Elevated autoantibody content in rheumatoid arthritis synovia with lymphoid aggregates and the effect of rituximab.

INTRODUCTION: The purpose of this study was to quantitatively evaluate the contribution of synovial lymphoid aggregates to autoantibody (rheumatoid factor [RF] and anti-cyclic citrullinated peptide [anti-CCP]) and total immunoglobulin (IgG and IgM) production in rheumatoid arthritis (RA) patients and the effect thereon of the B-cell-depleting antibody, rituximab, in the ARISE (Assessment of Rituximab's Immunomodulatory Synovial Effects) trial. METHODS: Autoantibodies as well as total IgM and IgG were quantified by enzyme-linked immunosorbent assay in extracts of synovial tissues and matched serum from patients with RA or osteoarthritis (OA). Synovial biopsies and serum were obtained at baseline and 8 weeks following rituximab therapy in 14 RA patients. A synovial/serum index (SSI) was calculated as the ratio of synovial to serum antibody/albumin, with values above 1 representing synovial enrichment. Lymphoid aggregates were evaluated histologically. RESULTS: Anti-CCP IgG, but not RF-IgM, was significantly enriched in RA synovia compared with serum. Total IgM and IgG were also enriched in RA, but not in OA. SSI correlated significantly with mRNA content for both IgM and IgG, demonstrating that it reflected synovial immunoglobulin production. RA synovia with lymphocyte aggregates contained significantly elevated RF-IgM and anti-CCP IgG compared with tissues with diffuse lymphoid infiltration. Rituximab treatment did not affect synovial autoantibody or total immunoglobulin SSI overall. However, in aggregate-containing tissues, rituximab significantly reduced total IgM and IgG SSI as well as IgM and IgG1 mRNA. Surprisingly, RF-IgM and anti-CCP IgG SSIs were unchanged by rituximab in aggregate-containing synovia. CONCLUSIONS: Combined with earlier observations that synovial lymphoid aggregates are unaltered by rituximab treatment, these data suggest that lymphoid aggregates may provide a protective niche for autoantibody-producing cells.

Rosuvastatin: an independent analysis of risks and benefits.

BACKGROUND: Although the effectiveness of statins is well established, analyses of spontaneous adverse event reports have recently questioned the safety of rosuvastatin. METHODS AND RESULTS: We evaluated the risks and benefits of rosuvastatin and compared it with other statins presently on the market. Information was obtained from a search of medical and scientific literature that produced 3001 entries, of which 591 publications containing particularly relevant data were identified, and from the US Food and Drug Administration (FDA) Adverse Events Reporting System (AERS) and Spontaneous Reporting System through June 30, 2004. For the AERS data and to control for overreporting in the first postmarketing year and the effect on reporting due to the withdrawal of cerivastatin in 2001, we used the rate of a given adverse event among all adverse events as a measure of risk. We found that adverse effects of rosuvastatin in skeletal muscle, liver, and kidney function did not substantially differ in frequency from those reported for those of other statins in the market in 2004, except for the uncommon development of a mild form of presumably "tubular" proteinuria at doses of 40 mg/day or greater. In contrast, cerivastatin had significantly higher rates of myopathy and rhabdomyolysis than rosuvastatin's, but there was no additional effect on renal failure beyond that mediated through rhabdomyolysis. From our literature review, we found that rosuvastatin reduces abnormal lipids on a milligram-per-milligram comparison more than atorvastatin. CONCLUSION: We conclude that rosuvastatin at approved doses incurs no greater risk for adverse events than other marketed statins, except for a mild form of tubular proteinuria when doses at or above the maximum recommended levels (> or = 40 mg/day) were administered. Its risk-benefit ratio is acceptable when compared with other statins on the market in 2006.

Relevance of the stroma and epithelial-mesenchymal transition (EMT) for the rheumatic diseases.

Epithelial-mesenchymal transition (EMT) is a term applied to the process whereby cells undergo a switch from an epithelial phenotype with tight junctions, lateral, apical, and basal membranes, and lack of mobility into mesenchymal cells that have loose interactions with other cells, are non-polarized, motile and produce an extracellular matrix. The importance of this process was initially recognized from a very early step in embryology, but more recently as a potential mechanism for the progression and spread of epithelial cancers. As the sequence of morphological changes has become understood in molecular terms, diseases characterized by alterations in stromal elements and fibrosis are being considered as examples of EMT. This review will focus on the pathogenetic features of immune-mediated renal disease, systemic sclerosis and rheumatoid arthritis that could be explained by EMT.

Nurselike cells express BAFF and APRIL, which can promote survival of chronic lymphocytic leukemia cells via a paracrine pathway distinct from that of SDF-1alpha.

We examined expression of B cell-activating factor of the tumor necrosis factor (TNF) family (BAFF) and a proliferation-inducing ligand (APRIL) on chronic lymphocytic leukemia (CLL) B cells and nurselike cells (NLCs), which differentiate from CD14+ cells when cultured with CLL B cells. NLCs expressed significantly higher levels of APRIL than monocytes and significantly higher levels of BAFF and APRIL than CLL B cells. Also, the viability of CLL B cells cultured with NLCs was significantly reduced when CLL B cells were cultured with decoy receptor of B-cell maturation antigen (BCMA), which can bind both BAFF and APRIL, but not with BAFF receptor:Fc (BAFF-R:Fc), which binds only to BAFF. The effect(s) of BAFF or APRIL on leukemia cell survival appeared additive and distinct from that of stromal cell-derived factor-1alpha (SDF-1alpha), which in contrast to BAFF or APRIL induced leukemia cell phosphorylation of p44/42 mitogen-activated protein kinase (extracellular signal-regulated kinase-1/2 [ERK1/2]) and AKT. Conversely, BAFF and APRIL, but not SDF-1alpha, induced CLL-cell activation of the nuclear factor-kappaB1 (NF-kappaB1) and enhanced CLL-cell expression of the antiapoptotic protein Mcl-1. However, BAFF, but not APRIL, also induced CLL-cell activation of NF-kappaB2. We conclude that BAFF and APRIL from NLCs can function in a paracrine manner to support leukemia cell survival via mechanisms that are distinct from those of SDF-1alpha, indicating that NLCs use multiple distinct pathways to support CLL-cell survival.

Fibroblast-like synoviocytes of mesenchymal origin express functional B cell-activating factor of the TNF family in response to proinflammatory cytokines.

Immunohistochemical analysis revealed that the intimal lining cells of synovial tissue of inflamed joints of patients with rheumatoid arthritis differed from that of normal joints or of diseased joints in osteoarthritis in that they stained with mAb specific for the B cell-activating factor of the TNF family (BAFF; also called BLyS). We generated fibroblast-like synoviocytes (FLS) cell lines that were bereft of myelomonocytic cells to examine whether mesenchymal-derived FLS could express this critical B cell survival factor. We found that FLS expressed low amounts of BAFF mRNA relative to that of myelomonocytic cells. However, when various cytokines/factors were added to such FLS cell lines, we found that IFN-gamma or TNF-alpha were unique in that they could induce significant increases in BAFF mRNA and protein. Even minute amounts of IFN-gamma primed FLS for TNF-alpha, allowing the latter to stimulate significantly higher levels of BAFF mRNA and protein than could TNF-alpha alone. Consistent with this, B cells cocultured with IFN-gamma and/or TNF-alpha-treated FLS had a significantly greater viability than B cells cocultured with nontreated FLS. The enhanced protection of B cells afforded by IFN-gamma/TNF-alpha-treated FLS was inhibited by the addition of BAFF-R:Fc fusion protein. We conclude that the proinflammatory cytokines IFN-gamma and TNF-alpha can induce mesenchymal-derived FLS to express functional BAFF in vitro. The induced expression of BAFF on FLS by proinflammatory cytokines may enhance the capacity of such cells to protect B cells from apoptosis in inflammatory microenvironments in vivo.

Regional analysis of p53 mutations in rheumatoid arthritis synovium.

The p53 tumor suppressor protein plays a central role in cell cycle regulation, DNA repair, and apoptosis. Recent studies indicate that DNA damage and somatic mutations in the p53 gene can occur because of genotoxic stress in many tissues, including the skin, colon, and synovium. Although somatic mutations in the p53 gene have been demonstrated in rheumatoid arthritis (RA) synovial tissue and synoviocytes, no information is available on the location or extent of p53 mutations. Using microdissected RA synovial tissue sections, we observed abundant p53 transition mutations, which are characteristic DNA damage caused by oxidative stress. p53 mutations, as well as p53 mRNA expression, were located mainly in the synovial intimal lining rather than the sublining (P < 0.01). Clusters of p53 mutant subclones were observed in some microdissected regions, suggesting oligoclonal expansion. Because IL-6 gene expression is regulated by wild-type p53, IL-6 mRNA expression in microdissected tissues was quantified by using real-time PCR. The regions with high rates of p53 mutations contained significantly greater amounts of IL-6 mRNA compared with the low mutation samples (P < 0.02). The microdissection findings suggest that p53 mutations are induced in RA synovial tissues by inflammatory oxidative stress. This process, as in sun-exposed skin and inflamed colonic epithelium, provides some of the mutant clones with a selective growth advantage. A relatively low percentage of cells containing p53 mutations can potentially affect neighboring cells and enhance inflammation through the elaboration of proinflammatory cytokines.

Distinctive features of "nurselike" cells that differentiate in the context of chronic lymphocytic leukemia.

A subset of blood mononuclear cells from patients with chronic lymphocytic leukemia (CLL) can differentiate in vitro into "nurselike" cells (NLCs) that can protect CLL cells from apoptosis. NLCs express cytoplasmic vimentin and stromal-derived factor 1 (SDF-1). NLCs also express CD14, as well as CD11b, CD33, CD40, CD45RO, CD68, CD80, CD86, HLA-DQ, and HLA-DR, but not CD1a, CD2, CD3, CD11c, CD19, CD45RA, CD83, CD106, or CD154. Consistent with this phenotype, NLCs failed to differentiate from blood mononuclear cells that were depleted of CD14+ cells or from isolated CD19+ cells. CD14+ blood cells of healthy donors could differentiate into cells with the morphology and phenotype of NLCs when cultured in direct contact with CLL B cells, but not with normal B cells. Despite expressing antigens in common with blood monocytes, monocyte-derived dendritic cells, and macrophages, NLCs expressed significantly higher levels of CD68 than these other cell types. Consistent with the notion that NLCs are present in vivo, CD14+ splenocytes from CLL patients have NLC morphology and express significantly higher levels of CD68 than CD14+ splenocytes from persons without known B-cell malignancy. These findings indicate that although NLCs may differentiate from blood monocytes, they probably represent a distinctive hematopoietic cell type that exists in vivo, differentiates from hematopoietic CD14+ cells in the context of CLL, and in turn protect CLL cells from apoptosis via a mechanism that is independent of CD106 (vascular cell adhesion molecule-1). The interaction between CLL cells and NLCs may represent a novel target for therapy of patients with this disease.

Regulation of joint destruction and inflammation by p53 in collagen-induced arthritis.

The role of the tumor suppressor p53 as a key regulator of inflammation was examined in murine collagen-induced arthritis (CIA), a model of rheumatoid arthritis. Wild-type DBA/1 mice develop progressive arthritis in this model, in which p53 expression and apoptosis are evident in the synovial cells. In contrast, the joints of p53(-/-) DBA/1 animals with CIA showed increased severity of arthritis using clinical and histological scoring methods with almost no apoptosis. Consistent with this, collagenase-3 expression and cytokine production (interleukin-1 and interleukin-6) in the joints of p53(-/-) mice with CIA were significantly greater than in wild-type mice. Anti-collagen antibody titers, however, were not different. Therefore, p53 expression occurs during inflammation and acts to suppress local inflammatory responses. Because mutations in p53 have been described in the synovial membrane of rheumatoid arthritis patients, the loss of p53 function in synoviocytes or other cells in the joint because of dominant-negative mutations might contribute to invasion and destruction of the joint in this disease.