Elevated Serum Mannose-Binding Lectin Levels Are Associated with Poor Outcome After Acute Ischemic Stroke in Patients with Type 2 Diabetes

Role of the lectin pathway of complement in hematopoietic stem cell transplantation-associated endothelial injury and thrombotic microangiopathy

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a life-threatening syndrome that occurs in adult and pediatric patients after hematopoietic stem cell transplantation. Nonspecific symptoms, heterogeneity within study populations, and variability among current diagnostic criteria contribute to misdiagnosis and underdiagnosis of this syndrome. Hematopoietic stem cell transplantation and associated risk factors precipitate endothelial injury, leading to HSCT-TMA and other endothelial injury syndromes such as hepatic veno-occlusive disease/sinusoidal obstruction syndrome, idiopathic pneumonia syndrome, diffuse alveolar hemorrhage, capillary leak syndrome, and graft-versus-host disease. Endothelial injury can trigger activation of the complement system, promoting inflammation and the development of endothelial injury syndromes, ultimately leading to organ damage and failure. In particular, the lectin pathway of complement is activated by damage-associated molecular patterns (DAMPs) on the surface of injured endothelial cells. Pattern-recognition molecules such as mannose-binding lectin (MBL), collectins, and ficolins—collectively termed lectins—bind to DAMPs on injured host cells, forming activation complexes with MBL-associated serine proteases 1, 2, and 3 (MASP-1, MASP-2, and MASP-3). Activation of the lectin pathway may also trigger the coagulation cascade via MASP-2 cleavage of prothrombin to thrombin. Together, activation of complement and the coagulation cascade lead to a procoagulant state that may result in development of HSCT-TMA. Several complement inhibitors targeting various complement pathways are in clinical trials for the treatment of HSCT-TMA. In this article, we review the role of the complement system in HSCT-TMA pathogenesis, with a focus on the lectin pathway.

Plasma-derived and recombinant C1 esterase inhibitor: Binding profiles and neuroprotective properties in brain ischemia/reperfusion injury

C1 esterase inhibitor (C1INH) is known to exert its inhibitory effect by binding to several target proteases of the contact and complement systems. One of C1INH's targets comprise mannose-binding lectin (MBL), a critical player in post-stroke pathophysiology. We therefore explored the effects of recombinant human (rh) and plasma derived (pd) C1INH in C57BL/6J mice subjected to transient occlusion of the middle cerebral artery (tMCAo), receiving 15U/mouse of pd or rhC1INH intravenously, at reperfusion. We analyzed the compounds' (i)neuroprotective effects, (ii) plasma presence, (iii)effects on circulating and brain MBL, (iv)time course of endothelial deposition, and (v) effects on the formation of active complement products. rhC1INH-treated mice had neuroprotective effects, including reduced behavioral deficits and neuronal loss, associated with decreased MBL brain deposition and decreased formation of complement C4b active fragments. In contrast, pdC1INH did not show these neuroprotective effects despite its longer plasma residence time. We also analyzed the response to tMCAo in C1INH-deficient mice, observing a poorer ischemic outcome compared to the wild type mice, which could be partially prevented by rhC1INH administration. In conclusion, we show that rhC1INH exhibits stronger neuroprotective effects than the corresponding plasma-derived protein after experimental ischemia/reperfusion injury in the brain, placing it as a promising drug for stroke. Differential effects are likely related to more effective MBL inhibition which further confirms it as a useful pharmacological target for stroke.

Complement Component C3 Promotes Cerebral Ischemia/Reperfusion Injury Mediated by TLR2/NFκB Activation in Diabetic Mice

Complement component C3 (C3), a key factor in the complement system, is heavily involved in various inflammation-associated diseases. However, it remains obscure for its role in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury in diabetes. A transient middle cerebral artery occlusion (tMCAO) model was used for cerebral I/R injury in streptozotocin-induced diabetic mice. Cerebral infarct volume and neurological function were measured at different times of reperfusion. Complement C3 was measured by ELISA and western blotting. It was observed that complement C3 expression was increased in cerebral I/R injury of diabetic mice, whereas complement C3 deficiency abrogated the activation and injury. Furthermore, activating complement C3 promotes TLR2/NFκB activation after I/R injury in diabetic mice, which is inhibited by of the silencing of TLR2. Taken together, our data demonstrate that complement C3 promotes cerebral I/R injury via the TLR2/NFκB pathway in diabetic mice, and regulating the complement C3/TLR2/NFκB pathway may be a novel target for therapeutic intervention in diabetic stroke.

Elevated Lipoprotein (a) and Risk of Poor Functional Outcome in Chinese Patients with Ischemic Stroke and Type 2 Diabetes

The aim of this study was to evaluate the short-term prognostic value of early measurement of serum lipoprotein (a) [Lp(a)] levels in Chinese patients with type 2 diabetes (T2D) and acute ischemic stroke (AIS). The study population comprised 232 consecutive patients with an AIS diagnosis complicated with T2D. Functional outcome was obtained on month 3 according to the modified Rankin Scale (mRS). Unfavorable functional outcome was defined as a mRS score of 3 to 6 points. The prognostic value of Lp(a) at admission to predict the unfavorable functional outcome 3 months after stroke onset was compared with the National Institutes of Health Stroke Scale score and other known outcome predictors. The Lp(a) levels in those patients were obtained with a median value of 16.8 mg/dl (IQR, 9.5-34.4 mg/dl). At 3-month follow-up, an unfavorable functional outcome was found in 86 patients (37.1%). In multivariate models comparing the second (Q2), third, and fourth quartiles against the first quartile of Lp(a), concentrations of Lp(a) in Q2, Q3, and Q4 were associated with unfavorable outcome, and increased risk of unfavorable outcome by 42, 131, and 211%. Interestingly, an elevated Lp(a, > 30 mg/dl) was also associated with unfavorable outcome, and with adjusted OR of 2.25 (95% CI 1.39-3.68). The AUC was significantly increased by adding Lp(a) to established risk factors (difference, 0.041 [95% CI, 0.034-0.053]; P = 0.02). The addition of Lp(a) to established risk factors significantly improved net reclassification improvement and integrated discrimination improvement. Higher Lp(a) levels at admission were associated with increased risk of unfavorable functional outcome and might be useful in identifying stroke patients with T2D at risk for unfavorable functional outcome for early prevention strategies.

Prognostic Utility of Fatty Acid-Binding Protein 4 in Patients with Type 2 Diabetes and Acute Ischemic Stroke

The role of fatty acid-binding proteins (FABPs) in atherosclerosis has been investigated. The aim of this study was to verify the hypothesis that higher levels of serum fatty acid-binding protein 4 (FABP4) could be a prognostic factor in Chinese patients with type 2 diabetes (T2DM) and acute ischemic stroke (AIS). From September 2015 to August 2016, consecutive first-ever AIS patients combined with T2DM were included in this study. FABP4, NIH stroke scale (NIHSS), and conventional risk factors were evaluated to determine their value to predict functional outcomes within 3 months. Multivariate analyses were performed using logistic regression models. We measured FABP4 in 329 patients. The median age of patients included in this study was 63 (IQR, 56-72) years and 45.9% were women. FABP4 serum levels were obtained at a median of 8.5 h (IQR, 4.0-14.0 h) after the stroke onset with a median value of 21.4 ng/ml (IQR, 15.6-28.2 ng/ml). In multivariable models, FABP4 remained an independent stroke severity predictor with an adjusted OR of 1.05 (95% CI, 1.02-1.09). In multivariate models comparing the third (odd ratio (OR), 2.25; 95% confidence interval (CI), 1.59-3.54) and fourth quartiles (OR, 3.75; 95% CI, 2.48-5.03) against the first quartile of the FABP4, levels of FABP4 were associated with poor functional outcome. At 3 months, 38 patients (11.6%; 95%CI, 8.1-15.0%) had died. The mortality distribution across the FABP4 quartiles ranged between 3.7% (first quartile) and 20.7% (fourth quartile). Elevation of FABP4 is associated with an increased risk of death and poor functional outcome events in patients with type 2 diabetes and acute ischemic stroke and is independent of other established clinical risk predictors and biomarkers.

MicroRNAs regulating cluster of differentiation 46 (CD46) in cardioembolic and non-cardioembolic stroke

Ischemic stroke is a major cause of mortality and morbidity globally. Among the ischemic stroke subtypes, cardioembolic stroke is with poor functional outcome (Modified Rankin score ≥ 2). Early diagnosis of cardioembolic stroke will prove beneficial. This study examined the microRNAs targeting cluster of differentiation 46 (CD46), a potential biomarker for cardioembolic stroke. CD46 mRNA level was shown to be differentially expressed (p < 0.001) between cardioembolic stroke (median = 1.32) and non-cardioembolic stroke subtypes (large artery stroke median = 5.05; small vessel stroke median = 6.45). Bioinformatic search showed that miR-19a, -20a, -185 and -374b were found to target CD46 mRNA and further verified by luciferase reporter assay. The levels of miRNAs targeting CD46 were significantly reduced (p < 0.05) in non-cardioembolic stroke patients (large artery stroke median: miR-19a = 0.63, miR-20a = 0.42, miR-185 = 0.32, miR-374b = 0.27; small artery stroke median: miR-19a = 0.07, miR-20a = 0.06, miR-185 = 0.07, miR-374b = 0.05) as compared to cardioembolic stroke patients (median: miR-19a = 2.69, miR-20a = 1.36, miR-185 = 1.05, miR-374b = 1.23). ROC curve showed that the miRNAs could distinguish cardioembolic stroke from non-cardioembolic stroke with better AUC value as compared to CD46. Endogenous expression of CD46 in Human Umbilical Vein Endothelial Cells (HUVECs) were found to be regulated by miR-19a and miR-20a. Thus implicating that miR-19a and -20a may play a role in pathogenesis of cardioembolic stroke, possibly via the endothelial cells.

Plasma copeptin and functional outcome in patients with ischemic stroke and type 2 diabetes

BACKGROUND

The activation of the arginine vasopressin system may be involved in the pathology of stroke and diabetes. In this study, we therefore evaluated the short-term prognostic value of early measurement of plasma copeptin levels in Chinese patients with type 2 diabetes mellitus (T2DM) and acute ischemic stroke (AIS).

METHODS

From July 2014 to June 2015, all T2DM patients with first-ever AIS were included. Plasma levels of copeptin were tested at admission. The prognostic value of copeptin to predict the functional outcome and mortality 3months after stroke was compared with the National Institutes of Health Stroke Scale score and with other known outcome predictors.

RESULTS

We recorded 247 stroke patients with T2DM. The copeptin levels were obtained in those patients with a median value of 14.3pmol/L (IQR, 9.5-17.1pmol/L). At 3-month follow-up, a favorable functional outcome was found in 86 patients (34.8%). Plasma copeptin levels in patients with an unfavorable outcome were significantly greater than those in patients with a favorable outcome (16.2 [IQR, 12.2-20.3] vs. 12.4 [IQR, 8.6-15.2] pmol/L; Z=5.399; P<0.0001). In univariate logistic regression analysis, with an unadjusted OR of 1.123 (95% CI, 1.072-1.177, P<0.001), copeptin had a strong association with unfavorable functional outcome. In multivariate analyses, a copeptin level in the highest inter-quartile (>17.1pmol/L) was associated with a higher risk of unfavorable functional outcome (OR=4.62; 95% CI=2.63-9.21; P<0.001). After adjusting for other outcome predictors, a copeptin level in the highest inter-quartile (>17.1pmol/L) was associated with a higher risk of mortality (OR=5.12; 95% CI=2.20-11.38; P<0.001).

CONCLUSION

Our study suggested that copeptin levels may reliably predict short-term stroke prognosis at its onset in Chinese patients with T2DM and stroke.

Mannan binding lectin-associated serine protease-2 (MASP-2) critically contributes to post-ischemic brain injury independent of MASP-1

BACKGROUND

Complement activation via the lectin activation pathway (LP) has been identified as the key mechanism behind post-ischemic tissue inflammation causing ischemia-reperfusion injury (IRI) which can significantly impact the clinical outcome of ischemic disease. This work defines the contributions of each of the three LP-associated enzymes-mannan-binding lectin-associated serine protease (MASP)-1, MASP-2, and MASP-3-to ischemic brain injury in experimental mouse models of stroke.

METHODS

Focal cerebral ischemia was induced in wild-type (WT) mice or mice deficient for defined complement components by transient middle cerebral artery occlusion (tMCAO) or three-vessel occlusion (3VO). The inhibitory MASP-2 antibody was administered systemically 7 and 3.5 days before and at reperfusion in WT mice in order to assure an effective MASP-2 inhibition throughout the study. Forty-eight hours after ischemia, neurological deficits and infarct volumes were assessed. C3 deposition and microglia/macrophage morphology were detected by immunohistochemical, immunofluorescence, and confocal analyses.

RESULTS

MASP-2-deficient mice (MASP-2(-/-)) and WT mice treated with an antibody that blocks MASP-2 activity had significantly reduced neurological deficits and histopathological damage after transient ischemia and reperfusion compared to WT or control-treated mice. Surprisingly, MASP-1/3(-/-) mice were not protected, while mice deficient in factor B (fB(-/-)) showed reduced neurological deficits compared to WT mice. Consistent with behavioral and histological data, MASP-2(-/-) had attenuated C3 deposition and presented with a significantly higher proportion of ramified, surveying microglia in contrast to the hypertrophic pro-inflammatory microglia/macrophage phenotype seen in the ischemic brain tissue of WT mice.

CONCLUSIONS

This work demonstrates the essential role of the low-abundant MASP-2 in the mediation of cerebral ischemia-reperfusion injury and demonstrates that targeting MASP-2 by an inhibitory therapeutic antibody markedly improved the neurological and histopathological outcome after focal cerebral ischemia. These results contribute to identifying the key lectin pathway component driving brain tissue injury following cerebral ischemia and call for a revision of the presently widely accepted view that MASP-1 is an essential activator of the lectin pathway effector component MASP-2.

Early ficolin-1 is a sensitive prognostic marker for functional outcome in ischemic stroke

BACKGROUND

Several lines of evidence support the involvement of the lectin pathway of complement (LP) in the pathogenesis of acute ischemic stroke. The aim of this multicenter observational study was to assess the prognostic value of different circulating LP initiators in acute stroke.

METHODS

Plasma levels of the LP initiators ficolin-1, -2, and -3 and mannose-binding lectin (MBL) were measured in 80 stroke patients at 6 h only and in 85 patients at 48 h and later. Sixty-one age- and sex-matched healthy individuals served as controls. Stroke severity was measured on admission using the National Institutes of Health Stroke Scale (NIHSS). The outcome was measured at 90 days by the modified Rankin Scale (mRS).

RESULTS

Ficolin-1 was decreased in patients compared with controls measured at 6 h (median 0.13 vs 0.33 μg/ml, respectively, p < 0.0001). At 48 h, ficolin-1 was significantly higher (0.45 μg/ml, p < 0.0001) compared to the 6 h samples and to controls. Likewise, ficolin-2 was decreased at 6 h (2.70 vs 4.40 μg/ml, p < 0.0001) but not at 48 h. Ficolin-3 was decreased both at 6 and 48 h (17.3 and 18.23 vs 21.5 μg/ml, p < 0.001 and <0.05, respectively). For MBL no difference was detected between patients and controls or within patients at the different time points. In multivariate analysis, early ficolin-1 was independently associated with unfavorable mRS outcome (adjusted odds ratio (OR): 2.21, confidence interval (CI) 95 % 1.11-4.39, p = 0.023). Early ficolin-1 improved the discriminating ability of an outcome model including NIHSS and age (area under the curve (AUC) 0.95, CI 95 % 0.90-0.99, p = 0.0001).

CONCLUSIONS

The ficolins are consumed within 6 h after stroke implicating activation of the LP. Early ficolin-1 is selectively related to 3-month unfavorable outcome.

Neopterin as a Predictor of Functional Outcome and Mortality in Chinese Patients with Acute Ischemic Stroke

Immune responses and inflammation play an important role in the pathogenesis of ischemic stroke. We therefore evaluated the 6-month prognostic value of early measurement of serum neopterin levels, a marker of inflammation and immune system activation, in Chinese patients with acute ischemic stroke (AIS). Consecutive AIS patients admitted to the emergency department were identified. Clinical information was collected. Serum concentration of neopterin and NIH stroke scale (NIHSS) were measured at the time of admission. Functional outcome was measured by modified Rankin scale (mRS) 6 months after admission. Multivariate analyses were performed using logistic regression models. During the inclusion period, 312 patients with first-ever AIS were included and 290 completed follow-up. The results indicated that the serum neopterin levels were significantly (P < 0.0001) higher in acutely ischemic stroke patients as compared to normal controls. Neopterin was an independent prognostic marker of 6-month functional outcome and death [odds ratio (OR) 4.33 (1.83-10.32) and 6.68 (2.44-12.13), respectively, P < 0.0001 for both, adjusted for NIHSS, other predictors and vascular risk factors] in patients with AIS. Neopterin improved the area under the receiver operating characteristic curve of the NHISS score for functional outcome from 0.75 (95 % CI 0.69-0.83) to 0.85 (95 % CI 0.79-0.91; P < 0.001) and for mortality from 0.76 (95 % CI 0.68-0.85) to 0.87 (95 % CI 0.81-0.94; P < 0.001). Serum neopterin is a useful, independent tool to predict functional outcome and mortality 6 months after stroke.