BAFF expression correlates with idiopathic inflammatory myopathy disease activity measures and autoantibodies.

OBJECTIVE: To investigate B cell survival cytokine messenger RNA (mRNA) levels as biomarkers of idiopathic inflammatory myopathies (IIM). METHODS: We measured and compared mRNA levels of B cell survival cytokines by quantitative real-time polymerase chain reaction in 98 patients with IIM, 38 patients with systemic lupus erythematosus, and 21 healthy controls. The cytokines were B cell-activating factor belonging to the tumor necrosis factor family (BAFF); ΔBAFF; and a proliferation-inducing ligand (APRIL); and their receptors BAFF-R, transmembrane activator and calcium modulator and cyclophilin ligand interactor, and B cell maturation antigen (BCMA). We also identified autoantibodies, including anti-Sm, anti-RNP, anti-SSA/Ro, anti-SSB/La, anti-topoisomerase 1, anti-hystidyl-tRNA synthetase, anti-ribosomal P, and anti-chromatin. Clinical disease activity was assessed by the International Myositis Assessment and Clinical Studies core set tool. We examined correlation of mRNA with disease activity, medication use, and autoantibodies. RESULTS: We found a positive correlation of BAFF and ΔBAFF expression with 3 disease activity measures, with ΔBAFF having a stronger correlation. Similarly, anti-SSA/Ro-52 and/or anti-SSA/Ro-60 had a strong positive correlation with mRNA levels of BAFF and ΔBAFF, and with relative ratios of BAFF/APRIL and BCMA/BAFF-R. CONCLUSION: These findings highlight the potential importance of BAFF, ΔBAFF, and BAFF-R in the pathogenesis of IIM, and suggest an important role in the assessment of disease activity.

Maternal microchimerism in Hirschsprung's disease.

Hirschsprung's disease (HD) presents with severe constipation due to absent ganglion cells in the distal rectum. We sought to determine whether maternal chimeric cells are present in aganglionic bowel. We hypothesize that chimeric cells are part of the unfavorable microenvironment that leads to the destruction of enteric neurons in HD. Intestinal biopsies and resections from seven male patients with HD were compared with four male patients with chronic constipation and six with bowel atresia. Fluorescence in situ hybridization was used to identify chimeric cells based on male/female (XX/XY) differences. The location and immunophenotype of chimeric cells were also studied. Chimeric cells were present more often in the small intestine and rectum, compared with the appendix and colon. Patients with HD had a greater number of chimeric cells per 10× magnification field than patients with chronic constipation or congenital atresia. Chimeric cells were predominantly in the submucosa and outer longitudinal muscle layer in HD. Immunophenotyping identified over 40% of chimeric cells as inflammatory. Chimeric cells are present in greater numbers in aganglionic bowel than in other disorders. Clustering of chimeric cells in areas of absent ganglia lends support to the proposed role of maternal microchimerism in allo-autoimmune responses.

Interleukin-6 and type I interferon-regulated genes and chemokines mark disease activity in dermatomyositis.

OBJECTIVE: Up-regulation of whole blood type I interferon (IFN)-driven transcripts and chemokines has been described in a number of autoimmune diseases. An IFN gene expression "signature" is a candidate biomarker in patients with dermatomyositis (DM). This study was performed to evaluate the capacity of IFN-dependent peripheral blood gene and chemokine signatures and levels of proinflammatory cytokines to serve as biomarkers for disease activity in adult and juvenile DM. METHODS: Peripheral blood samples and clinical data were obtained from 56 patients with adult or juvenile DM. The type I IFN gene signature in the whole blood of patients with DM was defined by determining the expression levels of 3 IFN-regulated genes (IFIT1, G1P2, and IRF7) using quantitative real-time reverse transcription-polymerase chain reaction. Multiplexed immunoassays were used to quantify the serum levels of 4 type I IFN-regulated chemokines (IFN-inducible T cell alpha chemoattractant, IFNgamma-inducible 10-kd protein, monocyte chemotactic protein 1 [MCP-1], and MCP-2) and the serum levels of other proinflammatory cytokines, including interleukin-6 (IL-6). RESULTS: DM disease activity correlated significantly with the type I IFN gene signature (r = 0.41, P = 0.007) and with the type I IFN chemokine signature (r = 0.61, P < 0.0001). Furthermore, the serum levels of IL-6 were significantly correlated with disease activity (r = 0.45, P = 0.001). In addition, correlations between the serum levels of IL-6 and both the type I IFN gene signature (r = 0.47, P < 0.01) and the type I IFN chemokine signature (r = 0.71, P < 0.0001) were detected in patients with DM. CONCLUSION: These results suggest that serum IL-6 production and the type I IFN gene signature are candidate biomarkers for disease activity in adult and juvenile DM. Coregulation of the expression of IFN-driven chemokines and IL-6 suggests a novel pathogenic linkage in DM.

Extranodal lymphoid microstructures in inflamed muscle and disease severity of new-onset juvenile dermatomyositis.

OBJECTIVE: Juvenile dermatomyositis (DM) is an autoimmune disease of childhood characterized by lesions in skin and muscle that are populated by plasmacytoid dendritic cells (PDCs) and lymphocyte infiltrates. We undertook this study to examine the cellular composition, organization, and molecular milieu of the cellular infiltrates in muscle in juvenile DM and to correlate the infiltrates with clinical disease manifestations. METHODS: Since PDCs and lymphocyte foci express CCL19 and CCL21, we investigated for in situ formation of lymphoid microstructures that could be sites of extranodal immune activation. RESULTS: Analyses of muscle biopsy samples from children with new-onset juvenile DM showed 3 categories of lesions: diffuse infiltrates, lymphocytic aggregates lacking follicle-like organization, and follicle-like structures. The last of these exhibited elements of classic lymphoid follicles, including networks of follicular dendritic cells and high endothelial venules. They also expressed high levels of CXCL13 and lymphotoxins known to support lymphoid organogenesis. There were also resident naive CD45RA+ T cells and maternally derived B cells and PDCs. Patients with diffuse infiltrates or lymphocytic aggregates were responsive to standard therapy with steroids and methotrexate, but those with follicle-like structures tended to have severe disease that required additional agents such as intravenous Ig or rituximab. CONCLUSION: These data suggest that lymphoneogenesis is a component of the early disease process in juvenile DM. Ectopic lymphoid structures could indicate a severe course of disease; their early detection could be a tool for disease management.

Plasmacytoid dendritic cells in inflamed muscle of patients with juvenile dermatomyositis.

OBJECTIVE: To examine whether dendritic cells (DCs) are constituents of muscle inflammation in juvenile dermatomyositis (DM). METHODS: The types, numbers, and activation state of DC subsets in inflamed muscle tissue from patients with juvenile DM and in noninflamed muscle tissue from control subjects were examined by multicolor immunofluorescence. Chemokine expression of the muscle-infiltrating cells was examined by laser capture microdissection and quantitative polymerase chain reaction. RESULTS: Plasmacytoid DCs were the predominant component of the inflamed muscle tissue from patients with juvenile DM. These cells were identified by coexpression of CD4 and CD123, but not CD11c, and also expressed CD83, indicating maturity of the cells. In contrast, in noninflamed muscle, plasmacytoid DCs were scarce and did not express CD83. Mononuclear cells surrounding the blood vessels of inflamed muscle contained abundant transcripts of CCL19 and CCL21, but very little CCL18 transcripts. In contrast, cells from noninflamed muscle contained negligible amounts of CCL19 and CCL21, but had high amounts of CCL18. Both the inflamed and noninflamed muscle tissue had equivalent levels of CXCL12 transcripts, but inflamed muscle contained more transcripts of the CXCL12 receptor CXCR4. CONCLUSION: These findings are consistent with the idea that plasmacytoid DCs are mediators of muscle inflammation in juvenile DM. The abundance of CD83+ plasmacytoid DCs in perivascular areas and the overexpression of CCL19 and CCL21 in perivascular cellular foci suggest that in situ activation and maturation of resident plasmacytoid DCs are central to the initiation and perpetuation of muscle inflammation in juvenile DM.

Acute graft-versus-host disease after liver transplantation diagnosed by fluorescent in situ hybridization testing of skin biopsy specimens.

Acute graft-versus-host disease after orthotopic liver transplantation is an underrecognized entity with a guarded prognosis. We describe a patient who underwent orthotopic liver transplantation with an HLA-matched donor liver. She had an uneventful recovery from operation up until day 36 posttransplantation, when she developed a generalized, erythematous, mostly macular eruption, accompanied by ascites, diarrhea, and fever. The diagnosis of graft-versus-host disease was considered but a drug rash could not be excluded. A polymerase chain reaction-based chimerism assay failed to identify donor DNA in peripheral blood. A confirmatory fluorescent in situ hybridization analysis revealed significant numbers of donor lymphocytes in biopsied skin, with lesser amounts in biopsy specimens from the stomach and colon. Despite immunosuppressive treatment, the patient died of overwhelming sepsis 18 weeks after transplantation. We conclude that early testing of skin biopsy specimens using fluorescent in situ hybridization in sex-mismatched patients with orthotopic liver transplantation can serve as an early diagnostic tool for graft-versus-host disease.

Cysteine-tailed class I-binding peptides bind to CpG adjuvant and enhance primary CTL responses.

Immunostimulatory CpG motifs in synthetic oligonucleotides can be effective adjuvants for the priming of CTLs. We first observed that a single male-specific peptide (KCSRNRQYL) (HY2) was more efficient than another male-specific peptide (WMHHNMDLI) (HY1) at priming IFN-gamma-secreting CTLs in vivo when combined with lipid A and CpG and that it also visibly precipitated CpG. The addition of the six N-terminal residues (KCSRNR) from HY2 to HY1 yielded a peptide, KCSRNR-HY1, that both precipitated CpG and primed increased numbers of HY1-specific CTLs. We refer to this type of peptide as a primotope that includes a class I binding peptide tailed with amino acids that increase priming. Ala residues were substituted for the Arg/Lys residues (ACSANA-HY1), and these substitutions did not reduce in vivo priming potential. However, the substitution of Ala for Cys (KASRNR-HY1) resulted in the complete loss of priming, demonstrating the importance of Cys for in vivo priming when mixed with CpG. This result suggested that increased priming was based in disulfide bonding between Cys residues and internal phosphorothioate groups of synthetic CpG. The addition of Cys-bearing primotopes to radiolabeled CpG with a single thioate group resulted in the appearance of a new band that was inhibited by 1) Cys > Ala substitution and 2) reduction and alkylation of CpG. These results reveal a novel mechanism for complexing class I binding peptides and CpG adjuvant for development of new peptide-adjuvant combinations for vaccines for cancer and infectious diseases.

Does HLA-dependent chimerism underlie the pathogenesis of juvenile dermatomyositis?

Juvenile dermatomyositis (JDM) is a multisystem autoimmune disease that at times resembles chronic graft-vs-host disease. This led us to suggest that nonself cells may play a role in the disease process. In this study we examined the relationship between HLA genotype and the presence of maternally derived chimeric cells in JDM patients and healthy controls, and assessed immunologic activity in the chimeric cells. We identified chimeric cells more often in children with JDM (60 of 72) than in their unaffected siblings (11 of 48) or in healthy controls (5 of 29). The presence of chimerism in the JDM patients, their healthy siblings, and unaffected control children was associated with a HLA-DQA1*0501 allele in the mother (p = 0.011). Further, we show that maternally transferred chimeric T cells are responsive to the host's (JDM childs') lymphocytes (33.75 +/- 8.4 IFN-gamma-producing cells from JDM cells vs 5.0 +/- 1.25 from maternal cells), and that this is a memory response. These combined data indicate that chimeric cells play a direct role in the JDM disease process and that the mother's HLA genotype facilitates the transfer and/or persistence of maternal cells in the fetal circulation.