No abstract

The CD8 αβT cell receptor repertoire in joint fluid of individuals with active psoriatic arthritis contained an average of 32 major oligoclonal expansions in many variable genes of the TCR β chain (BV) families, as shown by β-chain CDR3 length analysis. Interestingly, a small number of oligoclonal expansions were shared between simultaneous samples of joint fluid and blood; however, most expansions found in joint fluid were not identifiable in blood emphasizing the immunologic specificity of the clonal events for the inflamed joint at a given point of time. The CD4 T cell joint fluid repertoire contained fewer and smaller oligoclonal expansions also largely restricted to the joint, suggesting that CD4 T cells participate perhaps by interacting cognitively to generate the CD8 clones. The inferred amino acid sequence of a single CD8 oligoclonal expansion revealed that they usually are composed of one or a few structurally related clones at the amino acid sequence level with β-chains that encode identical or highly homologous CDR3 motifs. These were not shared among patients. Moreover, several clones that encoded the same amino acid sequence were found to be structurally distinct at the nucleotide level, strongly implying clonal selection and expansion is operating at the level of specific TCR-peptide interactions. The findings support a model of psoriatic arthritis inflammation involving extensive and selective Ag, likely autoantigen, driven intra-articular CD4, and CD8 T cell clonal expansions.

Objective To better define the immunologic character of the T cell infiltrate in lupus nephritis. Methods We performed double immunohistochemical staining and clonotypic T cell receptor (TCR) beta-chain sequencing in multiple anatomic regions isolated by laser-capture microdissection from renal biopsies. Results SLE kidneys have a variably patterned and often extensive infiltrate of predominantly clonally expanded T cells of CD4 and CD8 lineages. CD4 T cells were prominent in nearly two-thirds of SLE biopsies, and distributed as broad periglomerular aggregates or intermixed with CD8 T cells forming periglomerular caps. Sequencing of the T cell TCR from periglomerular regions showed a predominance of clonally expanded T cells. The CD8 T cells, which were present in all biopsies, often adhered to Bowman's capsule and infiltrated the tubular epithelium. They exhibited features that suggest participation in an adaptive immune response: differentiation into CD28null memory-effector phenotype, trafficking of the same expanded clonotype to different regions of the kidney and to the peripheral blood, and clonal persistence for years in repeat biopsies. CD8 T cell tubulitis was especially associated with progressive changes. Conclusions The immunological characteristics of the infiltrating CD4 and CD8 T cells in the lupus kidney indicate they have the potential to mediate injury, which may be relevant to development of progressive renal failure. Whereas the oligoclonality of the CD4 T cell infiltrate is consistent with the paradigm of SLE as a class II-associated autoimmune disease, the finding of CD8 T cell clonality and trafficking implies participation in a distinct systemic adaptive immune response.

The molecular pathogenesis of focal/diffuse proliferative lupus glomerulonephritis was studied by cDNA microarray analysis of gene expression in glomeruli from clinical biopsies. Transcriptional phenotyping of glomeruli isolated by laser-capture microscopy revealed considerable kidney-to-kidney heterogeneity in increased transcript expression, resulting in four main gene clusters that identified the presence of B cells, several myelomonocytic lineages, fibroblast and epithelial cell proliferation, matrix alterations, and expression of type I IFN-inducible genes. Glomerulus-to-glomerulus variation within a kidney was less marked. The myeloid lineage transcripts, characteristic of those found in isolated activated macrophages and myeloid dendritic cells, were widely distributed in all biopsy samples. One major subgroup of the samples expressed fibrosis-related genes that correlated with pathological evidence of glomerulosclerosis; however, decreased expression of TGF-beta1 argued against its role in lupus renal fibrosis. Expression of type I IFN-inducible transcripts by a second subset of samples was associated with reduced expression of fibrosis-related genes and milder pathological features. This pattern of gene expression resembled that exhibited by activated NK cells. A large gene cluster with decreased expression found in all samples included ion channels and transcription factors, indicating a loss-of-function response to the glomerular injury.

Purpose Acute Hemorrhagic Leukoencephalitis (AHLE) is a rare demyelinating disorder of acute onset, rapid deterioration and significant morbidity and mortality. Most often described as a post-infectious complication of an upper respiratory illness, its precise pathophysiology remains unclear. We describe two pediatric patients with AHLE with partial complement factor I (FI) deficiency whose successful treatment included the interleukin-1 (IL-1) receptor antagonist, anakinra, implicating a role for FI and IL-1 in this disorder. Methods Extensive clinical workup of two patients presenting with AHLE revealed complement abnormalities, specifically related to the alternative pathway and its regulator, FI. Aggressive management with steroids, immunoglobulin, and anakinra ultimately led to improvement of clinical status and near return to neurologic baseline in both patients. Genetic sequencing of the FI coding regions of the patients and their families was performed. In vitro protein expression studies and immunohistochemistry of fixed brain tissue was used to investigate pathogenic mechanisms. Results Two novel mutations in FI were identified in our patients, which result in failure to secrete FI. Immunohistochemical evaluation of brain tissue demonstrated positive staining for C3, membrane attack complex (MAC) and IL-1. Conclusions We propose AHLE is an unreported, rare phenotype for partial FI deficiency. The upregulation of C3, MAC and IL-1 with subsequent demyelination support a pathologic role for complement activation in AHLE, and suggest anakinra as an important adjunctive therapy in this disease.