Regulation of T Cell Activities in Rheumatoid Arthritis by the Novel Fusion Protein IgD-Fc-Ig.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and T cell hyper-activation. Emerging evidence has shown that the stimulation of immunoglobulin D (IgD) induces T cell activation and may contribute to disease pathogenesis. In this study, the sIgD concentrations were positively associated with disease activity score in 28 joints (DAS28) and anti-cyclic citrullinated peptide (anti-CCP) in RA. We demonstrated that IgD-Fc-Ig (composed of human IgD Fc domain and IgG1 Fc domain, obtained through prokaryotic protein expression and chromatography purification) effectively inhibited the activation and proliferation of T cells in healthy controls and PBMCs in RA patients stimulated by IgD, recovered the Th17/Treg cell subset balance, and downregulated p-Lck and p-ZAP70 expression. Moreover, in vivo, IgD-Fc-Ig decreased the swollen joint counts and arthritis indices in mice with collagen-induced arthritis (CIA), and ameliorated histopathological changes in joint and spleen tissue. It also downregulated thymocyte proliferation and reduced the percentage of helper T cells (Th) and CD154+ T cells, reversed the imbalance of Th1/Th2 and Th17/Treg cell subsets, reduced cytokine and chemokine levels, and inhibited p-Lck and p-ZAP70 expression. Our data suggest that IgD-Fc-Ig fusion protein regulates T cell activity in RA. These findings have potential implications for IgD-targeted strategies to treat IgD-associated RA.

Primary vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in infants in Mali and Nigeria: a randomized controlled trial.

BACKGROUND: Pneumonia is still the leading cause of death among children in Africa, and pneumococcal serotypes 1 and 5 are frequently isolated from African children with invasive pneumococcal disease below the age of 5 years. The immunogenicity, safety and reactogenicity of 3-dose primary vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) were evaluated in infants in Mali and Nigeria. METHODS: In an open, randomized, controlled study, 357 infants received DTPw-HBV/Hib and OPV primary vaccination with (PHiD-CV group) or without (control group) PHiD-CV co-administration at 6, 10 and 14 weeks of age. Pneumococcal antibody responses and opsonophagocytic activity (OPA) were measured and adverse events (AEs) recorded. RESULTS: One month post-dose 3, ≥ 97.2% of PHiD-CV-vaccinated infants had an antibody concentration ≥ 0.2 µg/mL for each vaccine pneumococcal serotype except for 6B (82.0%) and 23F (87.6%) versus < 10% in the control group except for serotypes 14 (35.7%) and 19F (22.5%). For each vaccine serotype, ≥ 93.3% of PHiD-CV recipients had an OPA titre ≥ 8, except for serotypes 1 (87.6%) and 6B (85.4%), compared to < 10% in the control group, except for serotypes 7F (42.9%), 9V (24.1%) and 14 (24.5%). Anti-protein D geometric mean antibody concentrations were 3791.8 and 85.4 EL.U/mL in the PHiD-CV and control groups, respectively. Overall incidences of solicited and unsolicited AEs were similar between groups. CONCLUSIONS: In sub-Saharan African infants, PHiD-CV was immunogenic for all vaccine pneumococcal serotypes and protein D. Vaccine tolerability was generally comparable between the PHiD-CV and control groups. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00678301.

Anti-CD20 therapy in patients with rheumatoid arthritis: predictors of response and B cell subset regeneration after repeated treatment.

OBJECTIVE: B cell depletion with the anti-CD20 antibody rituximab has proven efficacy in patients with rheumatoid arthritis (RA). The effects on B cell homeostasis after repeated treatments and the relationship of certain B cell subsets to clinical response or relapse are currently not known. METHODS: In this open-label study, 17 patients with RA refractory to standard therapy were treated with 1 cycle of rituximab. Of these 17 patients, 11 received a second cycle of rituximab therapy. Immunophenotyping was performed before therapy and during B cell recovery. RESULTS: Twelve of 17 patients showed a good European League Against Rheumatism response after receiving 1 cycle of rituximab therapy. At the time of B cell recovery, the IgD+,CD27+ memory B cell subset was significantly larger (P = 0.019) in the nonresponder group. Within the group of 12 responders, 6 patients, whose disease was characterized by a significantly higher proportion of overall CD27+ memory B cells before therapy, experienced an early relapse (weeks 24-40 posttreatment). Eleven patients were re-treated, again resulting in a good clinical response. B cell reconstitution followed a similar pattern after each cycle. The early reconstitution phase was characterized by immature CD38++,IgD+,CD10+ B cells, whereas the number of naive B cells increased continuously thereafter. The number of memory B cells was still reduced at the time of the second depletion but recovered to levels similar to those following the first cycle of therapy. CONCLUSION: Data derived from repeated B lymphocyte depletion with rituximab in patients with RA suggest that analysis of certain memory B cell subsets provides information on efficacy, response, and late as well as early relapse, consistent with the conclusion that targeting memory B cells is a key to its mechanism of action.

Two steps in the intracellular transport of IgD are sensitive to energy depletion.

The secretory pathway of murine IgD can be dissected by the use of carbonylcyanide m-chlorophenylhydrazone (CCCP), which inhibits two distinct steps of intracellular transport. The newly synthesized IgD that accumulates at the first step contains high mannose type oligosaccharides which are partially trimmed. The IgD arrested at this step is less processed than the IgD arrested by treatment with monensin. The properties of this biosynthetic intermediate are consistent with inhibition of Ig passage from the endoplasmic reticulum to the Golgi complex. A second CCCP-sensitive step exists in the biosynthesis of IgD, and is characterized by delta-chains that are resistant to endoglycosidase H and contain galactose. This indicates that this second step occurs during or after the passage through the trans-Golgi compartment. The galactose-containing oligosaccharides of the delta-chains arrested at this step do not contain fucose (as do mature, secreted delta-chains). Fucosylation is not inhibited by CCCP, nor is the secretion of fucose-containing delta-chains. These results show that terminal sugars are added to secretory IgD in at least two transport compartments, separable by their sensitivity to CCCP. The inhibition of the secretory pathway at both steps is reversible; upon removal of the drug the arrested IgD is processed normally and is secreted. The sensitivity to CCCP probably reflects transport steps that are sensitive to even partial depletion of ATP, because treatments with other inhibitors of oxidative phosphorylation yield similarly arrested Ig molecules. Thus, by using the protonophore CCCP, we demonstrate two energy-requiring steps in IgD transport which seem to be at two transitions in the secretory pathway. One step is during the passage from the endoplasmic reticulum to the mid-Golgi compartment and the other step is during Ig passage through the trans-Golgi, or subsequent transport to the cell surface.