Angiogenic factors and the lectin pathway of complement in women with secondary recurrent pregnancy loss

The poor remodeling of placental spiral arteries seen in preeclampsia is also discussed to contribute to recurrent pregnancy loss (RPL) preceded by abnormal angiogenesis and excessive complement activation. Low levels of Mannose-binding-lectin (MBL), a pattern recognition molecule (PRM) of the lectin pathway, have been found in women with RPL. We propose that pregnancy loss is connected to defective angiogenesis with reperfusion damage in the placenta and decreased levels of PRM in the lectin pathway in women with RPL. In this cohort study, we investigate the angiogenic factors and the lectin complement pathway in early pregnancy and their time-dependent relationship with pregnancy outcomes in 76 women with secondary RPL (sRPL) who have at least four prior pregnancy losses and a live birth. We evaluated levels of Angiopoietin-1 (Ang-1), Angiopoietin-2 (Ang-2), Vascular Endothelial Growth Factor (VEGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and the PRMs, MBL, ficolin-1, -2, -3 and an additional soluble PRM, Pentraxin-3, during the 5th, 6th, and 7th gestational weeks. Our results showed that, compared to live births, pregnancies that ended in loss were associated with elevated VEGF levels and decreased levels of the Ang-2/Ang-1 ratio. Also, increasing levels of ficolin-2 were significantly associated with pregnancy loss, with MBL showing no association. Our research suggests that women with sRPL may have inadequate placentation with impaired angiogenesis in pregnancies ending in a loss.

Maternal carriage of H-Y restricting HLA class II alleles is a negative prognostic factor for women with recurrent pregnancy loss after birth of a boy

Immune system aberrations are suggested to be an important factor in the pathophysiology of unexplained secondary recurrent pregnancy loss (sRPL). The objective was to investigate if the sex ratio of the firstborn child in sRPL patients differs from the background population and whether the sex of the firstborn child has a negative impact on the pregnancy prognosis alone and/or in combination with carriage of male-specific minor histocompatibility (H-Y) restricting HLA class II alleles. From January 2016 to October 2022, 582 patients with unexplained RPL were admitted to the RPL Center of Western Denmark and continuously followed-up. HLA-DRB1 and -DQB1 typing was performed as part of the routine diagnostic work-up. In sRPL patients, a history of a firstborn boy was significantly more frequent than in the Danish background population and was associated with significantly lower odds of a successful reproductive outcome in the first pregnancy after admission compared to a firstborn girl (OR=0.41, 95% CI: 0.20-0.83, p = 0.014). The odds of a successful reproductive outcome were enhanced in patients carrying ≥ 1 H-Y-restricting HLA class II alleles with a first-born girl compared to a firstborn boy (OR=3.33, 95% CI: 1.40-7.88, p = 0.005), while no difference in successful reproductive outcome was seen in sRPL patients not carrying these alleles (OR=1.20, 95% CI: 0.33-4.43, p = 0.781). The sex ratio of children born after RPL was similar to the Danish background population. These findings confirm previous findings and suggests that a harmful immune response triggered by H-Y-antigen exposure during a previous pregnancy in preconditioned women may cause sRPL.

High MBL-expressing genotypes are associated with deterioration in renal function in type 2 diabetes

Introduction

Accumulating evidence support that mannan-binding lectin (MBL) is a promising prognostic biomarker for risk-stratification of diabetic micro- and macrovascular complications. Serum MBL levels are predominately genetically determined and depend on MBL genotype. However, Type 1 diabetes (T1D) is associated with higher MBL serum levels for a given MBL genotype, but it remains unknown if this is also the case for patients with T2D. In this study, we evaluated the impact of MBL genotypes on renal function trajectories serum MBL levels and compared MBL genotypes in newly diagnosed patients with T2D with age- and sex-matched healthy individuals. Furthermore, we evaluated differences in parameters of insulin resistance within MBL genotypes.

Methods

In a cross-sectional study, we included 100 patients who were recently diagnosed with T2D and 100 age- and sex-matched individuals. We measured serum MBL levels, MBL genotype, standard biochemistry, and DEXA, in all participants. A 5-year clinical follow-up study was conducted, followed by 12-year data on follow-up biochemistry and clinical status for the progression to micro- or macroalbuminuria for the patients with T2D.

Results

We found similar serum MBL levels and distribution of MBL genotypes between T2D patients and healthy individuals. The serum MBL level for a given MBL genotype did not differ between the groups neither at study entry nor at 5-year follow-up. We found that plasma creatinine increased more rapidly in patients with T2D with the high MBL expression genotype than with the medium/low MBL expression genotype over the 12-year follow-up period (p = 0.029). Serum MBL levels did not correlate with diabetes duration nor with HbA1c. Interestingly, serum MBL was inversely correlated with body fat percentage in individuals with high MBL expression genotypes both at study entry (p=0.0005) and 5-years follow-up (p=0.002).

Discussion

Contrary to T1D, T2D is not per se associated with increased MBL serum level for a given MBL genotype or with diabetes duration. Serum MBL was inversely correlated with body fat percentage, and T2D patients with the high MBL expression genotype presented with deterioration of renal function.

Plasma level of mannose-binding lectin is associated with the risk of recurrent pregnancy loss but not pregnancy outcome after the diagnosis

STUDY QUESTION

Are low or high plasma mannose-binding lectin (p-MBL) levels associated with recurrent pregnancy loss (RPL) and the reproductive and perinatal outcomes before and after RPL?

SUMMARY ANSWER

The prevalence of low p-MBL levels was significantly higher in RPL patients, while high levels were significantly less prevalent. No association was found between p-MBL level and reproductive and perinatal outcomes before and after RPL.

WHAT IS KNOWN ALREADY

Mannose-binding lectin (MBL) is an important component in the innate immune system. Low p-MBL levels have been associated with RPL, while the correlation with high levels has been poorly studied. Adverse perinatal outcomes are generally more frequent among RPL patients, but reports concerning the association between maternal p-MBL levels and perinatal outcomes, including birth weight (BW) and gestational age (GA), are conflicting.

STUDY DESIGN, SIZE, DURATION

This study was a combined cross-sectional and cohort study of 267 RPL patients admitted to the RPL Center of Western Denmark between January 2016 and March 2020. RPL patients were followed until birth of a liveborn child or until end of follow-up, March 2021. A sample of 185 healthy female blood donors of reproductive age was used as a MBL reference group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All RPL patients had ≥3 consecutive pregnancy losses, a regular menstrual cycle and no known significant chromosomal or uterine malformations. At the first consultation, routine blood samples including p-MBL measurement and detailed obstetrical and perinatal information were collected. p-MBL levels in RPL patients were compared to the MBL reference group. A logistic regression analysis adjusted for relevant confounders assessed the association between low p-MBL levels and an unsuccessful reproductive outcome in RPL patients in first pregnancy after admission. Perinatal outcomes before and after RPL were compared between RPL subgroups according to low (≤500 µg/l), intermediate (501–3000 µg/l) and high (>3000 µg/l) p-MBL levels.

MAIN RESULTS AND THE ROLE OF CHANCE

Significantly more RPL patients had low p-MBL levels (prevalence proportion ratio (PPR): 1.79, 95% CI: 1.34–2.38) and fewer had high p-MBL levels (PPR: 0.56, 95% CI: 0.40–0.79) compared to the reference group, while the prevalence of intermediate p-MBL level was not different between the groups (PPR: 0.86, 95% CI: 0.69–1.08). In the prospective study, low p-MBL level was not a significant risk factor for a pregnancy loss in the first pregnancy after admission after adjustment for age, BMI and smoking. Neither before nor after the RPL diagnosis were maternal p-MBL levels significantly associated with BW or GA.

LIMITATIONS, REASONS FOR CAUTION

Only 161 (60.3%) patients had given birth after RPL during the follow-up period, which limited the possibility to detect clear associations between p-MBL levels and perinatal outcomes after RPL.

WIDER IMPLICATIONS OF THE FINDINGS

In agreement with several previous studies, low p-MBL levels are strongly associated with RPL, while this study for the first time documents that high levels may play a protective role, which suggests a causal relationship. We suggest that larger prospective studies evaluate the association between p-MBL levels and RPL prognosis.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received. We acknowledge the Department of Obstetrics and Gynaecology at Aalborg University Hospital for financial support. U.S.K. has reported personal fees from Merck, consulting fees from IBSA Nordic, and a grant from Gedeon Richter, Merck and IBSA Nordic outside of the submitted work.

TRIAL REGISTRATION NUMBER

ID from clinicaltrials.gov is NCT04017754.

HLA-DRB1 polymorphism in recurrent pregnancy loss: New evidence for an association to HLA-DRB1*07

Many cases of recurrent pregnancy loss (RPL) defined as ≥3 consecutive pregnancy losses are suggested to be caused by an aberrant maternal immune response against the fetus or trophoblast. Human leukocyte antigen (HLA)-DRB1 and -DQB1 polymorphisms are associated with most autoimmune disorders and studies of HLA-DBB1 polymorphism in RPL patients are thus relevant. In previous studies, the HLA-DRB1*03 allele was found with increased prevalence in RPL patients. We wanted to clarify whether HLA-DRB1 alleles indeed were associated with RPL among women of Caucasian descent. A total of 1078 women with unexplained RPL and 2066 bone marrow donors were HLA-DRB1-typed and subsets were also HLA-DQB1 typed. All patients were initially HLA-DRB1-typed by DNA-based low-resolution techniques and subsets of patients and all controls were typed by high-resolution techniques. Among patients, the HLA-DRB1*07 allele frequency was significantly increased compared with controls; OR 1.29 (95 % CI 1.09-1.52), p < 0.0025; after correction for multiple comparisons pc = 0.031. The HLA-DRB1*07/*07 genotype was highly increased in patients with RPL compared with controls: OR 2.27 (1.31-3.93), p = 0.0027. The frequency of the HLA-DRB1*07 phenotype in RPL patients had increased significantly (p = 0.002) in three studies from our group published 1994-2021. The allele frequency of HLA-DRB1*03 was not increased in RPL patients compared with controls; OR 0.96 (0.83-1.12). In conclusion, the previous association between HLA-DRB1*03 and RPL could not be confirmed in our study whereas an association to HLA-DRB1*07 was detected for the first time. Since the latter association is a new finding, it should be confirmed in future studies.

AB0202 GENETIC SUSCEPTIBILITY AND PHENOTYPE OF RHEUMATOID ARTHRITIS IN DANISH AND TURKISH PATIENTS

Background:

Previous studies indicate that genetic susceptibility and phenotype of rheumatoid arthritis (RA) differ between the populations.

Objectives:

To compare the clinical, serologic expression and the presence of shared epitopes (SE) of incident RA in two different populations, one from Northern and the other from Southern Europe.

Methods:

Data on incident RA patients fulfilling EULAR/ACR 2010 classifications criteria for RA were collected at Rheumatology Departments in Denmark and Turkey in 2015-2016. Patients were assessed using the same standardized protocol in both populations. SE carrier status were assigned, according to the du Montcel classification based, into six allele groups:S1, S2,S3D,S3PandX, where S2 and S3P are RA risk-enhancing alleles and S1 and S3D are RA protective alleles of the shared epitope(1).

Results:

109 incident RA patients from Denmark and 114 incident RA patients from Turkey were enrolled. Genetic data were available from 87% of the patients.

Table 1.

Characteristics of incident rheumatoid arthritis patients in Denmark and Turkey

Danish patientsn=109Turkish patientsn=114P-valueAge at diagnosis, years60 (49-69)52 (43-64)0.003Female, %64740.12Symptom duration, months7 (4-21)6 (2-22)0.6Smoking status Never smoker, %43440.98 Former smoker, %28310.68 Current smoker, %29250.54VAS pain (0-100 mm)45 (28-66)60 (41-72)0.01VAS fatigue (0-100 mm)51 (29-69)50 (20-70)0.32VAS global, patient (0-100 mm)60 (31-80)60 (41-73)0.77Swollen joint count (0-28)7 (4-11)3 (1-6)<0.00001Tender joint count (0-28)7 (3-11)5 (2-8)0.04HAQ score (0-3)0.75 (0.34-1.25)1.0 (0.25-1.75)0.02DAS284.7 (4.1-5.5)4.3 (3.3-5.2)0.01CRP, mg/l7 (3.0-18.5)8 (3.1-22.6)0.54IgM RF positive, %70660.58ACPA positive, %63750.1

Medians (interquartile range) for continuous variables

VAS – Visual Analog Scale, HAQ - Health Assessment Questionnaire, DAS28 - Disease Activity Score 28 joints, CRP – C-reactive protein, RF – Rheumatoid Factor, ACPA - Anti-Citrullinated Protein Antibodies.

Table 2.

Shared epitope allele carrier frequencies.

AlleleDanish patientsn=98Turkish patientsn=95P-valueS1, % (n)19 (37)22 (42)0,43S2, % (n)26 (51)8 (16)<0,00001S3D, % (n)6 (12)21 (39)0,000029S3P, % (n)27 (52)29 (56)0,52X, % (n)22 (44)19 (37)0,47

We found no associations between the risk-enhancing alleles and the presence of IgM rheumatoid factor or ACPA.

Conclusion:

The Turkish patients were younger and had lower disease activity than Danish at the time of diagnosis. Our study found an enhanced genetic susceptibility to RA in Danish compared to Turkish patients with a higher prevalence of risk-enhancing RA alleles and a lower prevalence of protective alleles.

References:

[1]Tezenas du Montcel S, Michou L, Petit-Teixeira E, Osorio J, Lemaire I, Lasbleiz S, et al. New classification of HLA–DRB1 alleles supports the shared epitope hypothesis of rheumatoid arthritis susceptibility.Arthritis Rheum2005; 52: 1063–8.

Disclosure of Interests:

None declared

Plasma levels of MASP-1, MASP-3 and MAp44 in patients with type 2 diabetes: influence of glycaemic control, body composition and polymorphisms in the MASP1 gene

Mounting evidence indicates that adverse activation of the complement system plays a role in the development of diabetic vascular complications. Plasma levels of the complement proteins mannan-binding lectin (MBL) and its associated serine proteases (MASP-1 and MASP-2) are elevated in diabetes. We hypothesized that single nucleotide polymorphisms (SNPs) in the MASP1 gene may contribute to altered plasma levels of the belonging gene products; MASP-1, MASP-3 and mannan-binding lectin-associated protein of 44 kDa (MAp44) in patients with type 2 diabetes. To investigate this, we compared plasma levels of MASP-1, MASP-3 and MAp44 in 100 patients with type 2 diabetes and 100 sex- and age-matched controls. Ten carefully selected SNPs were analysed using TaqMan^® genotyping assay. Additionally, we included a streptozotocin-induced diabetes mouse model to directly examine the effect of inducing diabetes on MASP-1 levels. MASP-1 levels were significantly higher among patients with type 2 diabetes compared with healthy controls (P = 0·017). Five SNPs (rs874603, rs72549254, rs3774275, rs67143992, rs850312) in the MASP1 gene were associated with plasma levels of MASP-1, MASP-3 and MAp44. In the diabetes mouse model, diabetic mice had significantly higher MASP-1 levels than control mice (P = 0·003). In conclusion, MASP-1 levels were higher among patients with type 2 diabetes and diabetic mice. The mechanism behind this increase remains elusive.

Presence of HLA-DR Molecules and HLA-DRB1 mRNA in Circulating CD4(+) T Cells

The human major histocompatibility complex class II isotype HLA-DR is currently used as an activation marker for T cells. However, whether an endogenous protein expression or a molecular acquisition accounts for the presence of HLA-DR on T cells remains undetermined and still controversial. To further characterize this phenomenon, we compared several aspects of the presence of the HLA-DR protein to the presence of associated mRNA (HLA-DRB1), focusing on human T cells from peripheral blood of healthy individuals. Using a flow cytometric approach, we determined that the HLA-DR observed on CD4(+) T cells was almost exclusively cell surface-associated, while for autologous CD19(+) B cells, the protein could be located in the plasma membrane as well as in the cytoplasm. Moreover, negligible expression levels of HLA-DRB1 were found in CD4(+) T cells, using an HLA-DRB1 allele-specific qPCR assay. Finally, the presence of HLA-DR was not confined to activated CD4(+) and CD8(+) T cells, as evaluated by the co-expression of CD25. The functional role of the HLA-DR molecule on T cells remains enigmatic; however, this study presents evidence of fundamental differences for the presence of HLA-DR on T cells from HLA-DR in the context of antigen-presenting cells, which is a well-known phenomenon. Although an inducible endogenous protein expression cannot be excluded for the T cells, our findings suggest that a re-evaluation of the HLA-DR as a T cells activation marker is warranted.

Prognosis by C-reactive protein and matrix metalloproteinase-9 levels in stable coronary heart disease during 15 years of follow-up

BACKGROUND AND AIM

Elevated CRP and matrix metalloproteinase-9 associate with increased risk of cardiovascular events, possibly because these plasma proteins mark vulnerable atherosclerotic plaques. We tested the hypothesis that levels of C-reactive protein (CRP) and matrix metalloproteinase-9 associate with prognosis in patients with stable coronary heart disease.

METHODS AND RESULTS

We measured baseline plasma CRP and matrix metalloproteinase-9 in 1090 patients with stable coronary heart disease and as the primary composite endpoint detected incident unstable angina, myocardial infarction and any death during 15 years of follow-up. CRP above versus below the median of 3.0 mg/L was associated with an increased cumulative incidence of unstable angina, myocardial infarction and any death combined (log-rank p < 0.0001). CRP above versus below the median had a corresponding hazard ratio of 1.5(95% CI, 1.3-1.8) after age adjustment, of 1.4(1.2-1.6) after multifactorial adjustment, and of 1.4(1.2-1.6) after multifactorial adjustment including degree of coronary disease. In contrast, matrix metalloproteinase-9 above versus below the median was not associated with risk of unstable angina, myocardial infarction and death.

CONCLUSIONS

Elevated CRP, but not elevated matrix metalloproteinase-9, associates with increased risk of unstable angina, myocardial infarction and death in patients with stable coronary heart disease.

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) genotypes in colorectal cancer

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) are key factors of the lectin pathway of complement activation. Polymorphisms of the MBL2 and MASP-2 genes affect serum levels of MBL and MASP-2. In patients with colorectal cancer (CRC), the MBL and MASP-2 serum levels are increased and high MASP-2 levels are associated with recurrence and poor survival, whereas low MBL levels predict post-operative pneumonia. It is not known whether these associations are genetically based. In this study, the MBL and MASP-2 genotypes are investigated in 593 patients with CRC and 348 healthy controls. The potential association between genetic profile and infections, recurrence and survival is evaluated. Four single-nucleotide polymorphisms (SNPs) of MBL2 were analysed using TaqMan assays, with characterization of MBL2 wildtype A, variants B, C and D and alleles H/L, Y/X and P/Q. The SNP D120G for MASP-2 was determined. Serum levels of MBL and MASP-2 were measured. The MBL2 and MASP-2 genotype distribution was similar among patients with CRC and healthy controls and MBL2 genotype significantly associated with MBL concentration in serum (P<0.0001). No significant association between MBL2/MASP-2 genotype and post-operative infectious complications (P=0.33 and 0.22), recurrent cancer or survival (P=0.74 and P=0.61 respectively) was found. Thus, the increased serum levels of MBL and MASP-2 found in patients with CRC are not explained for by genetic profiles. In contrast to what has been demonstrated for serum levels of MBL and MASP-2, the genotypes do not predict disease course of the CRC patients.

Mannose-binding lectin genotype and phenotype in patients with type 2 diabetes and myocardial infarction: a report from the DIGAMI 2 trial

OBJECTIVE

The present study characterizes mannose-binding lectin (MBL), an activator of the complement system and thereby important for inflammatory activation, in patients with diabetes and myocardial infarction.

RESEARCH DESIGN AND METHODS

Serum (S)-MBL was determined at hospital admission in 387 patients with type 2 diabetes (median age 70 years; 68% male) with myocardial infarction, and genotyping was performed in 287 patients. Cardiovascular events (cardiovascular mortality and nonfatal myocardial infarction or stroke) were recorded during 2.5 years.

RESULTS

Median S-MBL was 1,212 μg/l (interquartile range [IQR] 346-2,681 μg/l). Of the subjects, 54% in the geno- and phenotype subgroup had a high-coding MBL genotype (median S-MBL=2,658 μg/l [IQR 1,715-3,829]) and 46% a low-coding MBL genotype (373 μg/l [100-765]). S-MBL did not correlate with age, BMI, creatinine clearance, glucose, or A1C. Cardiovascular events occurred in 136 (35%) patients. S-MBL did not predict events in univariable analyses (hazard ratio 0.93 [95% CI 0.85-1.01]; P=0.09). In unadjusted analyses, the risk of events was lower in patients with a high genotype and S-MBL above the median for their genotype (0.49 [0.26-0.92]; P=0.026) than for patients with a low genotype and S-MBL below the median for their genotype. The prediction capacity of the geno- and phenotype model was of borderline significance in adjusted Cox regression.

CONCLUSIONS

Patients with type 2 diabetes and myocardial infarction have MBL genotypes that are similar to those known in the general population. The combination of a low-coding MBL genotype with a low S-MBL appears to be prognostically unfavorable, but the association is blunted by traditional risk markers.

Hereditary thrombophilia and recurrent pregnancy loss: a retrospective cohort study of pregnancy outcome and obstetric complications

BACKGROUND

The association among hereditary thrombophilia, recurrent pregnancy loss (RPL) and obstetric complications is yet uncertain. The objective of the study was to assess the prognostic value of the factor V Leiden (FVL) and prothrombin (PT) mutations for the subsequent chance of live birth for women with RPL.

METHODS

Pregnancy outcome was recorded in a retrospective cohort of 363 women with a minimum of three consecutive pregnancy losses (early miscarriage, late miscarriage or stillbirth/neonatal death) who were not treated with anticoagulation therapy.

RESULTS

Of the 363 women, 29 were FVL-mutation carriers and 6 were PT-mutation carriers. The unadjusted live birth rate was 45.7% in FVL/PT carriers versus 63.4% in FVL/PT non-carriers, P = 0.04. The adjusted odds ratio for live birth in FVL/PT carriers was 0.48 (95% CI = 0.23-1.01), P = 0.05. Among the obstetric complications, only excessive bleeding was found to be associated with FVL/PT mutations.

CONCLUSIONS

In the unadjusted analysis, FVL and PT mutations have a negative prognostic impact on the live birth rate in women with RPL; however, when adjusting for significant covariates, the results no longer reach statistical significance. Strong conclusions on the association between obstetric complications and hereditary thrombophilia cannot be drawn from this study. Whether anticoagulation therapy would improve the prognosis in women with RPL and FVL/PT mutations remains to be documented in large randomized controlled trials.

H-Y antibody titers are increased in unexplained secondary recurrent miscarriage patients and associated with low male : female ratio in subsequent live births

BACKGROUND

The birth of a boy is significantly more common than a girl prior to secondary recurrent miscarriage (SRM) and is associated with a poorer chance of a subsequent live birth. Children born after SRM are more likely to be girls. High-titer antisera specific for male antigens (H-Y) have been shown to arrest development of male bovine embryos efficiently. We consequently questioned the role of H-Y antibodies in women with SRM.

METHODS

Serum samples from patients with unexplained SRM (n = 84), unexplained primary recurrent miscarriage (PRM) (n = 12) and healthy women (n = 37) were obtained. The samples were taken during pregnancy (gestational weeks 4-5) for 77 (80%) of the patients. Enzyme-linked immunosorbent assay was used to detect immunoglobulin G antibodies that specifically recognized any of the five recombinant H-Y proteins (EIF1AY, RPS4Y1, ZFY, DDX3Y and UTY) and their H-X homologs.

RESULTS

H-Y-specific antibodies were more frequent in SRM patients (46%) compared with female controls (19%, P = 0.004) and PRM patients (8%, P = 0.01). The presence of H-Y antibodies in early pregnancy was associated with a low male: female birth ratio among the subsequent live births, as only 12% of children born to H-Y antibody-positive patients were boys compared with 44% boys born to H-Y antibody negative patients (P = 0.03).

CONCLUSIONS

The high frequency of H-Y antibody-positive SRM patients and the association between the presence of these antibodies in early pregnancy and the low number of male offspring, suggest that maternal immune responses against H-Y antigens can cause pregnancy losses. Further exploring these mechanisms may increase our understanding of unexplained SRM.

KEL*02 alleles with alterations in and around exon 8 in individuals with apparent KEL:1,-2 phenotypes

BACKGROUND AND OBJECTIVES

Antibodies to antigens in the Kell blood group system, especially anti-KEL1, are involved in both haemolytic disease of the newborn and foetus and haemolytic transfusion reactions. Correct typing results are important and discrepancies between serologic and genetic typing must be resolved. Here, we describe the investigation of three healthy individuals who were initially phenotyped as KEL:1,-2.

MATERIALS AND METHODS

Antigen typing was performed by standard serological techniques and by flow cytometric analysis. The KEL*01/02 polymorphism was tested by an allele-discrimination TaqMan assay as well as by PCR with allele-specific primers and PCR-RFLP. DNA sequencing of the KEL coding region was also performed.

RESULTS

Two KEL*02N alleles with mutated splice sites around exon 8 were identified: intron 7 -1g>c (novel) and intron 8 +1g>t (previously reported in one case of K(0)). In the third sample, a missense mutation in exon 8, 787G>A (novel) predicting Gly263Arg, was detected on a KEL*02 allele and associated with dramatically weakened KEL2 antigen expression.

CONCLUSION

Resolution of discrepant phenotype/genotype results identified silencing mutations in or around exon 8. A combination of molecular and serologic methods has the potential to improve the quality of test results and was required to ensure both the accurate KEL2 antigen status and KEL*01 zygosity of these individuals.

Effects of infectious mononucleosis and HLA-DRB1*15 in multiple sclerosis

BACKGROUND

Both human leukocyte antigen (HLA)-DRB1*15 and Epstein-Barr virus infection presenting as infectious mononucleosis (IM) are recognized as risk factors for multiple sclerosis (MS). However, their combined effect and possible interaction on MS risk is not known.

OBJECTIVE

To assess the association between HLA-DRB1*15 and risk of MS in persons with and without IM.

METHODS

We compared the prevalence of DRB1*15 in MS patients with (n = 76) and without (n = 1,836) IM with the corresponding distributions in blood donors with (n = 62) and without (n = 484) IM histories. This allowed us to estimate the relative risk of MS associated with DRB1*15 in the presence and absence, respectively, of previous IM. We then estimated the interaction between DRB1*15 and IM as the ratio of the two individual odds ratios.

RESULTS

In IM-naïve individuals, DRB1*15 carried a 2.4-fold (95% confidence interval [CI], 2.0-3.0) increased MS risk. In contrast, among persons with IM history, DRB1*15 was associated with a 7.0-fold (95% CI, 3.3-15.4) increased MS risk. Thus, the MS risk conferred by HLA-DRB1*15 was 2.9 (95% CI, 1.3-6.5)-fold stronger in the presence than in the absence of IM. Combined with previous results, this result indicates that DRB1*15-positive persons with a history of IM may be at a 10.0-fold (95% CI, 6.0-17.9) increased risk of MS compared with persons who are DRB1*15 and IM-naïve.

CONCLUSION

DRB1*15 and IM may act in synergy causing MS.

Association between Mannose-Binding Lectin and Vascular Complications in Type 1 Diabetes

Complement activation and inflammation have been suggested in the pathogenesis of diabetic vascular lesions. We investigated serum mannose‐binding lectin (MBL) levels and polymorphisms in the MBL gene in type 1 diabetic (T1DM) patients with and without diabetic nephropathy and associated macrovascular complications. Polymorphisms in the MBL gene and serum MBL levels were determined in 199 T1DM patients with overt nephropathy and 192 T1DM patients with persistent normoalbuminuria matched for age, sex and duration of diabetes as well as in 100 healthy control subjects. The frequencies of high and low expression MBL genotypes were similar in patients with T1DM and healthy controls. High MBL genotypes were significantly more frequent in diabetic patients with nephropathy than in the normoalbuminuric group, and the risk of having nephropathy, given a high MBL genotype, assessed by odds ratio was 1.52 (1.02–2.27), P = 0.04. Median serum MBL concentrations were significantly higher in patients with nephropathy than in patients with normoalbuminuria [2306 µg/l (IQR 753–4867 µg/l) versus 1491 µg/l (IQR 577–2944), P = 0.0003], and even when comparing patients with identical genotypes, serum MBL levels were higher in the nephropathy group than in the normoalbuminuric group. Patients with a history of cardiovascular disease had significantly elevated MBL levels independently of nephropathy status [3178 µg/l (IQR 636–5231 µg/l) versus 1741 µg/l (IQR 656–3149 µg/l), P = 0.02]. The differences in MBL levels between patients with and without vascular complications were driven primarily by pronounced differences among carriers of high MBL genotypes (P < 0.0001). Our findings suggest that MBL may be involved in the pathogenesis of microvascular and macrovascular complications in type 1 diabetes and that determination of MBL status might be used to identify patients at increased risk of developing these complications.

Mannan-binding lectin MBL2 gene polymorphism in chronic hepatitis C: association with the severity of liver fibrosis and response to interferon therapy

Hepatitis C virus (HCV) is a major cause of hepatic disease and of liver transplantation worldwide. Mannan-binding lectin (MBL), encoded by the MBL2 gene, can have an important role as an opsonin and complement activating molecule in HCV persistence and liver injury. We assessed the MBL2 polymorphism in 102 Euro-Brazilian patients with moderate and severe chronic hepatitis C, paired for gender and age with 102 HCV seronegative healthy individuals. Six common single nucleotide polymorphisms in the MBL2 gene, three in the promoter (H/L, X/Y and P/Q) and three in exon 1 (A, the wild-type, and B, C or D also known as O) were evaluated using real-time polymerase chain reaction with fluorescent hybridization probes. The concentration of MBL in plasma was measured by enzyme-linked immunosorbent assay. The frequency of the YA/YO genotype was significantly higher in the HCV patients compared with the controls (P = 0.022). On the other hand, the genotypes associated with low levels of MBL (XA/XA, XA/YO and YO/YO) were decreased significantly in the patients with severe fibrosis (stage F4), when compared with the patients with moderate fibrosis (stage F2) (P = 0.04) and to the control group (P = 0.011). Furthermore, MBL2 genotypes containing X or O mutations were found to be associated with non-responsiveness to pginterferon and ribavirin treatment (P = 0.023). MBL2 polymorphisms may therefore be associated not only with the development of chronic hepatitis C, but also with its clinical evolution and response to treatment.

Deficiency of mannan-binding lectin associated serine protease-2 due to missense polymorphisms

Mannan-binding lectin (MBL) and ficolins distinguish between self, non-self and altered-self by recognizing patterns of ligands on the surface of microorganisms or aberrant cells. When this happens MBL-associated serine protease-2 (MASP-2) is activated and cleaves complement factors to start inflammatory actions. We examined human populations for MASP-2 levels, MASP-2 function and for the presence of mutations in coding exons of MASP2. The MASP-2 levels were lowest in Africans from Zambia (median, 196 ng/ml) followed by Hong Kong Chinese (262 ng/ml), Brazilian Amerindians (290 ng/ml) and Danish Caucasians (416 ng/ml). In the Chinese population, we uncovered a novel four amino-acid tandem duplication (p.156_159dupCHNH) associated with low levels of MASP-2. The frequency of this mutation as well as the SNPs p.R99C, p.R118C, p.D120G, p.P126L and p.V377A were analyzed. The p.156_159dupCHNH was only found in Chinese (gene frequency 0.26%) and p.D120G was found only in Caucasians and Inuits from West-Greenland. The p.P126L and p.R99Q were present in Africans and Amerindians only, except for p.R99Q in one Caucasian. The MASP-2 levels were reduced in individuals with p.V377A present. The MASP-2 present in individuals homozygous for p.377A or p.99Q had a normal enzyme activity whereas MASP-2 in individuals homozygous for p.126L was non-functional.

The mannan-binding lectin pathway and lung disease in cystic fibrosis--disfunction of mannan-binding lectin-associated serine protease 2 (MASP-2) may be a major modifier

The lectin pathway of complement activation is initiated by mannan-binding lectin (MBL) or the ficolins through the common MBL-associated serine protease-2 (MASP-2). Deficiency of MBL has been associated with poorer outcome in cystic fibrosis (CF). We investigated the MBL pathway further by analysis of the MASP-2 deficiency mutation (D105G) as well as MBL-2 genotypes. Concentrations and genotypes of MASP-2 and MBL in 109 CF patients were correlated to lung function and chronic infections. We describe the first CF patient homozygous for the mutation, a girl with extremely severe lung disease with no other precipitating factors. We suspect total MASP-2 dysfunction to be a major modifier of CF lung disease. However, heterozygosity for the D105G mutation of MASP-2 had no correlation to MBL pathway function or poor lung function. Lung function was higher in the MBL deficiency determining genotypes (XA/YO+YO/YO) than in the other genotypes.

MBL2 polymorphism and risk of severe infections in multiple myeloma patients receiving high-dose melphalan and autologous stem cell transplantation

Severe infections related to treatment are common in patients with multiple myeloma (MM). Genetic polymorphisms of the immune system may influence the risk of infections. Mannan-binding lectin (MBL) is part of the innate immune system, and individuals homozygous for wild-type MBL encoding gene (MBL2) have a well-functioning MBL pathway of complement activation, in contrast to individuals carrying one or two variant alleles. We evaluated 113 courses of high-dose melphalan and autologous stem cell transplantation (ASCT) in patients with MM. Patients homozygous for wild-type MBL2 had a significantly reduced risk of septicaemia during the ASCT procedure compared with patients carrying variant MBL2: Odds Ratio (OR) 0.19 (95% CI: 0.04-0.77), (P=0.02) in multivariate analysis. The risk of Common Toxicity Criteria grade 3-4 infections in general was not affected by wild-type MBL2: OR 1.20 (95% CI: 0.52-2.78), (P=0.67). The findings indicate that MBL to some extent protects against the most severe infections during ASCT.

Hormonal regulation of mannan-binding lectin synthesis in hepatocytes

Activation of the complement system via the plasma protein mannan-binding lectin (MBL) provides a first line of defence against infections. The plasma level of MBL is, in part, determined genetically, but may also be influenced by different hormones in vivo. Here we study the hormonal regulation of MBL synthesis from the human hepatocyte cell line HuH-7. Cells were exposed to medium with growth hormone (GH), hydrocortisone, insulin-like growth factor (IGF)-1, insulin, interleukin (IL)-6 or thyroid hormones (T3 or T4). After 3 days the concentration of MBL in the culture supernatants was determined and the amount of mRNA for MBL was measured, relative to mRNA for beta2 microglobulin. GH, IL-6, T3 and T4 significantly increased MBL synthesis in a dose-dependent manner, while hydrocortisone, insulin and IGF-1 had no effect. T3 caused a fourfold increase at 1 nM of T3 (P < 0.001) and at 100 nM of T3 the production was increased more than eightfold. The effect of T4 was less potent, reaching an eightfold increase at 1 microM of T4 (P < 0.001). GH augmented the production of MBL threefold at a concentration of 100 ng/ml (P = 0.018) with no further effect up to 10 microg/ml, whereas IL-6 caused only a very weak increase in MBL production. MBL mRNA levels were stable during the first 24 h of T3 stimulation but increased significantly between 24 and 48 h. The results suggest that MBL synthesis in humans may be increased by thyroid hormone and GH, whereas it does not exhibit a classical IL-6-dependent response.

Survival trends among Danish patients undergoing coronary angiography for known or suspected ischaemic heart disease: a population based follow up study, 1992-2000

OBJECTIVE

To determine, from population based clinical data, changes in the survival of Danish patients examined by coronary angiography for known or suspected ischaemic heart disease (IHD) during the 1990s.

DESIGN

Follow up study.

SETTING

The departments of cardiology at Rigshospitalet, Copenhagen University Hospital, and Skejby Hospital, Aarhus University Hospital, Denmark.

PATIENTS

Patients with IHD (n = 7021) who underwent first time coronary angiography in 1992, 1996, or 2000.

MAIN OUTCOMES MEASURES

Three year survival was compared between cohorts and with that of the general population. Cox proportional hazards regression was used to estimate mortality ratios adjusted for differences in patient characteristics.

RESULTS

Survival improved substantially--for example, adjusted mortality ratio was 0.69 (95% confidence interval (CI) 0.55 to 0.87) when comparing patients from 2000 with patients from 1992. The absolute standardised survival rates after three years of follow up were 87.1% (95% CI 85.4% to 88.8%), 89.9% (95% CI 88.5% to 91.3%), and 91.2% (95% CI 90.3% to 92.1%) among patients examined in 1992, 1996, and 2000, respectively. The improvement was not explained by the improvement in overall survival in the general population during the study period.

CONCLUSIONS

The survival of Danish patients with known or suspected IHD appears to have improved substantially during the 1990s.

Mannan-binding lectin and RSV lower respiratory tract infection leading to hospitalization in children: a case-control study from Soweto, South Africa

Respiratory syncytial virus (RSV) is the most important microbiological cause of lower respiratory tract infection (LRTI) in infants. Mannan-binding lectin (MBL) is believed to play a major protective role in the vulnerable period in infancy where the maternal antibodies have been catabolized, and the adaptive immune system has not yet matured. Mutations in the promoter region and in exon 1 of the gene-encoding MBL result in low serum levels of MBL. MBL deficiency is the most common immunodeficiency on the African Continent with frequencies of the variant alleles up to 0.29. We investigated whether MBL deficiency has an impact on the hospitalization for LRTI caused by RSV in infants from Soweto, South Africa. The cases were ethnic black Africans identified through surveillance for RSV-LRTI at Chris Hani Baragwanath Hospital, Soweto, and the controls were sampled from four immunization clinics in the area. Fifty-five cases and 113 age- and sex-matched controls were identified. Seventy-six per cent were under 6 months of age, and 42% (n = 23) were under 3 months of age. No association was found between low levels of MBL or carriage of variant alleles and LRTI caused by RSV, odds ratio (OR) 1.00 (CI 0.99-1.03) and OR 1.24 (0.73-2.12). We did not find support for the hypothesis that MBL deficiency leads to the hospitalization for LRTI caused by RSV.

A study of HLA-DR and -DQ alleles in 588 patients and 562 controls confirms that HLA-DRB1*03 is associated with recurrent miscarriage

BACKGROUND

Previous studies have demonstrated an association between recurrent miscarriage (RM) and the maternal HLA-DRB1*01 and -DRB1*03 alleles. The primary aim of the present study was to confirm or reject the hypothesis about this association in a larger case-control study.

METHODS

HLA-DRB1, -DQA1 and -DQB1 genotyping was carried out by the PCR-sequence-specific primer (SSP) method in 354 patients with unexplained RM and 202 fertile controls. These results were combined with the results from a previous study of 234 RM patients and 360 controls.

RESULTS

The prevalence of patients with HLA-DRB1*03 was significantly increased compared with controls [odds ratio (OR) = 1.4, 95% confidence interval (CI) = 1.1-1.9, P = 0.01, P corrected for the number of comparisons (Pc) = 0.02]. In patients with at least four previous miscarriages or with secondary RM, the association became even stronger (OR = 1.8, 95% CI = 1.3-2.5, P = 0.0005, Pc = 0.004; and OR = 1.8, 95% CI = 1.3-2.5, P = 0.0007, Pc = 0.006, respectively). There was no significant difference between patients and controls with regard to HLA-DRB1*01.

CONCLUSION

The HLA-DRB1*03 allele or genes in linkage disequilibrium with it confer susceptibility to RM.

Rapid genotyping of MBL2 gene mutations using real-time PCR with fluorescent hybridisation probes

In this study, we describe a real-time polymerase chain reaction (PCR) for genotyping all known polymorphisms of the human mannose-binding lectin 2 (MBL2) gene. These comprised two variations in the 5' regulatory region at positions -550 (H/L) and -221 (X/Y), one in the 5' untranslated sequence at position +4 (P/Q) and three structural mutations within exon 1 at codons 52, 54, and 57, also known as the D, B and C variants, respectively. Three reactions with two different conditions were sufficient to genotype one individual unambiguously. The three mutations in exon 1 were detected in one capillary using a sensor probe covering the three mutations, whereas amplification of the variants located upstream of the coding sequence was performed in only two reactions. Single colour detection was used for detection of the (H/L) polymorphism and multiplexing by dual colour probes was used for simultaneous genotyping of (X/Y) and (P/Q). The reliability of the system was evaluated by comparison with a conventional PCR method with sequence-specific primers (PCR-SSP). For this study, 100 individuals of Danish and 30 of African descent were analysed, and the genotypes obtained were concordant in all cases. This new method is rapid and provides reliable results without ambiguities.

An assay for the mannan-binding lectin pathway of complement activation

The mannan-binding lectin (MBL) pathway of complement activation has been established as the third pathway of complement activation. MBL is a carbohydrate-binding serum protein, which circulates in complex with serine proteases known as mannan-binding lectin associated serine proteases (MASPs). When bound to microorganisms, the MBL complex activates the complement components C4 and C2, thereby generating the C3 convertase and leading to opsonisation by the deposition of C4b and C3b fragments. This C4/C2 cleaving activity is shared with the C1 complex of the classical pathway of complement activation. Therefore, in a generally applicable complement activation assay specific for the MBL pathway, the activity of the classical pathway must be inhibited. This can be accomplished by exploiting the finding that high ionic strength buffers inhibit the binding of C1q to immune complexes and disrupt the C1 complex, whereas the carbohydrate-binding activity of MBL and the integrity of the MBL complex is maintained under hypertonic conditions. In the assay described here, the specific C4b-depositing capacity of the MBL pathway was determined by incubating serum diluted in buffer containing 1 M NaCl in mannan-coated microtiter wells before the addition of purified C4. The interassay coefficient of variation in the ELISA version was 7.3%. As expected no activity was found in MBL-deficient serum. When 100 normal serum samples were analysed we found that the MBL level correlated with the amount of C4b deposited on the mannan-coated surface. However, we also found a threefold variation in C4b-depositing capacity between individuals with similar MBL concentrations. The assay permits for the determination of MBL complex activity in serum and plasma samples and may thus be used to evaluate the clinical implications of complement activation via this pathway.

Angiotensinogen mutations and risk for ischemic heart disease, myocardial infarction, and ischemic cerebrovascular disease. Six case-control studies from the Copenhagen City Heart Study

BACKGROUND

The M235T and T174M angiotensinogen mutations have been linked to increased risk for ischemic heart and cerebrovascular disease.

OBJECTIVE

To determine whether angiotensinogen mutations are associated with ischemic heart disease, myocardial infarction, and ischemic cerebrovascular disease.

DESIGN

Six case-control studies from the Copenhagen City Heart Study.

SETTING

Copenhagen, Denmark.

PARTICIPANTS

Participants in the Copenhagen City Heart Study and patients from the same hospital with ischemic heart disease (n = 866 and n = 943, respectively), myocardial infarction (n = 519 and n = 493, respectively), or ischemic cerebrovascular disease (n = 489 and n = 434, respectively) and 7975 controls without these conditions.

MEASUREMENTS

Genotypes for the M235T and T174M angiotensinogen mutations were compared between controls and Copenhagen City Heart Study participants with ischemic heart disease, myocardial infarction, and cerebrovascular disease (studies 1a, 1b, and 1c) and patients from Copenhagen University Hospital with the same conditions (studies 2a, 2b, and 2c).

RESULTS

Relative allele frequencies of 235T and 174M in the general population were 0.41 and 0.12, respectively. Genotype was not associated with increased risk for ischemic heart or ischemic cerebrovascular disease in studies of either mutation alone or combined in women or men. Among compound heterozygotes (235MT /174TM ), women in case-control study 2a had decreased risk for ischemic heart disease in age-adjusted analysis; however, this decreased risk was not seen in multifactorial-adjusted or matched analyses, in men, or in case-control study 1a. Among double homozygotes (235TT /174MM ), women in case-control study 2b had increased risk for myocardial infarction in matched analysis; however, this increased risk was not seen in age- or multifactorial-adjusted analyses, in men, or in case-control study 1b. Among single homozygotes (235TT /174TT ), men in case-control study 2b had increased risk for myocardial infarction in multifactorial-adjusted and matched analyses. This risk was not present in age-adjusted analysis, in women, or in case-control study 1b. In addition, male single homozygotes had decreased risk for ischemic cerebrovascular disease in case-control study 2c in age- and multifactorial-adjusted analyses, but this finding was not seen in matched analysis, in women, or in case-control study 1c.

CONCLUSIONS

In six large case-control studies, the M235T and T174M angiotensinogen mutations were not consistently associated with increased (or decreased) risk for ischemic heart disease, myocardial infarction, or ischemic cerebrovascular disease. Statistically significant associations may represent chance findings rather than real phenomena.

Beneficial effects of ramipril on left ventricular end-diastolic and end-systolic volume indexes after uncomplicated invasive revascularization are associated with a reduction in cardiac events in patients with moderately impaired left ventricular function and no clinical heart failure

OBJECTIVES We sought to assess the effect of ramipril on left ventricular (LV) volumes, and the clinical significance thereof, in patients with moderate LV dysfunction and no clinical heart failure undergoing invasive revascularization for chronic stable angina.

BACKGROUND

It is unsettled whether treatment with an angiotensin-converting enzyme inhibitor has an impact on LV volumes in this patient group, and, if so, whether this is associated with the clinical outcome.

METHODS

A total of 133 patients with a left ventricular ejection fraction (LVEF) between 0.30 and 0.50 and no clinical heart failure undergoing invasive revascularization for chronic stable angina were randomized to receive ramipril 10 mg once daily or placebo and were followed for a median of 33 months with echocardiography at baseline and 3, 12 and 24 months postoperatively.

RESULTS

Repeated measures analysis of all time points showed that ramipril significantly reduced the end-diastolic volume index (EDVI) (p = 0.032) and end-systolic volume index (ESVI) (p = 0.006) as compared with placebo. Ramipril also reduced the incidence of the triple composite end point of cardiac death, acute myocardial infarction or development of heart failure (p = 0.046). Cox regression analysis, controlling for baseline LVEF and assignment to ramipril, revealed: 1) that increases in EDVI and ESVI up to three months predicted an increasing risk of a future adverse clinical outcome; and 2) that the benefit with ramipril on clinical outcome was partly dependent on a reduction in LV volumes.

CONCLUSIONS

Even in this patient group, LV dilation may supervene and lead to an adverse clinical outcome. Ramipril reduces the postoperative increase in LV volumes and may thereby improve clinical outcome.

Common cholesteryl ester transfer protein mutations, decreased HDL cholesterol, and possible decreased risk of ischemic heart disease: The Copenhagen City Heart Study

BACKGROUND

Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl ester from HDL in exchange for triglycerides in apolipoprotein B-containing lipoproteins.

METHODS AND RESULTS

We studied 2 common mutations in CETP, A373P and R451Q, in 8467 healthy women and men from the Danish general population and in 1636 Danish women and men with ischemic heart disease. The prevalence of 373P and 451Q was 0.10 and 0.07, respectively, for heterozygous carriers and 0.003 and 0.002, respectively, for homozygous carriers. All carriers of the 451Q allele also carried the 373P allele. HDL cholesterol in female noncarriers, heterozygotes, and homozygotes of 373P was 1.74+/-0.01 (mean+/-SE), 1.62+/-0.02, and 1.38+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). In men, equivalent values were 1.40+/-0.01, 1.26+/-0.02, and 1.19+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). HDL cholesterol decreased similarly as a function of 451Q genotypes and all 373P/451Q genotype combinations. Furthermore, apolipoprotein AI and the HDL cholesterol/apolipoprotein AI ratio was also lower in carriers of either of these mutations for both sexes. Finally, the CETP genotype was not associated with risk of ischemic heart disease unless we adjusted for HDL cholesterol: female heterozygous and homozygous carriers versus noncarriers had 36% lower risk of ischemic heart disease (95% CI 4% to 57%); in male carriers, we observed a similar trend.

CONCLUSIONS

The A373P/R451Q polymorphism in CETP is associated with decreases in HDL cholesterol of 0.12 to 0.36 mmol/L in women and 0.14 to 0.21 mmol/L in men and possibly with a paradoxical 36% decrease in the risk of ischemic heart disease in women.