An anticomplement homogeneous polysaccharide from Hedyotis diffusa attenuates lipopolysaccharide-induced acute lung injury and inhibits neutrophil extracellular trap formation

BACKGROUND

Owing to the involvement of the overactivated complement system in acute lung injury (ALI) development, anticomplement components may attenuate ALI. Hedyotis diffusa is a traditional Chinese medicine for treating lung heat and its crude polysaccharides (HDP) exhibit significant anticomplement activity in vitro.

PURPOSE

To obtain an anticomplement homogeneous polysaccharide from HDP and verify its therapeutic effect and mechanism on ALI.

METHODS

Diethylaminoethyl-52 (DEAE-52) cellulose and gel permeation columns were used to isolate a homogeneous polysaccharide HD-PS-3, which was then characterized using nuclear magnetic resonance (NMR) and methylation analysis. In vitro, the anticomplement activities of HD-PS-3 through classical and alternative pathways were determined using a hemolytic test. The therapeutic effects of HDP and HD-PS-3 on ALI were evaluated in lipopolysaccharide (LPS) intratracheal instilled mice. Hematoxylin and eosin (H&E) staining, enzyme-linked immunosorbent assay (ELISA), and immunohistochemical staining were used to assess histological changes, measure cytokine levels, and evaluate the degree of complement component 3c (C3c) deposition and neutrophil infiltration, respectively. ELISA, western blotting, and immunofluorescence were used to analyze neutrophil extracellular trap (NET) formation.

RESULTS

From HDP, 1.5 g of the homogeneous polysaccharide HD-PS-3 was obtained. HD-PS-3 was an acidic heteropolysaccharide with an acetyl group, which was composed of →4,6)-α-Glcp-(1→, →3,4)-α-Glcp-(1→, →4)-α-Glcp-(1→, →4,6)-α-Galp-(1→, →5)-α-Araf-(1→, α-Rhap-(1→, α-Araf-(1→, α-GlcpA-(1→, →4)-β-Manp-(1→, β-Manp-(1→ and →3)-β-Manp-(1→. The in vitro results suggest that HD-PS-3 exhibited anticomplement activity with CH₅₀ and AP₅₀ values of 115 ± 12 μg/ml and 307 ± 11 μg/ml, respectively. After confirming the efficacy of HDP (200 mg/kg) in attenuating lung injury, the effect of HD-PS-3 on ALI was also investigated. HD-PS-3 (75 and 150 mg/kg) attenuated LPS-induced ALI as well, evidenced by lung pathology, lung injury scores, protein concentration, leukocyte counts, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) contents in bronchoalveolar lavage fluid (BALF). Mechanistically, HD-PS-3 inhibited complement activation, manifested in reduced pulmonary C3c deposition in lung tissue and complement component 3a (C3a) content in BALF. Neutrophil recruitment was also reduced by HD-PS-3, with significantly reduced pulmonary neutrophil infiltration and lower levels of C-X-C motif chemokine ligand 1 (CXCL1) and myeloperoxidase (MPO) in BALF. In addition, HD-PS-3 reduced the levels of MPO-DNA complex in BALF, decreased citrullinated histone H3 (Cit H3) expression and NET formation (colocalization of MPO, Cit H3, and DNA) in lung tissue.

CONCLUSION

An anticomplement homogeneous polysaccharide HD-PS-3 was isolated from H. diffusa. HD-PS-3 exhibited a therapeutic effect against ALI, and the mechanism might be related to its inhibitory effects on complement activation, neutrophil recruitment, and NET formation.

Diagnostic Utility of C4d by Direct Immunofluorescence in Bullous Pemphigoid

ABSTRACT

Bullous pemphigoid (BP) is an autoimmune blistering disease that commonly affects elderly patients. Direct immunofluorescence (DIF) for immunoglobulin G (IgG) and C3c on frozen skin biopsies is the gold standard for the diagnosis of BP. In a minority of cases, IgG and/or C3c are found negative, and in these situations, there is a need for a more stable diagnostic marker of BP. C4d is biologically inactive, but has a long half-life, rendering it a long-lived marker for antibody-mediated complement activation. Previous studies already demonstrated that C4d was diagnostically useful in formalin-fixed paraffin-embedded skin biopsies of patients with BP. We hypothesized that C4d detected by DIF could also be a promising diagnostic marker for BP, particularly in IgG and/or C3c DIF-negative cases. In this single-center retrospective study, 69 cases of BP were analyzed for linear deposition of C4d; of the 69 cases, n = 26 were IgG+/C3c-, n = 10 IgG+/C3c+, and n = 33 IgG-/C3c-. Results were compared with n = 39 negative controls. Seven of the 26 (27%) IgG+/C3c- and 3 of the 33 (9%) IgG-/C3c- BP cases were positive for C4d. All 10 IgG+/C3c+ cases were also C4d positive. In the negative control group, 2 of the 39 (5%) were found positive for C4d. In conclusion, the current study shows that C4d is a more sensitive but not a 100% specific marker of BP. We conclude that C4d by DIF could be an interesting diagnostic adjunct for BP, particularly in IgG-/C3c- double negative cases.

The Spectrum of C4d Deposition in Renal Biopsies of Lupus Nephritis Patients

Objectives

This study aimed to determine the prevalence and localization of complement factor C4d in renal biopsies from patients with lupus nephritis (LN), as well as its associations with the disease's clinico-pathological features. The correlation between arteriolar C4d deposition and renal microvascular lesions (RVLs) was further analyzed.

Methods

A total of 325 biopsy-proven LN patients were enrolled, and their clinico-pathological data were collected. C4d staining of renal biopsies was performed by immunohistochemistry. The associations between C4d deposition and the clinico-pathological features were further analyzed.

Results

C4d deposition was present in most (98.8%) renal specimens in our cohort. These deposits were localized in the glomeruli (98.2%), tubular basement membrane (TBM) (43.7%), arterioles (31.4%), and peritubular capillary (33.8%). Patients with TBM C4d staining had higher disease activity (measured with the Systemic Lupus Erythematous Disease Activity Index) and higher National Institutes of Health pathological activity and chronicity indices (all P < 0.01). Patients with arteriolar C4d deposition were more likely to develop RVLs (91.2%) compared to those with no arteriolar C4d deposition (78.0%; P = 0.004), especially with two or more types of RVLs (P < 0.001). During the mean follow-up of 55.8 months, arteriolar C4d was related to worse renal outcomes [hazard ration (HR): 2.074, 95% confidence interval (CI) 1.056-4.075, P = 0.034]. Multivariate Cox hazard analysis showed that co-deposition of arteriolar C4d and C3c was an independent risk factor (HR: 3.681, 95% CI 1.519-8.921, P = 0.004) for predicting renal outcomes.

Conclusions

C4d deposition was common in renal tissues from LN patients. TBM C4d deposition was related to the disease activity, and arteriolar C4d deposition was associated with RVLs and worse renal outcomes.

Complement component 3c and tumor necrosis factor-α systemic assessment after Candida antigen immunotherapy in cutaneous warts

BACKGROUND

Cutaneous warts are the commonest benign lesion produced by human papillomavirus. Lesions often regress spontaneously yet have a high rate of recurrence. They impair patients' quality of life and carry the potential risk of cancer. Nowadays, Candida antigen immunotherapy has become an encouraging therapeutic modality for warts. We tried to assess the role of the complement pathway and T helper 1 immune response in clinical response to Candida antigen immunotherapy via complement component 3c (C3c) and tumor necrosis factor (TNF)-α, respectively.

METHODS

A total of 44 patients with cutaneous warts were enrolled in the study. Patients were injected with Candida antigen at 2-week interval until complete clearance of the lesion or for a maximum of 5 sessions. Blood samples were collected before initiation and after completion of immunotherapy. C3 and C4 were measured using an automated turbidimetric method. Mannose-binding lectin (MBL), C3c, and TNF-α were measured using enzyme-linked immune sorbent assay.

RESULTS

A total of 56.4%, 17.9%, and 25.7% of the patients showed complete, partial, and no response to immunotherapy, respectively. Lesions on the dorsum of the foot and sole showed significant clearance (p value = 0.037). All patients had no deficient C3, C4, and MBL serum levels. C3c and TNF-α serum levels were significantly higher in non-responder group (p value < 0.001 and < 0.001, respectively). C3c and TNF-α serum levels were strongly correlated in all the studied patients (r = 0.8, p value < 0.001).

CONCLUSIONS

Candida antigen immunotherapy is an effective therapeutic modality for cutaneous warts. C3c and TNF-α serum levels were higher in patients who failed to respond to immunotherapy.

CLINICAL TRIAL REGISTRY NUMBER

NCT04399577 , May 2020 "retrospectively registered".

Impact of Endograft Material on the Inflammatory Response After Elective Endovascular Abdominal Aortic Aneurysm Repair

The purpose of this paper is to examine the impact of endograft material on the inflammatory response after elective endovascular abdominal aortic aneurysm repair. Consecutive patients (n=22, all men, 53 to 82 years old) were divided into 2 groups according to the graft material used: In group A (n=12) the endovascular device was made of polyester and in group B (n=10) the device was made of expanded polytetrafluoroethylene (ePTFE). All patients received antiinflammatory drugs in the perioperative period. Fever, white blood cells and platelet count, serum concentrations of cytokines (interleukin 6 [IL-6], tumor necrosis factor alpha [TNF-a], interleukin 8 [IL-8], acute-phase proteins high-sensitivity C-reactive protein [hsCRP] and alpha1-antitrypsin [a1-antitrypsin]), and complement protein (C3a) were measured preoperatively and 1, 3, 6, 24, 48, and 72 hours after aneurysm exclusion. One patient in each group had a systemic inflammatory response syndrome with 2 of the systemic inflammatory response syndrome (SIRS) criteria. No other complication associated with inflammation were present in any patient. Fever was more frequent in group A patients. Increases of white blood cells and serum concentrations of IL-6, TNF-a, hsCRP, a1-antitrypsin, and C3a and decrease of platelet count were recorded in both groups, but no statistically significant difference between them was recorded. However, serum concentrations of IL-8 were significantly higher in group A patients 24 hours postoperatively (p=0.01). No significant difference was apparent in the biological response between patients receiving a polyester or an ePTFE stent graft, except for fever and serum concentrations of IL-8.

A revised mechanism for the activation of complement C3 to C3b: a molecular explanation of a disease-associated polymorphism

The solution structure of complement C3b is crucial for the understanding of complement activation and regulation. C3b is generated by the removal of C3a from C3. Hydrolysis of the C3 thioester produces C3u, an analog of C3b. C3b cleavage results in C3c and C3d (thioester-containing domain; TED). To resolve functional questions in relation to C3b and C3u, analytical ultracentrifugation and x-ray and neutron scattering studies were used with C3, C3b, C3u, C3c, and C3d, using the wild-type allotype with Arg(102). In 50 mm NaCl buffer, atomistic scattering modeling showed that both C3b and C3u adopted a compact structure, similar to the C3b crystal structure in which its TED and macroglobulin 1 (MG1) domains were connected through the Arg(102)-Glu(1032) salt bridge. In physiological 137 mm NaCl, scattering modeling showed that C3b and C3u were both extended in structure, with the TED and MG1 domains now separated by up to 6 nm. The importance of the Arg(102)-Glu(1032) salt bridge was determined using surface plasmon resonance to monitor the binding of wild-type C3d(E1032) and mutant C3d(A1032) to immobilized C3c. The mutant did not bind, whereas the wild-type form did. The high conformational variability of TED in C3b in physiological buffer showed that C3b is more reactive than previously thought. Because the Arg(102)-Glu(1032) salt bridge is essential for the C3b-Factor H complex during the regulatory control of C3b, the known clinical associations of the major C3S (Arg(102)) and disease-linked C3F (Gly(102)) allotypes of C3b were experimentally explained for the first time.

Role of humoral mechanisms in etiology of lichen planus

AIM

To examine the role of IgA, CIC and component C3 as indicators of humoral immune response in the etiopathogenesis of oral erosive lichen planus (OELP).

MATERIAL AND METHOD

The study comprised 19 patients with OELP whose samples of blood, saliva and tissue were obtained after carefully taken medical history and clinical examination. Samples of oral mucosa were taken from the site of lesion, i.e. exclusively from buccal mucosa (1 cm in width and length), and from the deep epithelium as well as a segment from the lamina propria. Determination of immunoglobulins in serum and saliva, and determination of component C3, was done using the micro-elisa technique by Rook&Cameron, Engvall and Ulman. Determination of CIC in serum and mixed saliva was done with the PEG (polyethylene glycol) method. Determination of immunoglobulin A and component C3 in biopsy material was done with direct immunofluorescence.

RESULTS

Levels of immunoglobulin A in serum in OELP during exacerbation were decreased (1.04±0.49 gr/l) and during remission increased (5.92±0.62) in comparison with the control group (p<0.001). Levels of CIC during exacerbation and remission were increased (p<0.001), and component C3 levels were increased in both examined phases in the examined group compared with the control group (p<0.05). Deposits of IgA were registered in one (5.88%) patient with OELP and component C3 was registered in 3 (17.64%) patients.

CONCLUSION

Changes in IgA values, as well as CIC and component C3, may correlate with changes in oral mucosa emphasizing the role of humoral immune response in the pathogenesis of oral lichen planus.

Complement-mediated muscle cell lysis: a possible mechanism of myonecrosis in anti-SRP associated necrotizing myopathy (ASANM)

The mechanism of necrotizing myopathy associated with antibodies to signal recognition particle (SRP) remains unclear. We investigated the effect of anti-SRP+serum and complement on cell viability in myoblast cultures. Cell viability was only slightly reduced by incubation with anti-SRP+serum compared with control serum. However, the addition of fresh complement resulted in a marked reduction in cell survival. Surface immunostaining for SRP, C3c and C5b-9 was demonstrated in cultures pre-incubated with anti-SRP+serum and complement, and in muscle biopsies from patients with myopathy. These findings provide further support for a complement-dependent antibody-mediated mechanism in anti-SRP associated myopathy.

Clinical and histological outcome predictors in renal limited pauci-immune crescentic glomerulonephritis: a single centre experience

Renal-limited vasculitis is a pauci-immune crescentic glomerulonephritis with no signs of systemic involvement, representing one of the most common causes of rapidly progressive glomerulonephritis. The study aims to examine clinical and histological features in twenty-four patients with RLV diagnosed by the Nephrology Department of Sapienza University of Rome, Italy, evaluating the role of these parameters in predicting renal survival. Patients details, clinical and histological features and outcomes were recorded at the time of renal biopsy and over a mean follow-up period of 36±6 months. In our study, serum creatinine at presentation was significantly higher in patients who had a poor outcome than in those who survived with independent renal function (6.3±2.47 mg/dl vs 2.84±2.01 mg/dl, P= 0.002). The presence of C3c was found in the area of glomerular fibrinoid necrosis and in small arteries and arterioles with fibrinoid necrosis in 17 patients (P= 0.018). In conclusion, serum creatinine at presentation and focal C3c depositions in areas of glomerular and arteriolar fibrinoid necrosis were the best determinants of poor renal outcome, maybe underlining the pathogenic role of alternative pathway activation of complement system but also demonstrating the focal distribution of necrotizing lesions.

Complement component C3 and complement receptor type 3 contribute to the phagocytosis and clearance of fibrillar Aβ by microglia

Complement components and their receptors are found within and around amyloid β (Aβ) cerebral plaques in Alzheimer's disease (AD). Microglia defend against pathogens through phagocytosis via complement component C3 and/or engagement of C3 cleavage product iC3b with complement receptor type 3 (CR3, Mac-1). Here, we provide direct evidence that C3 and Mac-1 mediate, in part, phagocytosis and clearance of fibrillar amyloid-β (fAβ) by murine microglia in vitro and in vivo. Microglia took up not only synthetic fAβ(42) but also amyloid cores from patients with AD, transporting them to lysosomes in vitro. Fibrillar Aβ(42) uptake was significantly attenuated by the deficiency or knockdown of C3 or Mac-1 and scavenger receptor class A ligands. In addition, C3 or Mac-1 knockdown combined with a scavenger receptor ligand, fucoidan, further attenuated fibrillar Aβ(42) uptake by N9 microglia. Fluorescent fibrillar Aβ(42) microinjected cortically was significantly higher in C3 and Mac-1 knockout mice compared with wild-type mice 5 days after surgery, indicating reduced clearance in vivo. Together, these results demonstrate that C3 and Mac-1 are involved in phagocytosis and clearance of fAβ by microglia, providing support for a potential beneficial role for microglia and the complement system in AD pathogenesis. © 2012 Wiley Periodicals, Inc.

Genetic associations of variants of the high affinity receptor for immunoglobulin E in Wegener's granulomatosis

Immunoglobulin E (IgE) and the high affinity IgE receptor (FcepsilonRI) have been suggested to contribute to the pathogenesis of autoimmune disorders. Their role in Wegener's granulomatosis (WG) are, however, poorly recognized. We sought a genetic association between laboratory markers for the disease, i.e. anti-proteinase 3 antibodies (anti-PR3), anti-myeloperoxidase antibodies, anti-cyclic citrullinated peptide antibodies, C-reactive protein (CRP), C3c and C4 complement components, and total serum IgE levels in WG subjects with common genetic variants of FcepsilonRI subunits. Anti-PR3 and CRP and serum IgE levels showed significant associations, while complement components tended to be associated, with -18483A > C and/or -344C > T FCER1A (FcepsilonRI alpha-subunit gene) polymorphisms. Moreover, a correlation between -109T > C FCER1B (FcepsilonRI beta-subunit gene) genotypes and serum IgE was observed. Both WG specific auto-antibodies and other blood inflammatory markers displayed correlations with serum total IgE levels and genetic variants of the high affinity receptor for this immunoglobulin. This observation suggests a functional relantionship of FcepsilonRI in the regulation of autoimmune response observed in WG.

Levels of complement components iC3b, C3c, C4, and SC5b-9 in peritoneal fluid and serum of infertile women with endometriosis

OBJECTIVE

To assess whether complement components iC3b, C3c, C4, and SC5b-9 may be involved in the pathogenesis of endometriosis.

DESIGN

Prospective, experimental trial.

SETTING

Medical university.

PATIENT(S)

112 women infertile women undergoing laparoscopy.

INTERVENTION(S)

Venipuncture and laparoscopic peritoneal fluid collection.

MAIN OUTCOME MEASURE(S)

Peritoneal fluid and serum iC3b, C3c, C4, and SC5b-9 levels were measured by the enzyme-linked immunosorbent assay (ELISA) method.

RESULT(S)

Higher levels of C3c, C4, and SC5b-9 complement components were found in the serum compared with the peritoneal fluid, but the levels of iC3b were higher in the peritoneal fluid. We observed higher concentrations of C3c, C4, and SC5b-9 in the peritoneal fluid and serum of women with endometriosis compared with healthy women. However, the levels of iC3b in both peritoneal fluid and serum were statistically significantly lower than in the control group.

CONCLUSION(S)

The impairment of the mechanisms involved in the regulation of activation of complement system may be an important factor in the pathogenesis of endometriosis and endometriosis-associated infertility.

Complement activation in experimental and human temporal lobe epilepsy

We investigated the involvement of the complement cascade during epileptogenesis in a rat model of temporal lobe epilepsy (TLE), and in the chronic epileptic phase in both experimental as well as human TLE. Previous rat gene expression analysis using microarrays indicated prominent activation of the classical complement pathway which peaked at 1 week after SE in CA3 and entorhinal cortex. Increased expression of C1q, C3 and C4 was confirmed in CA3 tissue using quantitative PCR at 1 day, 1 week and 3-4 months after status epilepticus (SE). Upregulation of C1q and C3d protein expression was confirmed mainly to be present in microglia and in a few hippocampal neurons. In human TLE with hippocampal sclerosis, astroglial, microglial and neuronal (5/8 cases) expression of C1q, C3c and C3d was observed particularly within regions where neuronal cell loss occurs. The membrane attack protein complex (C5b-C9) was predominantly detected in activated microglial cells. The persistence of complement activation could contribute to a sustained inflammatory response and could destabilize neuronal networks involved.

Structure of C3b in complex with CRIg gives insights into regulation of complement activation

The complement system is a key part of the innate immune system, and is required for clearance of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles, but it is unknown how CRIg selectively recognizes proteolytic C3-fragments and whether binding of CRIg to C3b inhibits convertase activation. Here we present the crystal structure of C3b in complex with CRIg and, using CRIg mutants, provide evidence that CRIg acts as an inhibitor of the alternative pathway of complement. The structure shows that activation of C3 induces major structural rearrangements, including a dramatic movement (>80 A) of the thioester-bond-containing domain through which C3b attaches to pathogen surfaces. We show that CRIg is not only a phagocytic receptor, but also a potent inhibitor of the alternative pathway convertases. The structure provides insights into the complex macromolecular structural rearrangements that occur during complement activation and inhibition. Moreover, our structure-function studies relating the structural basis of complement activation and the means by which CRIg inhibits the convertases provide important clues to the development of therapeutics that target complement.

Hypocomplementemic urticarial vasculitis: a rare presentation of systemic lupus erythematosus

BACKGROUND

Urticarial vasculitis is a small-vessel vasculitis, presenting clinically as persistent urticarial skin lesions and microscopically as leucocytoclastic vasculitis. Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a distinct type of urticarial vasculitis with multiorgan involvement, whose etiology and link with other diseases are still unknown. Some authors have suggested that HUVS can be accompanied by systemic lupus erythematosus (SLE), and others believe that it is a rare subtype of SLE. Urticarial vasculitis is seen in 7-8% of SLE, while 50% of HUVS patients are diagnosed with SLE.

OBSERVATIONS AND RESULTS

We report a case of HUVS associated with SLE with fatal outcome unresponsive to the combination of systemic corticosteroids and azathioprine.

CONCLUSIONS

SLE and HUVS share both clinical and laboratory features and are probably not separate entities. It is mostly likely that HUVS and SLE fall into the same spectrum of autoimmune diseases. HUVS is probably a subset of SLE. As both diseases can fatally, it should be kept in mind that the overlap of SLE and HUVS may exhibit a relatively rapid progression and poor prognosis.

Administration of C1-esterase inhibitor during emergency coronary artery bypass surgery in acute ST-elevation myocardial infarction☆

OBJECTIVE

Myocardial inflammatory response including complement activation was demonstrated as an important mechanism of ischemia-reperfusion injury and complement inhibition by C1-esterase inhibitor (C1-INH) has recently shown to have cardioprotective effects in experimental and clinical settings.

METHODS

The effects of C1-INH on complement activation, myocardial cell injury, and clinical outcome were studied in patients undergoing emergency CABG due to acute ST-elevation myocardial infarction (STEMI) with (group 1, CABG+STEMI+C1-INH, n=28) and without (group 2, CABG+STEMI, n=29) bolus administration of C1-INH (40 IU kg(-1)) during reperfusion and 6 h postoperatively (20 IU kg(-1)) besides the same study protocol. C1-INH activity, C3c and C4 complement activation fragments, and cardiac troponin I (cTnI) were measured preoperatively and up to 48 h postoperatively and compared to another elective set of CABG patients without STEMI as controls (group 3, CABG-STEMI, n=10). Clinical data, adverse events, and patient outcome were recorded prospectively.

RESULTS

Patient characteristics were not different between groups 1 and 2. No drug-related adverse events were observed. Constant plasma levels of C1-INH were found in group 1, but not in groups 2 and 3. Plasma levels of C3c and C4 complement fragments were reduced in all three groups after surgery throughout the observation time, but tended to be lower in groups 1 and 2 compared with group 3. Preoperative cTnI levels were elevated but not different between the groups 1 and 2. The area under curve (AUC), as well as the postoperative cTnI serum levels, was significantly lower (P<0.05) in group 1 with a treatment delay < or = 6 h between reperfusion and symptom onset compared to group 2 at 36 h (47.9+/-11.1 ng/ml vs 97.7+/-17.2 ng/ml; mean+/-SEM), and 48 h (33.5+/-5.8 ng/ml vs 86.5+/-19.2 ng/ml) after surgery, but remained unchanged between groups among patients with a treatment delay of more than 6-24 h. In-hospital adverse events and postoperative complications, ICU and hospital stay, as well as in-hospital mortality (14.3% vs 13.8%; P=NS) were not different between groups 1 and 2.

CONCLUSIONS

C1-INH administration in emergency CABG with acute STEMI is safe and effective to inhibit complement activation and may reduce myocardial ischemia-reperfusion injury as measured by cTnI.

Proteomic analysis of recurrent spontaneous abortion: Identification of an inadequately expressed set of proteins in human follicular fluid

Recurrent spontaneous abortion (RSA), defined as the loss of three or more consecutive pregnancies prior to the 20th week of gestation, affects up to 5% of the child-bearing population. To investigate the proteins associated with RSA, the protein expression in human follicular fluid was analyzed using 2-DE. Follicular fluid contains a variety of biologically important proteins for oocyte fertilization and follicle maturation in the mammalian reproductive process. Therefore, it can be used as a provisional source for identifying proteins involved in RSA. In this study, we identified five aberrantly expressed proteins (complement component C3c chain E, fibrinogen gamma, antithrombin, angiotensinogen, and hemopexin precursor) in follicular fluid from RSA patients with MALDI-TOF-MS and nano-LC MS/MS. Western blot analysis confirmed that the protein expression level of fibrinogen gamma and antithrombin was less in follicular fluid from RSA patients than those from normal controls. Semiquantitative RT-PCR and real-time PCR analyses revealed that mRNA level of these coagulation factors was also decreased significantly in chorionic villi of RSA patients compared with normal samples. Taken all together, it is likely that coagulation factors (fibrinogen gamma and antithrombin) play an important role in maintaining the normal pregnancy.

Complement inhibition abrogates nerve terminal injury in Miller Fisher syndrome

A large body of clinical and experimental data indicate that complement activation is an important mechanism for neuronal and glial injury in Guillain-Barré syndromes. Inhibition of complement activation therefore might be expected to limit the progression of the disease. Using in vitro and in vivo models of the Guillain-Barré syndrome variant, Miller Fisher syndrome, we have shown previously that anti-GQ1b ganglioside antibodies target the presynaptic motor nerve terminal axon and surrounding perisynaptic Schwann cells, thereby mediating destructive injury through deposition of membrane attack complex. Here, we have used this model to investigate the effects of a novel therapeutic inhibitor of complement activation, APT070 (Mirococept), both in vitro and in vivo. In these models, APT070 completely prevents membrane attack complex formation, and thereby has a major neuroprotective effect at the nerve terminal, as assessed by immunohistology of perisynaptic Schwann cell and axonal integrity. These data provide a rationale for considering clinical trials of APT070 in Guillain-Barré syndrome, its variant forms, and other complement dependent neuromuscular disorders.

Structures of complement component C3 provide insights into the function and evolution of immunity

The mammalian complement system is a phylogenetically ancient cascade system that has a major role in innate and adaptive immunity. Activation of component C3 (1,641 residues) is central to the three complement pathways and results in inflammation and elimination of self and non-self targets. Here we present crystal structures of native C3 and its final major proteolytic fragment C3c. The structures reveal thirteen domains, nine of which were unpredicted, and suggest that the proteins of the alpha2-macroglobulin family evolved from a core of eight homologous domains. A double mechanism prevents hydrolysis of the thioester group, essential for covalent attachment of activated C3 to target surfaces. Marked conformational changes in the alpha-chain, including movement of a critical interaction site through a ring formed by the domains of the beta-chain, indicate an unprecedented, conformation-dependent mechanism of activation, regulation and biological function of C3.

A case of acute humoral rejection with various depositions of C4d, IgG, IgM, and C3c in peritubular capillaries and/or glomerular capillaries

A 41-year-old Japanese male patient with end-stage renal disease received ABO compatible living related kidney transplantation from his sister on April 2003. The kidney functioned immediately after kidney transplantation. Protocol allograft biopsy at 1 yr after kidney transplantation was performed on April 2004. His serological data was not particular and he did not suffer with chronic inflammation. The allograft biopsy specimen revealed moderate accumulations of polymorphonuclear leukocytes in peritubular capillaries (PTCs), dilatation of PTCs and moderate infiltrations of polymorphonuclear and/or mononuclear cell in glomeruli (Transplant glomerulitis, moderate). Immunofluorescent study (IF) of a frozen section of the allograft biopsy specimen showed a strong, diffusely distributed endothelial-staining pattern in PTCs for C4d. The C4d was also strongly detected in a linear glomerular basement membrane (GBM) pattern. And widespread moderate C3c deposits, weak IgM, and IgG deposits were also seen in PTCs. Immunofluorescent study also showed granularly peripheral and mesangial deposits of strong IgM, C1q, and moderate IgG in glomeruli, IgA and C3c were faintly positive. The panel reactive antibody, which had been negative before transplantation, was positive for both HLA classes I and II at that time. We diagnosed as acute humoral rejection (AHR) and he was treated with course of steroid pulses and 5 d of gusperimus (DSG); and a total of three times Plasma exchange (PE) treatment was added. The level of serum creatinine, once increased to 1.7 mg/dL, decreased gradually to 1.4 mg/dL. He has a stable graft function. This is the only case of various depositions of immunoglobulins and complements in PTC and/or glomerular capillaries during AHR.

Up regulation of C3, C4, and soluble intercellular adhesion molecule-1 co-expresses with high sensitivity C reactive protein in familial hypoalphalipoproteinaemia: further evidence of inflammatory activation

OBJECTIVE

To test the working hypothesis that inflammation underlying precocious and severe coronary atherosclerotic disease in familial hypoalphalipoproteinaemia (FH) can be mediated by up regulation of the innate immune response.

METHODS AND RESULTS

52 patients with FH were compared with 52 healthy controls with regard to immune system markers such as C reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), C3c, and C4. Patients differed from controls in their significantly lower concentrations of high density lipoprotein cholesterol (30.2 (4.0) v 50.5 (13.6) mg/dl, p < 0.0001) and apolipoprotein A I (113.2 (19.9) v 148.7 (25.1) mg/dl, p < 0.0001) and their higher triglyceride (139.3 (63.2) v 81.4 (41.7) mg/dl, p < 0.0001) and CRP plasma concentrations (median 0.33 mg/dl, range 0.02-4.66 mg/dl v median 0.07 mg/dl, range 0.02-0.85 mg/dl, p < 0.0001), but not in their total cholesterol and low density lipoprotein cholesterol concentrations. Concentrations of protein complement were higher in patients (C3: 150.8 (42.3) v 101.9 (17.4) mg/dl, p < 0.0001; C4: 35.5 (13.6) v 22.8 (6.4) mg/dl, p < 0.0001) and sICAM-1 concentrations were more than double those found in the controls (335.1 (107.5) v 159.5 (78.2) mg/dl, p < 0.0001).

CONCLUSIONS

Increased concentrations of sICAM-1, C3c, and C4 co-express with high concentrations of CRP in FH. The lack of signs and symptoms of inflammation in these patients may suggest that the immune response is up regulated as part of the pro-inflammatory mechanisms that are activated in this atherogenic condition.

Enhanced phagocytosis of ring-parasitized mutant erythrocytes: a common mechanism that may explain protection against falciparum malaria in sickle trait and beta-thalassemia trait

High frequency of erythrocyte (red blood cell [RBC]) genetic disorders such as sickle cell trait, thalassemia trait, homozygous hemoglobin C (Hb-C), and glucose-6-phosphate dehydrogenase (G6PD) deficiency in regions with high incidence of Plasmodium falciparum malaria and case-control studies support the protective role of those conditions. Protection has been attributed to defective parasite growth or to enhanced removal of the parasitized RBCs. We suggested enhanced phagocytosis of rings, the early intraerythrocytic form of the parasite, as an alternative explanation for protection in G6PD deficiency. We show here that P falciparum developed similarly in normal RBCs and in sickle trait, beta- and alpha-thalassemia trait, and HbH RBCs. We also show that membrane-bound hemichromes, autologous immunoglobulin G (IgG) and complement C3c fragments, aggregated band 3, and phagocytosis by human monocytes were remarkably higher in rings developing in all mutant RBCs considered except alpha-thalassemia trait. Phagocytosis of ring-parasitized mutant RBCs was predominantly complement mediated and very similar to phagocytosis of senescent or damaged normal RBCs. Trophozoite-parasitized normal and mutant RBCs were phagocytosed similarly in all conditions examined. Enhanced phagocytosis of ring-parasitized mutant RBCs may represent the common mechanism for malaria protection in nonimmune individuals affected by widespread RBC mutations, while individuals with alpha-thalassemia trait are likely protected by a different mechanism.

Human alpha galactosidase and alpha 1,2 fucosyltransferase concordantly inhibit xenoreactivity of NIH 3T3 cells with human serum

AIM

To study the influence of the expression of human alpha galactosidase and alpha1,2 fucosyltransferase on Gal alpha 1,3 Gal and consequent xenoreactivity in NIH3T3 cells.

METHODS

The expression levels of G antigen and H antigen and binding of human natural antibodies (IgG and IgM) and complement (C3c) to NIH3T3 cells were analyzed by flow cytometry. Western blot was employed to further determine the expression of glycoproteins of G antigen. Cytolysis assay with normal human serum was performed by MTT assay.

RESULTS

Western blot showed that glycoproteins with molecular weight of 107 kDa, 98 kDa, 88 kDa, 56 kDa, 40 kDa, and 37 kDa were inhibited and even abrogated totally in alpha galactosidase transfectants and alpha 1,2 fucosyltransferase transfectants. The combined transfection of the two enzymes led to a much stronger inhibition of the glycoproteins. The binding of GS-IB4 was decreased by 57.4 % in alpha galactosidase transfectants, 28.8 % in alpha 1,2 fucosyltransferase transfectants, and 72.1 % in combined transfectants, respectively. In contrast, UEA-1 binding was increased about 6.7-fold, 6.0-fold, and 8.0-fold respectively. The xenoreactivity with human IgG was also reduced by 61.4 %, 67.0 %, and 73.4 %, respectively in the three kinds of transfectants. The resistance to cytolysis mediated by human serum was enhanced by 42.4 % in alpha galactosidase transfectants, 51.9 % in alpha 1,2 fucosyltranferase, and even 65.5 % in the combined transfectants.

CONCLUSION

Although alpha galactosidase and alpha 1,2 fucosyltransferase had different biochemical properties, they could inhibit the expression of Gal alpha 1,3 Gal synergistically, leading to stronger resistance of xenograft against cytolysis.

Short term effect of atorvastatin and vitamin E on serum levels of C3, a sensitive marker of the risk of myocardial infarction in men

C3 complement is produced in response to macrophage activation and is a reliable marker of the risk of myocardial infarction in men. This study was designed to ascertain whether the treatment with atorvastatin, a powerful cholesterol lowering drug, and/or vitamin E, a natural antioxidant, may induce a short term decrease in serum C3 in subjects with persistently elevated levels. From an initial random sample of 1100 men aged 55-64 years, 140 subjects with 3 consecutive C3 measurements in the high tertile (>1.19 g/l) were selected. Those with total cholesterol <5.56 mmol/l were double blindly randomized in groups 1 (placebo, N = 28, G1) and 2 (vitamin E 600 IU/day, N= 30, G2). The subjects with total cholesterol values >5.56 mmol/l were randomized in groups 3 (placebo, N= 30, G3), 4 (atorvastatin 10 mg/day, N = 27, G4) and 5 (atorvastatin 10 mg/day + vitamin E 600 IU/day, N = 25, G5). After 3 months C3 levels were substantially unchanged in the first 4 groups, while in G5 a very significant decrement occurred: -0.070 g/l (5.2%); 95% CI 0.043-0.098; p <0.0001. "Normal" levels of C3 (< 1.19 g/l) were reached by 28% of G5 subjects. In G2 and G5 vitamin E levels increased by 60 and 36%, while in G4 they decreased by 23% (p < 0.0001), paralleling cholesterol and triglyceride fall. In all groups a progressive decrease in HDL cholesterol occurred (-17%, p < 0.0001). In conclusion, treatment with atorvastatin plus vitamin E for three months can lower persistently elevated C3 levels.

Kinetic analysis of the interactions of complement receptor 2 (CR2, CD21) with its ligands C3d, iC3b, and the EBV glycoprotein gp350/220

The molecular mechanisms involved in the interaction of complement receptor 2 (CR2) with its natural ligands iC3b and C3d are still not well understood. In addition, studies regarding the binding site(s) of the receptor on C3 as well as the affinities of the C3 fragments for CR2 have produced contradictory results. In the present study, we have used surface plasmon resonance technology to study the interaction of CR2 with its ligands C3d, iC3b, and the EBV surface glycoprotein gp350/220. We measured the kinetics of binding of the receptor to its ligands, examined the influence of ionic contacts on these interactions, and assessed whether immobilized and soluble iC3b bound with similar kinetics to CR2. Our results indicate that 1) gp350 binding to CR2 follows a simple 1:1 interaction, whereas that of the C3 fragments is more complex and involves more than one intramolecular component; 2) kinetic differences exist between the binding of C3d and iC3b to CR2, which may be due to an additional binding site found on the C3c region of iC3b; and 3) iC3b binds to CR2 with different kinetics, depending on whether the iC3b is in solution or immobilized on the surface. These findings suggest that binding of CR2 to iC3b and C3d is more complex than previously thought.

Complement C3b interactions studied with surface plasmon resonance technique

The surface plasmon resonance (SPR) phenomenon is utilized in a number of new real time biosensors. In this study, we have used this technique to study interactions between the central complement component C3b and its multiple ligands by using the Biacore equipment. The SPR technique is particularly suitable for analysis of the alternative complement pathway (AP) because the inherent nature of the latter is to amplify deposition of C3b on various surfaces. C3b was coupled onto the sensor surface and the coupling efficiency was compared under various conditions on both polystyrene and carboxymethylated dextran surfaces. After enzymatic C3b coupling or standard amine C3b coupling, we analyzed and compared the binding of four C3b ligands to the surface: factor B, factor H, C5 and the soluble complement receptor 1 (sCR1, CD35). Binding of each ligand to C3b was detected when C3b had been coupled either enzymatically or using the amine coupling, but the half-lives of the interactions were found to vary depending on the coupling procedure. Factor H binds to C3b via three interaction sites. The target sites are exposed on the C3b, C3c and C3d fragments of C3, respectively. Therefore, we also tested by using the Biacore whether factor B, C5 and sCR1 bind to C3c and/or C3d. It was found that factor B bound to C3d, but not to C3c. On the other hand, both C5 and sCR1 bound to C3c, but not to C3d. In conclusion, this study shows that SPR is a powerful tool in analyzing and mapping the interactions of C3b with its multiple ligands.

Complement activation in patients with rheumatoid arthritis mediated in part by C-reactive protein

OBJECTIVE

Complement activation in patients with rheumatoid arthritis (RA) is considered to be triggered by immune complexes. Recently, it was shown that C-reactive protein (CRP) can activate the complement system in vivo. We therefore hypothesized that part of the complement activation in RA is due to CRP. The aim of this study was to investigate CRP-mediated complement activation in RA, and to assess its correlation with disease activity.

METHODS

Complexes between CRP and the activated complement components C3d (C3d-CRP) and C4d (C4d-CRP), which reflect CRP-mediated complement activation, as well as the overall levels of activated C3 and C4 were measured in the plasma of 107 patients with active RA and 177 patients with inactive RA. Inactive RA was defined according to the American College of Rheumatology criteria for clinical remission. Disease activity was assessed by the modified Disease Activity Score (DAS28).

RESULTS

Plasma levels of C3d-CRP and C4d-CRP were increased in the majority of the patients, and were significantly higher in patients with active disease versus those with inactive RA (P < 0.001). In patients with active RA, the plasma concentrations of C3d-CRP and C4d-CRP correlated significantly with the DAS28 (Spearman's rho 0.61 and 0.55, respectively; P < 0.001), whereas these correlations were less pronounced in patients with inactive RA (Spearman's rho 0.28 [P < 0.001] and 0.25 [P = 0.001], respectively). Levels of activated C3 and C4 were also increased in the majority of the patients, particularly in patients with active RA.

CONCLUSION

Part of the activation of complement in RA is mediated by CRP and is correlated with disease activity. We suggest that this activation is involved in the pathogenesis of RA.

Comparison of three commercially available hollow fiber oxygenators: gas transfer performance and biocompatibility

The new generation of oxygenators have improved blood flow pathways that enable reduction in priming volume and, thus, hemodilution during cardiopulmonary bypass (CPB). We evaluated three oxygenators and two sizes of venous reservoirs in relation to priming volume, gas transfer, and blood activation. To compare priming volume, gas transfer, and biocompatibility of three hollow fiber oxygenators and two different size venous reservoirs, 60 patients were randomly allocated in groups to undergo cardiopulmonary bypass. In each group, an oxygenator with a different surface area and priming volume was used: 1.8 m2 and 220 ml (group 1, n = 23), 2.2 m2 and 290 ml (group 2, n = 20), and 2.5 m2 and 270 ml (group 3, n = 17). In groups 1 and 3, a large soft shell (1900 ml) venous reservoir was used, whereas in group 2, a smaller soft shell (600 ml) venous reservoir was used. Gas transfer was assessed by calculating the oxygen transfer rate for each group and per square meter for each oxygenator group. Partial arterial oxygen pressure (paO2) and partial arterial carbon dioxide pressure (paCO2) between the groups were assessed with forward stepwise regression analysis. Biocompatibility was evaluated through measurement of platelet numbers, complement activation products (C3b/c), coagulation (thrombin anti-thrombin III complex), and fibrinolysis (plasmin anti-plasmin complex). No differences were found in oxygen transfer rate per group. However, when correcting the oxygen transfer rate for surface area, group 1 demonstrated a higher oxygen transfer rate compared with group 2 (p < 0.05) at an FiO2 of 40 and 60% and compared with group 3 at an FiO2 of 60 and 70%. The regression analysis showed that the average arterial PO2 was the highest in group 3, i.e., 79.2 mm Hg higher than in group 1 (p < 0.001) and 73.5 mm Hg higher than in group 2 (p < 0.001). Group 3 also had the lowest average arterial pCO2, 0.57 mm Hg lower than in group 1 (p = 0.004) and 0.81 mm Hg lower than in group 2 (p < 0.001). During CPB, platelet numbers decreased significantly in all groups (p < 0.001), without differences between the groups. C3b/c levels increased in all groups during CPB. At cessation of CPB the C3b/c level in group 2 (398 nmol/L(-1)) was significantly higher compared to group 1(251 nmol/L(-1); p < 0.05) and group 3 (303 nmol/L(-1); p < 0.05). Thrombin anti-thrombin III complexes and plasmin anti-plasmin complex complexes increased during CPB to significantly high levels at cessation of CPB, but there were no differences between the groups. The oxygenator with the smallest surface area and lowest priming volume (group 1) had the highest oxygen transfer rate per square meter and showed the least blood damage, as depicted by complement activation. The oxygenator with the largest blood contact surface area and improved geometric configuration (group 3) showed the lowest oxygen transfer rate per square meter. However, this oxygenator elevated oxygen partial pressure the most and reduced carbon dioxide partial pressure the most. In group 2, where a smaller venous reservoir was used, the highest blood activation was observed.

Biodistribution of liposomes and C3 fragments associated with liposomes: evaluation of their relationship

The biodistribution of liposomes with two different kind phospholipids (hydrogenated egg phosphatidylcholine and egg phosphatidylcholine) plus cholesterol (CHOL) were investigated after intravenous administration to rats. Elimination of liposomes from blood circulation was affected by the lipid composition. It appeared that the inclusion of CHOL in liposomes accelerates the rate of liposome uptake by liver, resulting in rapid elimination of liposomes. The amount of C3 fragments bound to liposomes was quantitatively determined to assess the contribution of the complement system to liposome accumulation into organs and liposome destabilization in vivo and in vitro. The amount of bound C3 fragments was directly proportional to CHOL content, and the amount was also proportional to the CLh, CLs as well as CLrel. This relationship suggests that the complement system is responsible for the elimination of liposomes from blood circulation, presumably as a consequence of opsonization by C3 fragments and assembly of membrane attack complex (MAC) onto liposomes. In addition, substitution of cholesteryl methyl ether into the liposome formulation for CHOL significantly diminished not only the binding of C3 fragments but also the CLh, CLs and CLrel, resulting in increased mean resident time (MRT) of the liposomes. This result suggests that the hydroxyl-group on CHOL is a binding site for C3 fragments on the liposomes and that CHOL in a liposome formulation promotes the accumulation of liposomes into the liver and spleen, probably due to their uptake by phagocytic cells, and impairs the stability of the liposomes in blood circulation, via a mechanism involving the complement system.

Linkage analysis of systemic lupus erythematosus induced in diabetes-prone nonobese diabetic mice by Mycobacterium bovis

Systemic lupus erythematosus induced by Mycobacterium bovis in diabetes-prone nonobese diabetic mice was mapped in a backcross to the BALB/c strain. The subphenotypes-hemolytic anemia, antinuclear autoantibodies, and glomerular immune complex deposition-did not cosegregate, and linkage analysis for each trait was performed independently. Hemolytic anemia mapped to two loci: Bah1 at the MHC on chromosome 17 and Bah2 on distal chromosome 16. Antinuclear autoantibodies mapped to three loci: Bana1 at the MHC on chromosome 17, Bana2 on chromosome 10, and Bana3 on distal chromosome 1. Glomerular immune complex deposition did not show significant linkage to any genomic region. Mapping of autoantibodies (Coombs' or antinuclear autoantibodies) identified two loci: Babs1 at the MHC and Babs2 on distal chromosome 1. It has previously been reported that genes conferring susceptibility to different autoimmune diseases map nonrandomly to defined regions of the genome. One possible explanation for this clustering is that some alleles at loci within these regions confer susceptibility to multiple autoimmune diseases-the "common gene" hypothesis. With the exception of the H2, this study failed to provide direct support for the common gene hypothesis, because the loci identified as conferring susceptibility to systemic lupus erythematosus did not colocalize with those previously implicated in diabetes. However, three of the four regions identified had been previously implicated in other autoimmune diseases.

An in vivo model of hyperacute rejection: characterization and evaluation of the effect of transgenic human complement inhibitors

Hyperacute rejection (HAR) occurring after transplantation within phylogenetically distant species is a severe reaction triggered by preexisting xenoreactive antibodies and complement activation, leading to the destruction of the donor organ. Expression of human complement inhibitors in transgenic pig organs prolongs the survival of xenograft in experimental models. Moreover, the extent of protection from hyperacute rejection is dependent on the level and site of expression of the transgenic molecules and, probably, on the combination of different molecules. In this regard a small animal model to test the efficacy of expression vectors and different human molecules could be very advantageous. A murine model developed in our laboratory was characterized by measurement of several parameters characteristic of HAR in the livers of control and transgenic mice expressing transgenic human DAF (CD55) or MCP (CD46) at the end of 2 h of perfusion with human plasma and after I day. The parameters studied were heamatological values of hepatic functions (GOT and GPT), induction of pro-inflammatory molecules and histopathological evaluation. Cytokines (IL-1alpha, IL-1beta, IL-6) induction and exposure of P-selectin on the endothelial cell surface, was only observed in control animals after 2 h of perfusion, as an early event. GOT and GPT values increase dramatically after 2 h perfusion and 1 day after the treatment according to the histopathological observation of liver damage. On the contrary, the livers of hDAF or hMCP transgenic mice, under the same treatment were significantly protected although the extent of this protection is dependent on the level of expression of transgenic human molecules.

Significance of glomerular deposition of C3c and C3d in IgA nephropathy

BACKGROUND

Complement activation plays an important role in the pathogenesis of IgA nephropathy. The clinico-pathological significance of the glomerular deposition of complement breakdown products, C3c and C3d in IgA nephropathy remains to be clarified.

METHODS

We examined the relationship between glomerular staining patterns of C3c and C3d and clinico-pathological findings with 163 patients with IgA nephropathy. Renal biopsy specimens were stained with C3c and C3d by immunofluorescence, and patients were divided into the following two groups: the intensity of C3c deposition stronger than C3d deposition, or equal to it (group A); the intensity of C3d deposition stronger than C3c deposition (group B).

RESULTS

In group A, the incidence of severe hematuria (over 20 urinary red blood cells in high-power field microscope (x400)) or of higher urinary fibrinogen degenerated products (over 0.1 microg/ml) was significantly higher than that in group B. In addition, group A showed a significant decrease in the glomerular filtration rate. Group A also showed a significantly higher incidence of glomerular endocapillary proliferation than in group B.

CONCLUSION

These findings suggest that the glomerular deposition of C3c is associated with the inflammatory active phase of glomeruli in IgA nephropathy.

The effects of gonadotropin treatment on the immunological features of male patients with idiopathic hypogonadotropic hypogonadism

There is a significant line of evidence for a role of androgens in the modulation of the immune system. However, little is known about immunological features of male patients with idiopathic hypogonadotropic hypogonadism (IHH) and the potential effects of gonadotropin treatment. Thus, the objective of this study was to evaluate the levels of selected soluble immune parameters [IgA, IgG, IgM, C3c, C4, interleukin-2 (IL-2), and IL-4], the CD4+/CD8 ratio, and counts of total lymphocyte and some subpopulation of lymphocytes (CD3+, CD4+, CD8+, and CD19+ cells) before and after gonadotropin treatment in men with IHH. Twenty-nine IHH patients and 19 age-matched healthy controls were included in the study. The patients were treated with human menopausal gonadotropin/hCG for 6 months. The pretreatment levels of serum Igs, C3c, IL-2, and IL-4 in the patients were significantly higher than those in the controls (P<0.001 for all). After treatment, all Igs (P<0.001), C3c (P<0.01), and IL-2 and IL-4 levels (P<0.005) were decreased significantly compared to pretreatment levels. Pretreatment lymphocyte counts (P<0.05); the percentages of CD3+ cells (P<0.001), CD4+ cells (P< 0.001), and CD19+ cells (P<0.001); and the CD4/CD8+ ratio in the patient group were significantly higher (P<0.05) than those in the controls. After treatment, the lymphocyte count (P<0.001); CD3+ (P<0.01), CD4+ (P<0.001), and CD19+ (P<0.005) cells; and the CD4-/CD8+ ratio (P<0.001) were decreased, but CD8+ cells were increased significantly (P<0.001). In summary, lack of testosterone action results in the enhancement of cellular and humoral immunity. The results of this study allowed us to conclude that testosterone deficiency affects both cell-mediated and humoral immunity, and these may be modulated with gonadotropin therapy in male patients with IHH.

Inflammation and intracranial aneurysms

OBJECTIVE

An intracranial aneurysm is an important acquired cerebrovascular disease that can cause a catastrophic subarachnoid hemorrhage. Despite modern therapy, most patients die or are left disabled as a direct result of a severe initial hemorrhage. The development of more effective treatment strategies depends on understanding the fundamental biology of cerebral aneurysms. The purpose of the present study is to determine whether inflammation or immunological reaction occurs in cerebral aneurysms.

METHODS

Aneurysm tissue was collected at the time of microsurgical repair from 23 unruptured and 2 ruptured aneurysms (25 patients) and compared with 11 control basilar arteries harvested at autopsy. Immunohistochemistry was used to localize complement (C3c, C9), immunoglobulins (IgG, IgM), vascular cell adhesion molecule-1, macrophages and monocytes (CD68), T lymphocytes (CD3), and B lymphocytes (CD20).

RESULTS

Complement (C3c, P < 0.0001; C9, P = 0.0017), immunoglobulin (IgG, P = 0.0013; IgM, P = 0.031), vascular cell adhesion molecule-1 (P = 0.0022), macrophages (CD68, P = 0.004), and T lymphocytes (CD3, P = 0.0004) were all frequently present in the wall of aneurysm tissue but were rarely identified in control basilar arteries. A few B lymphocytes (CD20, P = 0.41) were found in aneurysm tissue, but none were found in the basilar arteries.

CONCLUSION

Extensive inflammatory and immunological reactions are common in unruptured intracranial aneurysms and may be related to aneurysm formation and rupture.

Humoral immunity in Nigerians with Schistosoma haematobium infection

Circulating soluble immune complexes (CIC), immunoglobulin classes (IgG, IgA, and IgM), acute phase proteins (alpha-l-fetoprotein and alpha-1-acid glycoprotein) and complement factors (C4 and C3c) levels were determined in 52 Nigerian patients with urinary schistosomiasis (USS) and 39 healthy subjects by polyethylene glycol precipitation and single radial immunodiffusion methods respectively. A considerably higher proportion of USS patients than the controls had elevated levels of soluble immune complexes. IgM, IgA and C3c levels were significantly higher in USS patients than the controls. However, serum concentration of C4 was significantly reduced in USS patients than the controls while that of IgG was not significantly reduced in these patients. The mean levels of alpha-l-fetoprotein and alpha-l-acid glycoprotein were comparable in the USS subjects and the controls. Correlation analysis showed association between S. haematobium egg numbers with serum concentration of IgM, C3c and CIC. These observations could be the results of increased rate of CIC formation, and inflammatory responses to schistosome antigens. The study concluded that IgM associated-CIC may be responsible for the immunopathology of chronic schistosomiasis.

Complement activation and expression of membrane regulators in the middle ear mucosa in otitis media with effusion

The aetiopathogenesis of chronic otitis media with effusion (OME) in children is not yet fully understood. OME is characterized by metaplasia of the epithelium and accumulation of sticky, glue-like effusion in the middle ear containing different mediators of inflammation, including activation fragments of the complement system. Here we examined whether the fluid phase complement activation is reflected in the middle ear mucosa and how the mucosa is protected against the cytolytic activity of complement. Mucosal biopsies from 18 middle ears of children with a history of chronic OME were taken. The biopsies were analysed by immunofluorescence microscopy after staining for complement fragments iC3b/C3c, C3d and C9, and regulators membrane cofactor protein (MCP; CD46), decay-accelerating factor (DAF; CD55) and protectin (CD59). There was a strong staining for iC3b/C3c, and a weaker one for C3d and C9 on the surface of the middle ear epithelial cells of OME patients but not in controls without OME. MCP was expressed on the hyperplastic three to four outer cell layers of the epithelium, while CD59 was expressed throughout the middle ear mucosa. The results suggest a strong ongoing complement activation and consequent inflammation in the middle ear cavity. Unrestricted complement damage of the epithelial lining is prevented by the strong expression of MCP and CD59.

Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused pig xenografts

Compstatin, a newly described C3-binding peptide, inhibits complement activation by blocking C3 convertase-mediated cleavage of C3. As the complement activation is an essential part of the rejection reaction, we evaluated the ability of Compstatin to delay or prevent hyperacute rejection in an ex vivo xenograft model. Pig kidneys were perfused with fresh human blood containing either Compstatin (n=6) or a control agent (n=6). Graft survival and activation of complement, leukocytes and platelets both in the fluid-phase and in the tissue were examined. The survival of the Compstatin-perfused kidneys (median, 380 min) was significantly (P=0.0036) longer than that of the controls (median, 90 min). The classical complement pathway (C1rs-C1inhibitor and C4bc) was significantly and equally activated in both groups during the first 60 min. C3 activation products increased fivefold and terminal complement complex eightfold in the control group, but no increase occurred in the Compstatin group during this period. Immunohistochemistry showed less C3 and fibrin deposition and immune electron microscopy showed less terminal SC5b-9 complement complex deposition in the Compstatin group. A significant change in total white cells, neutrophils, myeloperoxidase, and expression of the surface activation markers CD11b (CR3) and CD35 (CR1) and CD62L (L-selectin) was observed in both groups. Leukocyte activation was lower in the Compstatin group but the difference was not statistically significant. There were no differences in platelet counts, thrombospondin, soluble P-selectin or beta-thromboglobulin between the groups. We conclude that Compstatin prolongs graft survival and suggest that it may be a useful agent for attenuating hyperacute rejection by inhibiting C3 and thus terminal complement pathway activation.

Characterization of estrogenicity of phytoestrogens in an endometrial-derived experimental model

Severe developmental and reproductive disorders in wild animals have been linked to high exposure to persistent environmental chemicals with hormonal activity. These adverse effects of environmental estrogens have raised considerable concern and have received increasing attention. Although numerous chemicals with the capacity to interfere with the estrogen receptor (ER) have been identified, information on their molecular mechanism of action and their relative potency is rather limited. For the endometrium, the lack of information is due to the lack of a suitable experimental model. We investigated the functions of phytoestrogens in an endometrial-derived model, RUCA-I rat endometrial adenocarcinoma cells. The cells were cultured on a reconstituted basement membrane to preserve their functional differentiation and estrogen responsiveness. We assessed the relative binding affinity to the estrogen receptor of the selected phytoestrogens coumestrol, genistein, daidzein, and the putative phytoestrogen mangostin compared to estradiol by a competitive Scatchard analysis. The following affinity ranking was measured: 17beta-estradiol >>> coumestrol > genistein > daidzein >>> mangostin. In addition, we investigated the capacity of these compounds to promote the increased production of complement C3, a well-known estradiol-regulated protein of the rat endometrium. All substances tested increased the production of complement C3, although different concentrations were necessary to achieve equivalent levels of induction compared to estradiol. Mechanistically we were able to demonstrate that the increase of complement C3 production was mediated by primarily increasing its steady-state mRNA level. These findings indicate that RUCA-I cells represent a sensitive model system to elucidate relative potencies and functions of environmental estrogens in an endometrium-derived model.

Interaction of vaccinia virus complement control protein with human complement proteins: factor I-mediated degradation of C3b to iC3b1 inactivates the alternative complement pathway

Vaccinia virus complement control protein (VCP) is a virulence determinant of vaccinia virus that helps protect the virus from the complement attack of the host. To characterize the interaction of VCP with C3 and C4 and understand the mechanism by which VCP inactivates complement, we have expressed VCP in a yeast expression system and compared the biologic activity of the purified protein to that of human factor H and complement receptor 1 (CR1). Recombinant VCP bound to C3 and the proteolytically cleaved form of C3 (C3b), but not to the 135,300-m.w. fragment of C3 generated using elastase (C3c) and the 35,000-m.w. fragment of C3 generated using elastase (C3d) and inhibited both the classical and alternative pathways of complement activation. Although rVCP was less effective at inhibiting the alternative pathway than factor H or CR1, it was more effective than factor H at inhibiting the classical pathway. Unlike factor H, rVCP was unable discriminate between alternative pathway-mediated lysis of rabbit and sheep E. A comparison of the cofactor activity in factor I-mediated cleavage of C3b suggested that in contrast to factor H and CR1, which displayed cofactor activity for the three sites, rVCP displayed cofactor activity primarily for the first site, leading to generation of C3b cleaved by factor I between Arg1281-Ser1282 (iC3b1). Its cofactor activity for C4b cleavages was similar to that of soluble complement receptor type 1. Purification and functional analysis of iC3b1 showed that it was unable to interact with factor B to form the alternative pathway C3 convertase, C3b,Bb. These results suggest that the interaction of VCP with C3 is different from that of factor H and CR1 and that VCP-supported first cleavage of C3b by factor I is sufficient to render C3b nonfunctional.

High-level endothelial expression of human CD59 prolongs heart function in an ex vivo model of xenograft rejection

BACKGROUND

Hyperacute rejection of discordant xenografts is dependent on activation of the complement system of the recipient. Transgenic expression of recipient complement regulatory factors in donor tissue has proved to be a promising approach to dealing with hyperacute rejection, although the relationship between the level of complement regulatory factor expression and the degree of protection is not well established. Here, we examine this relationship using CD59 transgenic mouse hearts in an ex vivo model of xenograft rejection.

METHODS

The level of expression of CD59 in two lines of transgenic mice, in which CD59 is expressed under the control of either the murine H2Kb (MHC class I) promoter (line CA-17) or the endothelium-specific human intercellular adhesion molecule-2 promoter (line 237-7), was compared by immunohistochemistry and flow cytometry. Hearts from both groups and wild-type controls were perfused ex vivo with human plasma, and mean heart work for each group was compared over a 60-min period.

RESULTS

CD59 expression on cardiac endothelial cells isolated from homozygous CA-17 mice was 25- to 30-fold lower than that on cardiac endothelial cells from heterozygous 237-7 mice. CA-17 hearts perfused with 6% human plasma exhibited a reduction in deposition of the membrane attack complex, but not a prolongation of function, compared with nontransgenic mouse hearts. In contrast, 237-7 hearts showed significantly prolonged function during perfusion with 20% plasma.

CONCLUSIONS

High-level endothelial-specific expression of CD59 was effective in prolonging the function of mouse hearts perfused with 20% human plasma, whereas low-level, broader expression did not provide protection from 6% plasma.

Mouse susceptibility to infection by the Salmonella abortusovis vaccine strain Rv6 is controlled by the Ity/Nramp 1 gene and influences the antibody but not the complement responses

Early growth of Salmonella typhimurium in spleen and liver of mice is controlled by the mouse chromosome 1 locus Ity/Nramp 1. Genetic control of resistance to the attenuated vaccine strain Rv6 of Salmonella abortusovis was studied in mice infected by the intravenous route. Comparison of kinetics of bacterial colonization of spleen and liver in two congenic BALB/c-susceptible (Itys) and -resistant (Ityr) mouse lines showed that BALB/c mice (Itys) were significantly more susceptible to infection than C.D2 mice (Ityr) suggesting that infection by this vaccine strain is controlled by a gene which is close or identical to Ity/Nramp 1. Congenic mice also differed in their anti-Salmonella antibody response, measured by ELISA: susceptible mice had a significantly higher antibody level than resistant mice, whatever the immunoglobulin isotype (IgM, IgG1, IgG2a, IgG3, IgA, and total immunoglobulins). The two congenic BALB/c mouse lines had equal serum C3c levels in response to infection. However, we observed a highly significant difference according to the sex of mice, suggesting a role of sex hormones in the regulation of the level of some complement factors. These results, obtained with congenic mice, strongly suggest that the Ity/Nramp 1 locus controls susceptibility to infection by the S. abortusovis vaccine strain Rv6 and influences the antibody response.

Further characterization of a complement-sensitive mutant of a virulent avian Escherichia coli isolate

An attempt was made to characterize the mechanism of complement resistance operating in a virulent avian Escherichia coli isolate. Using flow cytometry to detect antibody to C3, we found that there was significantly more antibody bound to a complement-sensitive mutant of this wild type than to the parent organism, suggesting that more C3 subunits were bound to the wild type. Neither the wild type nor the mutant degraded C3. Further, the mutant was phagocytosed to a significantly greater degree than the wild type by cultured phagocytes in the presence of C5-deficient serum. These data suggest that the wild type is resistant to complement, at least in part, because of its ability to restrict C3 deposition on its surface. Therefore, the decrease in virulence seen in the mutant may be related to its increased sensitivity to complement-mediated bacteriolysis or its enhanced susceptibility to complement-opsonized phagocytosis or both.

The value of immunoglobulin and complement levels in the early diagnosis of neonatal sepsis

Serum IgG, IgG1, G2, G3, G4, IgM, C3c and C4 concentrations were measured in 24 term neonates with sepsis and 17 healthy normal neonates of similar age, sex and weight (control group). The serum IgG, IgG1, G2, G3, G4, IgM, C3c, and C4 levels were similar in the patients with sepsis and the control group (p > 0.05). In the neonates with sepsis, serum IgG, G1, G2, IgM and C4 levels were not significantly different between the 1st and 10th days, while there were significant differences for IgG3, G4 and C3c (p < 0.05). We conclude that the serum levels of IgG, IgG1, G2, G3, G4, IgM, C3c and C4 concentrations are of no value for the early diagnosis of neonatal sepsis.

Methotrexate in patients with moderate systemic lupus erythematosus (exclusion of renal and central nervous system disease)

OBJECTIVES

Methotrexate (MTX) has been used in several autoimmune diseases. Apart from its use in rheumatoid arthritis, MTX has been assessed in small studies in patients with vasculitis, uveitis, and inflammatory bowel disease. The aim of this study was to evaluate the efficacy of MTX in a particular group of patients with systemic lupus erythematosus (SLE).

PATIENTS

In an open prospective study 22 patients fulfilling the ACR criteria for SLE were included. Patients had one or more of the following manifestations; active non-destructive polyarthritis, dermatitis, vasculitis of the skin, pleuritis. All patients had been treated with corticosteroids for at least six months without achieving remission. Sixteen patients were taking antimalarial drugs in addition to corticosteroids, which were stopped at the beginning of the trial. Patients with renal and central nervous involvement were excluded from the study. All patients received MTX orally at a dose of 15 mg/week over six months. Corticosteroids were continued. As additional medication only indomethacin up to 100 mg/day was permitted if used before the start of the study. The outcome was evaluated using the SLE disease activity index (SLEDAI).

RESULTS

Disease activity was evaluated after six months of MTX treatment. All patients completed the study period. The SLEDAI decreased significantly from mean (SD) 12.2 (3.99) to 4 (3.75) (p = 0.001). The prednisolone dose was reduced from a mean (SD) of 17.4 (12.8) at the beginning to 8.8 (5.36) mg/day at the end point of the study (p = 0.01). MTX was well tolerated. Four patients complained of general malaise. Two patients had transient increases in liver enzymes. In no case did MTX have to be stopped.

CONCLUSIONS

In an open prospective study methotrexate was used in SLE patients with particular clinical characteristics. MTX was shown to be effective in reducing disease activity and sparing the dose of corticosteroids. Further controlled studies are necessary.

Cleavage of the complement system C3 component by HIV-1 proteinase

The C3 factor of the complement system and its C3b fragment are cleaved in vitro by the proteinase of the human immunodeficiency virus, type 1 (HIV PR). The cleavage occurs in the alpha-chain of both substrates at multiple sites yielding a 100 kDa fragment of the C3 alpha-chain and multiple fragments of the C3b alpha-chain. The scissile bonds are: Ala86-Glu87, Leu310-Leu311, His641-Trp642 and Arg649-Ser650. The resulting fragments resemble the physiologically occurring inactive fragments of C3: C3c and C3d, suggesting a possible biological role of the HIV-proteinase in the complement inactivation process.

Complement activates neutrophils during PTCA procedure in patients with unstable angina pectoris

We estimated adherence, aggregation and chemiluminescence of neutrophils as well as concentrations of C3c, C4 and C5 complement components and complement haemolytic activity (CH50) in 27 patients with unstable angina pectoris subjected to percutaneous transluminal coronary angioplasty (PTCA). The control group consisted of 12 patients with unstable angina pectoris, in whom coronary angiography was performed but PTCA was decided against for various reasons. Blood samples for examination were taken from coronary sinus and peripheral vein just before, 1 min and 20 min after PTCA or coronary angiography. We observed enhancement of neutrophil adherence, aggregation and chemiluminescence, and decrease in concentrations of C3c, C5 and complement haemolytic activity (CH50) after PTCA procedure. In conclusion we think that ischemia resulting from PTCA causes complement activation in an alternative pathway which seems to be connected with neutrophil activation.

Evidence for the involvement of complement proteins in platelet aggregation by Streptococcus sanguis NCTC 7863

We investigated the mechanisms of platelet aggregation by the type strain of Streptococcus sanguis (NCTC 7863). This species is one of the major aetiological agents of infective endocarditis. S. sanguis NCTC 7863 caused aggregation of normal human platelets in vitro following a lag period that varied between donors (7-19 min). Platelet aggregation was dependent on one or more plasma constituents and all the necessary factors gradually became bound to the bacterial surface during the lag period. The length of the lag period was determined by the plasma of the donor and not by a feature of their platelets. Platelet aggregation by S. sanguis NCTC 7863 could be inhibited by heating plasma at 56 degrees C, by treating plasma with cobra venom factor, or by incubating with soluble Complement Receptor 1, all of which inhibit or deplete complement. Complement activation required Mg2+, but not Ca2+ ions and the the cleavage fragment, Ba, of factor B was produced, indicating that the alternative pathway was operative. Zymosan- and S. sanguis-induced aggregation showed similarities, including the same variability in lag times among donors, and absorption of plasma with zymosan prevented the plasma from supporting platelet aggregation by S. sanguis, C3, C9 and vitronectin were found to bind to S. sanguis NCTC 7863, but the latter two were present at very low levels on a non-aggregating strain of S. sanguis, SK96. The rate of assembly of the C5b-9 complex on the NCTC 7863 bacterial surface correlated with the lag time. These data suggest a role for the complement pathway in platelet aggregation by the type strain of S. sanguis.

Vitronectin modulates the expression of complement components of the terminal pathway synthesized by human umbilical vein endothelial cells in vitro

In this study we demonstrate that human endothelial cells (EC) synthesize mRNA for vitronectin by using techniques based on reverse transcriptase (RT) reaction and polymerase chain reaction (PCR). The identification of vitronectin mRNA, shown by sequence analysis of PCR-amplified RT product of RNA extracted from EC, clearly demonstrates that these cells synthesize mRNA for vitronection. We further investigated whether vitronectin in serum-free EC cultures regulates the net expression of the terminal complement pathway, measured as the terminal complement complex (TCC) bound to co-cultured agarose beads which activate the alternative pathway. Presence of polyclonal F(ab')2 anti-human vitronectin (VN) antibodies, regardless of concentration (10-80 micrograms/ml), significantly reduced the binding of monoclonal anti-C3c antibodies to co-cultured beads, whereas the binding of monoclonal anti-TCC antibodies was unaltered or significantly increased compared with controls. Despite some interexperimental variation in the results, addition of vitronectin (10-80 micrograms/ml) to the EC resulted in an inversely related pattern compared with experiments using anti-VN antibodies. The binding indices of anti-C3c are comparable to the controls. On the other hand, there is a steady concentration-dependent (10-80 micrograms of vitronectin added) reduction in binding of anti-TCC up to approximately 60%. The results indicate that vitronectin regulates the expression of synthezised and surface-bound TCC in serum-free EC cultures, comparable to previous findings in serum.