Kinetics and persistence of anti-SARS-CoV-2 neutralisation and antibodies after BNT162b2 vaccination in a Swiss cohort

Introduction

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), substantial effort has been made to gain knowledge about the immunity elicited by infection or vaccination.

Methods

We studied the kinetics of antibodies and virus neutralisation induced by vaccination with BNT162b2 in a Swiss cohort of SARS‐CoV‐2 naïve (n = 40) and convalescent (n = 9) persons. Blood sera were analysed in a live virus neutralisation assay and specific IgG and IgA levels were measured by enzyme‐linked immunoassay and analysed by descriptive statistics.

Results

Virus neutralisation was detected in all individuals 2–4 weeks after the second vaccine. Both neutralisation and antibodies remained positive for >4 months. Neutralisation and antibodies showed positive correlation, but immunoglobulin G (IgG) and immunoglobulin A (IgA) seroconversion took place 2–4 weeks faster than neutralisation. Spike‐protein specific IgG levels rose significantly faster and were more stable over time than virus neutralisation titres or IgA responses. For naïve but not convalescent persons, a clear boosting effect was observed. Convalescent individuals showed faster, more robust and longer‐lasting immune responses after vaccination compared to noninfected persons. No threshold could be determined for spike protein‐specific IgG or IgA that would confer protection in the neutralisation assay, implicating the need for a better correlate of protection then antibody titres alone.

Conclusions

This study clearly shows the complex translation of antibody data and virus neutralisation, while supporting the evidence of a single dose being sufficient for effective antibody response in convalescent individuals.

Photochemically-Mediated Inflammation and Cross-Presentation of Mycobacterium bovis BCG Proteins Stimulates Strong CD4 and CD8 T-Cell Responses in Mice

Conventional vaccines are very efficient in the prevention of bacterial infections caused by extracellular pathogens due to effective stimulation of pathogen-specific antibodies. In contrast, considering that intracellular surveillance by antibodies is not possible, they are typically less effective in preventing or treating infections caused by intracellular pathogens such as Mycobacterium tuberculosis. The objective of the current study was to use so-called photochemical internalization (PCI) to deliver a live bacterial vaccine to the cytosol of antigen-presenting cells (APCs) for the purpose of stimulating major histocompatibility complex (MHC) I-restricted CD8 T-cell responses. For this purpose, Mycobacterium bovis BCG (BCG) was combined with the photosensitiser tetraphenyl chlorine disulfonate (TPCS2a) and injected intradermally into mice. TPCS2a was then activated by illumination of the injection site with light of defined energy. Antigen-specific CD4 and CD8 T-cell responses were monitored in blood, spleen, and lymph nodes at different time points thereafter using flow cytometry, ELISA and ELISPOT. Finally, APCs were infected and PCI-treated in vitro for analysis of their activation of T cells in vitro or in vivo after autologous vaccination of mice. Combination of BCG with PCI induced stronger BCG-specific CD4 and CD8 T-cell responses than treatment with BCG only or with BCG and TPCS2a without light. The overall T-cell responses were multifunctional as characterized by the production of IFN-γ, TNF-α, IL-2 and IL-17. Importantly, PCI induced cross-presentation of BCG proteins for stimulation of antigen-specific CD8 T-cells that were particularly producing IFN-γ and TNF-α. PCI further facilitated antigen presentation by causing up-regulation of MHC and co-stimulatory proteins on the surface of APCs as well as their production of TNF-α and IL-1β in vivo. Furthermore, PCI-based vaccination also caused local inflammation at the site of vaccination, showing strong infiltration of immune cells, which could contribute to the stimulation of antigen-specific immune responses. This study is the first to demonstrate that a live microbial vaccine can be combined with a photochemical compound and light for cross presentation of antigens to CD8 T cells. Moreover, the results revealed that PCI treatment strongly improved the immunogenicity of M. bovis BCG.

A tissue culture infectious dose-derived protocol for testing of SARS-CoV-2 neutralization of serum antibodies on adherent cells

For a cytopathic virus such as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), the neutralization capacity of serum from convalescent or vaccinated persons or of therapeutic antibodies can be tested on adherent cell cultures. Here, a simple and tissue culture infectious dose-derived protocol for assessment of neutralization of SARS-CoV-2 is described. Compared with the often applied plaque-forming unit assay, the working load is lower, and fewer manipulations of the infected cultures are required. Hence, the method is safer for the personnel.

A Comparative Study of Real-Time RT-PCR-Based SARS-CoV-2 Detection Methods and Its Application to Human-Derived and Surface Swabbed Material

Real-time RT-PCR remains a gold standard in the detection of various viral diseases. In the coronavirus 2019 pandemic, multiple RT-PCR-based tests were developed to screen for viral infection. As an emergency response to increasing testing demand, we established a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PCR diagnostics platform for which we compared different commercial and in-house RT-PCR protocols. Four commercial, one customized, and one in-house RT-PCR protocols were evaluated with 92 SARS-CoV-2-positive and 92 SARS-CoV-2-negative samples. Furthermore, economical and practical characteristics of these protocols were compared. In addition, a highly sensitive digital droplet PCR (ddPCR) method was developed, and application of RT-PCR and ddPCR methods on SARS-CoV-2 environmental samples was examined. Very low limits of detection (1 or 2 viral copies/μL), high sensitivities (93.6% to 97.8%), and high specificities (98.7% to 100%) for the tested RT-PCR protocols were found. Furthermore, the feasibility of downscaling two of the commercial protocols, which could optimize testing capacity, was demonstrated. Tested commercial and customized RT-PCR detection kits show very good and comparable sensitivity and specificity, and the kits could be further optimized for use on SARS-CoV-2 viral samples derived from human and surface swabbed samples.

Microcrystalline Tyrosine and Aluminum as Adjuvants in Allergen-Specific Immunotherapy Protect from IgE-Mediated Reactivity in Mouse Models and Act Independently of Inflammasome and TLR Signaling

Allergen immunotherapy (AIT) is the only modality that can modify immune responses to allergen exposure, but therapeutic coverage is low. One strategy to improve AIT safety and efficacy is the use of new or improved adjuvants. This study investigates immune responses produced by microcrystalline tyrosine (MCT)–based vaccines as compared with conventional aluminum hydroxide (alum). Wild-type, immune-signaling–deficient, and TCR-transgenic mice were treated with different Ags (e.g., OVA and cat dander Fel d 1), plus MCT or alum as depot adjuvants. Specific Ab responses in serum were measured by ELISA, whereas cytokine secretion was measured both in culture supernatants by ELISA or by flow cytometry of spleen cells. Upon initiation of AIT in allergic mice, body temperature and further clinical signs were used as indicators for anaphylaxis. Overall, MCT and alum induced comparable B and T cell responses, which were independent of TLR signaling. Alum induced stronger IgE and IL-4 secretion than MCT. MCT and alum induced caspase-dependent IL-1β secretion in human monocytes in vitro, but inflammasome activation had no functional effect on inflammatory and Ab responses measured in vivo. In sensitized mice, AIT with MCT-adjuvanted allergens caused fewer anaphylactic reactions compared with alum-adjuvanted allergens. As depot adjuvants, MCT and alum are comparably effective in strength and mechanism of Ag-specific IgG induction and induction of T cell responses. The biocompatible and biodegradable MCT seems therefore a suitable alternative adjuvant to alum-based vaccines and AIT.

Self-Assembly of Triblock Copolymers from Cyclic Esters as a Tool for Tuning Their Particle Morphology

This paper presents the effect of end groups, chain structure, and stereocomplexation on the microparticle and nanoparticle morphology and thermal properties of the supramolecular triblock copolyesters. Therefore, the series of the triblock copolymers composed of l,l- and d,d-lactide, trimethylene carbonate (TMC), and ε-caprolactone (CL) with isopropyl ( iPr) or 2-ureido-4-[1 H]-pyrimidinone (UPy) end groups at both chain ends were synthesized. In addition, these copolymers were intermoleculary stereocomplexed by polylactide (PLA) blocks with an opposite configuration of repeating units to promote their self-assembly in various organic solvents. The combination of two noncovalent interactions of the end groups and PLA enantiomeric chains leads to stronger interactions between macromolecules and allows for alteration of their segmental mobility. The simple tuning of the copolymer microstructure and functionality induced the self-assembly of macromolecules at liquid/liquid interfaces, which consequently leads to their phase separation in the form of particles with diameters ranging from 0.1 μm to 10 μm. This control is essential for their potential applications in the biomedical field, where biocompatible and well-defined microparticles and nanoparticles are highly desirable.

Streamlining homogeneous glycoprotein production for biophysical and structural applications by targeted cell line development

Studying the biophysical characteristics of glycosylated proteins and solving their three-dimensional structures requires homogeneous recombinant protein of high quality.We introduce here a new approach to produce glycoproteins in homogenous form with the well-established, glycosylation mutant CHO Lec3.2.8.1 cells. Using preparative cell sorting, stable, high-expressing GFP 'master' cell lines were generated that can be converted fast and reliably by targeted integration via Flp recombinase-mediated cassette exchange (RMCE) to produce any glycoprotein. Small-scale transient transfection of HEK293 cells was used to identify genetically engineered constructs suitable for constructing stable cell lines. Stable cell lines expressing 10 different proteins were established. The system was validated by expression, purification, deglycosylation and crystallization of the heavily glycosylated luminal domains of lysosome-associated membrane proteins (LAMP).

The Performance of Cu(In, Ga)Se2-Based Solar Cells in Conventional and Concentrator Applications

Cu(In, Ga)Se2 (CIGS) solar cells are under investigation for 1-sun and concentrator applications. Design criteria are examined and reveal that only grid design modifications are required. In the special case where cell width dimensions are 4–5 cm, an interdigitated design removes the back contact as a loss mechanism. Processing issues relating to the intrinsic ZnO layer are critical to optimal and reproducible cell performance. 1-sun and 20 sun performance of 17.7% are reported for different cells. The latter represents a 2.9% absolute improvement over the 1-sun control measurement. 20% performance is therefore a realistic goal. CIGS-based cells represent a viable concentrator technology.

High-Efficiency CdTe Polycrystalline Thin-Film Solar Cells with an Ultra-Thin CuxTe Transparent Back-Contact

To fabricate a high-efficiency polycrystalline thin-film tandem cell, the most critical work is to make a high-efficiency top cell (>15%) with high bandgap (Eg=1.5-1.8 eV) and high transmission (T>70%) in the near-infrared (NIR) wavelength region. The CdTe cell is one of the candidates for the top cell, because CdTe state-of-the-art single-junction devices with efficiencies of more than 16% are available, although its bandgap (1.48 eV) is slightly lower for a top cell in a dual-junction device. In this paper, we focus on the development of an ultra-thin, low-bandgap CuxTe transparent back-contact to produce high-efficiency CdTe cells with high NIR transmission. We have achieved an NREL-confirmed 13.9%-efficient CdTe transparent solar cell with an infrared transmission of ~50% and a CdTe/CIS polycrystalline mechanically stacked thin-film tandem cell with an NREL-confirmed efficiency of 15.3%.

HLA-associated clinical progression correlates with epitope reversion rates in early human immunodeficiency virus infection

Human immunodeficiency virus type 1 (HIV-1) can evade immunity shortly after transmission to a new host but the clinical significance of this early viral adaptation in HIV infection is not clear. We present an analysis of sequence variation from a longitudinal cohort study of HIV adaptation in 189 acute seroconverters followed for up to 3 years. We measured the rates of variation within well-defined epitopes to determine associations with the HLA-linked hazard of disease progression. We found early reversion across both the gag and pol genes, with a 10-fold faster rate of escape in gag (2.2 versus 0.27 forward mutations/1,000 amino acid sites). For most epitopes (23/34), variation in the HLA-matched and HLA-unmatched controls was similar. For a minority of epitopes (8/34, and generally associated with HLA class I alleles that confer clinical benefit), new variants appeared early and consistently over the first 3 years of infection. Reversion occurred early at a rate which was HLA-dependent and correlated with the HLA class 1-associated relative hazard of disease progression and death (P = 0.0008), reinforcing the association between strong cytotoxic T-lymphocyte responses, viral fitness, and disease status. These data provide a comprehensive overview of viral adaptation in the first 3 years of infection. Our findings of HLA-dependent reversion suggest that costs are borne by some escape variants which may benefit the host, a finding contrary to a simple immune evasion paradigm. These epitopes, which are both strongly and frequently recognized, and for which escape involves a high cost to the virus, have the potential to optimize vaccine design.

[Pars plana vitrectomy in treatment of ocular toxocariasis complications--case report]

Ocular toxocariasis in adults may cause serious diagnostic and therapeutic problems. We describe a case of a 54-year-old farmer who developed peripheral granuloma with dense connective tissue strands joined to the disc. The diagnosis was confirmed by high ELISA titers in the serum and vitreous body. We performed pars plana vitrectomy with epiretinal membrane removal and laser photocoagulation of the inferior retina, obtaining improvement of visual acuity. After a few weeks the patient returned with central retinal detachment and macular hole. After the second vitrectomy with use of silicon oil we obtained reattachment of the retina but without functional improvement.

Cancerogenesis in Helicobacter pylori infected stomach--role of growth factors, apoptosis and cyclooxygenases

BACKGROUND

Epidemiological and animal studies demonstrated a link between gastric cancer (GC) or mucosal associated lymphoid tissue (MALT) lymphoma and chronic infection with Helicobacter pylori (H. pylori). The exact mechanism responsible for the development of GC and MALT-lymphoma in H. pylori-infected patients still remains obscure. This report is designed to overview the molecular biology, especially the gene expression and histochemical manifestation of gastrin and other growth factors such as transforming growth factor alpha (TGF alpha) and hepatocyte growth factor (HGF) in the GC before and after eradication of H. pylori. Furthermore, gene expression of cyclooxygenase-1 (COX-1) and COX-2 and apoptosis-related proteins such as Bax and Bcl-2 are discussed.

MATERIAL AND METHODS

The findings originate from two series of patients; Series I involving 337 GC patients and 400 age- and gender-matched controls and series 2 including 20 MALT-lymphoma patients and 40 matched controls.

RESULTS

An overall H.pylori-seropositivity reached about 80% in GC and about 90% in MALT-lymphoma, significantly higher than in non-cancer controls (60%). The prevalence of CagA-positive strains was about twice as high (about 70%) in GC and MALT-lymphomas as in sex- and age-matched controls. Expression of gastrin was detected in antrum of all tested patients but also in majority (90%) of GCs and MALT-lymphomas tumor tissue. HGF and TGF alpha were expressed more frequently in GC tissue than in normal fundic mucosa. COX-1 was similarly expressed in GC and MALT as in intact mucosa, while COX-2 mRNA was detected only in tumor tissue, being attenuated by H.pylori eradication in GC and abolished by this therapy in MALT-lymphoma. The plasma levels of alpha-amidated gastrin in GC and MALT were several folds higher than in controls. Gene expression of bcl-2 was detected in all, while bax--only in about 50% of GC samples.

CONCLUSIONS

Infection with H. pylori, especially that expressing CagA-positivity, is primum movens in developing GC and MALT-lymphoma and the upregulation of growth factors, particularly of gastrin, and COX-2 and dysregulation of the Bax/Bcl-2 system seem to contribute to gastric cancerogenesis.

Implication of gastrin in cyclooxygenase-2 expression in Helicobacter pylori infected gastric ulceration

Gastroduodenal ulcerations have worldwide distribution and the infection with Helicobacter pylori (HP) has been implicated in pathogenesis of this disease. The HP infection is usually accompanied by hypergastrinemia and enhanced generation of prostaglandins (PG), both implicated in the pathogenesis of peptic ulcerations but no study has been undertaken to assess the relationship between the HP infection and coexpression of gastrin and cyclooxygenases (COX), the rate limiting enzymes in the PG production. Since HP infection, usually accompanying peptic ulcerations, results in increased release of gastrin, a potent gastric mitogen that might be capable to induce COX-2 and to generate PG, we decided 1) to compare the seroprevalence of HP and its cytotoxic protein, CagA, in gastric ulcer patients with those in age- and gender-matched controls; 2) to determine the gene expression of gastrin and its receptors (CCK(B)-R) at the margin of gastric ulcer and in the mucosa of antrum and corpus before and after successful eradication of HP, 3) to assess the plasma levels and gastric luminal contents of gastrin before and after HP eradication and 4) to examine the mRNA and enzyme protein expression of COX-1 and COX-2 as well as the PGE2 generation in ulcer margin tissue and gastric antral and fundic mucosa before and after the HP eradication. The trial material included 20 patients with gastric ulcer and 40 age- and gender-matched controls. Anti-HP and anti-CagA IgG seroprevalence was estimated by specific antisera using ELISA tests. Gene expressions of gastrin, CCK(B)-R, COX-1 and COX-2 were examined using RT-PCR with beta-actin as a reference and employing Western blotting for COX-2 expression, while gastrin and PGE2 were measured by RIA. All gastric ulcers were located at smaller curvature within the antral mucosal area. The seroprevalence of HP, especially that expressing CagA, was significantly higher in gastric ulcers (85%) than in controls (62.5%). Both gastrin and CCK(B)-R mRNA were detected by RT-PCR in ulcer margin and gastrin mRNA was overexpressed in remaining antral mucosa, while CCK(B)-R mRNA was overexpressed in fundic mucosa of HP infected patients. Similarly, COX-2 mRNA and protein were found in margin of gastric ulcer and in the HP infected antral and fundic mucosa but not in the mucosa of HP eradicated patients in whom ulcers completely healed and gastrin was expressed only in antrum, CCK(B)-R only in corpus, while COX-1 was detected both in antrum and corpus. HP positive gastric ulcer patients showed about three times higher levels of plasma immunoreactive gastrin and about 50% higher luminal gastrin contents than the HP negative controls and this increased plasma and luminal gastrin was normalized following the HP eradication. A significant fall in gastrin and CCK(B)-R mRNA expression was noticed six weeks after HP eradication in gastric antral and fundic mucosa, while COX-2 mRNA completely disappeared after this treatment. We conclude that 1) HP infected gastric ulcer margin coexpresses gastrin, its receptors (CCK(B)-R), and COX-2; 2) HP infection may be implicated in gastric ulceration via increased release of gastrin that could be responsible for the overexpression of COX-2 that in turn could help ulcer healing through the stimulation of mucosal cell growth, restoration of the glandular structure and angiogenesis in the ulcer area and 3) gastrin produced in HP infected antral mucosa seems to be involved in the induction of COX-2 and PG production by this enzyme and this may contribute to the ulcer healing.

Comparison of nitric oxide-releasing NSAID and vitamin C with classic NSAID in healing of chronic gastric ulcers; involvement of reactive oxygen species

BACKGROUND

Nonsteroidal anti-inflammatory drugs such as aspirin (ASA) are known to induce gastric mucosal damage including bleeding, ulceration and perforation in humans and experimental animals. These adverse effects of ASA were originally attributed to the inhibition of cyclooxygenase and the deficiency of endogenous prostaglandins induced by this drug but the role of reactive oxygen species (ROS), lipid peroxidation and antioxidizing mechanism in the pathogenesis of ASA damage has been little studied. New class of nitric oxide (NO)-releasing nonsteroidal anti-inflammatory drugs was shown to inhibit cyclooxygenase and prostaglandin generation without causing mucosal damage but it remains unknown whether these agents affect the healing process of chronic gastric ulcers.

MATERIAL AND METHODS

In this study the effect of NO-releasing aspirin (NO-ASA) and was compared with that of native aspirin applied with or without vitamin C on the healing of acetic acid ulcers. The area of gastric ulcer was determined by planimetry, the gastric blood flow (GBF) at ulcer margin was measured by H2 gas clearance method and mucosal release of ROS was quantified by measuring the chemiluminescence before and after the treatment with ASA or NO-ASA alone and ASA combined with vitamin C. The plasma antiinflammatory cytokine such as IL-1b and oxygen radical-mediated lipid peroxidation was measured in the ulcerated gastric mucosa of ASA and NO-ASA-treated animals.

RESULTS

ASA delayed significantly ulcer healing and this effect was accompanied by a marked increase in the chemiluminescence, lipid peroxidation and the fall in the GBF at ulcer margin. Vitamin C attenuated significantly both the ASA-induced gastric damage and accompanying fall in the GBF at ulcer margin and the rise in the chemiluminescence and reversed the ASA-induced lipid peroxidation. In contrast, NO-ASA failed to affect healing of gastric ulcers and failed to produce the rise in the plasma IL-1b levels and the increase of lipid peroxidation as compared to those recorded in ASA-treated animals.

CONCLUSIONS

1) ROS-induced enhancement in lipid peroxidation plays an important role in the mechanism of gastric damage induced by ASA, 2) vitamin C attenuates the deleterious effect of ASA on ulcer healing due to its antioxidizing activity by mechanism involving preservation of gastric microcirculation and attenuation of lipid peroxidation and cytokine release and 3) coupling of NO to aspirin fails to delay the ulcer healing suggesting that NO might compensate for prostaglandin deficiency induced by NSAID.

Water extracts of Helicobacter pylori suppress the expression of histidine decarboxylase and reduce histamine content in the rat gastric mucosa

BACKGROUND

Acute Helicobacter pylori (Hp) infection in humans may be associated with markedly reduced gastric acid secretion, but the mechanism of this hypochlorhydria has not been fully explained.

AIMS

This study was designed to investigate how water extracts (WE) of Hp applied on rat gastric mucosa affect gastric secretion and mucosal histamine concentration as well as the gene expression for histamine decarboxylase (HDC), the key enzyme converting histidine to histamine and for interleukin-1beta (IL-1beta), the important proinflammatory cytokine.

MATERIALS AND METHODS

Wistar rats were surgically equipped with small cannulas to form gastric fistulas (GF). Four weeks after formation of GF, rats received either saline (control group) or WE obtained from type I Hp strain expressing CagA/VacA proteins and from type II Hp strain negative for CagA/VacA. Hp-WE was applied intragastrically (i.g.) in a volume of 1 ml at days 0, 2, 4 and 6 (total 4 times). At days 7 and 14, the secretory tests were performed during which basal gastric acid and pepsin secretion was examined and acid and pepsin outputs were measured. After secretory tests, the rats were sacrificed, the stomachs removed and the damage to the gastric mucosa was assessed by measuring the lesion area planimetrically and by histology, the gene expression in gastric mucosa for HDC and interleukin-1beta (IL-1beta) was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot. Additionally, somatostatin concentration in gastric juice, gastric mucosal histamine content and plasma gastrin and IL-1beta levels were determined using radioimmunoassay (RIA).

RESULTS

Administration of Hp-WE failed to induce gross mucosal damage but microscopic examination revealed partial denudation of gastric surface epithelium without causing deep necrosis. In secretory tests, Hp-WE produced marked hypochlorhydria but type I Hp-WE induced significantly stronger inhibition of acid and pepsin secretion than type II Hp-WE, both at days 7 and 14. Both, type I and type II Hp-WE suppressed significantly the gene expression for HDC mRNA and lowered significantly gastric mucosal histamine content as compared to respective values in vehicle-treated control gastric mucosa. Furthermore, Hp-WE, resulted in a significant increase in expression of IL-1beta mRNA and a significant fall in luminal somatostatin concentration as well as a insignificant elevation of plasma gastrin level, the type I Hp-WE being more effective in these alterations than type II Hp-WE.

CONCLUSIONS

(1) Ability of Hp-WE to induce superficial damage, the reduction in HDC mRNA and accompanying fall in gastric histamine release, contribute, at least in part, to marked hypochlorhydria observed in the stomach exposed to repeated Hp-WE treatments, and (2) the deleterious effect of Hp-WE on the gastric mucosa involves an impairment of gastrin-somatostatin link possibly resulting from the action of Hp-derived toxins and the induction in mucosal cells of proinflammatory cytokine such as IL-1beta.

Role of leptin in ulcer healing

Leptin was shown to exhibit similar to cholecystokinin (CCK) cytoprotective activity against acute gastric lesions, but its role in ulcer healing has not been examined. The aims of this study were: (1) to compare the effects of exogenous leptin to those of CCK on the course of healing of chronic gastric ulcers; (2) to study the gene and protein expression of leptin at the ulcer margin during ulcer healing; and (3) to assess the effects of leptin administration on the mucosal gene expression of main growth factor such as transforming growth factor alpha (TGFalpha). Gastric ulcers were produced in rats by the acetic acid method. Rats with ulcers were divided in following treatment groups: (1) vehicle; (2) leptin (10 microg/kg i.p.); (3) CCK (10 microg/kg s.c.); and (4) leptin or CCK with or without tyrphostin A46 (200 microg/kg i.p.), an inhibitor of epidermal growth factor (EGF)-receptor tyrosine kinase or NG-nitro-L-arginine (20 mg/kg i.g.), a blocker of nitric oxide synthase. Animals were euthanized 9 days after ulcer induction. The area of gastric ulcers and the gastric blood flow at the ulcer area were determined. In addition, mucosal biopsy samples were taken from the ulcer area for histological evaluation as well as for the determination of mRNA and protein expression for leptin and constitutive nitric oxide synthase (cNOS) and inducibile nitric oxide synthase (iNOS) by reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot, respectively. In addition, the gene expression for TGFalpha was analyzed by RT-PCR. Both leptin and CCK reduced significantly the ulcer area as compared to vehicle-treated group by approximately 50%. The treatment with tyrphostin or N(G)-nitro-L-arginine reversed in part the acceleration of ulcer healing by leptin and CCK. The expression of leptin mRNA and protein was significantly increased at the ulcer edge. The leptin-induced acceleration of ulcer healing was associated with increased expression of transcripts for TGFalpha as well as increased mRNA and protein expression for cNOS and iNOS at the ulcer margin. We conclude that leptin accelerates ulcer healing by mechanisms involving the up-regulation of TGFalpha and increased production of nitric oxide due to up-regulation of cNOS and iNOS in the ulcer area.

Epidermal growth factor and prostaglandin E(2) accelerate mucosal recovery from stress-induced gastric lesions via inhibition of apoptosis

The repair of damaged gastric mucosa is a complex process involving prostaglandins (PG) and mucosal growth factors such as epidermal growth factor (EGF). Recently, we postulated that the increased occurrence of apoptosis in the gastric epithelium might be of pathophysiological importance in the development of stress lesions. The aim of the present study was to assess the effect of the pretreatment of rats, exposed to 3.5 h of water immersion and restraint stress (WRS), with EGF and PG (16,16 dmPGE(2)) on the number of stress lesions, recovery of gastric mucosa from stress and the expression of apoptosis related genes such as caspase-3 and antiapoptotic bcl-2. Rats were divided in following groups: (1) vehicle; (2) EGF 100 microg/kg i.p.; (3) 16,16 dm-PGE(2) (5 microg/kg i.g.) and caspase-1 inhibitor (ICE-I; 100 microg/kg i.p.). One hour later, the rats were exposed to 3.5 h of WRS and then sacrificed immediately (0 h) or at 6, 12, or 24 h after WRS. The number of acute gastric lesions was determined. Gastric epithelial apoptosis was assessed by TUNEL staining. In addition, mRNA expression of caspase-3, Bcl-2 and proinflammatory cytokines (IL-1 beta, TNFalpha) was assessed by RT-PCR. PGE(2) generation in gastric mucosa and luminal EGF were determined by RIA. Exposure to WRS resulted in the development of multiple acute stress erosions ( approximately 18) which almost completely healed during 24 h. The gastric blood flow was significantly reduced (approximately 70% of intact mucosa) immediately after WRS. The expression of mRNA for IL-1 beta and TNF alpha reached their peak at 12 h after stress exposure. The apoptosis rate was highest at 6 h after WRS and was accompanied by the highest caspase-3 expression. In rats pretreated with EGF or 16,16 dm-PGE(2), a significant decrease in caspase-3 mRNA and upregulation of bcl-2 mRNA as observed as compared to vehicle controls. Caspase-1 inhibitor significantly reduced the number of stress lesions. We conclude that EGF and PGE(2) accelerate healing of stress-induced lesions due to the attenuation of apoptosis via upregulation of bcl-2 in gastric mucosa. Inhibitors of apoptosis accelerate healing of stress lesions and may be potentially effective agents in the healing of damaged gastric mucosa.

Helicobacter pylori, gastrin and cyclooxygenase-2 in lung cancer

INTRODUCTION

Tumors arising in the lungs are in over 90% bronchogenic carcinomas that have been attributed predominantly to tobacco smoking, asbestos or air pollution but little is known about endogenous factors that could facilitate their development and invasiveness. The lungs originate embryologically from the same endoderm cells which form the epithelia lining the digestive tract, where gastrin is the major proliferative stimulus.

AIMS

Since lung cancer patients were recruited mostly among smokers, who also have been found to exhibit significantly higher infection rate of Helicobacter pylori (HP) infection than non-smokers and, as since the HP-infected subjects show enhanced plasma levels of gastrin, we decided 1) to compare the seroprevalence of HP and the expression of its cytotoxin, CagA, in lung cancer patients with those in the age- and gender-matched controls without cancer: 2) to determine the gene expression for gastrin and its receptors (CCKB-R) in lung cancer, 3) to assess the gastrin levels in plasma bronchial lavage and in tumor tissue and 4) to examine the expression of cyclooxygenase (COX)-1 and COX-2 in cancer tissue resection margin and intact bronchial mucosa.

MATERIAL AND METHODS

The trial material included 50 patients with lung carcinoma and 100 age- and gender-matched controls. Anti-HP and anti-CagA IgG seroprevalence was estimated by specific antisera using ELISA tests. Gene expression of gastrin, CCKB-R, COX-1 and COX-2 was examined using RT-PCR, while gastrin was measured by specific RIA.

RESULTS

The seroprevalence of HP, especially that expressing CagA, is significantly higher in lung cancers than in healthy controls. Both gastrin and CCKB-R mRNA were detected in the cancer tissue and at the resection margin and similarly COX-2 mRNA was expressed in most cancers and resection margin but not in bronchial mucosa where only COX-1 was found. The lung cancer tissue and resection margin contained many folds larger amounts of immunoreactive gastrin than intact bronchial mucosa.

Activation of genes for superoxide dismutase, interleukin-1beta, tumor necrosis factor-alpha, and intercellular adhesion molecule-1 during healing of ischemia-reperfusion-induced gastric injury

BACKGROUND

Ischemia followed by reperfusion (I/R) induces gastric lesions, probably due to excessive formation of free radicals, but the role of the scavenger of these radicals, proinflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), in the healing of these lesions has not been extensively studied. It is also unknown whether expression of intercellular adhesion molecule-1 (ICAM-1), which mediates neutrophil-induced injury and neutrophil infiltration, is involved in the recovery from I/R lesions.

METHODS

I/R lesions were induced in Wistar rats by applying a small clamp to the celiac artery for 30 min (ischemia phase), followed by the removal of the clamp for 60 min (reperfusion phase). The influence of I/R on gastric secretion was also tested in rats equipped with a gastric fistula (GF) without or with the exposure to a standard period of I/R. Two series of rats (A and B) were used to determine the effects of exogenous and endogenous superoxide dismutase SOD (series A) and allopurinol, a xanthine oxidase inhibitor (series B), on the mucosal recovery from the gastric lesions induced by I/R. The animals were killed immediately after the exposure to I/R (0 h) and at 3 h, 24 h, or 3, 5, or 10 days after this I/R, the area of gastric lesions being measured by planimetry, and the gastric blood flow (GBF) determined by the H2 gas clearance method. Blood was withdrawn for measurement of plasma IL-1beta and TNF-alpha levels with enzyme-linked immunosorbent assay, and plasma gastrin with radioimmunoassay. Biopsy samples of oxyntic mucosa were taken for the assessment of SOD, IL-1beta, TNF-alpha, and ICAM-1 mRNAs by reverse-transcription polymerase chain reaction and Southern blot.

RESULTS

Exposure to I/R resulted in acute gastric erosions, with the maximal increase of the area of these lesions observed 3 h after the end of I/R. This effect was accompanied by a decrease in the GBF, a significant increase in blood free radicals and plasma gastrin increments, and almost complete suppression of gastric secretion. Starting 24 h after I/R, the gastric superficial lesions progressed into deeper ulcers that healed progressively within 10 days, and this was accompanied by gradual restoration of the gastric secretion and the GBF. Treatment with SOD and allopurinol accelerated significantly the healing of I/R erosions, and this effect was accompanied by a significant increase in the GBF and the attenuation of blood free radicals. At 0, 3, and 12 h after I/R a significant decrease in SOD mRNA was observed, whereas expression of TNF-alpha, IL-1beta, and ICAM-1 showed a progressive increase starting immediately after I/R, reaching a maximum on day 3. The plasma level of TNF-alpha and IL-1beta started to increase on day 3 and peaked on day 5 after I/R, being still significantly higher at day 10 than that measured in the vehicle-treated control gastric mucosa. On day 10 the gastric ulcers were almost completely healed, and a decrease in the expression for TNF-alpha, IL-1beta, and ICAM-1 mRNA and an increase in the expression of SOD mRNA were observed.

CONCLUSIONS

1) exposure to I/R produces gastric lesions mediated by the excessive formation of free radicals, resulting in suppression of both gastric microcirculation and secretory activity of the stomach; 2) SOD and allopurinol accelerate the healing of I/R lesions, probably due to suppression of oxygen free radicals and improvement of gastric microcirculation; and 3) the upregulation of SOD mRNA, with subsequent increase in the SOD production and local release of IL-1beta and TNF-alpha, may activate ICAM-1 expression and neutrophil infiltration, which appear to play an important role in the progression of I/R-induced acute gastric erosions into chronic ulcers.

Association of Helicobacter pylori infection with coronary heart disease

The role of Helicobacter pylori (HP) as the main etiological factor in gastritis and peptic ulcer disease is undisputable. Gastric mucosal damage caused by HP involves various bacterial and host-dependent toxic substances that have been recently associated with an increased risk of coronary artery disease (CAD), possibly through the activation acute phase response and of procoagulant hemostatic factors. Recent studies showed a close and strong correlation between plasma increments of some cytokines such as IL-6 or TNFalpha and cardiovascular diseases. HP infection induces platelet activation and aggregation that could be the pathogenic explanation of the association between HP infection and CAD. The aim of this study was to determine the seroprevalence of HP infection and antibodies to CagA, an antigen that is expressed by the most virulent HP strains inducing an enhanced gastric inflammatory response, in patients undergoing routine coronary artery examination. We studied 76 patients with CAD and 81 healthy controls patients without significant change in coronary circulation. Angiograms were read by two independent experienced cardiologists blinded to the results of HP status. The presence of serum IgG antibodies to HP and to CagA and plasma interleukin-8 (IL-8) levels was measured by ELISA. In addition plasma C-reactive protein fibrinogen, total cholesterol and lipids levels were measured in all studied patients. Seropositivity to HP was found in 81.5 % of cases and in 51% of controls and the difference in prevalence was statistically significant, the odds ratio being 4.3 for Hp patients. Antibody to CagA protein was detected in 47.3% of CAD but only in 28% of healthy controls (OR = 2.3 vs OR = 10). C-reactive protein, plasma fibrinogen and total cholesterol were, respectively higher in patients with CAD than in controls. Present data show that there is significant link between CAD and HP infection. The HP infection significantly increases the risk of CAD, especially when both the anti-HP IgG and anti-CagA IgG are considered. Higher prevalence of cytotoxic HP strains might enhance the atherosclerotic process by inducing a persistent, low grade inflammatory response in arterial wall with enhanced synthesis of acute phase reactants.

Role of gastrin in gastric cancerogenesis in Helicobacter pylori infected humans

Numerous epidemiological studies demonstrated the association between Helicobacter pylori (H. pylori) infection and gastric cancer but the mechanism of the involvement of H. pylori in gastric cancerogenesis remains virtually unknown. This study was designed to determine the seropositivity of H. pylori and cytotoxin associated gene A (CagA), serum gastrin and gastric lumen gastrin levels under basal conditions and following stimulation with histamine in gastric cancer patients and controls. 100 gastric cancer patients aging from 21 to 60 years and 300 gender- and age-adjusted controls hospitalized with non-ulcer dyspepsia (NUD) entered this study. 13C-Urea Breath Test (UBT), serum immunoglobulin (IgG) antibodies to H. pylori and CagA were used to assess the H. pylori infection and serum levels of IL-1beta, IL-8 and TNFalpha were measured by enzyme-linked immunosorbent assay (ELISA) to evaluate the degree of gastric inflammation by H. pylori . Gastrin-17 mRNA and gastrin receptors (CCK(B)) mRNA expression in gastric mucosal samples taken by biopsy from the macroscopically intact fundic and antral mucosa as well as from the gastric tumor was determined using RT-PCR. The overall H. pylori seropositivity in gastric cancer patients at age 21-60 years was about 92%, compared, respectively, to 68%, in controls. A summary odds ratio (OR) for gastric cancer in H. pylori infected patients was about 5.0 . The H. pylori CagA seropositivity in gastric cancer patients was about 58.5% compared to 32.4% in controls, giving the summary OR for gastric cancer in CagA positive patients about 8.0. The prevalence of H. pylori- and H. pylori CagA-seropositivity was significantly higher in cancers than in controls, irrespective of the histology of gastric tumor (intestinal, diffuse or mixed type). Median IL-1beta and IL-8 reached significantly higher values in gastric cancer patients (9.31 and 30.8 pg/ml) than in controls (0.21 and 3.12, respectively). In contrast, median serum gastrin in cancers (as total group) was several folds higher (62.6 pM) than in controls (19.3 pM). Also median luminal gastrin concentration in gastric cancer patients was many folds higher (310 pM) than in controls (20 pM). This study shows for the first time that cancer patients are capable of releasing large amounts of gastrin into the gastric lumen to increase luminal hormone concentration to the level that was recently reported to stimulate the growth of H. pylori. There was no any correlation between plasma gastrin levels and gastric luminal concentration of gastrin suggesting that: 1) luminal gastrin originates from different source than plasma hormone, most probably from the cancer cells, 2) cancer cells are capable of expressing gastrin and releasing it mainly into the gastric juice and 3) the gastric cancer cells are equipped with gastrin-specific (CCK(B)) receptor so they exhibit the self-growth promoting activity in autocrine fashion. This notion is supported by direct detection of gastrin mRNA and gastrin receptor (CCK(B)-receptors) mRNA using RT-PCR in cancer tissue. To our knowledge this is the first study showing an important role of gastrin as self-stimulant of cancer cells in patients infected with H. pylori. Basal and histamine maximally stimulated acid outputs were significantly lower in gastric cancer patients than in controls despite of enhanced gastrin release, particularly in cancer patients and this might reflect the mucosal inflammatory changes (increased serum levels of proinflammtory interleukins - IL-1beta and IL-8), that are known to increase gastrin release. We conclude that: 1) H. pylori infected patients, particularly those showing CagA-seropositivity, are at greatly increased risk of development of gastric cancer, 2) H. pylori-infected cancer patients produce significantly more IL-1beta and IL-8 that might reflect an H. (ABSTRACT TRUNCATED)

Leptin in gastroprotection induced by cholecystokinin or by a meal. Role of vagal and sensory nerves and nitric oxide

Leptin, detected recently in the stomach, is a product of the ob gene released by cholecystokinin (CCK) and plays an important role in the control of food intake but its influence on gastroprotection against the damage caused by noxious agents has not been studied. This study was designed to compare the effects of leptin and cholecystokinin-8 (CCK-8) on gastric mucosal lesions induced by topical application of 75% ethanol or acidified aspirin. Four series of Wistar rats (A, B, C and D) were used to determine the effects of: (A) suppression of prostaglandin biosynthesis by indomethacin (5 mg/kg i.p.); (B) inhibition of nitric oxide (NO)-synthase by nitro-L-arginine methyl ester (L-NAME) (5 mg/kg i.v.); (C) blockade of sensory nerves by capsaicin (125 mg/kg s.c.) and (D) bilateral vagotomy, on the gastric lesions induced by intragastric (i.g.) application of ethanol with or without pretreatment with CCK-8, a known gastroprotective substance or leptin. CCK-8 (1-100 microg/kg i.p.) and leptin (0.1-50 microg/kg i.p.) dose dependently attenuated gastric lesions induced by 75% ethanol; the dose reducing these lesions by 50% being about 10 microg/kg and 8 microg/kg, respectively. The protective effects of CCK-8 and leptin were accompanied by a significant rise in gastric blood flow (GBF) and luminal NO concentration. Leptin was also effective to attenuate aspirin-induced damage and the accompanying fall in the GBF, whereas CCK-8 dose dependently worsened aspirin damage and failed to influence GBF. CCK (1-100 microg/kg i.p.), given in graded doses, produced a dose-dependent increase in the plasma leptin level and a rise of the expression of ob messenger RNA (mRNA) in gastric mucosa, the maximum being reached at a dose of 100 microg/kg. Pretreatment with CCK-8 (10 microg/kg i.p.) or with 8% peptone, that is known to stimulate CCK release, also produced a significant rise in plasma leptin levels and up-regulation of ob mRNA while reducing significantly the gastric lesions induced by 75% ethanol to the same extent as that induced by exogenous leptin (10 microg/kg i.p.). Indomethacin, which suppressed prostaglandin generation by approximately 90%, failed to influence leptin- or CCK-8-induced protection against ethanol, whereas L-NAME attenuated significantly CCK-8- and leptin-induced protection and hyperemia but addition to L-NAME of L-arginine, but not D-arginine, restored the protective and hyperemic effects of both hormones. The ob mRNA was detected as a weak signal in the intact gastric mucosa and in that exposed to ethanol alone but this was further enhanced after treatment with graded doses of CCK-8 or peptone meal applied prior to ethanol. We conclude that: (1) exogenous leptin or that released endogenously by CCK or meal exerts a potent gastroprotective action depending upon vagal activity, and involving hyperemia probably mediated by NO and sensory nerves but unrelated to endogenous prostaglandins; (2) leptin mimics the gastroprotective effect of CCK and probably mediates the protective and hyperemic actions of CCK in the rat stomach.

Detection of Blastocystis sp. in domestic dogs and cats

Blastocystis sp. was detected in faecal samples from domestic dogs and cats in Brisbane, Australia. The prevalence rates were high, with 70.8% of the dogs and 67.3% of the cats infected with this organism. Blastocystis sp. from faecal material from two dogs was successfully cultured on inspissated egg slant medium for several months, but could not be maintained for longer periods. Blastocystis sp. from feline faecal samples failed to grow in culture. The parasites found in dogs and cats were generally smaller than Blastocystis hominis from human faecal material, and were the vacuolar form rather than the multivacuolar form. Otherwise, the general morphology of these organisms appeared similar to B. hominis when examined by light and transmission electron microscopy.