Serum concentration of complement components of the lectin pathway in maintenance hemodialysis patients, and relatively higher levels of L-Ficolin and MASP-2 in Mannose-binding lectin deficiency

Neutralizing Antibody Induction by HIV-1 Envelope Glycoprotein SOSIP Trimers on Iron Oxide Nanoparticles May Be Impaired by Mannose Binding Lectin

We covalently attached human immunodeficiency virus type 1 (HIV-1) Env SOSIP trimers to iron oxide nanoparticles (IO-NPs) to create a particulate immunogen for neutralizing antibody (NAb) induction. The attached trimers, ∼20 per particle, retained native-like antigenicity, judged by reactivity with NAbs and non-NAbs. Bivalent (BG505 and B41) trimer IO-NPs were made, as were IO-NPs displaying B41 trimers carrying a PADRE T-cell helper epitope (TCHE). We immunized mice with B41 soluble or IO-NP trimers after PADRE peptide priming. After two immunizations, IO-NP presentation and the TCHE tag independently and substantially increased anti-trimer antibody responses, but titer differences waned after two further doses. Notable and unexpected findings were that autologous NAbs to the N289 glycan hole epitope were consistently induced in mice given soluble but not IO-NP trimers. Various recombinant mannose binding lectins (MBLs) and MBLs in sera of both murine and human origin bound to soluble and IO-NP trimers. MBL binding occluded the autologous NAb epitope on the B41 IO-NP trimers, which may contribute to its poor immunogenicity. The exposure of a subset of broadly active NAb epitopes was also impaired by MBL binding, which could have substantial implications for the utility of trimer-bearing nanoparticles in general and perhaps also for soluble Env proteins.IMPORTANCE Recombinant trimeric SOSIP proteins are vaccine components intended to induce neutralizing antibodies (NAbs) that prevent cells from infection by human immunodeficiency virus type 1 (HIV-1). A way to increase the strength of antibody responses to these proteins is to present them on the surface of nanoparticles (NPs). We chemically attached about 20 SOSIP trimers to NPs made of iron oxide (IO). The resulting IO-NP trimers had appropriate properties when we studied them in the laboratory but, unexpectedly, were less able to induce NAbs than nonattached trimers when used to immunize mice. We found that mannose binding lectins, proteins naturally present in the serum of mice and other animals, bound strongly to the soluble and IO-NP trimers, blocking access to antibody epitopes in a way that may impede the development of NAb responses. These findings should influence how trimer-bearing NPs of various designs are made and used.

Mannose-binding lectin genotypes and outcome in end-stage renal disease: a prospective cohort study

Background

Patients with end-stage renal disease (ESRD) have high morbidity and mortality rates, with cardiovascular diseases and infections being the major causes of death. Mannose-binding lectin (MBL) has been suggested to play a protective role in this regard. The aim of this study was to investigate a possible clinical association of MBL genotypes (MBL2) with outcome among patients on dialysis or with a functioning graft.

Methods

A total of 98 patients with ESRD accepted for living-donor renal transplantation or on the waiting list for transplantation were included and prospectively followed for an average of 9 years (range 7.5-9.9). Medical records were evaluated regarding transplantation status, diabetes mellitus, vascular parameters and infections for all the patients. Cox regression models and logistic regression analysis were used for statistical analyses. The cohort was divided into two groups according to the MBL2 genotype (normal A/A versus variant A/O or O/O).

Results

We found no evidence for an association between the MBL2 genotype and all-cause mortality, cardiovascular events or bacterial infections (pneumonia, urinary tract infection, fistula infection or other infections).

Conclusion

In this cohort, the MBL2 genotype did not seem to be associated with any long-term clinical effects in ESRD patients on dialysis or with a functioning graft.

Basic inflammatory indices and chosen neutrophil receptors expression in chronic haemodialysed patients

Aim of the study

End stage renal disease (ESRD) patients on chronic haemodialysis (HD) are immuno-compromised and prone to infection. Toll-like receptors (TLRs) play a role as both primary sensors of pathogen invasion and activators of inflammatory reaction. To test if the immune impairment in HD patients is connected with the defective expression of the neutrophil TLRs, we aimed to examine their expression and chosen inflammatory indices.

Material and methods

We tested CD14, TLR4, and TLR9 expressions on neutrophils using flow cytometry. Soluble CD14, C-reactive protein (CRP), and mannose-binding lectin (MBL) concentrations were tested using the ELISA method in 31 ESRD patients on chronic haemodialysis programs and in 17 healthy control subjects.

Results

Neutrophil TLR4 and TLR9 expressions did not differ significantly compared to the controls. The ESRD patients had markedly increased CRP and sCD14 levels alongside decreased MBL concentrations and neutrophil CD14 expression. The TLR4 expression correlated well with both TLR9 and CD14 neutrophil expressions; however, the increased CRP in the blood did not correlate with the MBL concentration or TLR expression.

Conclusions

The chronic program of haemodialysis and biochemical disorders in ESRD patients result in a low-grade chronic inflammation with no significant impact on the expression of neutrophil TLR4 and TLR9.

The Complement System in Dialysis: A Forgotten Story?

Significant advances have lead to a greater understanding of the role of the complement system within nephrology. The success of the first clinically approved complement inhibitor has created renewed appreciation of complement-targeting therapeutics. Several clinical trials are currently underway to evaluate the therapeutic potential of complement inhibition in renal diseases and kidney transplantation. Although, complement has been known to be activated during dialysis for over four decades, this area of research has been neglected in recent years. Despite significant progress in biocompatibility of hemodialysis (HD) membranes and peritoneal dialysis (PD) fluids, complement activation remains an undesired effect and relevant issue. Short-term effects of complement activation include promoting inflammation and coagulation. In addition, long-term complications of dialysis, such as infection, fibrosis and cardiovascular events, are linked to the complement system. These results suggest that interventions targeting the complement system in dialysis could improve biocompatibility, dialysis efficacy, and long-term outcome. Combined with the clinical availability to safely target complement in patients, the question is not if we should inhibit complement in dialysis, but when and how. The purpose of this review is to summarize previous findings and provide a comprehensive overview of the role of the complement system in both HD and PD.

Strong predictive value of mannose-binding lectin levels for cardiovascular risk of hemodialysis patients

Background

Hemodialysis patients have higher rates of cardiovascular morbidity and mortality compared to the general population. Mannose-binding lectin (MBL) plays an important role in the development of cardiovascular disease. In addition, hemodialysis alters MBL concentration and functional activity. The present study determines the predictive value of MBL levels for future cardiac events (C-event), cardiovascular events (CV-event) and all-cause mortality in HD patients.

Methods

We conducted a prospective study of 107 patients on maintenance hemodialysis. Plasma MBL, properdin, C3d and sC5b-9 was measured before and after one dialysis session. The association with future C-events, CV-events, and all-cause mortality was evaluated using Cox regression models.

Results

During median follow-up of 27 months, 36 participants developed 21 C-events and 36 CV-events, whereas 37 patients died. The incidence of C-events and CV-events was significantly higher in patients with low MBL levels (<319 ng/mL, lower quartile). In fully adjusted models, low MBL level was independently associated with increased CV-events (hazard ratio 3.98; 95 % CI 1.88–8.24; P < 0.001) and C-events (hazard ratio 3.96; 95 % CI 1.49–10.54; P = 0.006). No association was found between low MBL levels and all-cause mortality. Furthermore, MBL substantially improved risk prediction for CV-events beyond currently used clinical markers.

Conclusions

Low MBL levels are associated with a higher risk for future C-events and CV-events. Therefore, MBL levels may help to identify hemodialysis patients who are at risk to develop cardiovascular disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0995-5) contains supplementary material, which is available to authorized users.

Frequency and distribution of FCN2 and FCN3 functional variants among MBL2 genotypes

The six types of pattern recognition molecules (PRMs) that initiate complement via the lectin pathway (LP) comprise collectins and ficolins. The importance of having various PRMs to initiate the LP is currently unclear. Mannan-binding lectin (MBL) is a collectin member of the LP PRMs. MBL deficiency is common with mild clinical consequence. Thus, the lack of MBL may be compensated for by the other PRMs. We hypothesized that variants FCN2 + 6424 and FCN3 + 1637delC that cause gene-dose-dependent reduction in ficolin-2 and ficolin-3 levels, respectively, may be rare in MBL-deficient individuals due to the importance of compensation within the LP. The aim of this study was to investigate the distribution and frequency of these variants among MBL2 genotypes in healthy subjects. The allele frequency of FCN2 + 6424 and FCN3 + 1637delC was 0.099 and 0.015, respectively, in the cohort (n = 498). The frequency of FCN2 + 6424 tended to be lower among MBL-deficient subjects (n = 53) than among MBL-sufficient subjects (n = 445) (0.047 versus 0.106, P = 0.057). In addition, individuals who were homozygous for FCN2 + 6424 were sufficient MBL producers. The frequency of FCN3 + 1637delC did not differ between the groups. The frequency of FCN2 + 6424 was similar in FCN3 + 1637delC carriers (n = 15) versus wild type (n = 498). Furthermore, subjects that were heterozygote carriers of both FCN2 + 6424 and FCN3 + 1637delC were sufficient MBL producers. In conclusion, FCN2 + 6424 carriers with MBL deficiency tend to be rare among healthy individuals. MBL-deficient individuals with additional LP PRM defects may be at risk to morbidity.

An analysis of functional activity via the three complement pathways during hemodialysis sessions: a new insight into the association between the lectin pathway and C5 activation

Background

We have recently demonstrated that hemodialysis (HD) patients have significantly higher levels of functional complement activity (FCA) in all three pathways, i.e. the classical pathway, alternative pathway and lectin pathway (LP), than in age-matched controls, though the role of FCA during HD still remains unknown.

Methods

Serial plasma or serum samples were obtained from five patients during HD in order to investigate the kinetics of complement components. The levels of the C5b-9 complex, the FCA of the three pathways, a derivative of C3a (C3a desArg) and a derivative of C5a (C5a desArg) in the samples were analyzed.

Results

The levels of the C5b-9 complex at 60 min were significantly increased when compared with those at 0 min. Functional activities for all three pathways showed different patterns so the same tendency between pathways was not observed. The levels of C3a desArg and C5a desArg at 60 min were markedly increased when compared with those at 0 min. A Spearman's rho test showed a strong positive correlation between functional LP activity and C5a desArg.

Conclusions

These findings lead to new insights into the FCA during HD and suggest that functional LP activity has an important role in C5 activation.

Pathogenesis and treatment of chronic kidney disease: a review of our recent basic and clinical data

Chronic kidney disease (CKD) is a worldwide public health problem that affects millions of people from all racial and ethnic groups. At end of 2013, over 300,000 Japanese patients had maintenance dialysis therapy (JSDT). In Japan, the major causes of end stage kidney disease (ESKD) are chronic glomerulonephritis (particularly IgA nephropathy), type 2 diabetic nephropathy, and hypertensive nephrosclerosis. Hypertension is a major factor driving the progression of CKD to ESKD. Since many features of the pathogenesis of IgA nephropathy are still obscure, specific treatment is not yet available. However, efforts by investigators around the world have gradually clarified different aspects of the pathogenesis and treatment of IgA nephropathy. Today, around half of all diabetic patients in Japan receive medical treatment. Type 2 diabetic nephropathy is one of the major long-term microvascular complications occurring in nearly 40% of Japanese diabetic patients. The pathogenesis of diabetic nephropathy involves both genetic and environmental factors. However, the candidate genes related to the initiation and progression of the disorder are still obscure in patients with diabetic nephropathy. Regarding environmental factors, the toxicity of persistent hyperglycemia, reactive oxygen species, systemic and/or glomerular hypertension, dyslipidemia and complement are considered to play an important role. The first part of this review covers the pathogenesis of IgA nephropathy and type 2 diabetic nephropathy, and combines the clinicopathological findings in patients with our research on the ddY and KKA-y mouse models (spontaneous animal models for IgA nephropathy and diabetic nephropathy, respectively). In Japan, the major renal replacement therapies (RRT) are peritoneal dialysis (PD) and hemodialysis (HD). The second part of this review focuses on PD and HD. Based on our research findings from patients and as well as from animal models, we discuss strategies for the management of patients on PD and HD.

Impact of mannose-binding lectin deficiency on radiocontrast-induced renal dysfunction: a post-hoc analysis of a multicenter randomized controlled trial

Background

Local renal ischemia is regarded as an important factor in the development of contrast-induced nephropathy (CIN). Mannose-binding lectin (MBL) is involved in the tissue damage during experimental ischemia/reperfusion injury of the kidneys. The aim of the present study was to investigate the association of MBL deficiency with radiocontrast-induced renal dysfunction in a large prospective cohort.

Methods

246 patients with advanced non–dialysis-dependent renal dysfunction who underwent radiographic contrast procedures were included in the study. Baseline serum MBL levels were analyzed according to the occurrence of a creatinine-based (increase of ≥0.5 mg/dL or ≥25% within 48 hours) or cystatin C-based (increase of ≥10% within 24 hours) CIN.

Results

The incidence of creatinine-based and cystatin C-based CIN was 6.5% and 24%, respectively. MBL levels were not associated with the occurrence of creatinine-based CIN. However, patients that experienced a cystatin C increase of ≥10% showed significantly higher MBL levels than patients with a rise of <10% (median 2885 (IQR 1193–4471) vs. 1997 (IQR 439–3504)ng/mL, p = 0.01). In logistic regression analysis MBL deficiency (MBL levels≤500 ng/ml) was identified as an inverse predictor of a cystatin C increase ≥10% (OR 0.34, 95% CI 0.15-0.8, p = 0.01).

Conclusion

MBL deficiency was associated with a reduced radiocontrast-induced renal dysfunction as reflected by the course of cystatin C. Our findings support a possible role of MBL in the pathogenesis of CIN.