Natural Glycoforms of Human Interleukin 6 Show Atypical Plasma Clearance.

A library of glycoforms of human interleukin 6 (IL-6) comprising complex and mannosidic N-glycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by two-step refolding. The central glycopeptide segments were assembled by pseudoproline-assisted Lansbury aspartylation and subsequent enzymatic elongation of complex N-glycans. Nine IL-6 glycoforms were synthesized, seven of which were evaluated for in vivo plasma clearance in rats and compared to non-glycosylated recombinant IL-6 from E. coli. Each IL-6 glycoform was tested in three animals and reproducibly showed individual serum clearances depending on the structure of the N-glycan. The clearance rates were atypical, since the 2,6-sialylated glycoforms of IL-6 cleared faster than the corresponding asialo IL-6 with terminal galactoses. Compared to non-glycosylated IL-6 the plasma clearance of IL-6 glycoforms was delayed in the presence of larger and multibranched N-glycans in most cases.

Mutations in Craniosynostosis Patients Cause Defective Interleukin-11 Receptor Maturation and Drive Craniosynostosis-like Disease in Mice.

Premature closure of the sutures that connect the cranial bones during development of the mammalian skull results in a phenotype called craniosynostosis. Recently, several craniosynostosis patients with missense mutations within the gene encoding the interleukin-11 receptor (IL-11R) have been described, but the underlying molecular mechanisms have remained elusive. IL-11 is a cytokine that has a crucial role in bone remodeling and activates cells via binding to the IL-11R. Here, we show that patient mutations prevented maturation of the IL-11R, resulting in endoplasmic reticulum retention and diminished cell surface appearance. Disruption of a conserved tryptophan-arginine zipper within the third domain of the IL-11R was the underlying cause of the defective maturation. IL-11 classic signaling via the membrane-bound receptor, but not IL-11 trans-signaling via the soluble receptor, was the crucial pathway for normal skull development in mice in vivo. Thus, the specific therapeutic inhibition of IL-11 trans-signaling does not interfere with skull development.

Initial leukemic gene expression profiles of patients with poor in vivo prednisone response are similar to those of blasts persisting under prednisone treatment in childhood acute lymphoblastic leukemia.

Response to initial glucocorticoid (GC) treatment is a strong prognostic factor in childhood acute lymphoblastic leukemia (ALL). Patients with a poor prednisone response (PPR) have a poor event-free survival as compared to those with a good prednisone response (PGR). Causes of prednisone resistance are still not well understood. We hypothesized that GC resistance is an intrinsic feature of ALL cells which is reflected in the gene expression pattern and analyzed genome-wide gene expression using microarrays. A case-control study was performed comparing gene expression profiles from initial ALL samples of 20 patients with PPR and those of 20 patients with PGR. Differential gene expression of a subset of genes was confirmed by real-time quantitative polymerase chain reaction analysis and validation was performed in a second independent patient sample (n=20). We identified 121 genes that clearly distinguished prednisone-resistant from sensitive ALL samples (FDR<5%, fold change>or=1.5). Differential gene expression of 21 of these genes could be validated in a second independent set. Of importance, there was a remarkable concordance of genes identified by comparing expression signatures of PPR and PGR cells at diagnosis and those previously described to be up- or downregulated in leukemic cells persisting under GC treatment. Thus, GC resistance seems at least in part to be an intrinsic feature of leukemic cells. Leukemic cells of patients with PPR are characterized by gene expression pattern which are similar to those of resistant cells persisting under glucocorticoid treatment.

Unmutated immunoglobulin variable heavy-chain gene status remains an adverse prognostic factor after autologous stem cell transplantation for chronic lymphocytic leukemia.

An unmutated germ line configuration of the immunoglobulin variable heavy-chain gene (VH) has emerged to be a crucial adverse prognostic factor in chronic lymphocytic leukemia (CLL) under conventional treatment. The purpose of the present study was to investigate whether the VH mutational status retains its prognostic value in CLL also in the setting of autologous stem cell transplantation (SCT). Therefore, we investigated the mutational status in 58 patients with CLL who underwent myeloablative radiochemotherapy with SCT. Rearranged VH genes were analyzed by multiplex polymerase chain reaction (PCR) and direct sequencing using FR1 family-specific primers and JH consensus primers. Twenty patients (34%) showed less than 98% homology compared with germ line VH sequences and were considered as mutated, whereas 38 patients (66%) had an unmutated VH status (median mutational rate of 0%; range, 0%-1.7%). An unmutated VH configuration was strongly correlated with the presence of short lymphocyte doubling time (P =.003) and high lymphocyte count (P =.005). Time to clinical relapse and time to recurrence of monoclonal B cells as assessed by consensus IgH CDR3 PCR was significantly shorter in the group with unmutated VH genes (2-year probability 19% versus 0%, P =.0008, and 34% versus 9%, P =.0006, respectively). These results show that in CLL, an unmutated VH gene status of the tumor clone remains an adverse prognostic factor after SCT. Nevertheless, the hitherto only 3 deaths and the median treatment-free interval of 49 months in the unmutated cohort suggest a beneficial effect of SCT for this high-risk population in comparison to conventional treatment.