Serum complement proteins rather than inflammatory factors is effective in predicting psychosis in individuals at clinical high risk.

Immunological/inflammatory factors are implicated in the development of psychosis. Complement is a key driver of inflammation; however, it remains unknown which factor is better at predicting the onset of psychosis. This study aimed to compare the alteration and predictive performance of inflammation and complement in individuals at clinical high risk (CHR). We enrolled 49 individuals at CHR and 26 healthy controls (HCs). Twenty-five patients at CHR had converted to psychosis (converter) by the 3-year follow-up. Inflammatory cytokines, including interleukin (IL)-1ß, 6, 8, 10, tumor necrosis factor-alpha (TNF-alpha), macrophage colony-stimulating factor levels, and complement proteins (C1q, C2, C3, C3b, C4, C4b, C5, C5a, factor B, D, I, H) were measured by enzyme-linked immunosorbent assay at baseline. Except for TNF- alpha, none of the inflammatory cytokines reached a significant level in either the comparison of CHR individuals and HC or between CHR-converters and non-converters. The C5, C3, D, I, and H levels were significantly lower (C5, p = 0.006; C3, p = 0.009; D, p = 0.026; I, p = 0.016; H, p = 0.019) in the CHR group than in the HC group. Compared to non-converters, converters had significantly lower levels of C5 (p = 0.012) and C5a (p = 0.007). None of the inflammatory factors, but many complement factors, showed significant correlations with changes in general function and symptoms. None of the inflammatory markers, except for C5a and C5, were significant in the discrimination of conversion outcomes in CHR individuals. Our results suggest that altered complement levels in the CHR population are more associated with conversion to psychosis than inflammatory factors. Therefore, an activated complement system may precede the first-episode of psychosis and contribute to neurological pathogenesis at the CHR stage.

CD46 knock-out using CRISPR/Cas9 editing of hTERT immortalized human cells modulates complement activation.

The kidney is especially sensitive to diseases associated with overactivation of the complement system. While most of these diseases affect kidney glomeruli and the microvasculature, there is also evidence for tubulointerstitial deposition of complement factors. Complement inactivating factors on cell membranes comprise CD55, CD59 and CD46, which is also termed membrane cofactor protein (MCP). CD46 has been described as localized to glomeruli, but especially also to proximal tubular epithelial cells (RPTECs). However, human cell culture models to assess CD46 function on RPTECs are still missing. Therefore, we here performed gene editing of RPTEC/TERT1 cells generating a monoclonal CD46-/- cell line that did not show changes of the primary cell like characteristics. In addition, factor I and CD46-mediated cleavage of C4b into soluble C4c and membrane deposited C4d was clearly reduced in the knock-out cell line as compared to the maternal cells. Thus, human CD46-/- proximal tubular epithelial cells will be of interest to dissect the roles of the epithelium and the kidney in various complement activation mediated tubulointerstitial pathologies or in studying CD46 mediated uropathogenic internalization of bacteria. In addition, this gives proof-of-principle, that telomerized cells can be used in the generation of knock-out, knock-in or any kind of reporter cell lines without losing the primary cell characteristics of the maternal cells.

C4d as a Diagnostic Tool in Proliferative GN.

Proliferative GN is classified as immune complex-mediated or complement-mediated (C3 glomerulopathy). Immune complex-mediated GN results from glomerular deposition of immune-complexes/Ig and C3; the C3 is derived from activation of the classical and/or lectin pathways of complement. C3 glomerulopathy results from deposition of C3 and other complement fragments with minimal or no deposition of immune complexes/Ig; the C3 is derived from activation of the alternative pathway of complement. C4d is a byproduct of activation of the classic and lectin pathways. Although widely used as a marker for antibody-mediated rejection, the significance of C4d in C3 glomerulopathy is undetermined. We studied glomerular C4d staining in 18 biopsy specimens of immune-complex GN, 30 biopsy specimens of C3 GN, and 13 biopsy specimens of postinfectious GN. All specimens of immune complex-mediated GN, except two specimens of IgA nephropathy and one specimen of sclerosing membranoproliferative GN, showed bright (2-3+) C4d staining. The staining pattern of C4d mirrored the staining patterns of Ig and C3. Conversely, C4d staining was completely negative in 24 (80%) of 30 specimens of C3 glomerulopathy, and only trace/1+ C4d staining was detected in six (20%) specimens. With regard to postinfectious GN, C4d staining was negative in six (46%) of 13 specimens, suggesting an abnormality in the alternative pathway, and it was positive in seven (54%) specimens. To summarize, C4d serves as a positive marker for immune complex-mediated GN but is absent or minimally detected in C3 glomerulopathy.

Acute Rejection Clinically Defined Phenotypes Correlate With Long-term Renal Allograft Survival.

BACKGROUND: Classification of acute rejection (AR) based on etiology and timing may provide a means for enhancing therapeutic results and allograft survival. This study evaluated graft and patient survival after the first AR episodes among kidney transplant recipients with an early or late antibody-mediated rejection (AMR), acute cellular rejection (ACR) or mixed AR (MAR). METHODS: A prospective institutional review board-approved database was queried to identify biopsy-proven first AR episodes occurring from January 2005 to October 2012. The ACR was defined by Banff criteria; borderline AR was excluded. The AMR was defined as 3 of 4 criteria: renal dysfunction, donor specific antibody, C4d positivity on biopsy, and histological changes. The MAR met criteria for both ACR and AMR. Early AR occurred within six months post-transplant. AR episodes were then assigned to 1 of the 6 categories--early AMR, early ACR, early MAR, late AMR, late ACR, and late MAR. RESULTS: One hundred eighty-two kidney transplant recipients identified with a first AR episode. Mean follow-up was 773 days (± 715 days). No difference was observed in patient survival. Death-censored graft survival was 84%. Death-censored graft loss was higher with late versus early AMR (P = 0.01) and late versus early ACR (P = 0.03), but not late versus early MAR (P = 0.3). CONCLUSIONS: The AR type demonstrated a hierarchy for graft survival with ACR better than MAR better than AMR, which persisted for both early and late AR. Improvement in long-term results of AR may require development of specific treatment for individual AR types.

Antibodies reactive to cleaved sites in complement proteins enable highly specific measurement of soluble markers of complement activation.

An emerging number of diseases and therapeutic approaches with defined involvement of the complement system justify a need for specific markers reflecting activation of particular effector arms of the complement cascade. Measurement of such soluble markers in circulation is a challenge since the specificity of antibodies must be limited to activated complement fragments but not predominant and ubiquitous parental molecules. Existing assays for the measurement of soluble, activated complement proteins are based on the detection of conformational neoepitopes. We tested an alternative approach based on detection of short linear neoepitopes exposed at the cleavage sites after activation of the actual complement component. Obtained antibodies reactive to C4d and C5b fragments enabled us to set up highly specific sandwich ELISAs, which ensured trustful measurements without false positive readouts characteristic for some of the widely used assays.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy accompanied by renal arteriolar C4d deposition.

HSCT-associated thrombotic microangiopathy (TA-TMA) is a severe complication with a poor prognosis. Recently, it has been reported that complement system dysregulation, such as CFH autoantibodies and deletions CFH-related genes 3 and 1, induced TA-TMA. In addition, C4d-positive renal arterioles are both a good marker of complement system activation and a useful diagnostic tool for TA-TMA. Because dysregulation of the complement system is associated with TA-TMA, the complement system might be a therapeutic target, such as eculizumab, a terminal complement inhibitor. Herein, we describe an eight-yr-old boy who developed TA-TMA accompanied by severe renal dysfunction. His renal specimen showed diffuse C4d deposition in the renal arterioles, which is consistent with TA-TMA. Although the patient gradually improved without eculizumab, renal arteriolar C4d staining in sample with TA-TMA shows the complement system activation and may guide the target therapy using the eculizumab.

The severity of acute cellular rejection defined by Banff classification is associated with kidney allograft outcomes.

BACKGROUND: It is unclear if the severity or the timing of acute cellular rejection (ACR) defined by Banff classification 2009 is associated with graft survival. METHODS: Borderline changes, TCMR I (interstitial rejection), and TCMR II/III (vascular rejection) were defined as low, moderate, and high ACR severity, respectively. Approximately 270 patients who had at least one episode of ACR were enrolled, 270 biopsies were chosen which showed the highest ACR severity of each patient and were negative for donor-specific antibodies (DSA), C4d, and microcirculation changes (MC). Six months were used as the cutoff to define early and late ACR; 370 patients without biopsy posttransplantation were recruited in the control group. RESULTS: Up to 8-year posttransplantation, death-censored graft survival (DCGS) rates of control, borderline, TCMR I, and TCMR II/III groups were 97.6%, 93.3%, 79.6%, and 73.6% (log rank test, P<0.001); the control group had significantly higher DCGS rate than the three ACR groups (each pairwise comparison yields P<0.05). The DCGS rate of late ACR was significantly lower compared with early ACR (63.6% vs. 87.4%, P<0.001). Intimal arteritis (Banff v-lesion) was an independent histologic risk factor correlated with long-term graft loss regardless of the timing of ACR. The v-lesions with minimal or high-grade tubulitis displayed similar graft survival (72.7% vs. 72.9%, P=0.96). CONCLUSION: All types of ACR affect long-term graft survival. Vascular or late ACR predict poorer graft survival; the extent of tubulointerstitial inflammation (TI) is of no prognostic significance for vascular rejection.

Suppression of Th1 cytokine production by a peptide derived from C4b.

OBJECTIVES: The complement system has been proposed to play a significant role in the regulation of T-cell responses. However, the precise mechanism underlying C4-induced immune tolerance remains to be clarified. We recently reported that monomeric C4b inhibits CXCL10 production from blood cells. The purpose of this study was to verify the active site of monomeric C4b. MATERIALS AND METHODS: We investigated the in vitro effects of a C4b-derived peptide (VPAGSARPVAFSVVPTAAA), named HP2 (highly homologous peptide 2), on the IFN-ß-induced production of CXCL10 in human blood and the in vivo effects of the administration of HP2 on Th1/2 cytokine production in the spleen in mice. We also tested whether the administration of HP2 influences symptoms of experimentally induced ulcerative colitis in mice. RESULTS: HP2 inhibited CXCL10 production in human blood, and the administration of HP2 significantly suppressed the production of Th1 cytokines, such as IL-2, IFN-γ, and TNF-α, in spleen cells isolated from mice. The administration of HP2 in the mice significantly improved the symptoms of colitis, with down-regulation of colitogenic CD4(+)CD45RB(high) T cells and up-regulation of CD4(+)LAP/TGF-ß1(+) T cells. CONCLUSION: The amino acid sequence described above is suggested to be the active site in C4b for the inhibition of Th1 cytokine production. These results should contribute to the development of new drugs suppressing autoimmune responses.

Pretransplant donor-specific anti-HLA antibodies as predictors of early allograft rejection in ABO-compatible liver transplantation.

The significance of preexisting donor-specific HLA antibodies (HLA-DSAs) for liver allograft function is unclear. Our previous studies have shown that humoral alloreactivity frequently accompanies acute cellular rejection (ACR). In the present study, we set out to determine whether pretransplant HLA-DSAs correlate with clinically significant ACR in the first 90 days after transplantation and, if so, to determine their predictive values. Class I HLA-DSAs and class II HLA-DSAs were determined by single-antigen bead flow cytometry for 113 consecutive adult transplants. A statistical analysis was performed for data from 109 consecutive patients with graft survival greater than or equal to 90 days. All patients who developed biochemical graft dysfunction underwent liver biopsy for hematoxylin-eosin and complement component 4d staining. Cox proportional hazards models and associated hazard ratios revealed a significant association of pretransplant HLA-DSAs with clinically significant ACR: this association started with a mean fluorescence intensity (MFI) as low as 300 for both class I (hazard ratio = 2.7, P < 0.01) and class II (hazard ratio = 6.0, P < 0.01). Pretransplant HLA-DSAs were associated with an increased risk of ACR: P < 0.01 for class I (42% versus 18%), P < 0.001 for class II (37% versus 7%), and P < 0.001 for either class I or II (36% versus 3%). Class I or II HLA-DSAs with an MFI ≥ 1000 had the best positive predictive value for clinically significant ACR at 46%, whereas class I or II HLA-DSAs with an MFI ≥ 300 had the best negative predictive value at 97.1%. Although our study was based on consecutive patients, it was limited by the relatively low number of single-center subjects. In conclusion, the present study indicates that pretransplant HLA-DSAs, even at low levels of allosensitization, correlate with the risk of clinically significant ACR. Our findings suggest that anti-human leukocyte antigen antibodies could serve as donor-specific markers of immunoreactivity to the liver graft.

Failure of bortezomib to cure acute antibody-mediated rejection in a non-compliant renal transplant patient.

Bortezomib has appeared recently as a potential active treatment for acute AMR for few years. We reported a patient who received two courses of bortezomib for the treatment of an acute AMR associated with de novo HLA DSA that occurred 18 months after renal transplantation because of non-compliance. Graft biopsy revealed features of acute humoral rejection with plasmocyte infiltration and C4d staining. Bortezomib was associated with corticosteroid pulses, IVIgs, and PP. Despite this rapid management, the patient lost his graft and carried on dialysis. Bortezomib therapy in addition to current therapy of AMR is not always effective in the treatment for late acute AMR in renal transplantation. We discuss on the place of such a treatment and other therapeutic strategies in this indication.

Donor-specific antibodies: can they predict C4d deposition in pediatric heart recipients?

There is limited evidence regarding the utility of circulating DSA in surveillance for AMR of pediatric heart recipients. Our hypothesis is that quantitation of DSA improves their power for predicting a C4d+, an integral component in the current diagnostic criteria of AMR. All pediatric recipients transplanted between 10/2005 and 1/2011 were retrospectively reviewed for DSA determined within 48 h of EMB. C4d+ was defined as >25% endothelial cell staining by immunohistochemical methods. A total of 183 paired DSA-EMB determinations were identified in 60 patients, a median of three paired studies per patient (range: 1-9). DSA were detected in 60 of these determinations. A receiver-operating characteristic plot identified a threshold single-antibody MFI of >6000 that strongly correlated with C4d+ (p < 0.0001) with a high negative predictive value (0.97) and specificity (0.95). The sensitivity and positive predictive values were 0.71 and 0.60, respectively. The predictive power of single-antigen DSA for C4d deposition was improved in pediatric heart recipients using an institution-specific MFI threshold value. In post-transplant care, quantitative DSA should be an essential component in the surveillance for AMR.

Complement component 4d immunostaining in liver allografts of patients with de novo immune hepatitis.

De novo immune hepatitis (DNIH) is a form of late graft dysfunction after liver transplantation. The fine mechanisms leading to the development of DNIH are not known, and whether this hepatitis is a form of rejection or a result of an auto/alloimmune injury has not been established. In our patients, DNIH was always preceded by the production of donor-specific antibodies against the glutathione S-transferase T1 (GSTT1) enzyme because of a genetic mismatch in which the donors carried the wild-type gene and the recipients displayed the null genotype. Complement component 4d (C4d) immunopositivity in 12 paraffin-embedded liver biopsy samples from 8 patients diagnosed with DNIH associated with anti-GSTT1 antibodies was retrospectively evaluated. Six patients with a diagnosis of chronic rejection (CR) and 7 patients with hepatitis C virus recurrence were included as control groups. Among the patients with DNIH, 7 showed C4d-positive immunostaining localized in the portal tracts, whereas in the tested biopsy samples of the 2 control groups, this staining pattern was absent. Four biopsy samples of the CR group showed C4d-positive sinusoidal staining. This study confirms the activation of the complement pathway in the presence of donor-specific antibodies, which was shown by the deposition of C4d elements in liver biopsy samples of patients with DNIH. The use of C4d as a marker of antibody-mediated rejection in liver allografts in the presence of antidonor antibodies is discussed, and it may contribute to improved differential diagnoses based on biopsy findings.

C4d-fixing capability of low-level donor-specific HLA antibodies is not predictive for early antibody-mediated rejection.

BACKGROUND: Recent studies indicate that not all low-level donor-specific human leukocyte antigen (HLA) antibodies (HLA-DSA) (i.e., positive by solid-phase assays, negative by complement-dependent cytotoxic-crossmatch) have a detrimental clinical impact. The aim of this study was to investigate whether the pretransplant C4d-fixing capability allows distinguishing harmful from presumably clinically irrelevant HLA-DSA. METHODS: We retrospectively investigated 64 patients with low-level HLA-DSA detected by single-antigen flow beads (SAFB). Thirty-four of 64 patients (53%) experienced early antibody-mediated rejection (AMR), whereas 30 patients (47%) did not. HLA-DSA characteristics (i.e., number, class, and strength), frequency of retransplants, and immunosuppressive regimens were not different in these two groups. Pretransplant sera were reanalyzed using a modified SAFB assay measuring C4d fixation induced by HLA antibodies. RESULTS: C4d-fixing HLA-DSA were observed in 11 of 64 patients (17%). AMR occurred in 6 of 11 patients (55%) with C4d-fixing HLA-DSA and in 28 of 53 patients (53%) without C4d-fixing HLA-DSA (P=1.0). Positive C4d staining in peritubular capillaries was detected in 6 of 11 patients (55%) with C4d-fixing HLA-DSA and in 21 of 53 patients (40%) without C4d-fixing HLA-DSA (P=0.50). CONCLUSION: The pretransplant capability of low-level HLA-DSA to trigger C4d fixation in vitro is not predictive for early AMR or C4d deposition in peritubular capillaries in vivo. This argues against pretransplant C4d SAFB testing to define the clinical relevance of low-level HLA-DSA.

B-cell immunity in the context of T-cell tolerance after combined kidney and bone marrow transplantation in humans.

Five patients with end-stage kidney disease received combined kidney and bone marrow transplants from HLA haploidentical donors following nonmyeloablative conditioning to induce renal allograft tolerance. Immunosuppressive therapy was successfully discontinued in four patients with subsequent follow-up of 3 to more than 6 years. This allograft acceptance was accompanied by specific T-cell unresponsiveness to donor antigens. However, two of these four patients showed evidence of de novo antibodies reactive to donor antigens between 1 and 2 years posttransplant. These humoral responses were characterized by the presence of donor HLA-specific antibodies in the serum with or without the deposition of the complement molecule C4d in the graft. Immunofluorescence staining, ELISA assays and antibody profiling using protein microarrays demonstrated the co-development of auto- and alloantibodies in these two patients. These responses were preceded by elevated serum BAFF levels and coincided with B-cell reconstitution as revealed by a high frequency of transitional B cells in the periphery. To date, these B cell responses have not been associated with evidence of humoral rejection and their clinical significance is still unclear. Overall, our findings showed the development of B-cell allo- and autoimmunity in patients with T-cell tolerance to the donor graft.

A chemical approach to immunoprotein engineering: chemoselective functionalization of thioester proteins in their native state.

Less than 6 feet under: Serum proteins C3, C4, and alpha(2)M each contain a thioester domain buried within a hydrophobic pocket, which is thought to shield the labile thioester from hydrolysis. Herein, we make use of the inherent reactivity of the hydrazide for thioester moieties to chemoselectively label these crucial serum regulators in their native conformation; this demonstrates that access to the thioester site is much greater than previously supposed.

Differences in protein distribution between human plasma preparations, EDTA-plasma and heparin-plasma, analyzed by non-denaturing micro-2-DE and MALDI-MS PMF.

The effects of plasma preparation methods on the status of human plasma proteins were analyzed by non-denaturing micro-2-DE followed with polypeptide assignment with MALDI-TOF MS and PMF. In order to facilitate the separation of high-molecular-mass plasma proteins (up to ca. 2x10(3) kDa) in short separation time, agarose micro-IEF gels were employed. The comparisons of the 2-DE patterns between EDTA-plasma (1.0 mg EDTA/mL blood) and heparin-plasma (0.025 mg heparin/mL blood) revealed the differences in protein distribution around pI 5.4-6.5 and apparent molecular mass of ca. 1x10(3) kDa, which were mainly attributed to the presence of the complexes of complement C4b and C4b-binding protein in heparin-plasma and their absence in EDTA-plasma. The distribution of several spots around pI 5.0-5.6 and apparent molecular mass 1.2-1.5x10(2) kDa was also found to be different; the fragments of complement C3 and C4 were detected in heparin-plasma but not in EDTA-plasma. The 2-DE pattern of high-heparin-plasma (0.50 mg heparin/mL blood) showed pI changes of three plasma proteins, fibronectin, complement factor B, and pre-alpha-inhibitor when compared with that of heparin-plasma, suggesting the interactions between heparin and the proteins. These results demonstrated that subtle changes in plasma proteins, caused by the different plasma preparation procedures, can be analyzed by non-denaturing agarose-IEF/micro-2-DE followed by MALDI-MS and PMF.

Anti-human leukocyte antigen antibodies, vascular C4d deposition and increased soluble c4d in broncho-alveolar lavage of lung allografts.

BACKGROUND: The hallmark of humoral rejection is the presence of subendothelial C4d in the allograft. A simultaneous determination of vascular C4d with soluble C4d in broncho-alveolar lavage fluid (BAL) and circulating anti-human leukocyte antigen (HLA) antibodies (HLA-Ab) has not been reported in lung transplantation. METHODS: Forty-two consecutive lung-transplant patients were included in this cross-sectional study. The presence and specificity of HLA-Ab was determined at the same frequency with transbronchial biopsies. Soluble C4d levels were measured by enzyme-linked immunosorbent assay in all 42 patients. In a subgroup of 32 patients with available timely matched paraffin-embedded tissue sections, the vascular C4d deposition was also assessed. RESULTS: The presence of HLA-Ab in 16 patients was associated with biopsy-proven acute rejection (10/16 vs. 3/16, P<0.01) and increased immunosuppression (13/16 vs. 4/16, P<0.005). Pulmonary function was also decreased in patients with HLA-Ab (mean forced expiratory volume in 1 second=49%) when compared with the control group (mean forced expiratory volume in 1 second=66%, P<0.05). Nine patients exhibited specific vascular C4d deposition and in eight of nine (89%) cases HLA-Ab were detected, versus 8 of 23 (35%) in C4d-negative patients (P<0.05). Soluble C4d in BAL was highly (>0.5 microg/mL) elevated in patients with HLA-Ab and vascular C4d and was moderately (0.2 microg/mL) increased in patients with antibodies but C4d-negative. In contrast, only a slight elevation of soluble C4d (<0.1 microg/mL) was detected in patients without HLA-specific antibodies. CONCLUSIONS: The association of HLA-specific antibodies with vascular C4d deposition and soluble C4d in BAL, in addition to the reduced pulmonary function, might constitute a diagnostic triad for antibody-mediated rejection in lung transplant patients.

The Kaposi's sarcoma-associated herpesvirus complement control protein mimics human molecular mechanisms for inhibition of the complement system.

Kaposi's sarcoma-associated human herpesvirus (KSHV) is thought to cause Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. Previously, we reported that the KSHV complement control protein (KCP) encoded within the viral genome is a potent regulator of the complement system; it acts both as a cofactor for factor I and accelerates decay of the C3 convertases (Spiller, O. B., Blackbourn, D. J., Mark, L., Proctor, D. G., and Blom, A. M. (2003) J. Biol. Chem. 278, 9283-9289). KCP is a homologue to human complement regulators, being comprised of four complement control protein (CCP) domains. In this, the first study to identify the functional sites of a viral homologue at the amino acid level, we created a three-dimensional homology-based model followed by site-directed mutagenesis to locate complement regulatory sites. Classical pathway regulation, both through decay acceleration and factor I cleavage of C4b, required a cluster of positively charged amino acids in CCP1 stretching into CCP2 (Arg-20, Arg-33, Arg-35, Lys-64, Lys-65, and Lys-88) as well as positively (Lys-131, Lys-133, and His-135) and negatively (Glu-99, Glu-152, and Asp-155) charged areas at opposing faces of the border region between CCPs 2 and 3. The regulation of the alternative pathway (via factor I-mediated C3b cleavage) was found to both overlap with classical pathway regulatory sites (Lys-64, Lys-65, Lys-88 and Lys-131, Lys-133, His-135) as well as require unique, more C-terminal residues in CCPs 3 and 4 (His-158, His-171, and His-213) and CCP 4 (Phe-195, Phe-207, and Leu-209). We show here that KCP has evolved to maintain the spatial structure of its functional sites, especially the positively charged patches, compared with host complement regulators.