ISSN 2398-2969      

Sjögren's-like syndrome

icanis
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Introduction

  • Sjögrens syndrome in humans is an idiopathic autoimmune disease characterized by lymphoplasmacytic infiltration and destruction of lacrimal and salivary glands, resulting in reduced secretion from these glands and the clinical presentation of keratoconjunctivitis sicca (KCS) and xerostomia (dry mouth). In addition there is often dryness of other mucosal surfaces (nasal, trachea, bronchial, vaginal) and of the skin. This form of disease is sometimes termed primary Sjögrens syndrome.
  • Approximately one half of affected humans have concomitant rheumatoid arthritis or one of the other autoimmune connective tissue diseases, and in this instance the disease may be termed secondary Sjögrens syndrome. Lymphoplasmacytic infiltrates may occur in other organs (kidney, lung, lymph node, muscle) and some patients go on to develop lymphoma (generally ß cell lymphoma). The disease has a distinct gender predisposition (90% of cases occur in females) and the mean age of onset is 50 years. There are specific serological changes typified by hypergammaglobulinemia and the presence of autoantibodies including antinuclear antibody (ANA; present in 70% of patients), rheumatoid factor (RF; present in 90% of patients) and autoantibodies specific for salivary antigens (present in 50% of patients). A small proportion of patients (5%) develop lymphocytic thyroiditis (hypothyroidism). Medical treatment is with immunosuppressive drugs and artificial tears, with symptomatic therapy for dry mouth (eg oral hygiene, frequent water intake).
  • Although KCS Keratoconjunctivitis sicca is well-documented in the dog, true Sjögrens-like syndrome is rare. Only two dogs satisfying the criteria for diagnosis of this disease have been formally reported in the literature (with one further report as part of a case series), however there may be some overlap syndromes in which dogs presenting with apparently uncomplicated KCS have serological changes related to connective tissue disease (eg ANA and RF), or in which dogs with KCS have another concomitant autoimmune disease such as hypothyroidism Hypothyroidism , rheumatoid arthritisRheumatoid arthritis, diabetes mellitus Diabetes mellitus , chronic active hepatitis Liver: chronic hepatitis or autoimmune skin disease Skin: immunological disease - overview. The two affected canine patients were part of an experimental breeding colony of dogs with systemic lupus erythematosus (SLE) Systemic lupus erythematosus.
  • It has been suggested that canine Sjögrens-like syndrome may be under diagnosed. Dogs presenting with primary KCS have been shown to have subclinical histopathological changes in salivary gland tissue, and some dogs with KCS that are evaluated for parotid duct transposition also have a degree of xerostomia. One study of 50 dogs with KCS identified 10 animals as having evidence of xerostomia.

Pathogenesis

Pathophysiology

  • The pathogenesis of Sjögrens-like syndrome is presumed to be consistent with primary idiopathic autoimmune disease. As such, the disorder likely has a multifactorial etiology involving the interaction of genetic susceptibility, immunological imbalance and trigger factors. In this disease, the autoimmune response is directed against self tissue antigens located within the lacrimal and salivary glands. There is both a humoral and cell-mediated autoimmune response. The former is indicated by the lymphoplasmacytic infiltration of these tissues, and presumptively many of the lymphoid cells are self-reactive cytotoxic cells that mediate destruction of the glandular epithelium. There is also expansion of ß lymphocytes and plasma cells, and autoantibody to glandular epithelium may be demonstrated in the affected tissue and in serum. The glandular infiltration by ß cells and plasma cells suggests that these autoantibodies are produced locally and may have a direct role in antibody-mediated cytotoxic destruction of glandular epithelium.
  • One study has evaluated the numbers of CD4+ and CD8+ T lymphocytes in the gland of the third eyelid from dogs that were treated or untreated for uncomplicated KCS. The number of CD8+ cytotoxic T cells was much greater than CD4+ helper cells in lesional tissue, and with treatment the number of CD8+ cells decreased significantly. Moreover, there is evidence of increased apoptosis (programmed cell death or cell suicide) in epithelial cells in affected tissue consistent with cytotoxic destruction. By contrast, within the infiltrating lymphoid population there is down-regulation of apoptosis-related molecules which may account for the accumulation of these lymphoid cells within affected tissue. Antibody associated with acinar and ductular epithelial cells has been demonstrated in a proportion of KCS patients by direct immunohistochemistry.
  • There is clearly potential for the development of multisystemic autoimmunity in such patients, either at the clinical or serological level. Other autoantibodies (eg ANA, RF) or autoimmunity targeting other body systems may develop.

Diagnosis

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Treatment

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Prevention

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Izci C, Celik I, Alkan F, Ogurtan Z, Ceylan C, Sur E, Ozkan Y (2002) Histologic characteristics and local cellular immunity of the gland of the third eyelid after topical ophthalmic administration of 2% cyclosporin for treatment of dogs with keratoconjunctivitis sicca. Am J Vet Res 63 (5), 688-694 PubMed.
  • Canapp S O, Cohn L A, Maggs D J, Miller M A, Kerl M E, OBrien D P (2001) Xerostomia, xerophthalmia, and plasmacytic infiltrates of the salivary glands (Sjogrens-like syndrome) in a cat. JAVMA 218 (1), 59-65 PubMed.
  • Gao J, Schwalb T A, Addeo J V, Ghosn C R, Stern M E (1998) The role of apoptosis in the pathogenesis of canine keratoconjunctivitis sicca: the effect of topical cyclosporin A therapy. Cornea 17 (6), 654-663 PubMed.
  • Bistner S (1994) Allergic- and immunologic-mediated diseases of the eye and adnexae. Vet Clin N Am:Small Anim Pract 24 (4), 711-734 PubMed.
  • Kaswan R L, Salisbury M A (1990) A new perspective on canine keratoconjunctivitis sicca. Vet Clin N Am: Small Anim Pract 20 (3), 583-613 PubMed.
  • Kaswan R L, Martin C L, Dawe D L (1985) Keratoconjunctivitis sicca: immunological evaluation of 62 canine cases. Am J Vet Res 46 (2), 376-383 PubMed.
  • Kaswan R L, Martin C L, Dawe D L (1983) Rheumatoid factor determination in 50 dogs with keratoconjunctivitis sicca. JAVMA 183 (10), 1073-1075 PubMed.
  • Quimby F W, Schwartz R S, Roskitt T et al (1979) A disorder of dogs resembling Sjögren's syndrome. Clin Immunol Immunopathol 12 (4), 471-476 PubMed.

Other sources of information

  • Day M J (1999)Clinical Immunology of the Dog and Cat.Manson Publishing Ltd, London. pp 138, 187-188.

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