Enhanced jejunal production of antibodies to Klebsiella and other Enterobacteria in patients with ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE—To measure gut immunity directly in jejunal fluid in patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA).
METHODS—Antibodies against three different Enterobacterias were measured in jejunal perfusion fluids (collected by a double balloon perfusion device) of 19 patients with AS, 14 patients with RA, and 22 healthy controls using enzyme linked immunosorbent assay.
RESULTS—The AS patients had significantly increased jejunal fluid concentrations of IgM, IgG, and IgA class antibodies against Klebsiella pneumoniae, and IgM and IgA class antibodies against Escherichia coli and Proteus mirabilis compared with healthy controls. When compared with the patients with RA, the AS patients had higher concentrations of IgA and IgG class antibodies only against K pneumoniae. The RA patients had higher IgM class antibody concentrations against all three studied Enterobacterias, when compared with the healthy controls, suggesting an enhanced mucosal immune response in these patients. A three month treatment with sulphasalazine did not decrease enterobacterial antibody concentrations in the 10 patients with AS.
CONCLUSION—There is strong direct evidence for an abnormal mucosal humoral immune response particularly to K pneumoniae in patients with AS.

     

Detection of anti-colon antibodies in inflammatory bowel disease using human cultured colonic cells

Background—Investigationof anti-colon antibodies may be simplified if a sensitive method andhomogeneous source of antigen were available.
Aims—To examine theanti-colon antibody response using human colonic carcinoma cell linesas antigen.
Subjects—Patients withinflammatory bowel disease and other gastrointestinal disorders andhealthy controls were studied.
Methods—Comparativeenzyme linked immunosorbent assays (ELISAs) were performed to assessthe value of whole Caco-2, HT-29, and LS-180 cells as antigen. Theantigenic determinants of the immune response were characterised bywestern blot analysis.
Results—Serademonstrated immunoreactivity against each of the cell lines, butdifferent epitopes were recognised. Applying whole Caco-2 cells asantigen in an ELISA, the prevalence of anti-colon antibodies wassignificantly greater in patients with ulcerative colitis (36%) thanCrohn's disease (13%), other gastrointestinal disorders (13%) andhealthy controls (0) (p<0.05). The immune response was not associatedwith one predominant antigen.
Conclusions—Fixedwhole cell ELISA is a simple and feasible method for studying theanti-colon antibody response. This response is non-specific, beingdirected against multiple antigens, and is likely to be anepiphenomenon of inflammatory bowel disease, more so for ulcerativecolitis than Crohn's disease.

Keywords:anti-colon antibodies; inflammatory boweldisease

     

Antibodies directed against nitrosylated neoepitopes in sera of patients with human African trypanosomiasis

Antibodies directed against nitrosylated epitopes have been found in sera from patients suffering from human African trypanosomiasis (HAT) but not in sera from control subjects living in the same endemic area or African control subjects living in France. We conjugated amino acids to albumin by glutaraldehyde (conjugates) and then nitrosylated the conjugates. Both conjugates and nitrosylated conjugates were analysed by enzyme-linked immunosorbent assay (ELISA). We detected antibodies directed against nitrosylated L-cysteine and L-tyrosine conjugates; antibody levels were higher in stage II patients than in stage I. Patients with severe clinical signs had higher antibody levels, and antibody levels were highest in patients with major neurological signs. Antibody response was only associated with the IgM isotype. We evaluated antibody specificity and avidity by competition experiments using conjugates and nitrosylated conjugates. Avidity was around 2 x10(-6) m for the S-nitroso-cysteine epitope and 2 x 10(-8) m for the S-nitroso-tyrosine epitope. Detection of circulating antibodies to S-nitroso-cysteine and S-nitroso-tyrosine epitopes provides indirect evidence for nitric oxide (NO) involvement in HAT and their levels are correlated with disease severity.     

Monitoring of streptokinase resistance titre in acute myocardial infarction patients up to 30 months after giving streptokinase or anistreplase and related studies to measure specific antistreptokinase IgG

Objective—To examine the induction of antistreptokinase antibodies after giving streptokinase or anistreplase to patients with acute myocardial infarction.Design—Patients were randomly allocated to receive either 1·5 × 10⁶ IU, streptokinase or 30U anistreplase in a double blind study. Blood samples were collected immediately before treatment and subsequently at intervals up to 30 months; plasma samples were assayed for streptokinase resistance titre (functional assay) and streptokinase binding by IgG (microradioimmunoassay).Setting—Cardiology department in a general hospital.Patients—128 consecutive eligible patients. Samples were collected for up to one year according to a prospective design: a subsection of 47 patients was selected for intensive study over the first 14 days. After one year, all available patients (67) were sampled on one further occasion.Results—Antibody responses to streptokinase and anistreplase were similar. Streptokinase resistance titres exceeded pretreatment concentrations five days after dosing, and values peaked at 14 days. By 12 months after dosing, 92% of resistance titres (n = 84) had returned to within the pretreatment range. Antistreptokinase IgG concentrations also exceeded baseline concentrations within five days and peaked at 14 days. Half of the individual values had returned to within the pretreatment range by 12 months (n = 84) and 89% by 30 months (n = 18).Conclusion—Although we cannot be sure of the clinical significance, because of the increased likelihood of resistance due to antistreptokinase antibody, streptokinase and anistreplase may not be effective if administered more than five days after an earlier dose of streptokinase or anistreplase, particularly between five days and 12 months, and increased antistreptokinase antibody may increase the risk of allergic-type reactions.     

Synthesis,characterization, and immunogenicity in mice of Shigella sonnei O-specific oligosaccharide-core-protein conjugates

Shigellosis, an enteric disease, is on the World Health Organization''s priority prevention list. In one study, the Shigella sonnei O-specific polysaccharide (O-SP)-protein conjugate showed 72% protection against disease in Israeli army recruits exposed to high rates (8–14%) of infection. The protection was related to vaccine-induced IgG anti-O-SP levels. Synthetic oligosaccharides of Shigella dysenteriae type 1, bound by their reducing ends to a carrier protein (“sun”-type configuration), induced significantly higher antibody levels than the native O-SP bound to protein by multiple-point attachments (“lattice”-type configuration). Attempts to synthesize the S. sonnei O-SP based oligosaccharides were not successful. Here, we describe the isolation, characterization, and conjugation of low-molecular-mass O-SP-core (O-SPC) fragments. The O-SPC fragments were bound by their reducing ends similar to the preparation of the synthetic S. dysenteriae type 1 conjugates. The O-SPC conjugates used oxime linkages between the terminal Kdo residues at the reducing ends of the S. sonnei saccharides and aminooxy linkers bound to BSA or a recombinant diphtheria toxin. The coupling reaction was carried out at a neutral pH and room temperature. IgG antibody levels induced in young outbred mice by the S. sonnei O-SPC conjugates were significantly higher then those elicited by the O-SP conjugates. Accordingly, we propose to evaluate clinically these conjugates.     

Fasting enhances mucosal antigen specific B cell responses in rheumatoid arthritis

OBJECTIVE—To evaluate the influence of fasting on the antigen specific immune responsiveness in patients with rheumatoid arthritis and healthy volunteers.
METHODS—Seven rheumatoid arthritis patients and 17 healthy volunteers were immunised perorally or parenterally with influenza virus vaccine after a three to six day long period of total energy deprivation (water fast). The subsequent antigen specific antibody mediated immune response was recorded in the blood at the single cell level by the ELISPOT method.
RESULTS—Short term starvation induced an enhanced antigen specific mucosa derived B lymphocyte response in rheumatoid arthritis patients and healthy volunteers. In contrast, the systemic B cell responses were not significantly altered by a total energy deprivation.
CONCLUSIONS—Short term starvation increases the mucosa derived B cell responsiveness, while systemic responsiveness is largely unaffected. The similar pattern of response in rheumatoid arthritis patients and healthy volunteers indicates that fasting alters the mucosal immune response independently of medical treatment.

     

Default perception of high-speed motion

When human observers are exposed to even slight motion signals followed by brief visual transients—stimuli containing no detectable coherent motion signals—they perceive large and salient illusory jumps. This visually striking effect, which we call “high phi,” challenges well-entrenched assumptions about the perception of motion, namely the minimal-motion principle and the breakdown of coherent motion perception with steps above an upper limit called d_max. Our experiments with transients, such as texture randomization or contrast reversal, show that the magnitude of the jump depends on spatial frequency and transient duration—but not on the speed of the inducing motion signals—and the direction of the jump depends on the duration of the inducer. Jump magnitude is robust across jump directions and different types of transient. In addition, when a texture is actually displaced by a large step beyond the upper step size limit of d_max, a breakdown of coherent motion perception is expected; however, in the presence of an inducer, observers again perceive coherent displacements at or just above d_max. In summary, across a large variety of stimuli, we find that when incoherent motion noise is preceded by a small bias, instead of perceiving little or no motion—as suggested by the minimal-motion principle—observers perceive jumps whose amplitude closely follows their own d_max limits.     

High prevalence of cytotoxin positive Helicobacter pylori in patients unrelated to the presence of peptic ulcers in Japan

Background—It has been reported that infectionwith vacuolating cytotoxin positive Helicobacter pyloristrains is associated with gastroduodenal disease in Western countries.
Aims—To evaluate the prevalence ofcytotoxin producing strains among patients with H pyloriinfection in relation to gastrointestinal diseases in Japan.
Patients—Ninety seven patients undergoing endoscopy.
Methods—A Western blot assay was conducted todetect serum antibodies against the cytotoxin using recombinantcytotoxin (VacA protein) as an antigen. To obtain a purifiedrecombinant cytotoxin, the vacA gene (2233 nucleotides)was cloned into an expression vector to produce the protein (744 aminoacids), which was expressed in Escherichia coli.
Results—Serum IgG antibodies to thecytotoxin were present in 85%, 95%, 95%, and 100% of infectedpatients with gastric ulcer (n=26), duodenal ulcer (n=21), chronicgastritis (n=19), and endoscopically normal mucosa (n=14), respectively.
Conclusion—The western blot method usingrecombinant VacA protein is simple and useful for detecting antibody tovacuolating cytotoxin. This method showed antibodies against cytotoxinwere highly prevalent, even in subjects with endoscopically normal mucosa in Japan, indicating that the cytotoxin may not be anindependent cause of gastrointestinal diseases induced by Hpylori infection.

     

Antigen specificity of antihistone antibodies in systemic sclerosis

OBJECTIVES—The aim of the study was to determine the prevalence and clinical significance of antibodies to individual histone components in systemic sclerosis (SSc).
METHODS—Serum samples from patients with limited cutaneous SSc (lSSc; n=42) and diffuse cutaneous SSc (dSSc; n=28) were examined for IgG and/or IgM antibodies to individual histone components and complexes by enzyme linked immunosorbent assay (ELISA).
RESULTS—The level of IgG antibody to total histones was significantly higher in lSSc and dSSc than in normal controls. The level of IgM antibody to total histones was significantly higher in lSSc, but not in dSSc, than in normal controls. IgG antibody to total histones tended to be increased in dSSc when compared with that in lSSc. On the other hand, IgM antibody to total histones tended to be increased in lSSc when compared with that in dSSc. Although SSc showed various antihistone specificities, H2B, H2A-H2B, (H2A-H2B)-dsDNA were main antigens recognised by IgG antibodies in both lSSc and dSSc. Although IgM antibodies to H2B and H2A-H2B were also detected in both lSSc and dSSc, serum samples from lSSc patients exhibited highest IgM reactivity with H1.
CONCLUSION—SSc may be included among conditions in which heterogeneous antihistone antibodies are produced. IgM antibodies to the most accessible histone H1 may be related to mild clinical features (lSSc) and IgG antibodies to the inner core molecules of native histone such as H2B or complexes including H2B may be associated with severe clinical features (dSSc) in Ssc.

Keywords: histone; antibody; systemic sclerosis; enzyme linked immunosorbent assay     

Signing at the beginning makes ethics salient and decreases dishonest self-reports in comparison to signing at the end

Many written forms required by businesses and governments rely on honest reporting. Proof of honest intent is typically provided through signature at the end of, e.g., tax returns or insurance policy forms. Still, people sometimes cheat to advance their financial self-interests—at great costs to society. We test an easy-to-implement method to discourage dishonesty: signing at the beginning rather than at the end of a self-report, thereby reversing the order of the current practice. Using laboratory and field experiments, we find that signing before—rather than after—the opportunity to cheat makes ethics salient when they are needed most and significantly reduces dishonesty.     

Low frequency of recent parvovirus infection in a population-based cohort of patients with early inflammatory polyarthritis

OBJECTIVE—To determine the contribution of human parvovirus B19 infection in explaining the incidence of early inflammatory polyarthritis (IP) in a population.
SETTING—The Norfolk Arthritis Register (NOAR) is a community-based programme aiming to ascertain all new cases of IP arising in a population that lead to attendance at primary care.
SUBJECTS—147 newly ascertained subjects with IP with a disease duration of less than 16 weeks.
METHODS—Full clinical appraisal of all subjects who were followed up for three years. B19 IgM assayed with a third generation antibody capture enzyme immunoassay.
RESULTS—Only four (2.7%) patients had evidence of recent B19 infection, only one of whom did not satisfy criteria for rheumatoid arthritis (RA).
CONCLUSION—B19 infection does not explain more than a small proportion of either RA or undifferentiated IP cases occurring in the population.

Keywords: rheumatoid arthritis; epidemiology; human parvovirus B19     

Visualising E-selectin in the detection and evaluation of inflammatory bowel disease

Background—Vascular endothelial E-selectin expression is induced by proinflammatory cytokines andcontributes to accumulation of leucocytes in tissues.
Aims—To investigate the role ofE-selectin in inflammatory bowel disease (IBD).
Methods—E-selectin expression wasassessed in patients with ulcerative colitis and Crohn's disease bymeasuring the concentration of circulating soluble E-selectin(sE-selectin) using ELISA, by immunohistochemistry of colonic biopsyspecimens, and by abdominal immunoscintigraphy after injectingradiolabelled F(ab')₂ fragment of a monoclonalanti-E-selectin antibody. The value of scintigraphy usinganti-E-selectin was judged by a prospective comparative study ofautologous leucocyte scanning and E-selectin antibody scanning in 17 patients with IBD.
Results—Circulating sE-selectin waselevated in patients with clinically active disease. Tissue expressionof E-selectin was enhanced in patients with active inflammation, withweak or absent expression in inactive disease and healthy controls.In-111 labelled anti-E-selectin scintiscans were compared with Tc-99mlabelled leucocyte scans performed 24 hours earlier. Twelve patientshad areas of active inflammation on leucocyte scan while 11 patients had positive E-selectin scans. The results of the two scans were concordant in 14 patients, with those positive for both (10/17) showingsimilar disease localisation and extent.
Conclusions—Tissue E-selectinand circulating sE-selectin are increased during active inflammatorybowel disease. Anti-E-selectin imaging with radiolabelled monoclonalantibody identified areas of inflammation in Crohn's disease andulcerative colitis. The technique should prove useful clinically foridentifying the site and extent of disease.

Keywords:E-selectin; inflammatory bowel disease; Crohn'sdisease; ulcerative colitis

     

Gut barrier function in malnourished patients

Background—The integrity of the gastrointestinalmucosa is a key element in preventing systemic absorption of enterictoxins and bacteria. In the critically ill, breakdown of gut barrier function may fuel sepsis. Malnourished patients have an increased riskof postoperative sepsis; however, the effects of malnutrition onintestinal barrier function in man are unknown.
Aims—To quantify intestinal barrier function,endotoxin exposure, and the acute phase cytokine response inmalnourished patients.
Patients—Malnourished and well nourishedhospitalised patients.
Methods—Gastrointestinal permeability wasmeasured in malnourished patients and well nourished controls using thelactulose:mannitol test. Endoscopic biopsy specimens werestained and morphological and immunohistochemical featuresgraded. The polymerase chain reaction was used to determinemucosal cytokine expression. The immunoglobulin G antibody response toendotoxin and serum interleukin 6 were measured by enzyme linkedimmunosorbent assay.
Results—There was a significant increase inintestinal permeability in the malnourished patients in associationwith phenotypic and molecular evidence of activation of lamina propriamononuclear cells and enterocytes, and a heightened acute phase response.
Conclusions—Intestinal barrier function issignificantly compromised in malnourished patients, but the clinicalsignificance is unclear.

Keywords:protein-energy malnutrition; intestinalpermeability; endotoxin; cytokine

     

Multisystemic production of interleukin 10 limits the severity of acute pancreatitis in mice

Background—Interleukin 10 (IL-10)decreases the severity of experimental acute pancreatitis. The role ofendogenous IL-10 in modulating the course of pancreatitis is currently unknown.
Aims—To examine the systemicrelease of IL-10 and its messenger RNA production in the pancreas,liver, and lungs and analyse the effects of IL-10 neutralisation incaerulein induced acute pancreatitis in mice.
Methods—Acute necrotisingpancreatitis was induced by intraperitoneal caerulein. Serum levels ofIL-10 and tumour necrosis factor (TNF), and tissue IL-10 and TNF-αgene expression were assessed. After injecting control antibody orafter blocking the activity of endogenous IL-10 by a specificmonoclonal antibody, the severity of acute pancreatitis was assessed interms of serum enzyme release, histological changes, and systemic andtissue TNF production.
Results—In control conditions,serum IL-10 levels increased and correlated with the course ofpancreatitis, with a maximal value eight hours after induction. BothIL-10 and TNF-α messengers showed a similar course, and wereidentified in the pancreas, liver, and lungs. Neutralisation ofendogenous IL-10 significantly increased the severity of pancreatitisand associated lung injury as well as serum TNF protein levels (+75%)and pancreatic, pulmonary, and hepatic TNF messenger expression (+33%,+29%, +43%, respectively).
Conclusions—In this non-lethalmodel, systemic release of IL-10 correlates with the course of acutepancreatitis. This anti-inflammatory response parallels the release ofTNF and both cytokines are produced multisystemically. Endogenous IL-10controls TNF-α production and plays a protective role in the localand systemic consequences of the disease.

Keywords:pancreatitis; interleukin 10; tumour necrosis factorα; adult respiratory distress syndrome

     

Liver/kidney microsomal antibody type 1 and liver cytosol antibody type 1 concentrations in type 2 autoimmune hepatitis

Background—Liver/kidney microsomal antibody type 1 (LKM1) and liver cytosol antibody type 1 (LC1) are the serologicalmarkers of type 2 autoimmune hepatitis (AIH).
Aims—Since LKM1 and LC1 react against two distinctliver specific autoantigens (cytochrome P450IID6 (CYP2D6) and a 58 kDa cytosolic polypeptide respectively), the aim was to see whether LKM1and LC1 concentrations correlate with liver disease activity.
Patients—Twenty one patients with type 2 AIH were studied.
Methods—All sera were tested by indirectimmunofluorescence, counterimmunoelectrophoresis, and immunoblottingvisualised by enhanced chemiluminescence. To evaluate LKM1 and LC1levels, the 50 kDa microsomal reactivity (corresponding to CYP2D6) andthe 58 kDa cytosolic reactivity were quantified by densitometric analysis.
Results—Seven patients were positive for LKM1,nine for LC1, and five for both. Serial serum samples at onset andduring immunosuppressive treatment were analysed in 13 patients (fourpositive for LKM1, six positive for LC1 and three positive for both).During remission, LKM1 concentration remained essentially unchanged insix of seven patients, and decreased in only one. Conversely, in two ofnine patients, LC1 was completely lost, and, in the remaining seven, LC1 concentration was reduced by more than 50%. Afterimmunosuppression tapering or withdrawal, flare ups of liver necrosisensued with increasing LC1 concentration, but not LKM1.
Conclusions—LC1 concentration, at variance withthat of LKM1, parallels liver disease activity, and its participationin the pathogenic mechanisms of liver injury can be hypothesised.

     

Monitoring of streptokinase resistance titre in acute myocardial infarction patients up to 30 months after giving streptokinase or anistreplase and related studies to measure specific antistreptokinase IgG

Objective—To examine the induction of antistreptokinase antibodies after giving streptokinase or anistreplase to patients with acute myocardial infarction.

Design—Patients were randomly allocated to receive either 1·5 × 10⁶ IU, streptokinase or 30U anistreplase in a double blind study. Blood samples were collected immediately before treatment and subsequently at intervals up to 30 months; plasma samples were assayed for streptokinase resistance titre (functional assay) and streptokinase binding by IgG (microradioimmunoassay).

Setting—Cardiology department in a general hospital.

Patients—128 consecutive eligible patients. Samples were collected for up to one year according to a prospective design: a subsection of 47 patients was selected for intensive study over the first 14 days. After one year, all available patients (67) were sampled on one further occasion.

Results—Antibody responses to streptokinase and anistreplase were similar. Streptokinase resistance titres exceeded pretreatment concentrations five days after dosing, and values peaked at 14 days. By 12 months after dosing, 92% of resistance titres (n = 84) had returned to within the pretreatment range. Antistreptokinase IgG concentrations also exceeded baseline concentrations within five days and peaked at 14 days. Half of the individual values had returned to within the pretreatment range by 12 months (n = 84) and 89% by 30 months (n = 18).

Conclusion—Although we cannot be sure of the clinical significance, because of the increased likelihood of resistance due to antistreptokinase antibody, streptokinase and anistreplase may not be effective if administered more than five days after an earlier dose of streptokinase or anistreplase, particularly between five days and 12 months, and increased antistreptokinase antibody may increase the risk of allergic-type reactions.

     

Tumour necrosis factor-α enhances intraepithelial lymphocyte proliferation and migration

Background—Tumour necrosis factor α (TNF-α)is a proinflammatory cytokine found in abundance in diseased intestine.
Aims—The T cell production of TNF-α and theimpact of this cytokine on intestinal T cell proliferation, migration,and cytotoxicity were studied.
Methods—Intestinal lymphocytes from normaljejunum were used. TNF-α production in culture supernates wasmeasured by enzyme linked immunosorbent assay (ELISA). Lymphocyteproliferation was measured using ³H thymidine uptake;migration, using transwell chambers; and cytotoxicity of HT-29 coloncancer cells, using the chromium-51 release assay.
Results—TNF-α was produced mainly by the CD8+ Tcells in the intraepithelial lymphocytes (IEL) and the CD4+ T cells inthe lamina propria lymphocytes in response to CD2 stimulation: 478(94)and 782 (136) pg/ml, respectively. TNF-α (1 ng/ml or greater) augmented proliferation of IEL in response to interleukin 2 (IL-2), IL-7, or antibody to CD3 due to increased activation that did notinvolve IL-2 production or receptor generation. Conversely, antibody toTNF-α reduced IEL proliferation in response to IL-2 or IL-7. TNF-αalso induced calcium mobilisation and chemokinesis (by 2.8 (0.5) foldover spontaneous migration). TNF-α had no effect on lymphokineactivated killer cell activity.
Conclusions—TNF-α increases the proliferationand migration of IEL, which may expand their number in the epithelium.

     

The relation between gastric vitamin C concentrations, mucosal histology, and CagA seropositivity in the human stomach

Background—Vitamin C may beprotective against gastric cancer though infection withHelicobacter pylori is associated with areduction in intragastric concentrations of vitamin C.
Aims—To examine the effects ofH pylori infection, gastric juice pH, theseverity and extent of gastric inflammation, and CagA antibody statusof the individual on gastric juice and mucosal vitamin C concentrations.
Patients—One hundred andfifteen patients undergoing routine gastroscopy for investigation of dyspepsia.
Methods—High performance liquidchromatography was used to determine vitamin C concentrations. CagAantibody was detected by western blot analysis.
Results—Gastric juice ascorbic acidconcentration was significantly lower in patients infected withH pylori compared with those uninfected(19.3 µmol/l (interquartile range (IQR) 10.7-44.5) versus 66.9 µmol/l (IQR 24.4-94.2), p=0.003). The reduction in gastric juiceascorbic acid concentration was inversely related to the severity ofgastritis (p=0.01). CagA positive patients had significantly lowergastric juice ascorbic acid concentrations than CagA negative ones(14.8 µmol/l (IQR 7.9-52.2) versus 39µmol/l (IQR 19.9-142.2),p=0.05). Decreased gastric juice dehydroascorbic acid concentrationswere observed in patients with gastric atrophy and intestinalmetaplasia. Mucosal ascorbic acid concentrations were alsosignificantly lower in infected patients than uninfected patients(p=0.04).
Conclusions—The reduction ingastric vitamin C concentrations is related to gastric juice pH, theseverity and extent of gastritis, the presence of Hpylori, and the CagA antibody status of the individual. Thesefindings may have implications in H pyloriassociated carcinogenesis.

Keywords:ascorbic acid; Helicobacterpylori; gastric juice; gastric mucosa; premalignancy

     

Elicitation of structure-specific antibodies by epitope scaffolds

Elicitation of antibodies against targets that are immunorecessive, cryptic, or transient in their native context has been a challenge for vaccine design. Here we demonstrate the elicitation of structure-specific antibodies against the HIV-1 gp41 epitope of the broadly neutralizing antibody 2F5. This conformationally flexible region of gp41 assumes mostly helical conformations but adopts a kinked, extended structure when bound by antibody 2F5. Computational techniques were employed to transplant the 2F5 epitope into select acceptor scaffolds. The resultant “2F5-epitope scaffolds” possessed nanomolar affinity for antibody 2F5 and a range of epitope flexibilities and antigenic specificities. Crystallographic characterization of the epitope scaffold with highest affinity and antigenic discrimination confirmed good to near perfect attainment of the target conformation for the gp41 molecular graft in free and 2F5-bound states, respectively. Animals immunized with 2F5-epitope scaffolds showed levels of graft-specific immune responses that correlated with graft flexibility (p < 0.04), while antibody responses against the graft—as dissected residue-by-residue with alanine substitutions—resembled more closely those of 2F5 than sera elicited with flexible or cyclized peptides, a resemblance heightened by heterologous prime-boost. Lastly, crystal structures of a gp41 peptide in complex with monoclonal antibodies elicited by the 2F5-epitope scaffolds revealed that the elicited antibodies induce gp41 to assume its 2F5-recognized shape. Epitope scaffolds thus provide a means to elicit antibodies that recognize a predetermined target shape and sequence, even if that shape is transient in nature, and a means by which to dissect factors influencing such elicitation.     

Anti-inflammatory drugs and endothelial cell adhesion molecule expression in murine vascular beds

Background—Inflammatory boweldiseases (IBD) are characterised by an intense infiltration ofleucocytes that is mediated by adhesion molecules expressed on thesurface of activated endothelial cells.
Aims—To determine whether drugsused in the treatment of IBD, specifically dexamethasone (DEX),5-aminosalicylic acid (5-ASA), methotrexate (MTX), and 6-mercaptopurine(6-MP), alter the expression of endothelial cell adhesion molecules (ECAMs).
Methods—The expression ofP-selectin, E-selectin, intercellular adhesion molecule 1 (ICAM-1), andvascular CAM 1(VCAM-1) in different vascular beds of C57Bl/6J mice wasmeasured using the dual radiolabelled monoclonal antibody technique.
Results—Lipopolysaccharide (LPS)elicited a profound increase in the expression of all ECAMs in themesentery, small intestine, caecum, and distal colon. The LPS inducedincrease in CAM expression was not significantly affected by priortreatment with either MTX or 6-MP. However, pretreatment with eitherDEX or 5-ASA significantly attenuated LPS induced increases inexpression of P- and E-selectin, and VCAM-1 in the majority of tissuesevaluated. DEX also blunted the LPS induced increase in ICAM-1expression in the caecum and distal colon. DEX, but not 5-ASA, largelyabolished the rise in plasma tumour necrosis factor α elicited by LPS.
Conclusions—These findings suggestthat DEX and 5-ASA may exert their beneficial therapeutic action inIBD, at least in part, by inhibiting the expression of ECAMs whichmediate leucocyte adhesion and transmigration in the microvasculature.