Fab glycosylation of immunoglobulin G does not associate with improvement of rheumatoid arthritis during pregnancy

Background: Changes in immunoglobulin G (IgG) constant domain (Fc) glycosylation are associated with changes in rheumatoid arthritis (RA) disease activity in response to pregnancy. Here, we sought to determine whether the same holds true for variable domain (Fab) glycosylation. Methods: IgGs were captured from RA and control sera obtained before (RA only), during and after pregnancy, followed by Fc and Fab separation, glycan release, and mass spectrometric detection. In parallel,

Increased Right Atrial Stiffness in Patients With Heart Failure With Preserved Ejection Fraction and Pulmonary Hypertension

Abstract Background: Patients with Heart Failure with preserved Ejection Fraction (HFpEF) and Pulmonary Hypertension (PH) have increased right atrial (RA) pressures. Whether the higher RA pressures are related to increased afterload or overall stiffening of the heart is unknown. The aim of this study is to gain further insight into the right atrium in HFpEF-PH. Methods: This is a retrospective analysis of patients with HFpEF (no PH), HFpEF-PH and Pulmonary Arterial Hypertension (PAH) that underwent right heart catheterization and cardiac magnetic resonance (CMR) imaging. CMR was used to determine RA function by quantifying volume and strain on the 4-chamber view. Total, passive and active RA emptying fraction (RAEF) were calculated. RA stiffness was calculated by determining the slope of maximum and minimum pressure during v-wave and minimal and maximal RA volumes. Groups were compared with ANOVA and post-hoc comparison with Bonferroni correction. Results: 176 patients were included: 13 HFpEF, 33 HFpEF-PH and 130 PAH patients. Although afterload was lower in PAH and higher in HFpEF patients, as shown by mean pulmonary arterial pressure (mPAP) (41± 2 mmHg in HFpEF-PH vs 53± 21 mmHg in PAH vs 19± 1 mmHg in HFpEF, p<0.001) and pulmonary vascular resistance (PVR) (2.3± 0.3 wu/m2 in HFpEF-PH vs 5.7± 0.2 wu/m2 in PAH vs 0.4± 0.06 wu/m2 in HFpEF, p<0.001), mean RA pressure was significantly higher in HFpEF-PH patients compared to both groups (Figure 1A). HFpEF-PH patients had significantly increased RA stiffness compared to HFpEF and PAH patients (Figure 1B). Total RAEF was reduced in HFpEF-PH compared to PAH and HFpEF patients: passive RAEF was similar, but active RAEF was slightly reduced in HFpEF-PH (Figure 1C). This was in line with measurements of RA longitudinal strain (Figure 1D). Conclusions: Despite lower afterload, HFpEF-PH patients have worse RA function and increased RA stiffness compared to PAH. Higher RA pressures in HFpEF-PH may reflect additional stiffening of the heart

Unique patterns of glycosylation in immunoglobulin subclass G4‐related disease and primary sclerosing cholangitis

Background: Immunoglobulin subclass G4‐related disease (IgG4‐RD) is characterized by an abundance of IgG4 antibodies in the serum and tissue. Glycosylation status of antibodies can impact on immune effector functions and disease pathophysiology. We sought to establish glycosylation patterns in a prospective cohort of patients with IgG4‐RD and the relationship with disease activity and response to treatment. Methods: We assessed IgG Fc‐tail and Fab‐arm glycosylation status in patients with IgG4‐RD (n = 22), disease controls with primary sclerosing cholangitis (PSC) (n = 22), and healthy controls (n = 22). Serum IgG and subclasses were quantified using ELISA. Fc and Fab glycosylation were analyzed by mass spectrometry and lectin affinity chromatography, respectively. Disease activity, organ damage, and response to treatment were assessed using the IgG4 Responder Index. Results: Immunoglobulin G Fab sialylation was increased in IgG4‐RD compared with PSC and healthy control (P = 0.01), with a preferential increase in IgG4‐specific Fab sialylation, which was independent of IgG4 Fab‐arm exchange. There was a reduction in IgG1‐specific Fc bisection and hybrid structures in IgG4‐RD (P &lt; 0.01), which recovered upon steroid treatment and correlated with disease activity. Overall, IgG Fc galactosylation was reduced in both IgG4‐RD and PSC (P &lt; 0.01), with a preferential reduction in IgG1‐specific sialylation and enhancement of IgG4‐specific bisection in PSC. IgG4 fucosylation and IgG1/2/3 hybrid structures negatively correlated with complement C3 and C4 levels in IgG4‐RD (P &lt; 0.01), but not PSC. Conclusion: We report the first study showing unique antibody glycosylation status in a prospective cohort of IgG4‐RD and PSC patients, which may determine modulation of the immune system and contribute to disease pathophysiology.</p

Unique patterns of glycosylation in immunoglobulin subclass G4‐related disease and primary sclerosing cholangitis

Background: Immunoglobulin subclass G4‐related disease (IgG4‐RD) is characterized by an abundance of IgG4 antibodies in the serum and tissue. Glycosylation status of antibodies can impact on immune effector functions and disease pathophysiology. We sought to establish glycosylation patterns in a prospective cohort of patients with IgG4‐RD and the relationship with disease activity and response to treatment. Methods: We assessed IgG Fc‐tail and Fab‐arm glycosylation status in patients with IgG4‐RD (n = 22), disease controls with primary sclerosing cholangitis (PSC) (n = 22), and healthy controls (n = 22). Serum IgG and subclasses were quantified using ELISA. Fc and Fab glycosylation were analyzed by mass spectrometry and lectin affinity chromatography, respectively. Disease activity, organ damage, and response to treatment were assessed using the IgG4 Responder Index. Results: Immunoglobulin G Fab sialylation was increased in IgG4‐RD compared with PSC and healthy control (P = 0.01), with a preferential increase in IgG4‐specific Fab sialylation, which was independent of IgG4 Fab‐arm exchange. There was a reduction in IgG1‐specific Fc bisection and hybrid structures in IgG4‐RD (P Conclusion: We report the first study showing unique antibody glycosylation status in a prospective cohort of IgG4‐RD and PSC patients, which may determine modulation of the immune system and contribute to disease pathophysiology.</p

Decreased IL7R alpha and TdT expression underlie the skewed immunoglobulin repertoire of human B-cell precursors from fetal origin

Newborns are unable to mount antibody responses towards certain antigens. This has been related to the restricted repertoire of immunoglobulin (Ig) genes of their B cells. The mechanisms underlying the restricted fetal Ig gene repertoire are currently unresolved. We here addressed this with detailed molecular and cellular analysis of human precursor-B cells from fetal liver, fetal bone marrow (BM), and pediatric BM. In the absence of selection processes, fetal B-cell progenitors more frequently used proximal V, D and J genes in complete IGH gene rearrangements, despite normal Ig locus contraction. Fewer N-nucleotides were added in IGH gene rearrangements in the context of low TdT and XRCC4 expression. Moreover, fetal progenitor-B cells expressed lower levels of IL7R alpha than their pediatric counterparts. Analysis of progenitor-B cells from IL7R alpha-deficient patients revealed that TdT expression and N-nucleotides additions in Dh-Jh junctions were dependent on functional IL7R alpha. Thus, IL7R alpha affects TdT expression, and decreased expression of this receptor underlies at least in part the skewed Ig repertoire formation in fetal B-cell precursors. These new insights provide a better understanding of the formation of adaptive immunity in the developing fetus