A combined approach for individualized lymphadenectomy in gastric cancer patients.

Introduction: Gastric cancer ranks as the fifth most common cancer globally. The presence of lymph node metastasis is a significant prognostic factor influencing survival. Postoperative morbidity and nodal staging accuracy are heavily affected by the extent of lymph node dissection. Our study aimed to explore the potential integration of two contemporary methods, sentinel node navigation surgery (SNNS) and the Maruyama Computer Program (MCP), to improve the accuracy of nodal staging. Materials and methods: We conducted a prospective data collection involving patients with gastric adenocarcinoma from 2008 to 2018 at the Department of Surgery, University of Debrecen, Hungary. Data from 100 consecutive patients were collected. The primary and secondary endpoints included evaluating the rate of node-negative patients and the diagnostic accuracy of our combined approach. Results: Sentinel node mapping was successful in 97 out of 100 patients. We found that using the threshold value of the Maruyama Index (MI) ≥ 28, all metastatic stations of sentinel-node-negative patients could be identified. Our method achieved 100% sensitivity and negative predictive value, with a specificity of 60.42% (95% CI = 46.31%-72.98%). Discussion: The combined application of SNNS and MCP has proven to be an effective diagnostic technique in the synergistic approach for identifying metastasis-positive lymph node stations. Despite its limitations, this combination may assist clinicians in customizing lymphadenectomy for gastric cancer patients.

Organic Anion Transporting Polypeptide 3A1 (OATP3A1)-Gated Bio-Orthogonal Labeling of Intracellular Proteins.

Organic anion transporting polypeptides (OATPs) were found to readily deliver membrane impermeable, tetrazine bearing fluorescent probes into cells. This feature was explored in OATP3A1 conditioned bio-orthogonal labeling schemes of various intracellular proteins in live cells. Confocal microscopy and super-resolution microscopy (STED) studies have shown that highly specific and efficient staining of the selected intracellular proteins can be achieved with the otherwise non-permeable probes when OATP3A1 is present in the cell membrane of cells. Such a transport protein linked bio-orthogonal labeling scheme is believed to be useful in OATP3A1 activity-controlled protein expression studies in the future.

Bioorthogonal Ligation-Activated Fluorogenic FRET Dyads.

An energy transfer-based signal amplification relay concept enabling transmission of bioorthogonally activatable fluorogenicity of blue-excitable coumarins to yellow/red emitting cyanine frames is presented. Such relay mechanism resulted in improved cyanine fluorogenicities together with increased photostabilities and large apparent Stokes-shifts allowing lower background fluorescence even in no-wash bioorthogonal fluorogenic labeling schemes of intracellular structures in live cells. These energy transfer dyads sharing the same donor moiety together with their parent donor molecule allowed three-color imaging of intracellular targets using one single excitation source with separate emission windows. Sub-diffraction imaging of intracellular structures using the bioorthogonally activatable FRET dyads by STED microscopy is also presented.

Significance of preoperative blood tests in the prognosis of colorectal cancer: A prospective, multicenter study from Hungary.

BACKGROUND: The focus of this study was to analyze the prognostic value of different combinations of inflammatory and coagulation factors using preoperative blood and to appraise the clinical importance of these biomarkers in colorectal cancer patients. METHODS: A prospective, multicenter study included patients undergoing radical colorectal surgery in three county hospitals. Inflammatory and coagulation markers were analyzed preoperatively. RESULTS: Two hundred and one patients were included. We examined patients based on their tumor localization. Colon cancer group involved patients with the tumor localized in the colon (n = 105, 52.24%) and rectal cancer group the patients with the tumor in the rectum (n = 96, 47.76%). Examining coagulation factors, univariate Cox analysis of colon cancer patients showed that activated partial thromboplastin time (p = 0.020) was significantly associated with overall survival, but we could not prove it in multivariate analysis. In colon cancer patients, neutrophil-to-lymphocyte ratio (NLR, p < 0.001) was positively correlated with tumor size and had significant association (χ2  = 5.48, p = 0.019, df = 1) with perineural invasion. Univariate and multivariate Cox analysis of colon cancer patients showed that NLR (p = 0.011 and p = 0.048) was significantly associated with disease-free survival (DFS). CONCLUSION: NLR was proved to be an independent prognostic factor for DFS in patients with non-metastatic colon cancer. NLR might help to recognize the high-risk patients between patients with the same tumor-node-metastasis stage and could help with the decision on adjuvant chemotherapy. Since the biomarkers in preoperative blood tests are habitually evaluated, NLR could be an inexpensive prognostic marker that can be easily assessed in clinical practice.

A Genetically Encoded Isonitrile Lysine for Orthogonal Bioorthogonal Labeling Schemes.

Bioorthogonal click-reactions represent ideal means for labeling biomolecules selectively and specifically with suitable small synthetic dyes. Genetic code expansion (GCE) technology enables efficient site-selective installation of bioorthogonal handles onto proteins of interest (POIs). Incorporation of bioorthogonalized non-canonical amino acids is a minimally perturbing means of enabling the study of proteins in their native environment. The growing demand for the multiple modification of POIs has triggered the quest for developing orthogonal bioorthogonal reactions that allow simultaneous modification of biomolecules. The recently reported bioorthogonal [4 + 1] cycloaddition reaction of bulky tetrazines and sterically demanding isonitriles has prompted us to develop a non-canonical amino acid (ncAA) bearing a suitable isonitrile function. Herein we disclose the synthesis and genetic incorporation of this ncAA together with studies aiming at assessing the mutual orthogonality between its reaction with bulky tetrazines and the inverse electron demand Diels-Alder (IEDDA) reaction of bicyclononyne (BCN) and tetrazine. Results showed that the new ncAA, bulky-isonitrile-carbamate-lysine (BICK) is efficiently and specifically incorporated into proteins by genetic code expansion, and despite the slow [4 + 1] cycloaddition, enables the labeling of outer membrane receptors such as insulin receptor (IR) with a membrane-impermeable dye. Furthermore, double labeling of protein structures in live and fixed mammalian cells was achieved using the mutually orthogonal bioorthogonal IEDDA and [4 + 1] cycloaddition reaction pair, by introducing BICK through GCE and BCN through a HaloTag technique.

Epithelioid hemangioma of liver-The first reported case.

Epithelioid hemangioma, otherwise known as angiolymphoid hyperplasia with eosinophilia, is a rare benign vasoproliferative disease with an unknown etiology. We report the case of a 42-year-old man with routine bloods test showing mildly elevated serum bilirubin level. CT scan revealed a lesion in the left liver lobe not typical of FNH. PET/CT scan and a dynamic liver MRI were consistent with a malignant mass. Surgical resection was performed. Histopathology of the 45 mm mass reported well-defined, slightly lobular proliferations of capillary-sized vessels around several central muscular vessels. Although the endothelial cells revealed a "hobnail" appearance, none of them showed pleomorphism or mitotic activity. Endothelial cells showed reactivity for the endothelial markers (CD34, CD31) and smooth muscle was detected in the blood vessel walls via immunohistochemistry. Despite its benign nature, epithelioid hemangioma of the liver can lead to a diagnostic and therapeutic dilemma due to the malignant looking features on imaging modalities.

Is duodeno-jejunal bypass liner superior to pylorus preserving bariatric surgery in terms of complications and efficacy?

PURPOSE: Based on recent scientific evidence, bariatric surgery is more effective in the management of morbid obesity and related comorbidities than conservative therapy. Pylorus preserving surgical procedures (PPBS) such as laparoscopic single-anastomosis duodeno-jejunal or duodeno-ileal bypass with sleeve gastrectomy are modified duodenal switch (DS) surgical techniques. The duodeno-jejunal bypass liner (DJBL) is a novel surgical method in the inventory of metabolism focused manual interventions that excludes duodeno-jejunal mucosa from digestion, mimicking DS procedures without the risk of surgical intervention. The aim of this article is to summarize and compare differences between safety-related features and weight loss outcomes of DJBL and PPBS. METHODS: A literature search was conducted in the PubMed database. Records of DJBL-related adverse events (AEs), occurrence of PPBS-related complications and reintervention rates were collected. Mean weight, mean body mass index (BMI), percent of excess of weight loss (EWL%), percent of total weight loss (TWL%) and BMI value alterations were recorded for weight loss outcomes. RESULTS: A total of 11 publications on DJBL and 6 publications on PPBS were included, involving 800 and 1462 patients, respectively. The baseline characteristics of the patients were matched. Comparison of DJBL-related AEs and PPBS-related severe complications showed an almost equal risk (risk difference (RD): -0.03 and confidence interval (CI): -0.27 to 0.21), despite higher rates among patients having received endoscopic treatment. Overall AE and complication rates classified by Clavien-Dindo showed that PPBS was superior to DJBL due to an excess risk level of 25% (RD: 0.25, CI: 0.01-0.49). Reintervention rates were more favourable in the PPBS group, without significant differences in risk (RD: -0.03, CI: -0.27 to 0.20). However, PPBS seemed more efficient regarding weight loss outcomes at 1-year follow-up according to raw data, while meta-analysis did not reveal any significant difference (odds ratio (OR): 1.08, CI: 0.74-1.59 for BMI changes). CONCLUSION: Only limited conclusions can be made based on our findings. PPBS was superior to DJBL with regard to safety outcomes (GRADE IIB), which failed to support the authors' hypothesis. Surgical procedures showed lower complication rates than the incidence of DJBL-related AEs, although it should be emphasized that the low number of PPBS-related mild to moderate complications reported could be the result of incomplete data recording from the analysed publications. Weight loss outcomes favoured bariatric surgery (GRADE IIB). As the DJBL is implanted into the upper gastrointestinal tract for 6 to 12 months, it seems a promising additional method in the inventory of metabolic interventions.

Mesenteric actinomycosis / Mesenterialis actinomycosis.

Összefoglaló. Egy 46 éves nobeteg esetét ismertetjük, akinél láz és görcsös hasi fájdalom miatt kezdodött kivizsgálás. A hasi ultrahangvizsgálat során a colon transversum területén megvastagodott falú konglomerátum volt látható. A kolonoszkópia során organikus eltérés nem igazolódott. A hasi komputertomográfiás vizsgálat retroperitonealis térfoglalást írt le, ezért onkológiai bizottság javaslata alapján mutét mellett döntöttünk. Egy hónappal a panaszok jelentkezése után megtörtént a mutét, melynek során úgy tunt, hogy egy megközelítoleg 5 × 8 centiméteres, a vékonybélbol kiinduló, a colon ascendenst és a sigmabelet is érinto, daganatnak imponáló terimét találtunk. Jobb oldali hemicolectomiát végeztünk, és reszekáltuk a sigmabélfal részletét. A szövettani vizsgálat malignitást nem igazolt, hanem a bélfallal összefüggést nem mutató, mesenterialis actinomycosist írt le. A hasi, mesenterialis actinomycosis ritka kórkép, mégis fontos, hogy gondoljunk rá mint differenciáldiagnosztikai lehetoségre, így a beteg a leheto leghamarabb megkaphatja a megfelelo kezelést. Esettanulmányunk bemutatásával a kórkép ismeretének fontosságára szeretnénk felhívni a figyelmet. Orv Hetil. 2021; 162(3): 116-119. Summary. We present the case of a 46-year-old female, who presented with fever and abdominal pain. Abdominal ultrasound revealed a thickened-walled conglomerate near the transvers colon. Colonoscopy did not show any organic abnormality. Abdominal computed tomography described a retroperitoneal mass, so we decided on surgery based on the multidisciplinary team decision. One month after the onset of symptoms, laparotomy was performed, and it seemed that we found an approximately 5 × 8 centimetre tumour attached to the small intestine involving the ascending and sigmoid colon. We performed right hemicolectomy and sigmoid colon wall resection. Histology result showed mesenteric actinomycosis with no connection to the intestinal wall, no malignancy was revealed. Although the abdominal, mesenteric actinomycosis is a rare disease, it is important to think of it as a differential diagnostic option, so the patient can get proper treatment and cured sooner. Our aim with presenting this case report is to highlight the significance of this disease. Orv Hetil. 2021; 162(3): 116-119.

Comparison of different lymph node staging systems in prognosis of gastric cancer: a bi-institutional study from Hungary.

OBJECTIVE: The Union for International Cancer Control (UICC) Node (N) classification is the most common used staging method for the prognosis of gastric cancer. It demands adequate, at least 16 lymph nodes (LNs) to be dissected; therefore different staging systems were invented. METHODS: Between March 2005 and March 2010, 164 patients were evaluated at the Department of General Surgery in the Kenézy Gyula Hospital and at the Department of General, Thoracic and Vascular Surgery in the Kaposi Mór Hospital. The 6th, 7th and 8th UICC N-staging systems, the number of examined LNs, the number of harvested negative LNs, the metastatic lymph node ratio (MLR) and the log odds of positive LNs (LODDS) were determined to measure their 5-year survival rates and to compare them to each other. RESULTS: The overall 5-year survival rate for all patients was 55.5% with a median overall survival time of 102 months. The tumor stage, gender, UICC N-stages, MLR and the LODDS were significant prognostic factors for the 5-year survival with univariate analysis. The 6th UICC N-stage did not follow the adequate risk in comparing N2 vs. N0 and N3 vs. N0 with multivariate investigation. Comparison of performances of the residual N classifications proved that the LODDS system was first in the prediction of prognosis during the evaluation of all patients and in cases with less than 16 harvested LNs. The MLR gave the best prognostic prediction when adequate (more than or equal to 16) lymphadenectomy was performed. CONCLUSIONS: We suggest the application of LODDS system routinely in western patients and the usage of MLR classification in cases with extended lymphadenectomy.

[Role of a computer program in gastric cancer surgery - beyond the evidence]. / A számítógépes program szerepe a gyomortumor-sebészetben ­ Túl az evidencián.

INTRODUCTION: Forty percent of patients with gastric cancer have an unnecessarily extended lymph node dissection with a higher rate of morbidity and mortality. While the Maruyama computer program (MCP) can estimate the lymph node involvement before the surgery, the Maruyama Index (MI) could be a good predictor of overall and disease free survival. METHODS: To measure the probability calculations by MCP, we had to define different "cut-off" levels, with using the calculation of the receiver-operating characteristics analysis. The long term oncological results, as the overall survival (OS) and disease free survival (DFS) were calculated in correlation with the extension of lymphadenectomy (D1 versus D2) and Maruyama Index (MI < 5 versus MI ≥ 5). RESULTS: 74 patients were investigated by the Maruyama computer program preoperatively for the short-term results, and the data of 101 patients were eligible for evaluation of the long-term oncological outcomes. The MCP had a 90.2% of sensitivity, 63.3% of specificity and 78.4% of accuracy. The positive predictive value was 75.5% and the negative predictive value was 84%. In D1 group the DFS was 93.6 months and 68.7 months in D2 group (p = 0.41; HR = 1.34), and the OS was 74.6 and 72.2 months respectively (p = 0.66; HR = 0.87). In patients with MI < 5 the DFS was 92 months and 62.5 months in patients with MI ≥ 5 (p = 0.31; HR = 1.4), while the OS was 86 months and 60.4 months (p = 0.17; HR = 1.52). CONCLUSIONS: Our results proved, that the computerized prediction of LN metastases is efficient and the long term results suggest, that the MI < 5 has a better impact on survival, than the D-level guided surgery.

Epidermal growth factor-induced hydrogen peroxide production is mediated by dual oxidase 1.

Stimulation of mammalian cells by epidermal growth factor (EGF) elicits complex signaling events, including an increase in hydrogen peroxide (H2O2) production. Understanding the significance of this response is limited by the fact that the source of EGF-induced H2O2 production is unknown. Here we show that EGF-induced H2O2 production in epidermal cell lines is dependent on the agonist-induced calcium signal. We analyzed the expression of NADPH oxidase isoforms and found both A431 and HaCaT cells to express the calcium-sensitive NADPH oxidase, Dual oxidase 1 (Duox1) and its protein partner Duox activator 1 (DuoxA1). Inhibition of Duox1 expression by small interfering RNAs eliminated EGF-induced H2O2 production in both cell lines. We also demonstrate that H2O2 production by Duox1 leads to the oxidation of thioredoxin-1 and the cytosolic peroxiredoxins. Our observations provide evidence for a new signaling paradigm in which changes of intracellular calcium concentration are transformed into redox signals through the calcium-dependent activation of Duox1.

A novel persulfide detection method reveals protein persulfide- and polysulfide-reducing functions of thioredoxin and glutathione systems.

Hydrogen sulfide signaling involves persulfide formation at specific protein Cys residues. However, overcoming current methodological challenges in persulfide detection and elucidation of Cys regeneration mechanisms from persulfides are prerequisites for constructing a bona fide signaling model. We here establish a novel, highly specific protein persulfide detection protocol, ProPerDP, with which we quantify 1.52 ± 0.6 and 11.6 ± 6.9 µg/mg protein steady-state protein persulfide concentrations in human embryonic kidney 293 (HEK293) cells and mouse liver, respectively. Upon treatment with polysulfides, HEK293 and A549 cells exhibited increased protein persulfidation. Deletion of the sulfide-producing cystathionine-γ-lyase or cystathionine-ß-synthase enzymes in yeast diminished protein persulfide levels, thereby corroborating their involvement in protein persulfidation processes. We here establish that thioredoxin (Trx) and glutathione (GSH) systems can independently catalyze reductions of inorganic polysulfides and protein persulfides. Increased endogenous persulfide levels and protein persulfidation following polysulfide treatment in thioredoxin reductase-1 (TrxR1) or thioredoxin-related protein of 14 kDa (TRP14) knockdown HEK293 cells indicated that these enzymes constitute a potent regeneration system of Cys residues from persulfides in a cellular context. Furthermore, TrxR1-deficient cells were less viable upon treatment with toxic amounts of polysulfides compared to control cells. Emphasizing the dominant role of cytosolic disulfide reduction systems in maintaining sulfane sulfur homeostasis in vivo, protein persulfide levels were markedly elevated in mouse livers where hepatocytes lack both TrxR1 and glutathione reductase (TR/GR-null). The different persulfide patterns observed in wild-type, GR-null, and TR/GR-null livers suggest distinct roles for the Trx and GSH systems in regulating subsets of protein persulfides and thereby fine-tuning sulfide signaling pathways.

Enzymatically modified low-density lipoprotein is recognized by c1q and activates the classical complement pathway.

Several studies suggest that the complement system is involved in atherogenesis. To further investigate this question, we have studied the ability of native and modified forms of LDL to bind and activate C1, the complex protease that triggers the classical pathway of complement. Unlike native LDL, oxidized (oxLDL) and enzymatically modified (E-LDL) derivatives were both recognized by the C1q subunit of C1, but only E-LDL particles, obtained by sequential treatment with a protease and then with cholesterol esterase, had the ability to trigger C1 activation. Further investigations revealed that C1q recognizes a lipid component of E-LDL. Several approaches, including reconstitution of model lipid vesicles, cosedimentation, and electron microscopy analyses, provided evidence that C1 binding to E-LDL particles is mediated by the C1q globular domain, which senses unesterified fatty acids generated by cholesterol esterase. The potential implications of these findings in atherogenesis are discussed.

Proteins of the innate immune system crystallize on carbon nanotubes but are not activated.

The classical pathway of complement is an essential component of the human innate immune system involved in the defense against pathogens as well as in the clearance of altered self-components. Activation of this pathway is triggered by C1, a multimolecular complex comprising a recognition protein C1q associated with a catalytic subunit C1s-C1r-C1r-C1s. We report here the direct observation of organized binding of C1 components C1q and C1s-C1r-C1r-C1s on carbon nanotubes, an ubiquitous component in nanotechnology research. Electron microscopy imaging showed individual multiwalled carbon nanotubes with protein molecules organized along the length of the sidewalls, often over 1 µm long. Less well-organized protein attachment was also observed on double-walled carbon nanotubes. Protein-solubilized nanotubes continued to attract protein molecules after their surface was fully covered. Despite the C1q binding properties, none of the nanotubes activated the C1 complex. We discuss these results on the adsorption mechanisms of macromolecules on carbon nanotubes and the possibility of using carbon nanotubes for structural studies of macromolecules. Importantly, the observations suggest that carbon nanotubes may interfere with the human immune system when entering the bloodstream. Our results raise caution in the applications of carbon nanotubes in biomedicine but may also open possibilities of novel applications concerning the many biochemical processes involving the versatile C1 macromolecule.

Complement protein C1q recognizes enzymatically modified low-density lipoprotein through unesterified fatty acids generated by cholesterol esterase.

We previously reported that enzymatically modified low-density lipoprotein (E-LDL) particles obtained by LDL treatment with trypsin and then cholesterol esterase are recognized by C1q and activate the C1 complex of complement. The objective of this study was to identify the E-LDL component(s) recognized by C1q. In addition to trypsin, plasmin, thrombin, tryptase, and matrix metalloprotease-2 each yielded E-LDL particles with high C1-activating efficiency, and the C1 activation extent was strictly dependent on cholesterol esterase treatment in all cases. When incorporated into vesicles, the lipid fraction of E-LDL, but not of native LDL, triggered C1 activation, and activation correlated with the amount of unesterified cholesterol generated by cholesterol esterase. Whereas treatment of E-LDL particles with human serum albumin reduced their fatty acid content, both cholesterol and unesterified fatty acids were decreased by methyl-beta-cyclodextrin, both treatments resulting in dose-dependent inhibition of the C1-activating ability of the particles. Incorporation of linoleic acid into phosphatidylcholine-containing model vesicles enabled them to interact with the C1q globular domain and to trigger C1 activation, and cholesterol enhanced both processes by facilitating incorporation of the fatty acid into the vesicles. Direct evidence that C1q binds E-LDL through its globular domains was obtained by electron microscopy. This study demonstrates that C1 binding to E-LDL particles involves recognition by the C1q globular domain of the unesterified fatty acids generated by cholesterol esterase. The potential implications of these findings in atherogenesis are discussed.

New cholesterol-specific antibodies remodel HIV-1 target cells' surface and inhibit their in vitro virus production.

The importance of membrane rafts in HIV-1 infection is still in the focus of interest. Here, we report that new monoclonal anticholesterol IgG antibodies (ACHAs), recognizing clustered membrane cholesterol (e.g., in lipid rafts), rearrange the lateral molecular organization of HIV-1 receptors and coreceptors in the plasma membrane of HIV-1 permissive human T-cells and macrophages. This remodeling is accompanied with a substantial inhibition of their infection and HIV-1 production in vitro. ACHAs promote the association of CXCR4 with both CD4 and lipid rafts, consistent with the decreased lateral mobility of CXCR4, while Fab fragments of ACHAs do not show these effects. ACHAs do not directly mask the extracellular domains of either CD4 or CXCR4 nor do they affect CXCR4 internalization. No significant inhibition of HIV production is seen when the virus is preincubated with the antibodies prior to infection. Thus, we propose that the observed inhibition is mainly due to the membrane remodeling induced by cholesterol-specific antibodies on the target cells. This, in turn, may prevent the proper spatio-temporal juxtaposition of HIV-1 glycoproteins with CD4 and chemokine receptors, thus negatively interfering with virus attachment/entry.

The 8.1 ancestral MHC haplotype is strongly associated with colorectal cancer risk.

Many recent data indicate that some alleles encoded in the central major histocompatibility complex (MHC) region (Class III) of short arm of chromosome 6 may modify the risk of cancer development. Therefore we determined 4 single nucleotide polymorphisms (SNPs) of this region (TNF-alpha -308 G > A, RAGE -429 T > C, HSP70-2 -1267 A > G, LTA 252 A > G) in genomic DNA samples from 183 Hungarian patients with colorectal cancer and 141 age matched control subjects representing the Hungarian population of the same age and gender. No significant differences were found in either SNP tested. When, however, three- or four-locus haplotypes consisting of known constituents of the so-called 8.1 ancestral haplotype (8.1AH) were considered, marked differences were observed. Frequency of TNF-alpha -308A, RAGE -429C, HSP70-2 -1267G, LTA 252G (8.1AH) haplotype was significantly (p = 0.006) more frequent (19.1%) among patients than in the controls (7.7%). Age- and gender-adjusted ratio of the 8.1AH carriers vs. non-carriers to have colorectal cancer was 2.514 (1.130-5.594). This risk was higher in

Studies on the interactions between C-reactive protein and complement proteins.

Several studies have investigated the interactions between C-reactive protein (CRP) and various complement proteins but none of them took into consideration the different structural forms of CRP. The aim of our study was to investigate whether the different antigenic forms of CRP are able to bind C1q, to trigger activation of the C1 complex and to study the ability of the various CRP forms to bind complement factor H (FH) and C4b-binding protein (C4BP). Interactions between various CRP forms and complement proteins were analysed in enzyme-linked immunosorbent assay and surface plasmon resonance tests and activation of the C1 complex was followed in a reconstituted system using purified C1q, C1r and C1s in the presence of C1-INH. Native, ligand-unbound CRP activated the classical pathway weakly. After binding to phosphocholine, native CRP bound C1q and significantly activated C1. Native CRP complexed to phosphocholine did not bind the complement regulatory proteins FH and C4BP. After disruption of the pentameric structure of CRP, as achieved by urea-treatment or by site-directed mutagenesis, C1q binding and C1 activation further increased and the ability of CRP to bind complement regulatory proteins was revealed. C1q binds to CRP through its globular head domain. The binding sites on CRP for FH and C4BP seemed to be different from that of C1q. In conclusion, in parallel with the increase in the C1-activating ability of different CRP structural variants, the affinity for complement regulatory proteins also increased, providing the biological basis for limitation of excess complement activation.

Novel anti-cholesterol monoclonal immunoglobulin G antibodies as probes and potential modulators of membrane raft-dependent immune functions.

Natural autoantibodies against cholesterol are present in the sera of all healthy individuals; their function, production, and regulation, however, are still unclear. Here, we managed to produce two monoclonal anti-cholesterol antibodies (ACHAs) by immunizing mice with cholesterol-rich liposomes. The new ACHAs were specific to cholesterol and to some structurally closely related 3beta-hydroxyl sterols, and they reacted with human lipoproteins VLDL, LDL, and HDL. They bound, usually with low avidity, to live human or murine lymphocyte and monocyte-macrophage cell lines, which was enhanced substantially by a moderate papain digestion of the cell surface, removing some protruding extracellular protein domains. Cell-bound ACHAs strongly colocalized with markers of cholesterol-rich lipid rafts and caveolae at the cell surface and intracellularly with markers of the endoplasmic reticulum and Golgi complex. These data suggest that these IgG ACHAs may serve as probes of clustered cholesterol (e.g., different lipid rafts) in live cells and thus may also have immunomodulatory potential.