Sleep Position Detection for Closed-Loop Treatment of Sleep-Related Breathing Disorders

Reliable detection of sleep positions is essential for the development of technical aids for patients with position-dependent sleep-related breathing disorders. We compare personalized and generalizable sleeping position classifiers using unobtrusive eight-channel pressure-sensing mats. Data of six male patients with confirmed position-dependent sleep apnea was recorded during three subsequent nights. Personalized position classifiers trained using leave-one-night-out cross-validation on average reached an F1-score of 61.3% for supine/non-supine and an F1-score of 46.2% for supine/lateral-left/lateral-right classification. The generalizable classifiers reached average F1-scores of 62.1% and 49.1% for supine/non-supine and supine/lateral-left/lateral-right classification, respectively. In-bed presence ("bed occupancy") could be detected with an average F1-score of 98.1%. This work shows that personalized sleep-position classifiers trained with data from two nights have comparable performance to classifiers trained with large interpatient datasets. Simple eight-channel sensor mattresses can be used to accurately detect in-bed presence required for closed-loop systems but their use to classify sleep-positions is limited.

POS0060 MEASUREMENTS OF COMPLEMENT ACTIVITY SPECIFICALLY THOUGH THE LECTIN -OR THE CLASSICAL PATHWAY IN PATIENTS WITH SLE

Background

In systemic lupus erythematosus (SLE), the complement system (CS) is activated and thought to occur primarily through the classical pathway (CP) [1]. Traditionally, when diagnosing SLE or assessing disease activity, measurement of low C3 or C4 are used as proxies for complement activation [2]. However, measurement of C3 and C4 does not differentiate which complement pathway initiated the activation (i.e., the lectin pathway (LP), the CP, or the alternative pathway) [1, 3].

C1-esterase inhibitor (C1inh) is one of the key regulators of the CS. C1inh is the exclusive inhibitor of the active CP enzymes C1r and C1s [4], and the major inhibitor of active LP enzymes MASP-1 and MASP-2 [5]. A possible way of assessing complement activation through a specific pathway, is by measuring activated enzymes complexed with C1inh in plasma, as these complexes only exist after complement enzyme activation.

Objectives

Our aim was to investigate and unravel LP and CP complement activation in SLE, by measuring the protein complexes MASP1/C1inh (LP specific activation) and C1r/C1inh (CP specific activation). Furthermore, we aimed to investigate whether there is an association between complement activity, disease activity (SLEDAI) and disease manifestations (lupus nephritis (LN)).

Methods

A cross sectional cohort of 150 patients with SLE fulfilling the 1997 ACR classification criteria for SLE were included from the out-patient clinic at the department of Rheumatology, Aarhus University Hospital (AUH), Denmark. Disease manifestations and disease activity using SLEDAI score was assessed at inclusion. Fifty healthy individuals included at the Blood Bank, AUH, were used as controls. Both C1s/C1inh and MASP1/C1inh complexes were measured in all samples using two newly developed sandwich ELISAs (C1s/C1inh: cat# HK399; MASP1/C1inh: Cat#3001, Hycult Biotech, Uden, The Netherlands). EDTA-samples from both SLE patients and controls were measured in duplicates.

Results

When comparing SLE patients to controls, we observed a difference in complement activation through the LP, where a lower mean MASP1/C1inh plasma concentration was observed (p<0.01).

C1s/C1inh concentrations were significantly increased in active SLE patients (SLEDAI >6) when compared to SLE patients with low disease activity (SLEDAI <6, p<0.01) and correlated with SLEDAI score (r=0.285, p<0.01). C1s/C1inh concentrations were increased in SLE patients with active LN compared to non-active LN, however this not statistically significant (p=0.09).

No differences in MASP1/C1inh plasma concentrations were observed between active SLE patients and patients with low disease activity (p=0.11), nor did we observe a significant correlation with disease activity (r=0.12, p=0.13). In active LN, plasma concentrations of MASP1/C1inh were significantly elevated compared to non-active LN (p=0.02).

Conclusion

Our data suggest that the CP and the LP is activated in SLE. CS is generally activated in active SLE disease, whereas activation of the LP might be more specific to particular disease manifestations like LN.

Our findings warrant further research into activation of the specific complement pathways in relation to specific disease manifestations in SLE.

References

[1]Troldborg, A., et al., J Rheumatol, 2018.

[2]Weinstein, A., et al., Curr Rheumatol Rep, 2021.

[3]Atkinson, J.P., Clin Exp Rheumatol, 1989.

[4]Sim, R.B., et al., FEBS Lett, 1979.

[5]Paréj, K., et al., Mol Immunol, 2013.

Figure 1.

Measurements of plasma concentrations of C1r in complex with C1-inhibitor (C1r/C1inh) (a1-a4) and MASP1 in complex with C1-inhibitor (MASP1/C1inh) (b1-b4) in Systemic Lupus Erythematosus (SLE) patients and controls. A1 and b1 show measurements of SLE patients versus controls. A2 and b2 show measurements in SLE patients with active disease (SLEDAI >6) versus low disease activity (SLEDAI<6). A3 and b3 show correlation analysis between measurements and SLEDAI score in SLE patients. A4 and b4 show measurements in SLE patients with active lupus nephritis (LN) versus non-active LN.

Disclosure of Interests

Mads Christian Lamm Larsen: None declared, Anne Troldborg: None declared, Erik Toonen Employee of: ET is an employee of Hycult Biotech, Lisa Hurler: None declared, Zoltán Prohászka: None declared, László Cervenak: None declared, Annette G Hansen: None declared, Steffen Thiel: None declared

POS0059 COMPLEMENT PROTEINS ARE ELEVATED IN PATIENTS WITH axSpA COMPARED WITH RELEVANT CONTROLS OF PATIENTS WITH LOW BACK PAIN AND SpA-FEATURES WITHOUT AXSPA

Background

Axial spondyloarthritis (axSpA) is associated with a certain genetic predisposition, i.e., with the presence of human leukocyte antigen (HLA)-B27. However, the pathogenesis remains largely unexplained. Animal models of ankylosing spondylitis have shown inhibition of complement to be beneficial in terms of limiting structural damage (1). The lectin pathway of complement activation serves as a key component of the innate immune system and plays a pivotal role in both homeostasis and development. The influence of complement in axSpA is mainly unexplored. We have, however, previously reported elevated plasma levels of the lectin pathway proteins L-ficolin and H-ficolin in patients with axSpA compared with blood donors (2).

Objectives

Our aim was to investigate plasma levels of lectin pathway proteins in a clinical cohort of patients with axSpA and compare them to relevant controls that we often experience significant challenges in differentiating from axSpA.

Methods

Plasma samples were obtained from individuals in a cohort of patients suffering from low back pain (LBP) including: 1) 23 patients with axSpA, 2) 55 patients without axSpA experiencing SpA-features/symptoms, and 3) 64 patients with nonspecific LBP without SpA-features or MRI findings suggestive of axSpA. Diagnosis of axSpA was based on multidisciplinary team conference consensus after 3.5 years of follow-up (3). Plasma levels of 10 lectin pathway proteins (MBL, CL-L1, H-ficolin, L-ficolin, M-ficolin, MASP-1, MASP-2, MASP-3, MAp44, and MAp19) were measured by immunoassays developed in-house.

Results

Patient characteristics are shown in Table 1. Plasma levels of lectin pathway proteins L-ficolin, M-ficolin and CL-L1 differed significantly in the patient groups (p ≤ 0.03). L-ficolin and M-ficolin were elevated in axSpA-patients compared with patients with SpA-features without axSpA and nonspecific LBP patients (Figure 1). CL-L1 was elevated in axSpA-patients and patients with SpA-features without axSpA compared with nonspecific LBP patients (Figure 1). No significant differences were observed for MBL, H-ficolin, MASP-1, MASP-2, MASP-3, MAp44, and MAp19. L-ficolin levels correlated with CRP in axSpA-patients (Spearman’s rho=0.58 p=0.004). M-ficolin levels correlated weakly with CRP in nonspecific LBP patients (Spearman’s rho=0.36 p=0.003). Lectin pathway protein levels did not correlate with disease activity (ASDAS).

Table 1.

Patient characteristics

axSpA (n=23)Not axSpA (n=55)Non-specific low back pain (n=64)p-valueMedian age, years (range)32 (19-40)33 (19-41)32 (18-39)0.75aMales, n (%)10 (43)37 (67)26 (41)0.01bHLA-B27 positive, n (%)17 (74)11 (20)5 (8)0.00bInflammatory back pain, n (%)18 (78)28 (51)0.03cGood response to NSAID14 (61)17 (31)0.01cSacroiliitiis on MRI acc. ASAS, n (%)22 (96)45 (82)0.11cElevated CRP, n (%)3 (13)7 (13)0.97ASDAS (range)2.5 (1.2-3.7)2.3 (0.8-3.8)0.52d

a compared by Kruskal-Wallis test.

b all three groups compared by Chi2 test.

c compared by Chi2 test.

d compared by Mann Whitney U test.

Figure 1.

Plasma levels of L-ficolin, M-ficolin and CL-L1.

Conclusion

L-ficolin and M-ficolin are increased in patients with axSpA when compared with relevant control cohorts of patients with LBP or with SpA-features without axSpA. Our findings support a potential pathogenic role for complement in axSpA, however, further studies are needed to elucidate the diagnostic potential of the specific complement proteins.

References

[1]Yang, C. et al. Inhibition of complement retards ankylosing spondylitis progression. Sci. Rep. (2016) doi:10.1038/srep34643.

[2]Troldborg, A. et al. Plasma levels of H- and L-ficolin are increased in axial spondyloarthritis: improvement of disease identification. Clin. Exp. Immunol. (2020) doi:10.1111/cei.13374.

[3]Kiil, R. M. et al. Diagnosing axSpA by multidiciplinary team conference at 3.5 years’ follow-up in a cohort of patients with disease features according to the ASAS criteria. Scand. J. Rheumatol. (2021) doi:10.1080/03009742.2021.1933584.

Disclosure of Interests

None declared

Temporal Course of SARS-CoV-2 Antibody Positivity in Patients with COVID-19 following the First Clinical Presentation

Knowledge of the sensitivities of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests beyond 35 days after the clinical onset of COVID-19 is insufficient. We aimed to describe positivity rate of SARS-CoV-2 assays employing three different measurement principles over a prolonged period. Two hundred sixty-eight samples from 180 symptomatic patients with COVID-19 and a reverse transcription polymerase chain reaction (RT-PCR) test followed by serological investigation of SARS-CoV-2 antibodies were included. We conducted three chemiluminescence (including electrochemiluminescence assay (ECLIA)), four enzyme-linked immunosorbent assay (ELISA), and one lateral flow immunoassay (LFIA) test formats. Positivity rates, as well as positive (PPVs) and negative predictive values (NPVs), were calculated for each week after the first clinical presentation for COVID-19. Furthermore, combinations of tests were assessed within an orthogonal testing approach employing two independent assays and predictive values were calculated. Heat maps were constructed to graphically illustrate operational test characteristics. During a follow-up period of more than 9 weeks, chemiluminescence assays and one ELISA IgG test showed stable positivity rates after the third week. With the exception of ECLIA, the PPVs of the other chemiluminescence assays were ≥95% for COVID-19 only after the second week. ELISA and LFIA had somewhat lower PPVs. IgM exhibited insufficient predictive characteristics. An orthogonal testing approach provided PPVs ≥ 95% for patients with a moderate pretest probability (e.g., symptomatic patients), even for tests with a low single test performance. After the second week, NPVs of all but IgM assays were ≥95% for patients with low to moderate pretest probability. The confirmation of negative results using an orthogonal algorithm with another assay provided lower NPVs than the single assays. When interpreting results from SARS-CoV-2 tests, the pretest probability, time of blood draw, and assay characteristics must be carefully considered. An orthogonal testing approach increases the accuracy of positive, but not negative, predictions.

Severe COVID-19 is associated with elevated serum IgA and antiphospholipid IgA-antibodies

Background

Severe coronavirus disease 2019 (COVID-19) frequently entails complications that bear similarities to autoimmune diseases. To date, there is little data on possible IgA-mediated autoimmune responses. Here, we aim to determine whether COVID-19 is associated with a vigorous total IgA response and if IgA antibodies are associated with complications of severe illness. Since thrombotic events are frequent in severe COVID-19 and resemble hypercoagulation of antiphospholipid syndrome (APS), our approach focused on antiphospholipid antibodies (aPL).

Methods

In this retrospective cohort study clinical data and aPL from 64 patients with COVID-19 were compared from three independent tertiary hospitals (one in Liechtenstein, two in Switzerland). Samples were collected from April 9 ^th to May 1 ^st, 2020.

Results

Clinical records of 64 patients with COVID-19 were reviewed and divided into a cohort with mild illness (mCOVID) (41%), a discovery cohort with severe illness (sdCOVID) (22%) and a confirmation cohort with severe illness (scCOVID) (38%). Total IgA, IgG and aPL were measured with clinical diagnostic kits. Severe illness was significantly associated with increased total IgA (sdCOVID, P=0.01; scCOVID, p-value<0.001), but not total IgG. Among aPL, both cohorts with severe illness significantly correlated with elevated anti-Cardiolipin IgA (sdCOVID and scCOVID, p-value<0.001), anti-Cardiolipin IgM (sdCOVID, P=0.003; scCOVID, P<0.001), and anti-Beta2 Glycoprotein-1 IgA (sdCOVID and scCOVID, P<0.001). Systemic lupus erythematosus was excluded from all patients as a potential confounder.

Conclusions

Higher total IgA and IgA-aPL were consistently associated with severe illness. These novel data strongly suggest that a vigorous antiviral IgA-response, possibly triggered in the bronchial mucosa, induces systemic autoimmunity.

Frequency of serological non-responders and false-negative RT-PCR results in SARS-CoV-2 testing: a population-based study

Objectives The sensitivity of molecular and serological methods for COVID-19 testing in an epidemiological setting is not well described. The aim of the study was to determine the frequency of negative RT-PCR results at first clinical presentation as well as negative serological results after a follow-up of at least 3 weeks. Methods Among all patients seen for suspected COVID-19 in Liechtenstein (n=1921), we included initially RT-PCR positive index patients (n=85) as well as initially RT-PCR negative (n=66) for follow-up with SARS-CoV-2 antibody testing. Antibodies were detected with seven different commercially available immunoassays. Frequencies of negative RT-PCR and serology results in individuals with COVID-19 were determined and compared to those observed in a validation cohort of Swiss patients (n=211). Results Among COVID-19 patients in Liechtenstein, false-negative RT-PCR at initial presentation was seen in 18% (12/66), whereas negative serology in COVID-19 patients was 4% (3/85). The validation cohort showed similar frequencies: 2/66 (3%) for negative serology, and 16/155 (10%) for false negative RT-PCR. COVID-19 patients with negative follow-up serology tended to have a longer disease duration (p=0.05) and more clinical symptoms than other patients with COVID-19 (p<0.05). The antibody titer from quantitative immunoassays was positively associated with the number of disease symptoms and disease duration (p<0.001). Conclusions RT-PCR at initial presentation in patients with suspected COVID-19 can miss infected patients. Antibody titers of SARS-CoV-2 assays are linked to the number of disease symptoms and the duration of disease. One in 25 patients with RT-PCR-positive COVID-19 does not develop antibodies detectable with frequently employed and commercially available immunoassays.

Plasma levels of H- and L-ficolin are increased in axial spondyloarthritis: improvement of disease identification

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial skeleton. A predominance of innate versus adaptive immune responses have been reported in axSpA, indicating a prominent autoinflammatory component of the disease. Little is known about the lectin pathway proteins (LPPs) of the complement system in relation to axSpA. We have investigated LPPs in patients with axSpA and control individuals. Plasma samples were obtained from a cross-sectional cohort of 120 patients with a clinical diagnosis of axSpA and from 144 age- and gender-matched controls. The plasma concentrations of 11 LPPs were measured, using sandwich-type time-resolved immunofluorometric assays in patients and controls, and related to clinical diagnosis and disease activity. Three LPPs [H-ficolin (ficolin-3), L-ficolin (ficolin-2) and collectin liver 1 (CL-L1)] were significantly higher in axSpA patients than in controls (P < 0·0001) and one LPP, collectin kidney 1 (CL-K1), was significantly lower (P < 0·0001). Further, combining H- or L-ficolin concentrations above the 75th percentile of the respective H- or L-ficolin concentration measured in controls with human leucocyte antigen (HLA)-B27 positivity yielded axSpA diagnostic specificities of 99/99% and positive likelihood ratios of 68/62, respectively. H-ficolin and L-ficolin plasma concentrations were found to be elevated in axSpA patients regardless of time since diagnosis. H-ficolin and L-ficolin may represent diagnostic biomarkers for patients with axSpA and should be further evaluated. Our results showed no association between disease activity and the measured LPP concentrations. This result might be due to the cross-sectional design, and should be further investigated.

Circulating lectin pathway proteins do not predict short-term cardiac outcomes after myocardial infarction

Despite improvements in treatment, coronary artery disease is still responsible for one-third of all deaths globally, due predominantly to myocardial infarction (MI) and stroke. There is an important potential in developing new strategies for treatment of patients with these conditions. Inflammation, and in particular the actions of the complement system, has emerged as part of the pathogenesis in reperfusion injury in patients with MI. To further qualify this, we examined the association between the plasma levels of lectin pathway proteins and myocardial end-points, left ventricular ejection fraction (LVEF) and infarct size in a cohort of patients with ST-elevation myocardial infarction (STEMI). A blood sample was drawn the day after percutaneous coronary intervention from 73 patients with STEMI. The primary end-points, LVEF and infarct size, were measured with magnetic resonance imaging 6-9 days after the infarct. Complement pattern-recognition molecules of the lectin pathway (mannan-binding lectin, H-ficolin, L-ficolin and M-ficolin) were analysed along with soluble membrane attack complex (sMAC) and C-reactive protein (CRP) in plasma with immunofluorometric assays <50%. CRP correlated negatively with LVEF, regression coefficient = -0·17 (P = 0·01). None of the lectin pathway proteins correlated to LVEF or infarct size, nor did soluble membrane attack complex (sMAC). There were no differences in plasma levels of these complement proteins when comparing patients with ejection fraction <50% to patients with ejection fraction <50%. Pattern-recognition molecules of the lectin pathway and sMAC do not predict short-term cardiac outcomes after MI.

Changes in the Lectin Pathway Following Intracerebral or Spontaneous Subarachnoid Hemorrhage

Previous research indicates that the complement system is activated after occurrence of intracerebral hemorrhage (ICH) and spontaneous subarachnoid hemorrhage (SAH). The role of the lectin pathway (LP) of the complement system in this activation has only scarcely been investigated. The aim of this study was to determine the plasma concentration of the LP proteins in patients with ICH or SAH at admission compared to healthy individuals. Secondly, ICH and SAH patients were followed during the initial 24 h of disease, to investigate changes in LP protein concentrations during the critical acute phase. This prospective, observational study included 30 ICH and 33 SAH patients. EDTA plasma samples were collected at admission, 6 and 24 h after symptom onset. Time-resolved immuno-flourometric assays (TRIFMA) were used to measure all proteins of the LP in patient samples and in samples from age- and gender-matched healthy individuals. Compared to healthy individuals, ICH and SAH patients had increased levels of H-ficolin (p = 0.04, p = 0.03), M-ficolin (both p < 0.0001), and MAp44 (both p = 0.01) at admission. M-ficolin, H-ficolin, CL-L1, MASP-1, MASP-3, and MAp44 decreased significantly in both ICH and SAH patients during the initial 24 h after symptom onset. In conclusion, we observed significant differences in lectin pathway protein concentrations between patients with ICH or SAH and healthy individuals. Significant dynamics in lectin pathway protein levels were demonstrated during the initial 24 h after symptom onset. This indicates a potential role of the LP proteins during the acute phase of SAH and ICH.

The complement lectin pathway after cardiac arrest

The lectin pathway (LP) of the complement system may initiate inflammatory reactions when body tissue is altered. We aimed to investigate the levels of the LP proteins in out-of-hospital cardiac arrest patients, and to compare these with healthy individuals. Furthermore, we aimed to clarify whether the duration of targeted temperature management influenced LP protein levels, and we further examined whether LP proteins were associated with 30-day mortality. We included 82 patients resuscitated from out-of-hospital cardiac arrest. The patients were randomly assigned to 24 or 48 hours of targeted temperature management at 33 ± 1°C. Blood samples were obtained 22, 46 and 70 hours after target temperature was reached. Levels of the LP proteins (mannan-binding lectin [MBL], M-ficolin, H-ficolin, collectin liver 1 [CL-L1], MBL-associated serine protease 1 [MASP-1], MASP-2, MASP-3 and MBL-associated protein of 44 kDa [MAp44]) were measured using time-resolved immunofluorometric assays. Data from 82 gender matched healthy individuals were used for comparison. Levels of CL-L1, MASP-1, MASP-2 and MAp44 were significantly higher, whereas M-ficolin levels were significantly lower in cardiac arrest patients compared with healthy individuals. MASP-2, MASP-3 and M-ficolin levels changed significantly when comparing 24 and 48 hours of targeted temperature management. The LP protein levels were not different between 30-day survivors and non-survivors after cardiac arrest. The differences in LP protein levels between patients and healthy individuals may indicate that cardiac arrest patients have an activated LP. Overall, the LP protein levels were not influenced by the duration of targeted temperature management, and the levels were not associated with 30-day mortality.

High prevalence of Mycobacterium genavense within flocks of pet birds

Mycobacterium genavense is regarded as the primary cause of mycobacteriosis in psittaciform and passeriform birds, which are commonly kept as pets. In humans, Mycobacterium genavense is especially pathogenic for young, old, pregnant and immunocompromised people (YOPIs). In birds, only few studies, mainly case reports, exist and there is still little e information about occurrence and relevance of this zoonotic pathogen. In this first pilot study concerning the prevalence of Mycobacterium genavense within flocks of naturally infected pet birds, real-time PCR examinations of 170 individual passeriform and psittaciform birds, including commonly kept budgerigars, lovebirds and zebra finches as well as gold finches and weaver finches, were conducted to determine the infection rate in six different aviaries. Antemortem examinations of faeces and cloacal swabs were compared with postmortem examinations of tissue samples to evaluate the reliability of antemortem diagnostics. Additional ophthalmologic examinations were performed to evaluate their diagnostic potential. Molecular examinations for viral co-infections, including circovirus, polyomavirus and adenovirus, were conducted to identify potential risk factors. PCR results revealed a detection prevalence of Mycobacterium genavense in the flocks varying from 3% to 91% based on postmortem testing, while antemortem diagnostics of faecal samples and swabs showed 64% discrepant (false negative) results. Ophthalmologic examinations were not useful in identifying infected birds within the flocks. Viral co-infections, especially with polyomavirus, were common. It has to be assumed that Mycobacterium genavense infections are widespread and underdiagnosed in companion birds. Viral infections might be an important risk factor. There is urgent need to improve antemortem diagnostics.

Communication of healthcare professionals: Is there ageism?

Elderspeak is often used when talking to older individuals and is characterised by a slower and/or louder speech, a patronising tone, etc. A part of the reason of such communication can be found in the actual context of negative view of ageing. However, the link between view of ageing and elderspeak has never been objectively studied in oncology. Therefore, 40 healthcare professionals (physicians and medical students) record a podcast where they have to explain an endocrine therapy to two fictional patients (40- vs. 70-year old). Results show that when participants explained the treatment to the older patient, they used shorter utterances and made more repetitions. They also evoked fewer side effects such as sexual issues. Moreover, reduction in length of utterances and of word-per-minute rate was observed for older patient when participants have a positive view of ageing but for both patients when they have a negative view of ageing. In conclusion, physicians and medical students used elderspeak when they explained a treatment to older patients. Participants with a more negative view of ageing also unconsciously talked slower and made shorter utterances to a 40 -year-old patient.

Incident microalbuminuria and complement factor mannan-binding lectin-associated protein 19 in people with newly diagnosed type 1 diabetes

BACKGROUND

Evidence links the lectin pathway of complement activation to diabetic kidney disease. Upon carbohydrate-recognition by pattern-recognition molecules, eg, mannan-binding lectin (MBL), the MBL-associated serine protease (MASP-2) is activated and initiates the complement cascade. The MASP2 gene encodes MASP-2 and the alternative splice product MBL-associated protein 19 (MAp19). Both MAp19 and MASP-2 circulate in complex with MBL. We tested the hypothesis that MAp19 and MASP-2 concentrations predict the risk of incident microalbuminuria.

METHODS

Baseline MAp19 and MASP-2 were measured in 270 persons with newly diagnosed type 1 diabetes tracked for incidence of persistent microalbuminuria in a prospective observational 18-year-follow-up study.

RESULTS

Seventy-five participants (28%) developed microalbuminuria during follow-up. MBL-associated protein 19 concentrations were higher in participants that later progressed to microalbuminuria as compared with those with persistent normoalbuminuria (268 ng/mL [95% CI, 243-293] vs 236 ng/mL [95% CI, 223-250], P = .02). Participants with MAp19 concentration within the highest quartile of the cohort had an increased risk of microalbuminuria as compared with participants with MAp19 concentration within the combined lower 3 quartiles in unadjusted Cox analysis, hazard ratio 1.86 ([95% CI, 1.17-2.96], P = .009). This remained significant in adjusted models, eg, adjusting for age, sex, HbA_1c , systolic blood pressure, urinary albumin excretion, smoking, serum creatinine, and serum cholesterol. MBL-associated serine protease concentration was not associated with incidence of microalbuminuria.

CONCLUSIONS

In conclusion, the results show an association between baseline MAp19 concentration and the incidence of microalbuminuria in an 18-year-follow-up study on persons with newly diagnosed type 1 diabetes.

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.

Oligomerization of Mannan-binding Lectin Dictates Binding Properties and Complement Activation

The complement system is a part of the innate immune system and is involved in recognition and clearance of pathogens and altered-self structures. The lectin pathway of the complement system is initiated when soluble pattern recognition molecules (PRMs) with collagen-like regions bind to foreign or altered self-surfaces. Associated with the collagen-like stems of these PRMs are three mannan-binding lectin (MBL)-associated serine proteases (MASPs) and two MBL-associated proteins (MAps). The most studied of the PRMs, MBL, is present in serum mainly as trimeric and tetrameric oligomers of the structural subunit. We hypothesized that oligomerization of MBL may influence both the potential to bind to micro organisms and the interaction with the MASPs and MAps, thus influencing the ability to initiate complement activation. When testing binding at 37 °C, we found higher binding of tetrameric MBL to Staphylococcus aureus (S. aureus) than trimeric and dimeric MBL. In serum, we found that tetrameric MBL was the main oligomeric form present in complexes with the MASPs and MAp44. Such preference was confirmed using purified forms of recombinant MBL (rMBL) oligomers, where tetrameric rMBL interacted stronger with all of the MASPs and MAp44, compared to trimeric MBL. As a direct consequence of the weaker interaction with the MASPs, we found that trimeric rMBL was inferior to tetrameric rMBL in activating the complement system. Our data suggest that the oligomeric state of MBL is crucial both for the binding properties and the effector function of MBL.

Collectin Liver 1 and Collectin Kidney 1 of the Lectin Complement Pathway Are Associated With Mortality After Kidney Transplantation

Kidney transplanted patients still have significantly higher mortality compared with the general population. The innate immune system may play an important role during periods, with suppression of the adaptive immune system. In the present study, two soluble pattern recognition molecules of the innate immune system were investigated, collectin liver 1 (CL-L1) and collectin kidney 1 (CL-K1). Potential associations of their pretransplant levels and long-term graft and recipient survival were examined. The levels of CL-L1 and CL-K1 were measured at the time of transplantation in 382 patients (≥17 years) transplanted in 2000-2001. The cohort was subsequently followed until December 31, 2014. Data on patient and graft survival were obtained from the Norwegian Renal Registry. Both high CL-L1 (≥376 ng/mL) and high CL-K1 (≥304 ng/mL) levels were significantly associated with overall mortality in multivariate Cox analyses with hazard ration (HR) 1.50, 95% confidence interval (CI) 1.09-2.07, p = 0.013 and HR 1.43, 95% CI 1.02-1.99, p = 0.038, respectively. Moreover, high CL-K1 levels were significantly associated with cardiovascular mortality. No association between measured biomarkers and death-censored graft loss was found. Finally, there was a significant correlation between these two collectins, r = 0.83 (95% CI 0.80-0.86). In conclusion, CL-L1 and CL-K1 were significantly associated with mortality in kidney transplant recipients.

Collectin liver 1 and collectin kidney 1 and other complement-associated pattern recognition molecules in systemic lupus erythematosus

The objective of this study was to explore the involvement of collectin liver 1 (CL-L1) and collectin kidney 1 (CL-K1) and other pattern recognition molecules (PRMs) of the lectin pathway of the complement system in a cross-sectional cohort of systemic lupus erythematosus (SLE) patients. Concentrations in plasma of CL-L1, CL-K1, mannan-binding lectin (MBL), M-ficolin, H-ficolin and L-ficolin were determined in 58 patients with SLE and 65 healthy controls using time-resolved immunoflourometric assays. The SLE patients' demographic, diagnostic, clinical and biochemical data and collection of plasma samples were performed prospectively during 4 months. CL-L1, CL-K1 and M-ficolin plasma concentrations were lower in SLE patients than healthy controls (P-values < 0.001, 0.033 and < 0.001, respectively). H-ficolin concentration was higher in SLE patients (P < 0.0001). CL-L1 and CL-K1 plasma concentrations in the individuals correlated in both patients and controls. Patients with low complement component 3 (C3) demonstrated a negative correlation between C3 and CL-L1 and CL-K1 (P = 0.022 and 0.031, respectively). Patients positive for anti-dsDNA antibodies had lower levels of MBL in plasma than patients negative for anti-dsDNA antibodies (P = 0.02). In a cross-sectional cohort of SLE patients, we found differences in the plasma concentrations of CL-L1, CL-K1, M-ficolin and H-ficolin compared to a group of healthy controls. Alterations in plasma concentrations of the PRMs of the lectin pathway in SLE patients and associations to key elements of the disease support the hypothesis that the lectin pathway plays a role in the pathogenesis of SLE.

[Considerations and recommondations for species-appropriate and welfare friendly keeping of ratitae in Germany]

Ostrich farming and keeping in Germany is of increasing interest. Ostrich farming includes keeping the animals as agricultural livestock (production of meat, leather, eggs), for display, hobby farming and keeping in zoological collections. Based on scientific research there is a steady increase in knowledge of keeping ratites according to sophisticated standards in terms of animal welfare legislation. Legislation and recommondations for keeping of ratitae are described.

Plasma levels of mannan-binding lectin-associated serine proteases MASP-1 and MASP-2 are elevated in type 1 diabetes and correlate with glycaemic control

There is increasing evidence that the complement system plays an important role in diabetes and the development of diabetic vascular complications. In particular, mannan-binding lectin (MBL) levels are elevated in diabetes patients, and diabetes patients with diabetic nephropathy have higher MBL levels than diabetes patients with normal renal function. The MBL-associated serine proteases (MASPs) MASP-1, MASP-2 and MASP-3 and MBL-associated protein MAp44 have not yet been studied in diabetes patients. We therefore measured plasma levels of MASP-1, MASP-2, MASP-3 and MAp44 in 30 children with type 1 diabetes mellitus (T1DM) and 17 matched control subjects, and in 45 adults with T1DM and 31 matched control subjects. MASP-1 and MASP-2 levels were significantly higher in children and adults with T1DM than in their respective control groups, whereas MASP-3 and MAp44 levels did not differ between patients and controls. MASP-1 and MASP-2 levels correlated with HbA1c, and MASP levels decreased when glycaemic control improved. Because MASP-1 and MASP-2 have been shown to interact directly with blood coagulation, elevated levels of these proteins may play a role in the enhanced thrombotic environment and consequent vascular complications in diabetes.