Interaction between antigen presenting cells and autoreactive T cells derived from BXSB mice with murine lupus

Neutrophils, Dendritic Cells, Toll-Like Receptors, and Interferon-α in Lupus Nephritis

Finding better treatments for lupus nephritis requires an understanding of the pathogenesis of the causative systemic disease, how this leads to kidney disease, and how lupus nephritis progresses to end-stage kidney disease. Here, we provide a brief conceptual overview on the related pathomechanisms. As a main focus we discuss in detail the roles of neutrophils, dendritic cells, Toll-like receptors, and interferon-α in the pathogenesis of lupus nephritis by separately reviewing their roles in extrarenal systemic autoimmunity and in intrarenal inflammation and immunopathology.

Breakdown of Immune Tolerance in Systemic Lupus Erythematosus by Dendritic Cells

Dendritic cells (DC) play an important role in the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease with multiple tissue manifestations. In this review, we summarize recent studies on the roles of conventional DC and plasmacytoid DC in the development of both murine lupus and human SLE. In the past decade, studies using selective DC depletions have demonstrated critical roles of DC in lupus progression. Comprehensive in vitro and in vivo studies suggest activation of DC by self-antigens in lupus pathogenesis, followed by breakdown of immune tolerance to self. Potential treatment strategies targeting DC have been developed. However, many questions remain regarding the mechanisms by which DC modulate lupus pathogenesis that require further investigations.

Prednisone treatment inhibits the differentiation of B lymphocytes into plasma cells in MRL/MpSlac-lpr mice

AIM

A number of evidence shows that the differentiation of B lymphocytes into plasma cells plays an important role in lupus pathogenesis. In this study we investigated how prednisone, a classical therapeutic drug for autoimmune diseases, regulated plasma cell differentiation in MRL/MpSlac-lpr mice.

METHODS

MRL/lpr mice were treated with prednisone (2.5 or 5 mg·kg(-1)·d(-1), ig) for 13 weeks, and the proteinuria levels and survival times were monitored. After the mice were euthanized, blood sample, spleen and thymus were collected. The serum levels of anti-dsDNA antibody, anti-nuclear antibody, IL-21, and IL-10 were detected using ELISA kits. Subsets of splenic B and T lymphocytes were quantified with flow cytometry. Transcription factor Blimp-1 and Bcl-6 expression was determined using qPCR and Western blot.

RESULTS

Prednisone treatment dose-dependently attenuated the lupus symptoms in MRL/lpr mice with decreased proteinuria levels, prolonged survival times, decreased serum anti-nuclear antibody levels, and reduced spleen and thymus indices. Prednisone treatment also significantly decreased the elevated percentages of plasma cells and plasma cell precursors, decreased the percentages of activated T cells, and increased the frequency of CD4(+)CD62L(+) cells, demonstrated that decreased anti-nuclear antibodies and improvements in lupus symptoms were associated with decreased plasma cells. Furthermore, prednisone treatment decreased serum IL-21 and IL-10 levels and reduced the expression of splenic Blimp-1 and Bcl-6 (two key regulatory factors for plasma cell differentiation) in MRL/lpr mice.

CONCLUSION

Prednisone treatment restricts B lymphocyte differentiation into plasma cells in MRL/lpr mice, which may be correlated with the inhibition of IL-21 production and the restoration of the balance between Blimp-1 and Bcl-6.

Long-term follow-up after non-myeloablative transplant of bone and marrow in BXSB mice

We present long-term outcomes of BXSB mice after non-myeloablative bone marrow transplants using major histocompatability complex (MHC)-matched cells. Groups differed in sources of donor lymphocytes or mesenchymal stromal cells (MSC). Unfractionated marrow cells from green fluorescent protein (GFP) transgenic (Tg) mice (BMT group) or from RAG1−/− B6 mice (RAG group) were injected intravenously (i.v.) into irradiated (550 cGy) hosts. As a source of mesenchymal cells, bone chips from GFP-Tg were injected intraperitoneally alone (MSC group) or along with i.v. bone marrow cells (BMT + MSC group). Controls were untreated mice (UnTx) or mice exposed to radiation only (Rad Cont). At 62 weeks post-transplant, surviving mice were harvested for histopathology, flow cytometry and real time polymerase chain reaction (RT-PCR). The mice from BMT + MSC group had the best outcomes for survival rates (71.4% vs. 43.8%), renal scores (2.9% vs. 28.8% glomerular sclerosis) and percent splenic monocytes (4.2 vs. 11.3%) compared with mice from Rad Cont. Improvement in RAG and BMT groups was less prominent but were comparable with one another. Although MSC alone were not sufficient to control the renal pathology, it limited the expansion of CD4−CD8− T cell populations without a change in Foxp3 expression. The results suggest the importance of the innate immune system in disease pathogenesis and a role for MSC in immunomodulation.