Membrane attack complex (MAC) deposition in renal tubules is associated with interstitial fibrosis and tubular atrophy: a pilot study

IntroductionTreatment failures for lupus nephritis (LN) are high with 10%–30% of patients progressing to end-stage renal disease (ESRD) within 10 years. Interstitial fibrosis/tubular atrophy (IFTA) is a predictor of progression to ESRD. Prior studies suggest that tubulointerstitial injury secondary to proteinuria in LN is mediated by complement activation in the tubules, specifically through the membrane attack complex (MAC). This study aimed to investigate the associations between tubular MAC deposition with IFTA and proteinuria.MethodsIn this cross-sectional study, LN kidney biopsies were assessed for MAC deposition by staining for Complement C9, a component of the MAC. Chromogenic immunohistochemistry was performed on paraffin-embedded human renal biopsy sections using unconjugated, murine anti-human Complement C9 (Hycult Biotech, clone X197). Tubular C9 staining intensity was analysed as present versus absent. IFTA was defined as minimal (<10%), mild (10%–24%), moderate (25%–50%) and severe (>50%).ResultsRenal biopsies from 30 patients with LN were studied. There were 24 (80%) female sex, mean age (SD) was 33 (12) years old and 23 (77%) had pure/mixed proliferative LN. Tubular C9 staining was present in 7 (23%) biopsies. 27 patients had minimal-to-mild IFTA and 3 patients had moderate IFTA. Among the C9 + patients, 3 (43%) had moderate IFTA as compared with none in the C9- group, p=0.009. C9 + patients had higher median (IQR) proteinuria as compared with C9- patients: 6.2 g (3.3–13.1) vs 2.4 g (1.3–4.6), p=0.001 at the time of biopsy. There was no difference in estimated glomerular filtration rate (eGFR) between the C9 + and C9- groups.ConclusionThis study demonstrated that tubular MAC deposition is associated with higher degree of IFTA and proteinuria, which are predictors of progression to ESRD. These results suggest that tubular MAC deposition may be useful in classification of LN. Understanding the role of complement in tubulointerstitial injury will also identify new avenues for LN treatment.

EndoScreen Chip: Serum Complement C9 Immunoassays Improve Risk Prediction and Early Diagnosis of Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) detection relies on endoscopy-biopsy diagnosis, with routine endoscopic surveillance recommended for Barrett&rsquo;s esophagus (BE) patients. Here, we examine the utility of blood biomarkers in patient risk stratification by translating the EAC blood biomarker Jacalin lectin binding complement C9 (JAC-C9) into a novel microfluidic immunoassay, the EndoScreen Chip. Cohort evaluation (n=46) showed elevated serum total C9 and JAC-C9 in EAC. Logistic regression modeling demonstrated that addition of C9 and JAC-C9 to patient risk factors (age, body mass index and heartburn/reflux history) improved EAC prediction from AUROC of 0.838 to 0.931. Serum JAC-C9 strongly predicted EAC (vs BE OR= 4.6, 95% CI: 1.6-15.6, p = 0.014; vs Healthy OR=4.1, 95% CI:1.2-13.7, p = 0.024) while total C9 was moderately predictive for BE (vs EAC OR=1.4; 95% CI: 1.0-1.8, p = 0.032; vs Healthy OR=0.8; 95% CI: 0.6-1.0, p = 0.039). This translational study demonstrates the potential utility of blood biomarkers in improving triaging for diagnostic endoscopy.

Complement C9 expression is associated with damaged myocardial cells in pediatric sudden death cases of fulminant myocarditis

Background Because disease progression is so fast in sudden death of acute fulminant myocarditis, damage of myocardial cells is not evident in routine hematoxylin and eosin staining. To understand damage to myocardial cells and the mechanism of sudden death, immunohistochemical staining was performed for two forensic autopsy cases. Case presentation The patients were a healthy 5-year-old girl and 8-year-old boy. They suddenly died within 2 days of appearance of flu-like symptoms. An autopsy showed accumulation of yellowish-clear pericardial fluid containing fibrin deposits, fluid blood in the heart, and congestion of visceral organs. Histologically, minor necrosis or degeneration of myocardial cells with mainly lymphocytic infiltration was observed sometimes in tissue sections. Immunohistochemically, positive complement C9 staining and negative sirtuin 1 staining were found. These findings suggested wide damage of myocardial cells, even in regions with no marked changes in myocardial cells with hematoxylin and eosin staining. These areas corresponded to those with strong accumulation of lymphocytes. Conclusions Immunohistochemistry for complement C9 and sirtuin 1 might become a new tool for evaluating damage of myocardial cells of fulminant acute myocarditis.

Glycoproteomic Analysis Reveals Aberrant Expression of Complement C9 and Fibronectin in the Plasma of Patients with Colorectal Cancer

Colorectal cancer (CRC) is a major cause of cancer mortality. Currently used CRC biomarkers provide insufficient sensitivity and specificity; therefore, novel biomarkers are needed to improve the CRC detection. Label-free quantitative proteomics were used to identify and compare glycoproteins, enriched by wheat germ agglutinin, from plasma of CRC patients and age-matched healthy controls. Among 189 identified glycoproteins, the levels of 7 and 15 glycoproteins were significantly altered in the non-metastatic and metastatic CRC groups, respectively. Protein-protein interaction analysis revealed that they were predominantly involved in immune responses, complement pathways, wound healing and coagulation. Of these, the levels of complement C9 (C9) was increased and fibronectin (FN1) was decreased in both CRC states in comparison to those of the healthy controls. Moreover, their levels detected by immunoblotting were validated in another independent cohort and the results were consistent with in the study cohort. Combination of CEA, a commercial CRC biomarker, with C9 and FN1 showed better diagnostic performance. Interestingly, predominant glycoforms associated with acetylneuraminic acid were obviously detected in alpha-2 macroglobulin, haptoglobin, alpha-1-acid glycoprotein 1, and complement C4-A of CRC patient groups. This glycoproteomic approach provides invaluable information of plasma proteome profiles of CRC patients and identification of CRC biomarker candidates.

4336 Renal Tubular Complement C9 Deposition is Associated with Renal Tubular Damage and Fibrosis in Lupus Nephritis

OBJECTIVES/GOALS: Tubulointerstitial damage in lupus nephritis (LN) is a strong predictor of progression to chronic kidney disease and end stage renal disease (ESRD). While complement activation mediates glomerular injury, the role of complement in renal tubular damage has not been evaluated. We investigated the association between complement activation and tubulointerstitial fibrosis. METHODS/STUDY POPULATION: Patients with LN were selected randomly between July 2014 - July 2016. Chromogenic immunohistochemistry was performed on formalin-fixed, paraffin-embedded, 4-µm human renal biopsy sections using unconjugated, murine anti-human Complement C9 (Hycult Biotech, clone X197) as a marker of the terminal complement activation. Positive control is C3 glomerulopathy and negative control is normal kidney. Tubular basement membrane C9 staining intensity were analyzed on semiquantitative scale 0 to 3 by a renal pathologist. Interstitial fibrosis/tubular atrophy were categorized into low (0–10%), medium (11–20%), or high (≥21%). Clinical parameters were assessed at time of biopsy and 6 months post biopsy. Bivariate associations were assessed between presence of tubular C9 (C9+) and other covariates. RESULTS/ANTICIPATED RESULTS: Renal biopsies from 30 LN studied, 23 (77%) of which had proliferative LN. There were 24 (80%) women, mean (SD) age 33 (12) years. Positive tubular C9 staining was observed in 7/30 (23%) biopsies. At time of renal biopsy, C9+ patients had significantly higher urine protein, compared to C9- patients: median (IQR) 6.2g (3.3-13.1) vs. 2.4g (1.3-4.6), p<0.01. The differences persisted at 6 months after induction therapy: 1.08g (1.0-8.3) in C9+ vs. 0.68g (0.2-2.1) in C9- patients, p = 0.06. There was no significant difference in creatinine at renal biopsy between the two groups. Tubular C9 deposition was associated with interstitial fibrosis: 49% had severe interstitial fibrosis vs. none in the C9- group, p = <0.01. Higher proportion of C9+ patients had moderate NIH Chronicity index: 42.9% vs 8.7% in the C9- group, p = 0.07. DISCUSSION/SIGNIFICANCE OF IMPACT: Tubular C9 deposition is significantly associated with proteinuria, interstitial fibrosis and increased chronicity which predict progression to ESRD and high mortality. This finding suggests that complement activation in the tubules may be linked to proteinuria and contribute to mechanism in tubulointerstitial damage in LN.

Significant changes in ITIH4, AHSG, ORM1, and CD46 content in milk fat globule membrane proteins of ketotic dairy cows

High concentrations of non-esterified fatty acid (NEFA) and β-hydroxybutyrate (BHBA) in cows’ blood caused by ketosis are associated with inflammatory states. We hypothesised that ketosis in postparturient dairy cows would result in altered levels on inflammation-related proteins not only in plasma but also in the milk fat globule membranes (MFGM). Thirty cows were selected from a dairy farm in Heilongjiang, China. Inflammatory milk fat globule membrane proteins were detected using ELISA kits, and a fully automatic biochemical analyser was used to measure the concentrations of BHBA, NEFA, glucose (GLU) and triglyceride (TG) in plasma. MFGM protein from milk of ketotic cows contained significantly different concentrations of acute-phase response proteins (complement C3 (C3), prothrombin (F2), alpha-1-acid glycoprotein (ORM1), inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4), alpha-2-HS-glycoprotein (AHSG), complement C9 (C9), complement regulatory protein variant 4 (CD46)) in comparison with milk from non-ketotic cows. Blood concentrations of C3, complement C9 (C9), tumour necrosis factor α (TNFα), MFGM C3, monocyte differentiation antigen CD14 (CD14) and ORM1 levels were correlated with energy balance. ITIH4 and CD46 increased, and AHSG and ORM1 decreased before the onset of ketosis. These biomarkers offer potential as predictors and monitors of ketosis in at-risk cows.