An intracellular VHH targeting the Luteinizing Hormone receptor modulates G protein-dependent signaling and steroidogenesis

Luteinizing hormone (LH) is essential for reproduction, controlling ovulation and steroidogenesis. Its receptor (LHR) recruits various transducers leading to the activation of a complex signaling network. We recently identified iPRC1, the first variable fragment from heavy-chain-only antibody (VHH) interacting with intracellular loop 3 (ICL3) of the follicle-stimulating hormone receptor (FSHR). Because of the high sequence similarity of the human FSHR and LHR (LHCGR), here we examined the ability of the iPRC1 intra-VHH to modulate LHCGR activity. In this study, we demonstrated that iPRC1 binds LHCGR, to a greater extent when the receptor was stimulated by the hormone. In addition, it decreased LH-induced cAMP production, cAMP-responsive element-dependent transcription, progesterone and testosterone production. These impairments are not due to Gs nor β-arrestin recruitment to the LHCGR. Consequently, iPRC1 is the first intra-VHH to bind and modulate LHCGR biological activity, including steroidogenesis. It should help further understand signaling mechanisms elicited at this receptor and their outcomes on reproduction.

A single-domain intrabody targeting the follicle-stimulating hormone receptor impacts FSH-induced G protein-dependent signalling

Intracellular variable fragments of heavy-chain antibody from camelids (intra-VHH) have been successfully used as chaperones to solve the 3D structure of active G protein-coupled receptors bound to their transducers. However, their effect on signalling has been poorly explored, although they may provide a better understanding of the relationships between receptor conformation and activity. Here, we isolated and characterized iPRC1, the first intra-VHH recognizing a member of the large glycoprotein hormone receptor family, the follicle-stimulating hormone receptor (FSHR). This intra-VHH recognizes the FSHR third intracellular loop and decreases cAMP production in response to FSH, without altering Gαs recruitment. Hence, iPRC1 behaves as an allosteric modulator and provides a new tool to complete structure/activity studies performed thus far on this receptor.

Combined Multiplexed Phage Display, High-Throughput Sequencing, and Functional Assays as a Platform for Identifying Modulatory VHHs Targeting the FSHR

Developing modulatory antibodies against G protein-coupled receptors is challenging. In this study, we targeted the follicle-stimulating hormone receptor (FSHR), a significant regulator of reproduction, with variable domains of heavy chain-only antibodies (VHHs). We built two immune VHH libraries and submitted them to multiplexed phage display approaches. We used next-generation sequencing to identify 34 clusters of specifically enriched sequences that were functionally assessed in a primary screen based on a cAMP response element (CRE)-dependent reporter gene assay. In this assay, 23 VHHs displayed negative or positive modulation of FSH-induced responses, suggesting a high success rate of the multiplexed strategy. We then focused on the largest cluster identified (i.e., PRC1) that displayed positive modulation of FSH action. We demonstrated that PRC1 specifically binds to the human FSHR and human FSHR/FSH complex while potentiating FSH-induced cAMP production and Gs recruitment. We conclude that the improved selection strategy reported here is effective for rapidly identifying functionally active VHHs and could be adapted to target other challenging membrane receptors. This study also led to the identification of PRC1, the first potential positive modulator VHH reported for the human FSHR.

The AF-2 cofactor binding region is key for the selective SUMOylation of estrogen receptor alpha by antiestrogens

Antiestrogens (AEs) are used to treat all stages of estrogen receptor (ER)-positive breast cancer. Selective estrogen receptor modulators such as tamoxifen have tissue-specific partial agonist activity, while selective estrogen receptor downregulators such as fulvestrant (ICI182,780) display a more complete antiestrogenic profile. We have previously observed that fulvestrant-induced ERα SUMOylation contributes to transcriptional suppression, but whether this effect is seen with other AEs and is specific to ERα is unclear. Here we show that several AEs induce SUMOylation of ERα, but not ERβ, at different levels. Swapping domains between ERα and ERβ indicates that the ERα identity of the ligand-binding domain helices 3 and 4 (H3-H4 region), which contribute to the static part of the activation function-2 (AF-2) cofactor binding groove, is sufficient to confer fulvestrant-induced SUMOylation to ERβ. This region does not contain lysine residues unique to ERα, suggesting that ERα-specific residues in H3-H4 determine the capacity of the AE-bound ERα ligand-binding domain to recruit the SUMOylation machinery. We also show that the SUMO E3 ligase protein inhibitor of activated STAT 1 increases SUMOylation of ERα and of ERβ containing the H3-H4 region of ERα, but not of ERβ. Together, these results shed new light on the molecular basis for the differential capacity of selective estrogen receptor modulators and selective estrogen receptor downregulators to suppress transcription by ERα.

A New in Silico Antibody Similarity Measure Both Identifies Large Sets of Epitope Binders with Distinct CDRs and Accurately Predicts Off-Target Reactivity

Developing a therapeutic antibody is a long, tedious, and expensive process. Many obstacles need to be overcome, such as biophysical properties (issues of solubility, stability, weak production yields, etc.), as well as cross-reactivity and subsequent toxicity, which are major issues. No in silico method exists today to solve such issues. We hypothesized that if we were able to properly measure the similarity between the CDRs of antibodies (Ab) by considering not only their evolutionary proximity (sequence identity) but also their structural features, we would be able to identify families of Ab recognizing similar epitopes. As a consequence, Ab within the family would share the property to recognize their targets, which would allow (i) to identify off-targets and forecast the cross-reactions, and (ii) to identify new Ab specific for a given target. Testing our method on 238D2, an antagonistic anti-CXCR4 nanobody, we were able to find new nanobodies against CXCR4 and to identify influenza hemagglutinin as an off-target of 238D2.

Complex regulation of orphan nuclear receptor Nur77 (Nr4a1) transcriptional activity by SUMO2 and PIASγ

Nur77 (NGFI-B) is a nuclear receptor that belongs to the Nr4a family of orphan nuclear receptors (Nr4a1). This transcription factor has been implicated in the regulation of multiple functions, such as cell cycle regulation, apoptosis, inflammation, glucose and lipid metabolism, and brain function. However, the mechanisms involved in its different regulatory properties remain unclear. In search for regulatory mechanisms of Nur77 function, we identified that Protein Inhibitor of Activated STAT gamma (PIASγ), an E3 SUMO-protein ligase, potently repressed Nur77 transcriptional activity in HEK-293T cells. This PIASγ activity was sensitive to Sentrin SUMO-specific protease 1 (SENP1). Substitution of two putative phylogenetically well-conserved small ubiquitin-like modifier (SUMO) acceptor sites, lysine 102 (K102) and 577 (K577) by arginine residues (R) modulated Nur77 transcriptional activity. In particular, Nur77-K102R and Nur77-K102R/K577R mutants strongly decreased the transcriptional activity of Nur77, whereas single K577R substitution increased transcriptional activity of Nur77. Repression of Nur77 transcriptional activity by SUMO2 and PIASγ was reduced by the K577R mutation, whereas the K102R mutant remained insensitive to SUMO2. Interestingly, the roles of these SUMO acceptor sites in Nur77 are distinct from previously observed activities on its close homolog Nurr1. Thus, the present study identified SUMO2 and PIASγ as important transcriptional co-regulators of Nur77.

Altered expression of the CCN genes in the lungs of mice in response to cigarette smoke exposure and viral and bacterial infections

The CCN proteins are key signaling and regulatory molecules involved in many biological functions and contribute to malignant and non-malignant lung diseases. Despite the high morbidity and mortality of the lung respiratory infectious diseases, there is very little data related to the expression of the CCNs during infection. We investigated in mice the pulmonary mRNA expression levels of five CCNs (1 to 5) in response to influenza A virus (IAV) and bacterial agents (Nontypeable Haemophilus influenzae (NTHi), lipopolysaccharide (LPS) and lipoteichoic acid (LTA)). IAV, NTHi, LPS or LTA were instilled intranasally into mice. Mice were also exposed for 4days or 8weeks to cigarette smoke alone or prior infection to IAV in order to determine if CS modifies the CCN response to a viral infection. All challenges induced a robust inflammation. The mRNA expression of CCN1, CCN2 and CCN3 was decreased after short exposure to CS whereas prolonged exposure altered the expression of CCN1, CCN3 and CCN4. Influenza A virus infection increased CCN1, 2, 4 and 5 mRNA levels but expression of CCN3 was significantly decreased. Acute CS exposure prior infection had little effect on the expression of CCN genes but prolonged exposure abolished the IAV-dependent induction. Treatment with LPS or LTA and infection with NTHi revealed that both Gram-positive and Gram-negative bacteria rapidly modulate the expression of the CCN genes. Our findings reveal that several triggers of lung inflammation influence differently the CCN genes. CCN3 deserves special attention since its mRNA expression is decreased by all the triggers studied.

Growth and survival of lung cancer cells: regulation by kallikrein-related peptidase 6 via activation of proteinase-activated receptor 2 and the epidermal growth factor receptor

The dysregulated expression of kallikrein-related peptidase 6 (KLK6) is involved in non-small cancer (NSCLC) cell growth. However, the mechanism that sustains KLK6 signaling remains unknown. We used an isogenic non-small cell lung cancer (NSCLC) cell model system to demonstrate that KLK6 promotes the proliferation of lung tumoral cells and restrains their apoptosis in vitro via ligand-dependent EGFR transactivation. KLK6 activated the ERK and Akt pathways and triggered the nuclear translocation of β-catenin. The stimulating effects of KLK6 required its proteolytic activity and were dependent on the protease-activated receptor 2 (PAR2). These observations support the concept of a role for KLK6 in the oncogenesis of NSCLC.

Gigabar spherical shock generation on the OMEGA laser

This Letter presents the first experimental demonstration of the capability to launch shocks of several-hundred Mbar in spherical targets--a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using the temporal delay between the launching of the strong shock at the outer surface of the spherical target and the time when the shock converges at the center, the shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures exceeding 300 Mbar are inferred at absorbed laser intensities of ∼3×10(15)  W/cm2. The shock strength is shown to be significantly enhanced by the coupling of suprathermal electrons with a total converted energy of up to 8% of the incident laser energy. At the end of the laser pulse, the shock pressure is estimated to exceed ∼1  Gbar because of convergence effects.

Ni/Fe-supported over hydrotalcites precursors as catalysts for clean and selective oxidation of Basic Yellow 11: reaction intermediates determination

In this work, Basic Yellow 11 (BY 11) was employed as model compound to study catalytic wet air oxidation as a pre-treatment step to the conventional biological oxidation. Ni and Fe catalysts supported over hydrotalcite (HT) were prepared by incipient wetness and excess impregnation to obtain catalysts with different metal loadings (from 1 to 10 wt.%). HTs were synthesized by co-precipitation and characterized with XRD, X-ray fluorescence (XRF), BET, thermogravimetric analysis and SEM. Results showed that dye conversion increased with Ni and Fe content up to 7 wt.% and that the most effective catalyst were prepared by incipient wetness impregnation. The influence of metal loading in the catalyst, and the preparation method as well as the reaction conditions was investigated. A mechanism and reaction pathways for BY 11 during catalytic liquid phase oxidation have also been proposed.

Catalytic wet air oxidation with Ni- and Fe-doped mixed oxides derived from hydrotalcites

Catalytic wet air oxidation of Basic Yellow 11 (BY11), a basic dye, was studied in a batch reactor. Layered double hydroxides with the hydrotalcite-like structure containing nickel or iron cations have been prepared by coprecipitation and subsequently calcined leading to Ni- and Fe-doped mixed oxides, respectively. Compared with the results in the wet air oxidation of BY11, these catalysts showed high activity for total organic carbon (TOC), toxicity and dye removal at 120 degrees C and 50 bars after 120 min. It has been demonstrated that the activity depended strongly on the presence of catalyst. The results show that catalysts containing nickel provide a higher extent of oxidation of the dye whereas the reaction carried out with the iron catalyst is faster. The Ni and Fe dispersion determined from the TPR results was higher for the catalysts with a lower Ni or Fe content and decreased for higher Ni or Fe contents. On the basis of activity and selectivity, the Ni containing catalyst with the medium (3%) Ni content was found to be the best catalyst. Finally, a relationship between metal content of the catalyst and reaction rate has been established.

Purification of an alcohol dehydrogenase involved in the conversion of methional to methionol in Oenococcus oeni IOEB 8406

Oenococcus oeni, the major lactic acid bacteria involved in malolactic fermentation (MLF) in wine, is able to produce volatile sulfur compounds from methionine. Methional reduction is the last enzymatic step of methionol synthesis in methionine catabolism. Alcohol dehydrogenase (ADH) activity was found to be present in the soluble fraction of O. oeni IOEB 8406. An NAD(P)H-dependent ADH involved in the reduction of methional was then purified to homogeneity. Sequencing of the purified enzyme and amino acid sequence comparison with the database revealed the presence of a conserved sequence motif specific to the medium-chain zinc-containing NAD(P)H-dependent ADHs. Despite the great importance of ADH activities in wine flavor modification, this is the first report of the purification of an ADH isolated from O. oeni. The purified ADH does not seem to be involved in the modification of buttery and lactic notes or to be involved in the specific formation of volatile alcohols during MLF. The enzyme was not strictly specific of methional reduction and the highest reducing activity was obtained with acetaldehyde as substrate. The function of the purified ADH remains unclear, although the role of the sulfur atom in methional molecules in the interaction between enzyme and substrate was evidenced.

Recombinant protein Bd37 protected gerbils against heterologous challenges with isolates ofBabesia divergenspolymorphic for thebd37gene

The Bd37gene encoding for a glycosyl-phosphatidyl-inositol anchored protein ofBabesia divergensdisplays genetic polymorphisms among isolates. Five major polymorphic groups (clades) were shown by PCR-RFLP among differentB. divergensisolates. Each group has been characterized according to a reference Bd37 gene (Rouen87, W8843, Y5, 6303E and 1705B). Recombinant (GST fusion) protein (Bd37r) expressed from the Bd37 gene, was used as antigen in a saponin-based formulation and was able to protect gerbils, after 2 injections at low dose vaccine concentration (1 μg per dose), against a virulent challenge with theB. divergensRouen87 isolate. In spite of polymorphism ofBd37gene, Bd37r induced complete immunoprotection against challenges with each of the 5 reference isolate groups defined by PCR-RFLP.

Coup de chaleur d'exercice avec hépatite fulminante : intérêt du système MARS® ?

Exertional heat stroke (EHS) is a life-threatening condition caused by an extreme elevation in core body temperature. Acute liver failure has been reported during EHS justifying liver transplantation in some cases. The Molecular Adsorbent Recirculating System (MARS) could be indicated in such situations. We report a case of a 58-year old patient who suffered acute liver failure occurring after EHS. The patient was referred for liver transplantation and benefited of MARS therapy. After three sessions of MARS, liver function improved progressively and the transplantation was not necessary. The patient completely recovered.

Changes to hepatocyte ploidy and binuclearity profiles during human chronic viral hepatitis

BACKGROUND AND AIMS

The importance of the hepatocyte ploidisation pattern to the control of cell proliferation and differentiation has been well established. However, there are no data that have characterised hepatocyte ploidy at various stages of chronic liver inflammation and fibrosis in vivo.

METHODS

We therefore investigated hepatocyte ploidy/binuclearity patterns in 57 patients with chronic hepatitis, using a recently developed methodology which allows simultaneous hepatocyte ploidy and binuclearity analyses on the same liver section.

RESULTS

The percentage of mononuclear diploid hepatocytes was significantly reduced in patients with high hepatitis activity and marked fibrosis (low activity: 75.1 (18.8)% v high activity: 61.8 (21.6)%, p=0.0111, and low fibrosis: 77.3 (13.8)% v high fibrosis: 57.4 (23.3)%, p=0.0002). Accordingly, the percentage of mononuclear polyploid hepatocytes increased in patients with high hepatitis activity and marked fibrosis (low activity: 11.9 (15.5)% v high activity: 22.2 (20.1)%, p=0.0166, and low fibrosis: 9.4 (10.7)% v high fibrosis: 26.4 (21.6)%, p=0.0001). In addition, the fraction of binuclear hepatocytes was significantly higher in patients with hepatitis B virus (HBV) than in those with hepatitis C virus (HCV) infections (HBV: 18.2 (7.6)% v HCV: 12.0 (4.8)%; p=0.0020). Under multivariate analysis, HBV infection was an independent factor accounting for the larger binuclear hepatocyte fraction (p=0.0294).

CONCLUSION

Our results revealed an increase in the polyploid hepatocyte fraction which correlates with the severity of chronic hepatitis; moreover, we demonstrated that HBV and HCV related chronic hepatitis exhibited distinctive hepatocyte ploidy patterns, thus allowing the suggestion that these two viral infections may modulate liver ploidy through different mechanisms.

Association between sequence polymorphism in an epitope of Babesia divergens Bd37 exoantigen and protection induced by passive transfer

In Europe, Babesia divergens is the major agent responsible for babesiosis in cattle and can occasionally infect splenectomised humans. Recently, we reported the characterisation of a 37 kDa exoantigen (Bd37) anchored in the merozoite membrane of B. divergens by a glycosylphosphatidyl-inositol. After phospholipase hydrolyse of the glycosylphosphatidyl-inositol anchor, the Bd37 antigen could be isolated in the plasma of the infected host and from the in vitro culture supernatants. Immunisation of mice with a gel-filtration protective fraction of B. divergens exoantigens, produced a monoclonal antibody (MAb), called F4.2F8-INT, directed against Bd37. In the present study, we report data on passive protection using MAb F4.2F8-INT. This MAb was able to completely protect against virulent challenges with B. divergens isolates Rouen 1987 (Rouen87) and Weybridge 8843 (W8843) but had no protective effect against another French isolate from Massif Central (6303E). Physical characterisation of the epitope recognised by F4.2F8-INT allowed us to explain the differences observed between these isolates by western blotting and passive protection. These results suggest that the antigen carrying this epitope could be used as a target in the development of a recombinant vaccine against B. divergens babesiosis.

Babesia divergens: cloning and biochemical characterization of Bd37

The immunoprotective potential of Babesia divergens antigens released in supernatants of in vitro cultures of the parasite is generally known. Among a number of parasite molecules, a 37 kDa protein has been found in the supernatants of Babesia divergens cultures. In this report the cloning and biochemical characterization of this protein, called Bd37, are described. In addition, the processing of the protein was studied in vitro. Results suggest that Bd37 is encoded by a single copy gene. Bd37 appears to be a merozoite-associated molecule attached to the surface by a glycosylphosphatidylinositol moiety containing a palmitate residue attached to the inositol ring. In addition, it is demonstrated that both extremities of the protein are linked by a disulphide bond. Results further indicate that a soluble, hydrophilic form of Bd37 can be released from the merozoite surface by GPI-specific phospholipase D. The potential role the Bd37 protein and the GPI anchor are discussed.

Pontine myelinolysis following liver transplantation: a report of two cases

Two cases of central pontine myelinolysis (CPM) following orthotopic liver transplantation (OLT) are reported. Several months after the onset of this neurological syndrome, the two patients are still alive but with severe neurological sequelae. Some patients undergoing emergency OLT present a high risk of CPM because of pre-existing malnutrition, encephalopathy, and hepatic insufficiency. All of these are associated with an inevitable abrupt rise in sodium serum concentration due to intraoperative compensation of blood losses with high-sodium content blood products. Whenever the renal capacity to excrete sodium is impaired by the surgical procedure, continuous intraoperative venovenous hemofiltration is recommended.

[Use of homologous erythrocyte concentrates. Analysis of economical factors]

The factors involved in reducing consumption of bank packed red cells (PRC) were studied over three one year periods (1983, 1987 and 1989) in a Department of Vascular and General Surgery. The effects of autologous blood salvage (started in 1987), associated with the management of homologous blood by a branch of the blood bank inside the operating theater suite were assessed. In 1989, intentional normovolaemic haemodilution became virtually systematic, on top of the intraoperative blood salvage, for all patients due to undergo surgery with a risk of severe blood loss. The number of surgical procedures carried out during those three years did not vary. However, in the same time, the annual consumption of homologous PRC decreased by an overall 56% (36.7% between 1983 and 1987, and 29.8% between 1987 and 1989). This decrease was mostly due to a fall in prescription in the operating theaters, and not in the wards. In the same time, albumin consumption increased sixfold. Such transfusional policies can only be carried out if there is good cooperation between the blood bank and the prescribers of blood products.

[Hemodynamic and gasometric modifications during the anesthesia recovery period in patients undergoing ventilation after surgery of the abdominal aorta]

This study was carried out on 12 patients (mean age 61) in order to assess the oxygen consumption (VO2) in the post-operative stage of an elective surgical procedure (replacement of the abdominal aorta). Anesthesia was a combination of thiopentone, pancuronium bromide and high doses of droperidol and fentanyl. Patients were kept intubated and ventilated in the post-operative period. VO2 and other related metabolic parameters as well as hemodynamic parameters were measured every 45 minutes over a period of 5 hours. A VO2 increase (127%) related to the increase in body temperature was noted. Mean VO2 for all patients during the whole period was 170 +/- 13 ml.min-1.m-2 (range: 51-411 ml.min-1.m-2). Mean value of maximal VO2 was 240 +/- 21 ml.min-1.m-2 (range: 1471-411 ml.min-1.m-2). Large dose of droperidol are shown to limit VO2 increase. In patients with shivering, the maximal value of VO2 was found during shivering. The amount of droperidol administered during anesthesia was greater in patients without shivering. VO2 increase was due to a rise in tissular O2 extraction. Cardiac index was insufficiently increased (+ 9.4%) and a certain extent of myocardial inadaptability was suspected in relation with: high blood pressure, hypovolaemia and/or myocardial effect of anesthesia agents.

Treatment of deep venous thrombosis with a very low molecular weight heparin fragment (CY 222)

Thirty patients presenting with phlebographically confirmed deep venous thrombosis were treated with a very low molecular weight heparin fragment (CY 222) in an open and prospective phase-2 trial. A uniform dosage of 750 IC anti-factor Xa units/kg/day was administered subcutaneously for 10 days or more to patients whose thromboses were categorized as postsurgical (17 cases) or medical (13 cases). The clinical symptoms of venous thrombosis diminished in 93% of the patients overall. The extent of vascular clearing was assessed by an original scoring system which compared the pre- and posttreatment phlebographies. The effect of treatment was globally rated 'very good' (more than 75% lysis) in 37% of the patients, 'good' (about 50% lysis) in 40% and 'poor' (0-25% lysis) in 17%; the phlebographic thrombosis worsened in 6.6%. Little change occurred in laboratory tests exploring thrombolysis, but a strong anti-factor Xa activity was detected.

[Hemodynamic changes caused by laparotomy during aorto-iliac surgery]

A haemodynamic study was carried out on 53 patients undergoing elective surgery of the abdominal aorta in order to assess the haemodynamic changes consequent to abdominal manipulations prior to aortic clamping. Surgery was carried out under general anaesthesia and ventilation was controlled. The following parameters were monitored: mean arterial pressure (Pa), cardiac index (CI), systolic index (SI), systemic vascular resistances (Rsa), pulmonary vascular resistances (Rpa), heart rate (fC). Cutaneous circulation was monitored using a photoplethysmographic transducer. The following haemodynamic pattern was seen as the peritoneal cavity was opened and traction on the mesentery was applied: CI +40.7%; fC +28.61%; SI +9.85%; Rsa -39.16%; Rpa -28.43%; Pa -15.7%. The recording of the facial cutaneous photoplethysmographic wave showed an increase of 50%. In some extreme cases, a state of cardiovascular collapse with marked cutaneous erythema strongly resembling anaphylactic shock ensued. The physiopathology of these cardiovascular reactions is unclear, but the haemodynamic pattern as well as the cutaneous vasodilation suggest a stimulation of both vagal and sympathetic nervous systems and the release of vasoactive substances into the general circulation.

[Peroperative autotransfusion]

Between April 1976 and December 1984, 297 patients underwent major elective and emergency surgery using intraoperative autotransfusion (Bentley ATS unit). An amount of 732 l of blood was reinfused, representing 61% of the total intraoperative blood transfusion. Thanks to this method, an average 2.46 l of blood per patient was spared, with a range of 0.9 to 6 l according to the type of surgery (elective or emergency). Twelve accidents are reported, including four bradycardias (less than 45 b X min-1), two air emboli and six haemorrhages due to an excess of anticoagulation. These complications were related either to poor technique (too great a transfusion output) or insufficient blood anticoagulation control. Simplicity of use and high transfusion output of the device adapted to the blood loss are the advantages of intraoperative autotransfusion.