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Biomedical subjects

A W Cripps

Publications and source records attributed to A W Cripps.

At least 19 recordsLinked to original sources
PubMed2001

Vaccines and mucosal immunisation.

The earliest attempts to protect humans against infectious diseases and toxins were by administering foreign substances to mucosal membranes, predominantly by the oral route. In the late 1880s, significant attention was given to the concept of 'local' immunisation, and the discipline of mucosal immunology was born in the early 1900s. However, despite the early enthusiasm, progress has been slow, with few mucosal vaccines being efficacious. The complexities of mucosal immune regulation and the lack of appropriate antigen delivery systems which can access mucosal inductive sites, have remained substantial obstacles. Recent studies demonstrating compartmentalisation of the common mucosal immune system create further challenges for the development of organ-specific vaccines. In the 21st century, our knowledge of mucosal immunoregulatory mechanisms, coupled with new technology for antigen delivery and immunomodulation will provide the necessary know-how to see the development and widespread use of mucosal vaccines for both preventative and therapeutic use.

Administration, Oral↗
PubMed2001

Programmed inflammatory processes induced by mucosal immunisation.

Inflammation is essential to repair tissue damaged by physical, microbial or allergic mechanisms. Inappropriately zealous responses lead to destructive pathology or chronic disease cycles, whereas ideal outcomes are associated with complete and rapid restoration of tissue structure and function. The establishment of a rodent model investigating the different immune responses to non-typeable Haemophilus influenzae infection in both the lung and the ear indicate an ability to clear bacteria and reduce inflammation following mucosal immunisation. Lung histochemistry, upregulaion of macrophages and polymorphonuclear neutrophils, recruitment of gammadelta(+) and CD8(+) T cells, cytokine levels and depletion studies all support the hypothesis that mucosal immunisation facilitates control of the immune response resulting in enhanced bacterial clearance and programming of inflammation which limits damage and promotes the rapid restoration of structural normality.

Animals↗
PubMed2001

Mucosal immunity in the lung and upper airway.

The mucosal surfaces of the lungs and upper airways are common sites for infection. Extensive studies of the mechanisms associated with immune responses in the respiratory tract have found that understanding the system is challenging and involves many complex interactions to prevent and eliminate infection. Immune protection against diseases transmitted through the respiratory tract requires an understanding of the important aspects associated with beneficial, detrimental or ineffective immune responses. Two critical aspects of an immune response against a pathogen are that of the inductive stage, either induced by vaccination or primary infection, and the effector stage, the ability to recognise, respond to and eliminate the infection without detriment to the host. An immunisation strategy must not only have a measure of the induced antigen specific response, but this response must also be protective.

Animals↗
PubMed2001

CD8+ T cells have an essential role in pulmonary clearance of nontypeable Haemophilus influenzae following mucosal immunization.

A rodent respiratory experimental model has proved useful for investigating the immune mechanisms responsible for clearance of bacteria from the lungs. Immunohistochemical studies in immune and nonimmune rats have identified the cellular kinetics of response to bacterial pulmonary infection for CD8+, CD4+, and gammadelta+ T cells; B cells; and the expression of major histocompatibility complex class II (MHC-II). During the course of bacterial clearance, there was no apparent proliferation or extravasation of lymphocytes, nor was there increased expression of MHC-II in nonimmune animals despite an influx of polymorphonuclear leukocytes, whereas in immunized animals there was an early influx of CD8+ and gammadelta+ T cells, followed by enhanced expression of the MHC-II marker, cellular infiltration by polymorphonuclear leukocytes, and finally an increased number of CD4+ T cells. Depletion of CD8+ T cells confirmed their vital contribution in the preprimed immune response to pulmonary infection by significantly decreasing the animals' ability to clear bacteria following challenge.

Animals↗
PubMed2000

Catalase immunization from Pseudomonas aeruginosa enhances bacterial clearance in the rat lung.

Pseudomonas aeruginosa is a common cause of infection in immunocompromised patients and is the major contributor to morbidity in individuals with cystic fibrosis (CF). The antibiotic resistance shown by this pathogen and morbidity in patients with chronic infection has encouraged investigations into the development of a vaccine. This study reports the purification of a 60 kDa protein, isolated from a mucoid strain of P. aeruginosa, identified by amino acid sequence analysis as the catalase protein (KatA). A rat model of acute P. aeruginosa respiratory infection was used to investigate the immunogenicity of KatA and determine the potential of mucosal immunization with KatA to protect against infection. Immunization regimens compared a single intra-Peyer's patch (IPP) immunization with an IPP primary inoculation followed by an intratracheal boost to the lungs. Mucosal immunization with KatA resulted in significant pulmonary clearance of both homologous (p<0.001) and heterologous (p<0.05) strains of P. aeruginosa. Both immunization regimens enhanced bacterial clearance, increased the rate of recruitment of phagocytes to the bronchoalveoli and induced KatA-specific antibody. However, the regimen that included a boost induced a more effective immune response that also resulted in better clearance of P. aeruginosa from the lungs. Mucosal immunization induced KatA- specific antibodies in the serum and the bronchoalveolar lavage, and KatA-specific lymphocyte proliferation in vitro in cells isolated from the mesenteric lymph nodes of immunized rats. The data presented suggests that KatA has the potential to afford a protective immune response against pulmonary infection by P. aeruginosa

Animals↗
PubMed2000

Haemophilus influenzae oral vaccination against acute bronchitis.

OBJECTIVES: To assess the effects of an oral whole cell nontypeable Haemophilus influenzae (NTHi) vaccine in protecting against recurrent episodes of bronchitis. SEARCH STRATEGY: We searched the Cochrane trials register, MEDLINE, Extramed, ISI Current Contents, Carl Uncover and contacted investigators of the studies. SELECTION CRITERIA: Randomised trials comparing the effects of an oral monobacterial NTHi vaccine on patients with recurrent exacerbations of bronchitis were included when there was overt matching of the vaccine and placebo groups on clinical grounds. DATA COLLECTION AND ANALYSIS: Two reviewers extracted data and assessed trial quality independently from original records and publications for incidence and severity of bronchitis episodes and carriage rate of nontypeable Haemophilus influenzae in the upper respiratory tract every three months following vaccination. MAIN RESULTS: Six trials were included in the study with a total of 440 participants. Oral vaccination using a monobacterial whole cell killed nontypeable Haemophilus influenzae significantly reduced the incidence of bronchitic episodes at 3 months (Weighted Mean Difference [WMD] 6.694; 95% confidence interval [CI] 6.963 - -6.424; p < 0.01) and 6 months (WMD 4.496; 95% CI 4.664 - -4.327; p < 0.01) following vaccination. The effect diminished by 9 months. The severity of exacerbations in the treatment group was likewise reduced by 58% at 3 months (Peto OR = 0. 42; 95% CI 0.16 1.13), and 65% at 6 months (Peto OR = 0.35; 95% CI 0. 16 0.75) following vaccination. REVIEWER'S CONCLUSIONS: Vaccination, in the autumn, of patients with recurrent exacerbations of bronchitis reduced the number and severity of exacerbations over the winter months. A large clinical trial to assess longer term prognosis needs to be completed.

Acute Disease↗
PubMed2000

Studies on the IgA-independent immunological responses in mice to influenza virus challenge after oral vaccination with irradiated whole virus and an erythrocyte complex.

Previous studies have described an oral influenza vaccine comprising whole irradiated virus and an erythrocyte complex (IV-EC), which gave broad-based protection against influenza virus challenge in mice. The present study examined the immune responses generated after live virus challenge of vaccinated mice, particularly to determine whether mice vaccinated with IV-EC had enhanced CTL activity to compensate for the previously reported diminution in lung IgA response. Oral vaccine groups examined were IV-EC, live virus alone (LV) or live virus-erythrocyte complex (LV-EC), compared with irradiated virus and erythrocyte alone controls. The antibody responses of IV-EC and LV-EC vaccinated mice showed significantly elevated lung and serum IgG2a levels post live virus challenge, with no comparable increases in IgG1 levels compared to controls. Spleen cells from IV-EC mice showed an enhanced post-challenge proliferative response to antigen compared with mice that had received live oral vaccines, indicating enhanced cellular activity post IV-EC immunization. However, CTL activity was not enhanced for IV-EC mice, and live virus-vaccinated mice had reduced CTL activity compared with controls, indicating that CTL were not important for post-vaccine protection. Cytokine analysis revealed a predominant IFN-gamma response in spleen cells from orally vaccinated mice, whereas IL-4 was not detected in any lung or spleen culture analysed. The results suggest, therefore, that protection from live influenza challenge after IV-EC or LV-EC vaccination was due to an IFN-mediated IgG2a response. Definitive confirmation of the role of these factors in post-vaccine protection can now be tested in IgG2a-depleted or IFN-gamma gene knockout mouse models.

Administration, Oral↗
PubMed2000

Immune status and respiratory illness for elite swimmers during a 12-week training cycle.

The impact of a 12-week training program by elite swimmers on systemic and mucosal immunity was studied prospectively to examine the relationship between changes in immune parameters and the incidence of respiratory illness. Saliva was collected before and after selected training sessions at 2 weekly intervals. There were significant decreases in salivary IgA (p=0.05) and salivary IgM (p < 0.0001) concentrations after individual training sessions, but no significant changes in salivary IgG or albumin concentrations. Over the 12-week training program there were small but statistically significant increases in pre-exercise concentrations of salivary IgA (p<0.001), IgM (p=0.015) and IgG (p=0.003) and post-exercise salivary IgA (p <0.001). There were no significant trends over the 12 weeks for any class of serum immunoglobulins but a significant fall in NK-cell numbers (p<0.001). There were no associations between serum or salivary immunoglobulin levels or NK-cell numbers and upper respiratory tract illness (URTI) during the 12-week program. The data indicated that despite changes in some immune parameters during this final training program prior to competition there were no associations detected with URTI for this cohort of elite swimmers.

Adolescent↗
PubMed2000

A P5 peptide that is homologous to peptide 10 of OprF from Pseudomonas aeruginosa enhances clearance of nontypeable Haemophilus influenzae from acutely infected rat lung in the absence of detectable peptide-specific antibody.

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen associated with otitis media and the exacerbation of chronic bronchitis. This study reports the vaccine potential of three peptides representing conserved regions of the NTHi P5 outer membrane protein which have been fused to a promiscuous measles virus F protein T-cell eptitope (MVF). The peptides correspond to a region in surface loop one (MVF/L1A), the central region of loop four (MVF/L4), and a C-terminal region homologous to peptide 10 of OprF from Pseudomonas aeruginosa (MVF/H3). Immunization of rats with MVF/H3 was the most efficacious in significantly reducing the number of viable NTHi in both the broncho-alveolar lavage fluid (74%) and lung homogenates (70%), compared to control rats. Importantly, despite significantly increased rates of clearance, immunization with MVF/H3 elicited poor antibody responses, suggesting that cell-mediated rather than humoral responses play an important role in the enhanced clearance of NTHi in this model.

Acute Disease↗
PubMed1999

Killed whole bacterial cells, a mucosal delivery system for the induction of immunity in the respiratory tract and middle ear: an overview.

Infectious diseases remain a leading cause of morbidity and mortality worldwide with mucosal membranes being the most frequent portals of entry of pathogenic micro-organisms. This has prompted studies aimed at the development of vaccination protocols that would lead to an increased protection of mucosae through an understanding of the common mucosal immune system as an immune communication network between mucosal sites. Recent studies have suggested that preferential sub-networks exist within the system and these studies have exploited the gut-associated lymphoid tissue (GALT)-lung sub-network in the development of oral vaccine strategies for infections of the respiratory tract and middle ear. Mucosal immunization with whole formalin killed Pseudomonas aeruginosa (Pa), Branhamella catarrhalis, nontypable Haemophilus influenzae (NTHi) or Streptococcus pneumoniae (Spn) results in enhanced homologous bacterial clearance from the lung of immune animals challenged with live bacteria. These studies have been extended to the middle ear where similar results have been observed for NTHi and Spn. Mechanisms responsible for inducing enhanced bacterial clearance from the airways include opsonising antibody, antigen specific CD4+ T helper cells, cytokine responses and recruitment of activated polymophonuclear neutrophils. The mechanisms induced by immunization which stimulates the immune system to rapidly mobilise both innate and specific immune responses during infection are the subject of ongoing research.

Animals↗
PubMed1999

A method for the purification and refolding of a recombinant form of the nontypeable Haemophilus influenzae P5 outer membrane protein fused to polyhistidine.

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen, commonly associated with otitis media and exacerbations of chronic bronchitis. Studies concerning the pathogenesis of NTHi have proposed an important function for P5, an outer membrane protein believed to play a role in the initiation of infection by mediating adherence to respiratory mucin. P5 has also generated interest as a potential vaccine candidate. In a previous study, an NTHi library screen with antibodies raised against P5 purified from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that the purified protein was contaminated with closely migrating proteins. Consequently, the aim of this study was to express P5 in a heterologous system to overcome potential contamination with NTHi proteins that may complicate analytical or vaccine studies. Recombinant P5, with an N terminal extension of 10 residues that included six histidines, was cloned and expressed in Escherichia coli. The rP5 was purified with the Talon metal affinity resin in a denatured form and then refolded by incorporation into mixed-detergent micelles of octylglucoside and SDS. Circular dichroism of the refolded rP5 demonstrated 55% beta-strand content, which is consistent with the beta-strand content of native P5 and the homologous E. coli protein OmpA.

Bacterial Outer Membrane Proteins↗
PubMed1999

Salivary IgA levels and infection risk in elite swimmers.

UNLABELLED: The effects of exercise on the immune system has been shown to be dependent on the level of fitness of the subjects, the degree of intensity, and the duration of the exercise. A reduction in salivary IgA levels occurs after individual sessions of exercise. PURPOSE: The purpose of this study was to assess the relationship between changes in salivary IgA and training volume, psychological stress, and infection rates in a cohort of 26 elite swimmers over a 7-month training period and to compare the changes with a group of 12 moderately exercising controls. METHODS: Salivary IgA concentrations were measured by an electroimmunodiffusion. Exercise gradings were assessed by a standardized aerobic-anaerobic rating system. Psychological stress/anxiety was evaluated by the Spielberger State-Trait Anxiety Inventory. Infections were physician-verified. RESULTS: Salivary IgA levels showed an inverse correlation with the number of infections in both elite swimmers and moderately exercising control subjects. The pretraining salivary IgA levels in swimmers were 4.1% lower for each additional month of training and 5.8% lower for each additional infection. The posttraining salivary IgA levels in swimmers were not significantly correlated with infection rates but were 8.5% lower for each additional 1 km swum in a training session and 7.0% lower for each additional month of training. The number of infections observed in the elite swimmers was predicted from regression models by the preseason (P = 0.05) and the mean pretraining salivary IgA levels (P = 0.006). The trends in pretraining salivary IgA levels over the 7-month season, calculated as individual slopes of pretraining IgA levels over time, were also predictive of the number of infections (P = 0.03) in the swimmers. CONCLUSIONS: These results indicate that measurement of salivary IgA levels over a training season may be predictive for athletes at risk of infection.

Adolescent↗
PubMed1999

Characterization of the gene encoding a 26-kilodalton protein (OMP26) from nontypeable Haemophilus influenzae and immune responses to the recombinant protein.

A 26-kDa protein (OMP26) isolated and purified from nontypeable Haemophilus influenzae (NTHI) strain 289 has been shown to enhance clearance of infection following pulmonary challenge with NTHI in rats. DNA sequence analysis revealed that it was 99% identical to a gene encoding a cell envelope protein of the H. influenzae Rd strain (TIGR accession no. HI0916). The deduced amino acid sequence revealed a hydrophilic polypeptide rich in basic amino acids. Restriction fragment length polymorphism analysis suggested that the OMP26 gene was relatively conserved among isolates of NTHI. Analysis of the deduced amino acid sequence of the OMP26 gene from 20 different isolates showed that similarity with NTHI-289 ranged from 96.5% (1 isolate) to 99.5% (14 isolates). Two recombinant forms of OMP26, a full length 28-kDa protein (equivalent to preprotein) and a 26-kDa protein lacking a 23-amino-acid leader peptide (equivalent to processed protein), were assessed in immunization studies for the ability to induce an immune response that would be as effective as the native protein in enhancing the clearance of NTHI following pulmonary challenge in rats. Immunization with the recombinant protein that included the leader peptide was more effective in enhancing pulmonary clearance, and it induced a better cell-mediated response and higher titers of systemic and mucosal antibody. This study has characterized a 26-kDa protein from NTHI that shows significant potential as a vaccine candidate.

Amino Acid Sequence↗
PubMed1999

Immunization with recombinant transferrin binding protein B enhances clearance of nontypeable Haemophilus influenzae from the rat lung.

Nontypeable Haemophilus influenzae (NTHI) is an opportunistic pathogen, and heterogeneity in the surface-exposed immunodominant domains of NTHI proteins is thought to be associated with the failure of an infection to stimulate an immune response that is cross-protective against heterologous NTHI strains. The aim of this study was to assess the vaccine potential of a surface-exposed component of the NTHI human transferrin receptor, TbpB, and to determine if the antibody response elicited was cross-reactive with heterologous strains of NTHI. The efficacy of immunization with a recombinant form of TbpB (rTbpB) was determined by assessing the pulmonary clearance of viable bacteria 4 h after a live challenge with NTHI. There was a significant reduction in the number of viable bacteria in both the bronchoalveolar lavage fluid (34% for the 20-microgram dose and 58% for the 40-microgram dose) and lung homogenates (26% for the 20-microgram dose and 60% for the 40-microgram dose) of rats immunized with rTbpB compared to the control animals. While rTbpB-specific antibodies from immunized rats were nonspecific in the recognition of TbpB from six heterologous NTHI strains on Western blots, these antibodies differed in their ability to block transferrin binding to heterologous strains and to cross-react in bactericidal assays. If bactericidal antibodies are key indicators of the efficacy of the immune response in eliminating NTHI, this data suggests that while immunization with rTbpB stimulates protective responses against the homologous isolate, variability in the recognition of TbpB from heterologous isolates may limit the potential of rTbpB as an NTHI vaccine component.

Amino Acid Sequence↗
PubMed1998

The effect of successful contact lens wear on mucosal immunity of the eye.

OBJECTIVE: This study aimed to assess the effect of contact lens wear on the mucosal defenses of the outer eye against infection. DESIGN: A case-controlled study of daily contact lens wearers in their initial 6 months of contact lens wear. PARTICIPANTS: Contact lens wearers (mean age, 23.1 years; 47 subjects) were compared with age-matched control subjects (mean age, 24.7 years; 44 subjects). INTERVENTION: Outer eye defenses were studied by assay of tear constituents and quantitative conjunctival microbiology. MAIN OUTCOME MEASURES: Antimicrobial activity of tears was studied by assay of total immunoglobulin A (IgA), IgA isotype-specific antibodies reactive with Escherichia coli, Haemophilus influenzae, Staphylococcus epidermidis, albumin and lysozyme, and the ocular surface microbial load determined using quantitative microbiology of the conjunctival sac. RESULTS: The IgA isotype-specific antibodies reactive with E. coli (P = 0.03) and S. epidermidis (P = 0.068) were lower in contact lens wearers, but antibody:albumin ratios were not significantly different in the two groups. Contact lens wear also had no significant effect on tear IgA, albumin, or lysozyme or its ratios with albumin. Bacterial numbers and colonization rates for coagulase-negative staphylococci were greater in contact lens wearers than in age-matched control subjects. Corynebacterium sp. and non-Enterobacteriaceae (P = 0.007) were isolated more frequently and in greater numbers from contact lens wearers. Colonization rates were increased for Corynebacterium sp., but non-Enterobacteriaceae were transient. In both daily contact lens wearers and age-matched control subjects, most conjunctival flora were transient rather than colonizing, and no subject developed an outer eye infection during the study. CONCLUSION: These results suggest that daily contact lens wear does not significantly alter the mucosal defenses of the outer eye that function to eliminate organisms from the conjunctival sac and prevent outer eye infection.

Adult↗
PubMed1998

Characteristics of the immunological response in the clearance of non-typeable Haemophilus influenzae from the lung.

Clearance of non-typeable Haemophilus influenzae (NTHi) from the respiratory tract was investigated, over time, in immune and non-immune rats. A triphasic pattern characterized the clearance of bacteria from the lungs. Mucosal immunization enhanced bacterial clearance from the lungs in each of the three phases compared with clearance from non-immunized animals. Total clearance of bacteria was observed from lung tissue by 12 h in immune animals and 24 h in non-immune animals. Polymorphonuclear leucocytes not only arrived earlier and initially in greater numbers, but disappeared earlier in immune animals (peaking at 8 h post-challenge), compared with non-immune animals (peaking at 12h post-challenge). Systemically derived and locally produced NTHi-specific IgA and IgG correlated with enhanced bacterial clearance during the secondary phase. This model demonstrates that immunized animals up-regulate and resolve inflammatory responses to pulmonary infection more rapidly than the non-immunized controls.

Adult↗
PubMed1998

Kinetics of inflammatory cytokines in the clearance of non-typeable Haemophilus influenzae from the lung.

Levels of the pro-inflammatory cytokines TNF-alpha and IFN-gamma were measured from the time of infection to the time of complete clearance of non-typeable Haemophilus influenzae (NTHi) from the lung in immune and non-immune rats. Mucosal immunization facilitated production of significant levels of TNF-alpha as early as 30 min post-pulmonary challenge with NTHi in immune animals. Following the peak at 2 h, rapid decline of TNF-alpha levels occurred from the alveolar spaces. Levels of TNF-alpha in non-immunized animals increased at a slower rate, peaked at a lower concentration and were slower to decline. The significantly larger number of macrophages seen in the immune animals at 1 h after bacterial challenge could partially account for the higher levels of TNF-alpha. Interferon-gamma was not detected in immune or non-immune rats at any time point before NTHi clearance after pulmonary challenge. Study of the kinetics of TNF-alpha release demonstrates that immunized animals control the release of pro-inflammatory cytokines more effectively than non-immunized animals for enhanced clearance of bacterial infection from the lungs.

Animals↗