells. It is also common for affected animals to produce high levels of antibodies against extracted nuclear antigens, particularly the nuclear robonucleoprotein antigen SSB/La. (Tizard, 2009). The production of ANAs may be due to the animals TLR loosing the ability to discriminate between microbial and self-DNA, and a proportion of B cell surface immunoglobulins binding to self-DNA. This would require the animal’s B cells to undergo a somatic mutation. Another possible explanation for the production of ANAs is that cross-reactive antibodies that react with mammalian DNA are produced in response to bacterial infection. (Tizard, 2009). A further defect seen in some affected animals is impaired clearance of aptopic cells. Defective phagocytosis of aptopic cells results in their accumulation in tissues. Dendric cells may process the nuclear fragments from the accumulated aptopic cells and thereby trigger autoantibody formation. (Tizard, 2009). As mentioned previously, animals suffering from lupus produce many types of autoantibodies suggesting abnormal B cells. Indeed, abnormalities in B cell signalling and migration are seen in affected animals alongside over-expression of CD154 (CD40L) and enhanced production of interleukin-6 and interleukin-10. (Tizard, 2009). The initiating cause of lupus is unknown. It is thought that there is a genetic predisposition with the disease being transmitted vertically down to offspring. It is also thought that hormones may influence the disease and that virus infections may trigger the syndrome. (Vyse, 1998). Reference Gaudiano, F. 2005. Veterinary Dermatology; A manual for nurses and technicians. Elsevier Limited: London. Gershwin, L J, Krakowka, S and Olsen, R G. 1995. Immunology and Immunopathology of Domestic Animals. Mosby-Year Book Inc: Missouri. Medleau, L and Hnilica, K A. 2006. Small Animal Dermatology; A Colour Atlas and Therapeutic Guide. Mosby-Year Book Inc: Missouri. Tizard, I R. 2009. Veterinary Immunology an Introduction. Saunders Elsevier: Missouri. Vyse, T J and Kotzin, B L. 1998. Genetic susceptibility to systemic lupus erythematosus. Annual Review of Immunology, 16, 261-292.