Differences in MBL levels between juvenile patients newly diagnosed with type 1 diabetes and their healthy siblings

Mannan-binding lectin exacerbates the severity of psoriasis by promoting plasmacytoid dendritic cell differentiation via the signal transducer and activator of transcription 3-interferon regulatory factor 8 axis

Psoriasis is a chronic inflammatory skin disease mediated by host immune responses. Plasmacytoid dendritic cells (pDC) and interferon (IFN)-α secreted by pDC are involved in the initiation of psoriasis. Mannan-binding lectin (MBL), a vital component of the complement pathway, plays a critical role in innate immune defense and the inflammatory response. Our previous study found that MBL could exacerbate skin inflammation in psoriatic mice, but the effect of MBL on pDC remains unstudied. Herein, we revealed that the circulating level of MBL was elevated in patients with psoriasis compared with the healthy controls. Moreover, the MBL level was positively correlated with disease severity, relative inflammatory cytokine levels, and peripheral blood (PB) pDC frequency in psoriasis. An in vitro study determined that the MBL protein could promote the differentiation of human pDC and upregulate the production of relative inflammatory cytokines and chemokines. Additionally, MBL-deficient (MBL^-/- ) mice exhibited decreased accumulation of pDC in lymph nodes, spleens, and skin lesions with reduced secretion of pDC-related cytokines compared with wild-type (WT) mice in the preliminary stage of psoriasis induced by imiquimod. Notably, the differentiation of pDC from bone marrow (BM) cells derived from MBL^-/- mice was weakened compared with that from WT mice upon Fms-like tyrosine kinase 3 ligand (Flt3L) incubation. Mechanistic research indicated that the signal transducer and activator of transcription 3 (STAT3)-interferon regulatory factor 8 (IRF8) axis was responsible for MBL-modulated pDC differentiation. In summary, these results suggest that MBL exacerbates the severity of psoriasis by enhancing pDC differentiation and pDC-related cytokine secretion via the STAT3-IRF8 axis, thus providing a new target for psoriasis treatment.

Confirmation and Identification of Biomarkers Implicating Environmental Triggers in the Pathogenesis of Type 1 Diabetes

Multiple environmental triggers have been proposed to explain the increased incidence of type 1 diabetes (T1D). These include viral infections, microbiome disturbances, metabolic disorders, and vitamin D deficiency. Here, we used ELISA to examine blood plasma from juvenile T1D subjects and age-matched controls for the abundance of several circulating factors relevant to these hypotheses. We screened plasma for sCD14, mannose binding lectin (MBL), lipopolysaccharide binding protein (LBP), c-reactive protein (CRP), fatty acid binding protein 2 (FABP2), human growth hormone, leptin, total adiponectin, high molecular weight (HMW) adiponectin, total IgG, total IgA, total IgM, endotoxin core antibodies (EndoCAbs), 25(OH) vitamin D, vitamin D binding protein, IL-7, IL-10, IFN-γ, TNF-α, IL-17A, IL-18, and IL-18BPa. Subjects also were tested for prevalence of antibodies targeting adenovirus, parainfluenza 1/2/3, Coxsackievirus, cytomegalovirus, Epstein-Barr virus viral capsid antigen (EBV VCA), herpes simplex virus 1, and Saccharomyces cerevisiae. Finally, all subjects were screened for presence and abundance of autoantibodies targeting islet cell cytoplasmic proteins (ICA), glutamate decarboxylase 2 (GAD65), zinc transporter 8 (ZNT8), insulinoma antigen 2 (IA-2), tissue transglutaminase, and thyroid peroxidase, while β cell function was gauged by measuring c-peptide levels. We observed few differences between control and T1D subjects. Of these, we found elevated sCD14, IL-18BPa, and FABP2, and reduced total IgM. Female T1D subjects were notably elevated in CRP levels compared to control, while males were similar. T1D subjects also had significantly lower prevalence of EBV VCA antibodies compared to control. Lastly, we observed that c-peptide levels were significantly correlated with leptin levels among controls, but this relationship was not significant among T1D subjects. Alternatively, adiponectin levels were significantly correlated with c-peptide levels among T1D subjects, while controls showed no relationship between these two factors. Among T1D subjects, the highest c-peptide levels were associated with the lowest adiponectin levels, an indication of insulin resistance. In total, from our examination we found limited data that strongly support any of the hypotheses investigated. Rather, we observed an indication of unexplained monocyte/macrophage activation in T1D subjects judging from elevated levels of sCD14 and IL-18BPa. These observations were partnered with unique associations between adipokines and c-peptide levels among T1D subjects.

Association between Neonatal Whole Blood Iron Content and Cytokines, Adipokines, and Other Immune Response Proteins

(1) Background: High iron associates with inflammation and type 1 diabetes (T1D). Iron is essential not only for neonatal development but also for infectious microorganisms. The neonatal immune system is immature, and innate immunity prevails before immunocompetence develops. (2) Methods: In 398 newborns from the Danish Newborn Screening Biobank, we examined if whole blood iron (WB-Iron) content were associated with cytokines, adipokines, C-reactive protein (CRP), and mannose-binding lectin (MBL) in non-infected healthy neonates, and if these associations differed in newborns who later developed T1D (cases) (n = 199). WB-Iron was quantified using laser ablation inductively coupled plasma mass spectrometry on the neonatal dried blood spots. For each analyte, the relative change (RC) in the mean level was modeled by robust log-normal regression. (3) Results: A one unit increase in neonatal WB-Iron was associated with a 38% decrease in mean interleukin (IL)-6 levels (0.62; 95% CI: 0.40–0.95, p = 0.03), and a 37% decrease in mean MBL levels (0.63; 95% CI: 0.41–0.95, p = 0.03), but was not statistically significant after correction for multiple testing. (4) Conclusions: In summary, we found that higher neonatal WB-iron content was inversely associated with IL-6 and MBL, which may increase susceptibility to infections.

Levels of soluble TREM-1 in children with newly diagnosed type 1 diabetes and their siblings without type 1 diabetes: a Danish case-control study

BACKGROUND

Type 1 diabetes (T1D) is an organ-specific autoimmune disease with an increase in incidence worldwide including Denmark. The triggering receptor expressed on myeloid cells-1 (TREM-1) is a potent amplifier of pro-inflammatory responses and has been linked to autoimmunity, severe psychiatric disorders, sepsis, and cancer.

HYPOTHESIS

Our primary hypothesis was that levels of soluble TREM-1 (sTREM-1) differed between newly diagnosed children with T1D and their siblings without T1D.

METHODS

Since 1996, the Danish Childhood Diabetes Register has collected data on all patients who have developed T1D before the age of 18 years. Four hundred and eighty-one patients and 478 siblings with measurements of sTREM-1-blood samples were taken within 3 months after onset-were available for statistical analyses. Sample period was from 1997 through 2005. A robust log-normal regression model was used, which takes into account that measurements are left censored and accounts for correlation within siblings from the same family.

RESULTS

In the multiple regression model (case status, gender, age, HLA-risk, season, and period of sampling), levels of sTREM-1 were found to be significantly higher in patients (relative change [95%CI], 1.5 [1.1; 2.2],P = 0.02), but after adjustment for multiple testing our result was no longer statistically significant (P _adjust = 0.1). We observed a statistical significant temporal increase in levels of sTREM-1.

CONCLUSION

Our results need to be replicated by independent studies, but our study suggests that the TREM-1 pathway may have a role in T1D pathogenesis.

Neonatal levels of adiponectin, interleukin-10 and interleukin-12 are associated with the risk of developing type 1 diabetes in childhood and adolescence: A nationwide Danish case-control study

BACKGROUND/AIM

An in-depth understanding of the early phase of type 1 diabetes (T1D) pathogenesis is important for targeting primary prevention. We examined if 14 preselected mediators of immune responses differed in neonates that later developed T1D compared to control neonates.

METHODS

The study is a case-control study with a 1:2 matching. The individuals were born between 1981 through 2002. Cases were validated using the National Patient Register and the Danish Childhood Diabetes Register. Interleukin(IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12p70, interferon gamma, tumor necrosis factor alpha, transforming growth factor beta 1 (active form), leptin, adiponectin, c-reactive protein, mannose-binding lectin and soluble triggering receptor expressed on myeloid cells-1 were measured by using a flowmetric Luminex xMAP® technology. We tested two models both including a number of possible confounders. In the first model (model 1) we also adjusted for HLA-DQB1 genotype. A total of 1930 groups of assay-matched cases and controls (4746 individuals) were included in the statistical analyses.

RESULTS

Adiponectin was negatively associated with later risk of T1D in both models (relative change (RC), model 1: 0.95, P=0.046 and model 2: 0.95, P=0.006). IL-10 and IL-12 were both positively associated with T1D risk in the model 2 (RC, 1.19, P=0.006 and 1.07, P=0.02, respectively)-these results were borderline significant in model 1, but showed the same direction as the results from model 2.

CONCLUSIONS

Our results indicate that specific immunological signatures are already present at time of birth in children developing T1D before the age of 18years.

MASP1, THBS1, GPLD1 and ApoA-IV are novel biomarkers associated with prediabetes: the KORA F4 study

AIMS/HYPOTHESIS

Individuals at a high risk of type 2 diabetes demonstrate moderate impairments in glucose metabolism years before the clinical manifestation of type 2 diabetes, a state called 'prediabetes'. In order to elucidate the pathophysiological processes leading to type 2 diabetes, we aimed to identify protein biomarkers associated with prediabetes.

METHODS

In a proteomics study, we used targeted selected reaction monitoring (SRM)-MS to quantify 23 candidate proteins in the plasma of 439 randomly selected men and women aged 47-76 years from the population-based German KORA F4 study. Cross-sectional associations of protein levels with prediabetes (impaired fasting glucose and/or impaired glucose tolerance), type 2 diabetes, glucose levels in both the fasting state and 2 h after an OGTT, fasting insulin and insulin resistance were investigated using regression models adjusted for technical covariables, age, sex, BMI, smoking, alcohol intake, physical inactivity, actual hypertension, triacylglycerol levels, total cholesterol/HDL-cholesterol ratio, and high-sensitivity C-reactive protein levels.

RESULTS

Mannan-binding lectin serine peptidase 1 (MASP1; OR per SD 1.77 [95% CI 1.26, 2.47]), thrombospondin 1 (THBS1; OR per SD 1.55 [95% CI 1.16, 2.07]) and glycosylphosphatidylinositol-specific phospholipase D1 (GPLD1; OR per SD 1.40 [95% CI 1.01, 1.94]) were positively associated with prediabetes, and apolipoprotein A-IV (ApoA-IV; OR per SD 0.75 [95% CI 0.56, 1.00]) was inversely associated with prediabetes. MASP1 was positively associated with fasting and 2 h glucose levels. ApoA-IV was inversely and THBS1 was positively associated with 2 h glucose levels. MASP1 associations with prediabetes and fasting glucose resisted Bonferroni correction. Type 2 diabetes associations were partly influenced by glucose-lowering medication.

CONCLUSIONS/INTERPRETATION

We discovered novel and independent associations of prediabetes and related traits with MASP1, and some evidence for associations with THBS1, GPLD1 and ApoA-IV, suggesting a role for these proteins in the pathophysiology of type 2 diabetes.

Simultaneous pancreas-kidney transplantation in patients with type 1 diabetes reverses elevated MBL levels in association with MBL2 genotype and VEGF expression

AIMS/HYPOTHESIS

High levels of circulating mannan-binding lectin (MBL) are associated with the development of diabetic nephropathy and hyperglycaemia-induced vasculopathy. Here, we aimed to assess the effect of glycaemic control on circulating levels of MBL and the relationship of these levels with vascular damage.

METHODS

We assessed MBL levels and corresponding MBL2 genotype, together with vascular endothelial growth factor (VEGF) levels as a marker of vascular damage, in type 1 diabetes patients with diabetic nephropathy before and after simultaneous pancreas-kidney (SPK) transplantation. We included diabetic nephropathy patients (n = 21), SPK patients (n = 37), healthy controls (n = 19), type 1 diabetes patients (n = 15) and diabetic nephropathy patients receiving only a kidney transplant (n = 15). Fourteen diabetic nephropathy patients were followed up for 12 months after SPK.

RESULTS

We found elevated circulating MBL levels in diabetic nephropathy patients, and a trend towards elevated circulating MBL levels in type 1 diabetes patients, compared with healthy control individuals. MBL levels in SPK patients completely normalised and our data indicate that this predominantly occurs in patients with a polymorphism in the MBL2 gene. By contrast, MBL levels in kidney transplant only patients remained elevated, suggesting that glycaemic control but not reversal of renal failure is associated with decreased MBL levels. In line, levels of glucose and HbA1c, but not creatinine levels and estimated GFR, were correlated with MBL levels. VEGF levels were associated with levels of MBL and HbA1c in an MBL-polymorphism-dependent manner.

CONCLUSIONS/INTERPRETATION

Taken together, circulating MBL levels are associated with diabetic nephropathy and are dependent on glycaemic control, possibly in an MBL2-genotype-dependent manner.