Fungicide Sensitivity Profile of Pyrenophora teres f. teres in Field Population

Pyrenophora teres f. teres (Ptt) is a severe pathogen to spring barley in Northern Europe. Ptt with relevant mutations in fungicide target proteins, sterol 14α-demethylase (CYP51A), cytochrome b (Cyt b), and succinate dehydrogenase (SDH) would put efficient disease control at risk. In the growing seasons of 2021 and 2022, 193 Ptt isolates from Estonia were analysed. In this study, mutation detection and in vitro fungicide sensitivity assays of single-spore isolates were carried out. Reduced sensitivity phenotype to mefentrifluconazole was evident in Ptt isolates with a F489L mutation in CYP51A or with 129 bp insert in the Cyp51A gene-promoter region. However, sensitivity to a prothioconazole-desthio remained high regardless of these molecular changes. The Ptt population was mostly sensitive to bixafen, fluxapyroxad, pyraclostrobin, and azoxystrobin. The sensitivity of fluxapyroxad and bixafen has been affected by two mutations, C-S135R and D-H134R, found in SDH subunits. The F129L mutation in Cyt b influenced azoxystrobin but not pyraclostrobin sensitivity. In total, 30 isolates from five fields had relevant mutations in three target protein genes simultaneously. Most of these isolates had a reduced sensitivity phenotype to mefentrifluconazole, fluxapyroxad, and azoxystrobin, while sensitivity to other tested fungicides remained high. Furthermore, possible sexual reproduction may enhance the pathogen's fitness and help it adapt to fungicides.

ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis

Gastrointestinal disease caused by Salmonella enterica is associated with the pathogen's ability to replicate within epithelial cells and macrophages. Upon host cell entry, the bacteria express a type-three secretion system encoded within Salmonella pathogenicity island 2, through which host-manipulating effector proteins are secreted to establish a stable intracellular niche. Transcription of this intracellular virulence program is activated by the PhoPQ two-component system that senses the low pH and the reduced magnesium concentration of host cell vacuoles. In addition to transcriptional control, Salmonella commonly employ RNA-binding proteins (RBPs) and small regulatory RNAs (sRNAs) to regulate gene expression at the post-transcriptional level. ProQ is a globally acting RBP in Salmonella that promotes expression of the intracellular virulence program, but its RNA repertoire has previously been characterized only under standard laboratory growth conditions. Here, we provide a high-resolution ProQ interactome during conditions mimicking the environment of the Salmonella-containing vacuole (SCV), revealing hundreds of previously unknown ProQ binding sites in sRNAs and mRNA 3'UTRs. ProQ positively affected both the levels and the stability of many sRNA ligands, some of which were previously shown to associate with the well-studied and infection-relevant RBP Hfq. We further show that ProQ activates the expression of PhoP at the post-transcriptional level, which, in turn, leads to upregulation of the intracellular virulence program.

IMPORTANCE

Salmonella enterica is a major pathogen responsible for foodborne gastroenteritis, and a leading model organism for genetic and molecular studies of bacterial virulence mechanisms. One key trait of this pathogen is the ability to survive within infected host cells. During infection, the bacteria employ a type three secretion system that deliver effector proteins to target and manipulate host cell processes. The transcriptional regulation of this virulence program is well understood. By contrast, the factors and mechanisms operating at the post-transcriptional level to control virulence gene expression are less clear. In this study, we have charted the global RNA ligand repertoire of the RNA-binding protein ProQ during in vitro conditions mimicking the host cell environment. This identified hundreds of binding sites and revealed ProQ-dependent stabilization of intracellular-specific small RNAs. Importantly, we show that ProQ post-transcriptionally activates the expression of PhoP, a master transcriptional activator of intracellular virulence in Salmonella.

CLIP-Seq in Bacteria: Global Recognition Patterns of Bacterial RNA-Binding Proteins

RNA-protein interactions are at the heart of many central cellular processes, and RNA-binding proteins (RBPs) associate with virtually all RNA molecules in a cell. In bacteria, global RBPs, often in conjunction with small regulatory RNAs, affect physiology and virulence by controlling transcription, translation, and RNA decay. To understand how these regulatory proteins orchestrate global gene expression, detailed maps of their cellular RNA binding sites are required. To this end, cross-linking and immunoprecipitation followed by deep sequencing (CLIP-seq) has revolutionized RBP studies by providing knowledge about global recognition patterns of RBPs in both eukaryotic and bacterial cells. In this chapter, we provide a step-by-step protocol for global mapping of bona fide RBP binding sites using CLIP-seq in bacteria. This protocol has been successfully applied for charting the binding sites of Hfq, CsrA, and ProQ, three global regulatory RBPs in Salmonella enterica and Escherichia coli, and should be readily applicable to other RBPs and bacterial species.

Implementation of antimicrobial peptides for sample preparation prior to nucleic acid amplification in point-of-care settings

BACKGROUND

A variety of sample preparation techniques are used prior to nucleic acid amplification. However, their efficiency is not always sufficient and nucleic acid purification remains the preferred method for template preparation. Purification is difficult and costly to apply in point-of-care (POC) settings and there is a strong need for more robust, rapid, and efficient biological sample preparation techniques in molecular diagnostics.

METHODS

Here, the authors applied antimicrobial peptides (AMPs) for urine sample preparation prior to isothermal loop-mediated amplification (LAMP). AMPs bind to many microorganisms such as bacteria, fungi, protozoa and viruses causing disruption of their membrane integrity and facilitate nucleic acid release.

RESULTS

The authors show that incubation of E. coli with antimicrobial peptide cecropin P1 for 5 min had a significant effect on the availability of template DNA compared with untreated or even heat treated samples resulting in up to six times increase of the amplification efficiency.

CONCLUSION

These results show that AMPs treatment is a very efficient sample preparation technique that is suitable for application prior to nucleic acid amplification directly within biological samples. Furthermore, the entire process of AMPs treatment was performed at room temperature for 5 min thereby making it a good candidate for use in POC applications.

Cationic bactericidal peptide 1018 does not specifically target the stringent response alarmone (p)ppGpp

The bacterial stringent response is a key regulator of bacterial virulence, biofilm formation and antibiotic tolerance, and is a promising target for the development of new antibacterial compounds. The intracellular nucleotide (p)ppGpp acts as a messenger orchestrating the stringent response. A synthetic peptide 1018 was recently proposed to specifically disrupt biofilms by inhibiting the stringent response via direct interaction with (p)ppGpp (de la Fuente-Núñez et al. (2014) PLoS Pathogens). We have interrogated the specificity of the proposed molecular mechanism. When inhibition of Pseudomonas aeruginosa planktonic and biofilm growth is tested simultaneously in the same assay, peptides 1018 and the control peptide 8101 generated by an inversion of the amino acid sequence of 1018 are equally potent, and, importantly, do not display a preferential activity against biofilm. 1018 inhibits planktonic growth of Escherichia coli equally efficiently either when the alleged target, (p)ppGpp, is essential (MOPS media lacking amino acid L-valine), or dispensable for growth (MOPS media supplemented with L-valine). Genetic disruption of the genes relA and spoT responsible for (p)ppGpp synthesis moderately sensitizes – rather than protects – E. coli to 1018. We suggest that the antimicrobial activity of 1018 does not rely on specific recognition of the stringent response messenger (p)ppGpp.

Combination with antimicrobial peptide lyses improves loop-mediated isothermal amplification based method for Chlamydia trachomatis detection directly in urine sample

BACKGROUND

Chlamydia trachomatis is an obligate intracellular human pathogen and is the most common cause of sexually transmitted diseases affecting both men and women. The pathogen can cause prostatitis and epididymitis in men. In women, cervicitis, pelvic inflammatory disease, ectopic pregnancy and acute or chronic pelvic pain are frequent complications. More than half of C. trachomatis-positive patients have minimal or no symptoms, providing an ongoing reservoir for the infection. The lack of sensitive large-scale applicable point- of- care (POC) tests for C. trachomatis detection makes it difficult to diagnose chlamydia infection efficiently in resource-limited environments.

METHODS

A rapid and sensitive assay based on loop-mediated isothermal amplification method (LAMP) was combined with antimicrobial peptide lysis, which is able to detect at least 7 C. trachomatis pathogens per reaction directly from urine samples.

RESULTS

Our study comprising 91 first-void urine samples showed that specificity of the assay is 100 % and sensitivity 73 % when using antimicrobial peptide lysis mix. Additionally we demonstrate that our assay does not give any cross-reactivity with 30 pathogen's DNA potentially present in the urine samples. Furthermore, the assay's novel approach does not require purification or extraction of DNA from clinical sample prior to amplification, so the need for specialized equipment is eliminated.

CONCLUSIONS

The whole procedure is significantly less laborious, less time-consuming and consequently less expensive for early detection and identification of infectious disease. C. trachomatis specific LAMP assay is relatively simple to perform and could therefore be applied in numerous POC settings.

Dual role of RsmA in the coordinated regulation of expression of virulence genes in Pectobacterium wasabiae strain SCC3193

The CsrA/RsmA family of post-transcriptional regulators in bacteria is involved in regulating many cellular processes, including pathogenesis. Using a bioinformatics approach, we identified an RsmA binding motif, A(N)GGA, in the Shine-Dalgarno regions of 901 genes. Among these genes with the predicted RsmA binding motif, 358 were regulated by RsmA according to our previously published gene expression profiling analysis (WT vs rsmA negative mutant; Kõiv et al., 2013). A small subset of the predicted targets known to be important as virulence factors was selected for experimental validation. RNA footprint analyses demonstrated that RsmA binds specifically to the ANGGA motif in the 5'UTR sequences of celV1, pehA, pelB, pel2 and prtW. RsmA-dependent regulation of these five genes was examined in vivo using plasmid-borne translational and transcriptional fusions with a reporter gusA gene. They were all affected negatively by RsmA. However, we demonstrated that whereas the overall effect of RsmA on celV1 and prtW was determined on both the translational and transcriptional level, expression of pectinolytic enzyme genes (pehA, pel2 and pelB) was affected mainly on the level of transcription in tested conditions. In summary, these data indicate that RsmA controls virulence by integration of its regulatory activities at various levels.

Impact of radical operative treatment on the quality of life in women with vulvar cancer--a retrospective study

OBJECTIVES

For patients undergoing vulva surgery the quality of life (QoL) is generally accepted as an important outcome parameter in addition to long-term survival, mortality and complication rates. Less radical operative treatment can reduce morbidity and thereby improve quality of life. This study focuses on outcome in terms of QoL in patients comparing wide local excision (WLE) with radical vulvectomy and waiver of lymphonodectomy (LNE) with inguinofemoral lymphonodectomy.

METHODS

In a retrospective single-center study from 2000 to 2010, 199 patients underwent surgery for vulvar cancer. To assess QoL, the EORTC QLQ-C30 and a tumor-specific module questionnaire were sent to all patients in the follow-up period.

RESULTS

Women who underwent WLE have a superior QoL with regard to global health status and physical, role, emotional and cognitive functioning than those who underwent radical vulvectomy. Less radical surgery also implies less fatigue, nausea/vomiting, pain, insomnia, appetite loss, diarrhea and financial difficulties. After radical vulvectomy 89% of patients have sexual complications.

CONCLUSION

Radical operative treatment, such as radical vulvectomy, causes deterioration in the QoL of these patients. An individualized, less radical surgery must be the aim in the treatment of vulvar cancer.

Lack of RsmA-mediated control results in constant hypervirulence, cell elongation, and hyperflagellation in Pectobacterium wasabiae

The posttranscriptional regulator RsmA controls the production of plant cell wall degrading enzymes (PCWDE) and cell motility in the Pectobacterium genus of plant pathogens. In this study the physiological role of gene regulation by RsmA is under investigation. Disruption of rsmA gene of the Pectobacterium wasabiae strain, SCC3193 resulted in 3-fold decrease in growth rate and increased virulence. The comparison of mRNA levels of the rsmA⁻ mutant and wild-type using a genome-wide microarray showed, that genes responsible for successful infection, i.e. virulence factors, motility, butanediol fermentation, various secretion systems etc. were up-regulated in the rsmA⁻ strain. The rsmA⁻ strain exhibited a higher propensity to swarm and produce PCWDE compared to the wild-type strain. Virulence experiments in potato tubers demonstrated that in spite of its more efficient tissue maceration, the rsmA⁻ strain's ability to survive within the host is reduced and the infection site is taken over by resident bacteria. Taken together, in the absence of RsmA, cells revert to a constitutively infective phenotype characterized by expression of virulence factors and swarming. We hypothesize that lack of control over these costly energetic processes results in decreased growth rate and fitness. In addition, our findings suggest a relationship between swarming and virulence in plant pathogens.

A role for the Rcs phosphorelay in regulating expression of plant cell wall degrading enzymes in Pectobacterium carotovorum subsp. carotovorum

The Rcs phosphorelay is a signal transduction system that influences the virulence phenotype of several pathogenic bacteria. In the plant pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) the response regulator of the Rcs phosphorelay, RcsB, represses expression of plant cell wall degrading enzymes (PCWDE) and motility. The focus of this study was to identify genes directly regulated by the binding of RcsB that also regulate expression of PCWDE genes in Pcc. RcsB-binding sites within the regulatory regions of the flhDC operon and the rprA and rsmB genes were identified using DNase I protection assays, while in vivo studies using flhDC : : gusA, rsmB : : gusA and rprA : : gusA gene fusions revealed gene regulation. These experiments demonstrated that the operon flhDC, a flagellar master regulator, was repressed by RcsB, and transcription of rprA was activated by RcsB. Regulation of the rsmB promoter by RcsB is more complicated. Our results show that RcsB represses rsmB expression mainly through modulating flhDC transcription. Neverthless, direct binding of RcsB on the rsmB promoter region is possible in certain conditions. Using an rprA-negative mutant, it was further demonstrated that RprA RNA is not essential for regulating expression of PCWDE under the conditions tested, whereas overexpression of rprA increased protease expression in wild-type cells. Stationary-phase sigma factor, RpoS, is the only known target gene for RprA RNA in Escherichia coli; however, in Pcc the effect of RprA RNA was found to be rpoS-independent. Overall, our results show that the Rcs phosphorelay negatively affects expression of PCWDE by inhibiting expression of flhDC and rsmB.

Long-term high-physiological-dose growth hormone reduces intra-abdominal fat in HIV-infected patients with a neutral effect on glucose metabolism

OBJECTIVES

The aim of the study was to investigate the effect of long-term high-physiological-dose recombinant human growth hormone (rhGH) therapy on fat distribution and glucose metabolism in HIV-infected patients.

METHODS

Forty-six HIV-infected Caucasian men on highly active antiretroviral therapy (HAART), with an age range of 21-60 years and no significant comorbidity, were included in this randomized, placebo-controlled, double-blind, single-centre trial. Twenty-eight subjects were randomized to 0.7 mg/day rhGH, and 18 subjects to placebo, administered as daily subcutaneous injections between 1 and 3 pm for 40 weeks. Endpoints included changes in visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), limb fat mass, percentage of limb fat, plasma lipids, insulin resistance and glucose tolerance.

RESULTS

VAT and trunk fat mass decreased significantly in the GH group compared with the placebo group [-19 cm(2) (-11%) vs. 12 cm(2) (6%), P=0.03, and -548 g (-9%) vs. 353 g (6%), P<0.01, respectively]. The beneficial fat redistribution in the GH group occurred without concomitant changes in subcutaneous fat at the abdomen or extremities. rhGH therapy was well tolerated. Insulin resistance, glucose tolerance, and total plasma cholesterol and triglycerides did not significantly change during intervention.

CONCLUSIONS

Daily 0.7 mg rhGH treatment for 40 weeks reduced abdominal visceral fat and trunk fat mass in HIV-infected patients. This treatment appeared to be safe with respect to glucose tolerance and insulin sensitivity.

Effects of endotoxaemia on markers of permeability, metabolism and inflammation in the large bowel of healthy subjects

BACKGROUND

Increased permeability and increased luminal concentrations of L-lactate have previously been shown in the large bowel in septic patients. To advance these observations, a human model of colorectal barrier failure in sepsis is desirable. Therefore, we assessed the effects of endotoxaemia on markers of permeability, metabolism and inflammation in the large bowel in healthy subjects.

METHODS

Twelve healthy male subjects received intravenous endotoxin (2 ng/kg body weight) or saline in a paired cross-over design. Colorectal permeability was assessed after 3, 6, 9 and 12 h by the systemic recovery of luminally instilled (99m)Tc-diethylenetriaminepentaacetate. Luminal concentrations of L-lactate were assessed by equilibrium dialysis. Mucosal biopsies from the large bowel were sampled after 6 and 12 h, and the apoptotic ratio of the epithelium was assessed by terminal deoxynucleotidyl transferase-mediated desoxyuridinetriphosphate nick end-labelling (TUNEL) assay and the expression of inducible nitric oxide synthase (iNOS) mRNA by reverse transcriptase-polymerase chain reaction.

RESULTS

Systemic effects of endotoxaemia were observed, including fever, tachycardia and strongly increased plasma values of tumour necrosis factor-alpha. By contrast, the colorectal permeability, luminal lactate concentrations, mucosal infiltration of inflammatory cells, epithelial apoptotic ratio and expression of iNOS were all unaffected by endotoxin.

CONCLUSIONS

No effect of a single intravenous dose of endotoxin was observed on markers of large bowel permeability, metabolism and inflammation in healthy subjects. This suggests that this part of the gut is relatively resistant to the systemic inflammation induced by experimental endotoxaemia in humans.

The Rcs phosphorelay modulates the expression of plant cell wall degrading enzymes and virulence inPectobacterium carotovorumssp.carotovorum

Production of plant cell wall degrading enzymes, the major virulence factors of soft-rot Pectobacterium species, is controlled by many regulatory factors. Pectobacterium carotovorum ssp. carotovorum SCC3193 encodes an Rcs phosphorelay system that involves two sensor kinases, RcsC(Pcc) and RcsD(Pcc), and a response regulator RcsB(Pcc) as key components of this system, and an additional small lipoprotein RcsF(Pcc). This study indicates that inactivation of rcsC(Pcc), rcsD(Pcc) and rcsB(Pcc) enhances production of virulence factors with the highest effect detected for rcsB(Pcc). Interestingly, mutation of rcsF(Pcc) has no effect on virulence factors synthesis. These results suggest that in SCC3193 a parallel phosphorylation mechanism may activate the RcsB(Pcc) response regulator, which acts as a repressor suppressing the plant cell wall degrading enzyme production. Enhanced production of virulence factors in Rcs mutants is more pronounced when bacteria are growing in the absence of plant signal components.

Type II quorum sensing regulates virulence in Erwinia carotovora ssp. carotovora

Quorum sensing is a process by which bacteria communicate using secreted chemical signaling molecules called autoinducers. In this study, the opportunistic plant pathogen Erwinia carotovora ssp. carotovora was observed to secrete type II signaling molecules. A homolog of luxS, the gene required for AI-2 synthesis in Vibrio harveyi, was isolated from the genome of the pathogen. To determine the potential role of AI-2 in virulence, an isogenic luxS- (ECC) mutant was constructed and tested for its ability to cause tissue maceration. The findings reported here demonstrate that the LuxS-dependent signaling affects the progression of disease symptoms during the early stages of infection by modulating the expression of pectinolytic enzymes.

Expression of Toll-like receptor 9 and response to bacterial CpG oligodeoxynucleotides in human intestinal epithelium

Recognition of repeat CpG motifs, which are common in bacterial, but not in mammalian, DNA, through Toll-like receptor (TLR)9 is an integral part of the innate immune system. As the role of TLR9 in the human gut is unknown, we determined the spectrum of TLR9 expression in normal and inflamed colon and examined how epithelial cells respond to specific TLR9 ligand stimulation. TLR9 expression was measured in human colonic mucosal biopsies, freshly isolated human colonic epithelial cells and HT-29 cells by reverse transcriptase-polymerase chain reaction or Western blotting. Colonic epithelial cell cultures were stimulated with a synthetic CpG-oligodeoxynucleotide (ODN), exhibiting strong immunostimulatory effects in B cells. Interleukin (IL)-8 secretion was determined by enzyme-linked immunosorbent assay, nuclear factor-kappaB (NF-kB) activity by electrophoretic mobility shift assay and IkB phosphorylation by Western blotting. TLR9 mRNA was equally expressed in colonic mucosa from controls (n = 6) and patients with ulcerative colitis or Crohn's disease disease (n = 13). HT-29 cells expressed TLR9 mRNA and protein and responded to CpG-ODN (P < 0.01), but not to non-CpG-ODN stimulation, by secreting IL-8, apparently in the absence of NF-kB activation. Primary epithelial cells isolated from normal human colon expressed TLR9 mRNA, but were completely unresponsive to CpG-ODN stimulation in vitro. In conclusion, differentiated human colonic epithelial cells are unresponsive to TLR9 ligand stimulation in vitro despite spontaneous TLR9 gene expression. This suggests that the human epithelium is able to avoid inappropriate immune responses to luminal bacterial products through modulation of the TLR9 pathway.

Activation of nuclear factor kappaB in colonic mucosa from patients with collagenous and ulcerative colitis

BACKGROUND AND AIMS

Expression of inducible nitric oxide synthase (iNOS) is greatly upregulated in the colonic mucosa of patients with collagenous and ulcerative colitis. As the transcription factor nuclear factor kappaB (NFkappaB) is a major inducer of iNOS gene expression, we compared activation and transcriptional activity of NFkappaB in colonic mucosal biopsies from these patients.

PATIENTS

Eight patients with collagenous colitis, six with relapsing ulcerative colitis, and eight with uninflamed bowel were studied.

METHODS

NFkappaB DNA binding activity was assessed by electrophoretic mobility shift assay and inhibitor of NFkappaB (IkappaB) kinase (IKK) activity by immunocomplex kinase assay. In vivo recruitment of NFkappaB to the iNOS promoter was determined by chromatin immunoprecipitation analysis and transcriptional activity by NFkappaB gene expression profiling arrays. Cells showing NFkappaB activation were identified by immunohistochemistry.

RESULTS

In collagenous and ulcerative colitis, as opposed to uninflamed bowel, IKKbeta activity and strong NFkappaB DNA binding gave rise to activation of identical NFkappaB subunits and recruitment of transcriptionally active p65 to the iNOS promoter. In collagenous colitis, activated NFkappaB was observed only in epithelial cells while up to 10% of lamina propria macrophages showed activation in ulcerative colitis.

CONCLUSIONS

In collagenous and ulcerative colitis, colonic mucosal NFkappaB is activated and recruited to the iNOS promoter in vivo via an IKKbeta mediated pathway. As collagenous colitis is not associated with tissue injury, these data challenge the prevailing view that activation of NFkappaB per se mediates tissue injury. Our results suggest that downstream inflammatory reactions leading to tissue damage originate in lamina propria immune cells, as increased NFkappaB activity in collagenous colitis was localised solely in epithelial cells, but present also in macrophages in ulcerative colitis.

Superoxide production and expression of NAD(P)H oxidases by transformed and primary human colonic epithelial cells

BACKGROUND

Superoxide (O(2)(-)) generation through the activity of reduced nicotinamide dinucleotide (NADH) or reduced nicotinamide dinucleotide phosphate (NADPH) oxidases has been demonstrated in a variety of cell types, but not in human colonic epithelial cells.

AIMS

To measure O(2)(-) production and effects of modulators of NAD(P)H oxidase activity and inhibitors of potential O(2)(-) generating enzymes in cultures of human colonic epithelial cells. Expression of the catalytic subunits of NAD(P)H oxidase, Nox1 and gp91(phox) (phox, phagocytic oxidase), and the membrane bound subunit p22(phox) was assessed.

METHODS

The transformed colonic epithelial cell lines (DLD-1, HT-29, and Caco-2) were studied at subconfluence, confluence, and after differentiation. Primary colonic epithelial cells were isolated from mucosal biopsies from the normal human colon. Extracellular O(2)(-) production was measured by the cytochrome c reduction assay or luminol enhanced luminescence. Nox1, gp91(phox), and p22(phox) mRNA expression was assessed in colonic epithelial cells and blood neutrophils by reverse transcriptase-polymerase chain reaction.

RESULTS

Production rates of O(2)(-) were higher in subconfluent transformed cells (mean (SEM) 35.8 (4.2) nmol/mg of protein/h) and primary cells (40.4 (5.9)) than in confluent transformed cells (6.0 (0.9); p<0.01). The oxidoreductase inhibitor diphenylene iodonium significantly inhibited O(2)(-) production whereas NADPH and NADH increased production rates. In contrast, O(2)(-) was unaffected by phorbol myristate ester, N(G)-nitro-L-arginine methyl ester, indomethacin, or allopurinol. Nox1 mRNA was expressed in all colonic epithelial cells whereas gp91(phox) was detected only in HT-29 cells and neutrophils. p22(phox) was expressed in all cell types.

CONCLUSIONS

Cultures of transformed and primary epithelial cells from human colon may produce extracellular O(2)(-) through an NAD(P)H oxidase expressing Nox1 and p22(phox).

Constitutive expression of inducible nitric oxide synthase in the normal human colonic epithelium

BACKGROUND

Inducible nitric oxide synthase (iNOS) in the human colon is considered expressed only in inflammatory states such as ulcerative or collagenous colitis. As subtle iNOS labelling was previously observed in some colonic mucosal biopsies from a heterogeneous group of controls with non-inflamed bowel, we studied whether bowel preparation with bisacodyl or polyethylene glycol prior to sigmoidoscopy might induce iNOS expression.

METHODS

Ten healthy, non-smoking male subjects were investigated. Mucosal biopsies were taken from the sigmoid colon prior to bowel preparation and again 12 h after rectal administration of bisacodyl or polyethylene glycol in randomized order. Expression of iNOS protein was quantified by Western blot analysis and localized by immunohistochemistry.

RESULTS

iNOS was expressed in the colonic mucosal biopsies from all subjects and localized in the epithelial cells, particularly at the luminal border of the epithelial cells and more pronounced in the crypt epithelium. The expression of iNOS was unaffected by bowel preparation with bisacodyl or polyethylene glycol.

CONCLUSIONS

iNOS is constitutively expressed in the normal colonic epithelium. The results suggest that synthesis of iNOS protein is unaffected by bowel preparation with the secretagogue laxative, bisacodyl, or polyethylene glycol.

Expression of nitric oxide synthases and effects of L-arginine and L-NMMA on nitric oxide production and fluid transport in collagenous colitis

BACKGROUND AND AIMS

Luminal nitric oxide (NO) is greatly increased in the colon of patients with collagenous and ulcerative colitis. To define the source and consequence of enhanced NO production we have studied expression of NO synthase (NOS) isoforms and nitrotyrosine in mucosal biopsies from these patients. In addition, effects on colonic fluid transfer caused by manipulating the substrate of NOS were studied in patients with collagenous colitis.

PATIENTS

Eight patients with collagenous colitis, nine with active ulcerative colitis, and 10 with uninflamed bowel were included.

METHODS

Expression of NOS isoforms was quantified by western blotting. Inducible NOS (iNOS) and nitrotyrosine were localised by immunohistochemistry. Modulation of NOS activity by topical N(G)-monomethyl-L-arginine (L-NMMA) or L-arginine was assessed during perfusion of whole colon. Plasma and perfusate nitrite/nitrate (NOx) was measured by Griess' reaction.

RESULTS

Both in collagenous and ulcerative colitis, expression of iNOS was 10(2)-10(3) higher (p<0.001) than in uninflamed bowel and localised primarily to the epithelium. Endothelial NOS was evenly expressed in all groups while neuronal NOS was undetectable. Nitrotyrosine was markedly expressed in active ulcerative colitis but rarely detected in collagenous colitis and never in uninflamed bowel. In collagenous colitis, the output of NOx was markedly increased compared with uninflamed bowel (283 (58) v <37 nmol/min; p<0.01) and fluid was net secreted. L-NMMA reduced the output of NOx by 13-66% (95% confidence intervals) and secretion of fluid by 25-109% whereas L-arginine increased the output of NOx by 3-39% and secretion of fluid by 15-93%.

CONCLUSIONS

In collagenous colitis, as opposed to ulcerative colitis, upregulation of iNOS occurs in the absence of nitrotyrosine formation and mucosal damage. Excess generation of NO may be the primary cause of diarrhoea in this condition.

Serotonin modulates immune function in T cells from HIV-seropositive subjects

We have shown earlier increased intracellular levels of cAMP in peripheral lymphocytes from HIV-seropositive subjects and that a chemically induced decrease in this level increases cell proliferation and cytotoxicity. Others have shown that serotonin indirectly decreases intracellular cAMP levels in normal peripheral lymphocytes. In this study, we show that addition of serotonin decreases intracellular levels of cAMP in lymphocytes from HIV-seropositive subjects and significantly increases the proliferative capacity in vitro. However, the effect of serotonin varies with the initial proliferative response; e.g., these with the highest initial responses have the highest increases. An increase in IL-2 production may be a part of this mechanism since addition of serotonin to in vitro cultures of PHA-stimulated cells increases the expression of mRNA for IL-2 and IFN-gamma. The effect on lymphocyte proliferation was most likely mediated through the serotonin 5HT1a receptor because similar results could be obtained by using DPAT, a specific activator of this receptor. Changes in the expression of 5HT1a receptors as judged by the expression of mRNA could not explain why serotonin in vitro had a stronger enhancing effect on cell proliferation in some HIV-seropositive individuals than in others.

Pharmacodynamic dose finding of dimetindene in a sustained release formulation

A sustained release form of dimetindene (dimethindene maleate, Fenistil, CAS 3614-69-5) was developed based on a micropellet technique. Aim of the study was to evaluate the efficacy and duration of two doses of dimetindene in a sustained release pellet formulation with a standardised grass pollen provacation model (Vienna Challenge Chamber; VCC). The study with 12 grass pollen allergic volunteers--verified by case history, skin prick test (SPT), and radio allergo sorbent test (RAST)--was carried out in a placebo controlled, double blind, cross-over design. 12 h before a 4-h-lasting continuous challenge with permanent 1000 dactylis grass pollen in the VCC, administration of dimetindene (Fenistil R Pellets) in doses of 4 mg, 8 mg or identically appearing placebo was scheduled in three sessions. Nasal flow and resistance, nasal secretion and subjective symptoms were recorded at 15-min intervals during this long-term challenge under reproducible conditions. In comparison to placebo, dimetindene leads to a statistically significant reduction (p < 0.05) of nasal response and clinical symptoms for at least 16 h after treatment. The efficacy of 8 mg dimetindene was pronounced over 4 mg, however, the differences between both active treatments were not statistically significant. Therefore 4 mg dimetindene once a day is the adequate treatment for usual pollinotic disease conditions.