| Popis: |
Systemic lupus erythematosus (SLE) and Sj?gren?s syndrome (SS) are both heterogeneous autoimmune diseases with strong B cell aspects. A proportion of SLE and SS patients exhibit elevated serum BAFF (B cell activating factor of the TNF family); BAFF plays a key role in B cell homeostasis, survival and tolerance. BAFF transgenic (Tg) mice develop nephritis and salivary gland destruction that resemble aspects of SLE and SS respectively. Autoimmune disease development in BAFF Tg mice correlates with marginal zone (MZ) B cell expansion and the abnormal presence of MZ-like B cells outside of the spleen. The role of MZ B cells in BAFF induced autoimmune disease was analysed by crossing BAFF Tg mice with Lymphotoxin-β knockout mice (creating LTβ-BTg mice) which lack most peripheral lymph nodes, and also lack MZ B cells as a result of disrupted splenic architecture. LTβ-BTg mice were not protected against nephritis but exhibited reduced salivary gland infiltration and destruction. Indicating that the development of sialadenitis but not nephritis in BAFF Tg mice is MZ B cell dependent. Nephritis development in LTβ-BTg mice was associated with the detection of B-1 B cells in the inflamed kidneys. As B-1a B cell survival is dependent on the spleen, the contribution of B-1a B cells to nephritis development in BAFF Tg mice was assessed by crossing BAFF Tg mice to congenitally asplenic Hox11-/- mice (creating Hox11 -BTg mice). The absence of a spleen and B-1a B cells in Hox11-BTg mice delayed the nephritis development. In contrast, splenectomy of BAFF Tg mice at 12 weeks of age did not alter nephritis onset. In these mice B-1a B cells persisted in the peritoneal cavity and MZ-like B cells were detected in the periphery 8 months after surgery. In summary, nephritis development in BAFF Tg mice is unaltered by the absence of MZ B cells, but delayed in the absence of a spleen, MZ and B-1a B cells. Thus, B-1a and B-1b B cells may be potential targets for the treatment of nephritis in SLE patients with elevated BAFF. |
