White matter lesions in multiple sclerosis are enriched for CD20dim CD8+ tissue-resident memory T cells.

Brain CD8+ CD69+ tissue-resident memory T (TRM ) cells comprise a CD20dim subset, which is proportionally larger in CD103-negative TRM cells. In multiple sclerosis (MS) lesions, CD20dim TRM -cell proportions are increased. CD20-expression is associated with higher levels of CXCR6, Ki-67, and granzyme B, supporting CD20dim TRM cells as a relevant subset in MS.

MicroRNA-146a regulates survival and maturation of human plasmacytoid dendritic cells.

During microbial infections, plasmacytoid dendritic cells (pDCs) are a main source of type I interferons α/ß (IFN-α/-ß). Nucleic acids from microbes are sensed by Toll-like receptors 7/9 (TLR7/9), which are selectively expressed in pDCs. Activated pDCs also produce proinflammatory cytokines and upregulate costimulatory molecules. Together, this equips pDCs with the ability to prime T, B, and NK cells and conventional DCs, thereby initiating adaptive immune responses. To avoid deleterious effects to the host, tight regulation of pDC activation is required. Despite data linking aberrant activation of pDCs with autoimmune diseases, little is known about mechanisms controlling pDC activation. Here, we investigated the role of microRNA-146a (miR-146a) in TLR pathway regulation in human pDCs. MiR-146a expression was induced upon TLR7/9 signaling. Furthermore, ectopic miR-146a expression effectively impaired TLR-mediated signaling in pDCs as TLR-induced nuclear factor-κB activation was reduced. This consequently diminished the production of proinflammatory cytokines and reduced pDC survival. Moreover, miR-146a-expressing pDCs had decreased ability to induce CD4(+) T-cell proliferation likely due to reduced expression levels of major histocompatibility complex class II and costimulatory molecules. Our data unravel the crucial immunomodulatory role of miR-146a in pDCs and may add to our understanding of aberrant responses in autoimmune diseases.

Prediction of BRCA2-association in hereditary breast carcinomas using array-CGH.

Germline mutations in BRCA1/2 increase the lifetime risk for breast and ovarian cancer dramatically. Identification of such mutations is important for optimal treatment decisions and pre-symptomatic mutation screening in family members. Although current DNA diagnostics is able to identify many different mutations, it remains unclear, how many BRCA2-associated breast cancer cases remain unidentified as such. In addition, mutation scanning detects many unclassified variants (UV) for which the clinical relevance is uncertain. Therefore, our aim was to develop a test to identify BRCA2-association in breast tumors based on the genomic signature. A BRCA2-classifier was built using array-CGH profiles of 28 BRCA2-mutated and 28 sporadic breast tumors. The classifier was validated on an independent group of 19 BRCA2-mutated and 19 sporadic breast tumors. Subsequently, we tested 89 breast tumors from suspected hereditary breast (and ovarian) cancer (HBOC) families, in which either no BRCA1/2 mutation or an UV had been found by routine diagnostics. The classifier showed a sensitivity of 89% and specificity of 84% on the validation set of known BRCA2-mutation carriers and sporadic tumor cases. Of the 89 HBOC cases, 17 presented a BRCA2-like profile. In three of these cases additional indications for BRCA2-deficiency were found. Chromosomal aberrations that were specific for BRCA2-mutated tumors included loss on chromosome arm 13q and 14q, and gain on 17q. Since we could separate BRCA1-like, BRCA2-like, and sporadic-like tumors, using our current BRCA2- and previous BRCA1-classifier, this method of breast tumor classification could be applied as additional test for current diagnostics to help clinicians in decision making and classifying sequence variants of unknown significance.

Genomic signature of BRCA1 deficiency in sporadic basal-like breast tumors.

About 10-20% of all breast carcinomas show a basal-like phenotype, while ∼ 90% of breast tumors from BRCA1-mutation carriers are of this subtype. There is growing evidence that BRCA1-mutated tumors are not just a specific subset of the basal-like tumors, but that (the majority of) basal-like tumors show a dysfunctional BRCA1 pathway. This has major treatment implications, because emerging regimens specifically targeting DNA repair mechanisms would then be most effective against these tumors. To further understand the involvement of BRCA1 deficiency in sporadic basal-like tumors, we investigated 41 basal-like tumors for BRCA1 mRNA expression by quantitative real-time polymerase chain reaction, BRCA1 promoter methylation, their genomic profile by array-CGH, and gene expression levels by whole genome expression arrays. Array-CGH results were compared to those of 34 proven BRCA1-mutated tumors. Basal-like tumors were subdivided into two equal groups: deficient and proficient in BRCA1 gene expression. The chromosomal makeup of BRCA1 deficient sporadic basal-like tumors was similar to that of BRCA1-mutated tumors. BRCA1 proficient sporadic basal-like tumors were more similar to nonbasal-like tumors. Only half of the basal-like breast tumors are actually deficient in BRCA1 expression. Gain of chromosome arm 3q is a marker for BRCA1 deficiency in hereditary and sporadic breast tumors.

Usher syndrome and Leber congenital amaurosis are molecularly linked via a novel isoform of the centrosomal ninein-like protein.

Usher syndrome (USH) and Leber congenital amaurosis (LCA) are autosomal recessive disorders resulting in syndromic and non-syndromic forms of blindness. In order to gain insight into the pathogenic mechanisms underlying retinal degeneration, we searched for interacting proteins of USH2A isoform B (USH2A(isoB)) and the LCA5-encoded protein lebercilin. We identified a novel isoform of the centrosomal ninein-like protein, hereby named Nlp isoform B (Nlp(isoB)), as a common interactor. Although we identified the capacity of this protein to bind calcium with one of its three EF-hand domains, the interacton with USH2A(isoB) did not depend on this. Upon expression in ARPE-19 cells, recombinant Nlp(isoB), lebercilin and USH2A(isoB) were all found to co-localize at the centrosomes. Staining of retinal sections with specific antibodies against all three proteins revealed their co-localization at the basal bodies of the photoreceptor-connecting cilia. Based on this subcellular localization and the nature of their previously identified binding partners, we hypothesize that the pathogenic mechanisms for LCA and USH show significant overlap and involve defects in ciliogenesis, cilia maintenance and intraflagellar and/or microtubule-based transport. The direct association of Nlp(isoB) with USH2A(isoB) and lebercilin indicates that Nlp can be considered as a novel candidate gene for USH, LCA and allied retinal ciliopathies.