B-cell and T-cell receptor repertoire in chronic inflammatory demyelinating polyneuropathy, a prospective cohort study.

The immunopathophysiological mechanisms underlying chronic inflammatory demyelinating polyneuropathy (CIDP) in an individual patient are largely unknown. Better understanding of these mechanisms may aid development of biomarkers and targeted therapies. Both B- and T-cell dominant mechanisms have been implicated. We therefore investigated whether B-cell and T-cell receptor (BCR/TCR) repertoires might function as immunological biomarkers in CIDP. In this prospective cohort study, we longitudinally sampled peripheral blood of CIDP patients in three different phases of CIDP: starting induction treatment (IT), starting withdrawal from IVIg maintenance treatment (MT), and patients in remission (R). BCR and TCR repertoires were analyzed using RNA based high throughput sequencing. In baseline samples, the number of total clones, the number of dominant BCR and TCR clones and their impact on the repertoire was similar for patients in the IT, MT, and remission groups compared with healthy controls. Baseline samples in the IT or MT did not predict treatment response or potential relapse at follow-up. Treatment responders in the IT group showed a potential IVIg-induced increase in the number of dominant BCR clones and their impact at follow-up (baseline1.0 [IQR 1.0-2.8] vs. 6 m 3.5 [0.3-6.8]; P < .05, Wilcoxon test). Although the BCR repertoire changed over time, the TCR repertoire remained robustly stable. We conclude that TCR and BCR repertoire distributions do not predict disease activity, treatment response or response to treatment withdrawal.

Rheumatoid arthritis synovial tissue harbours dominant B-cell and plasma-cell clones associated with autoreactivity.

OBJECTIVE: To identify potential autoreactive B-cell and plasma-cell clones by quantitatively analysing the complete human B-cell receptor (BCR) repertoire in synovium and peripheral blood in early and established rheumatoid arthritis (RA). METHODS: The BCR repertoire was screened in synovium and blood of six patients with early RA (ERA) (<6 months) and six with established RA (ESRA) (>20 months). In two patients, the repertoires in different joints were compared. Repertoires were analysed by next-generation sequencing from mRNA, generating >10 000 BCR heavy-chain sequence reads per sample. For each clone, the degree of expansion was calculated as the percentage of the total number of reads encoding the specific clonal sequence. Clones with a frequency ≥ 0.5% were considered dominant. RESULTS: Multiple dominant clones were found in inflamed synovium but hardly any in blood. Within an individual patient, the same dominant clones were detected in different joints. The majority of the synovial clones were class-switched; however, the fraction of clones that expressed IgM was higher in ESRA than ERA patients. Dominant synovial clones showed autoreactive features: in ERA in particular the clones were enriched for immunoglobulin heavy chain gene segment V4-34 (IGHV4-34) and showed longer CDR3 lengths. Dominant synovial clones that did not encode IGHV4-34 also had longer CDR3s than peripheral blood. CONCLUSIONS: In RA, the synovium forms a niche where expanded--potentially autoreactive--B cells and plasma cells reside. The inflamed target tissue, especially in the earliest phase of disease, seems to be the most promising compartment for studying autoreactive cells.

Deep sequencing of antiviral T-cell responses to HCMV and EBV in humans reveals a stable repertoire that is maintained for many years.

CD8(+) T-cell responses against latent viruses can cover considerable portions of the CD8(+) T-cell compartment for many decades, yet their initiation and maintenance remains poorly characterized in humans. A key question is whether the clonal repertoire that is raised during the initial antiviral response can be maintained over these long periods. To investigate this we combined next-generation sequencing of the T-cell receptor repertoire with tetramer-sorting to identify, quantify and longitudinally follow virus-specific clones within the CD8(+) T-cell compartment. Using this approach we studied primary infections of human cytomegalovirus (hCMV) and Epstein Barr virus (EBV) in renal transplant recipients. For both viruses we found that nearly all virus-specific CD8(+) T-cell clones that appeared during the early phase of infection were maintained at high frequencies during the 5-year follow-up and hardly any new anti-viral clones appeared. Both in transplant recipients and in healthy carriers the clones specific for these latent viruses were highly dominant within the CD8(+) T-cell receptor Vß repertoire. These findings suggest that the initial antiviral response in humans is maintained in a stable fashion without signs of contraction or changes of the clonal repertoire.

Inflamed target tissue provides a specific niche for highly expanded T-cell clones in early human autoimmune disease.

OBJECTIVE: To profile quantitatively the T-cell repertoire in multiple joints and peripheral blood of patients with recent onset (early) or established rheumatoid arthritis (RA) using a novel next-generation sequencing protocol to identify potential autoreactive clones. METHODS: Synovium of patients with recent onset (early) RA (<6 months) (n=6) or established RA (>18 months) (n=6) was screened for T-cell clones by sequencing over 10 000 T-cell receptors (TCR) per sample. T cells from paired blood samples were analysed for comparison. From two patients synovial T cells were obtained from multiple inflamed joints. The degree of expansion of each individual clone was based on its unique CDR3 sequence frequency within a sample. Clones with a frequency of over 0.5% were considered to be highly expanded clones (HEC). RESULTS: In early RA synovium, the T-cell repertoire was dominated by 35 HEC (median, range 2-70) accounting for 56% of the TCR sequenced. The clonal dominance in the synovium was patient specific and significantly greater than in established RA (median of 11 HEC (range 5-24) in established RA synovium accounting for 9.8% of T cells; p<0.01). 34% (range 28-40%) of the most expanded T-cell clones were shared between different joints in the same patients, compared with only 4% (range 0-8%) between synovium and blood (p=0.01). CONCLUSIONS: In RA, a systemic autoimmune disease, the inflamed synovium forms a niche for specific expanded T-cell clones, especially in early disease. This suggests that, at least in RA, autoreactive T cells should be addressed specifically in the inflamed tissue, preferably in the early phase of the disease.

Genome sequence of Neisseria meningitidis serogroup B strain H44/76.

Neisseria meningitidis is an obligate human pathogen. While it is a frequent commensal of the upper respiratory tract, in some individuals the bacterium spreads to the bloodstream, causing meningitis and/or sepsis, which are serious conditions with high morbidity and mortality. Here we report the availability of the genome sequence of the widely used serogroup B laboratory strain H44/76.