Using quantitative polymerase chain reaction to correlate Chlamydia pecorum infectious load with ocular, urinary and reproductive tract disease in the koala (Phascolarctos cinereus)

Complex interactions between Chlamydia pecorum infection, the immune response and disease exist in the koala. We used quantitative polymerase chain reaction to investigate the relationship between C. pecorum infectious load and ocular and urogenital tract disease. Chlamydia pecorum shedding was generally higher in animals with chronic, active disease than in animals with inactive disease. The absence of ocular disease was generally associated with low levels of shedding, but relatively high levels of shedding in the urogenital tract were detected in some koalas without clinical disease signs. These results suggest a complex disease pathogenesis and clinical course in C. pecorum-infected koalas.

Differential interleukin-6 mRNA expression in Nippostrongylus brasiliensis infection of susceptible and resistant strains of mice

Intestinal parasitic infection is still a major problem in humans and animals, yet host immunity against gut parasitic infection remains partially understood. Eosinophilia and mastocytosis are features of such infection that have been shown to be genetically controlled. The expression of IL-6 is detected in eosinophils, mast cells and neutrophils and may be responsible for the regulation of leucocytes at infective sites. The relationships between IL-6 expression, eosinophilia, mastocytosis and host immunity remain unclear. In the present report, a close correlation between IL-6 mRNA+ cells, eosinophilia, mastocytosis and worm expulsion is demonstrated, which may indicate a role for IL-6 in regulation of host immunity against intestinal parasite infection.

Non-urease producing Helicobacter pylori in chronic gastritis

BACKGROUND

Helicobacter pylori infection is the commonest cause of gastritis. Different patterns of immune response to H. pylori infection and characteristics of bacteria are considered to contribute to clinical outcomes.

AIM

To determine characteristics of the host H. pylori relationship in subjects with non-ulcer dyspepsia and a histological diagnosis of gastritis.

METHODS

Thirty-five subjects with chronic gastritis undergoing endoscopy (mean age 53 years, range 24-82, 14 male and 21 female) were studied, none of whom was on nonsteroidal anti-inflammatory drugs or antibiotics. H. pylori infection was determined by rapid urease test (CLOtest), culture, antibody and RT-PCR for Ure C, Cag A and 26 kDa gene and histology. Cytokine production of mucosal IL-6 and IL-8 were measured by ELISA.

RESULTS

Fifteen subjects were positive by CLOtest and/or bacterial culture. In these subjects histology showed numerous helical forms of H. pylori (Group I). Nine subjects were negative by CLOtest, bacterial culture, and mRNA for urease C fragment, but positive by PCR for the 26 kDa protein encoding gene. Histology in these subjects showed the presence of either coccoid forms (four), or scant helical forms (two), or mixed coccoid/helical forms (three) (Group II). Eleven subjects were negative by all methods of detection (Group III). IgG and IgA antibody levels in serum (p<0.05) and gastric tissue culture supernatant (p<0.001) were significantly higher in Group I than those in Group II or III. There were significant differences in the IgG serum and IgA supernatant antibody levels (p<0.01 and p<0.05) when Group II was compared to Group III. Supernatant IL-6 levels were significantly higher in Group I (p<0.01) than those from Groups II and III. IL-8 levels were higher in Group I (p<0.01) and Group II (p<0.05) when compared to Group III.

CONCLUSIONS

'H. pylori-negative' gastritis can be associated with a non-urease producing form of H. pylori, with a reduction in both local and systemic antibody levels and mucosal pro-inflammatory cytokines.

Coccoid forms of Helicobacter pylori can be viable

Controversy exists as to whether the coccoid form of Helicobacter pylori can exist in a viable form. Conversion of helical to coccoid morphology occurs in culture over several days. In this study, the morphology was correlated with parameters of genetic integrity in the reference NCTC 11637 strain over 21 days of culture. The capacity to regrow colonies of helical form was demonstrated from a culture where the coccoid form constituted up to 95% and negligible urease activity could be detected. Urease enzyme activity and its mRNA decreased between day 0 and 10 while 26 kD mRNA and 16S rRNA were expressed unchanged for up to 14 and 21 days of culture, respectively. Expression of mRNA for the Cag A gene behaved in a similar fashion to that of urease. No evidence of DNA fragmentation was detected. These data suggest that a viable form of non-urease producing H. pylori exists after short to intermediate culture and that some if not all of these viable bacteria have coccoid morphology.

The endotoxin of Helicobacter pylori is a modulator of host-dependent gastritis

Atrophic gastritis caused by Helicobacter pylori is the precursor lesion in the development of intestinal-type gastric adenocarcinoma. In animal models, atrophic gastritis induced by Helicobacter felis has been shown to be host dependent, developing in some mouse strains and not in others. The lipopolysaccharide (LPS) of H. pylori has been suggested to play a role in the induction of gastritis. The goal of this study was to compare the inflammation induced by long-term infection of the C3H/He and the C3H/HeJ strains of mice with H. felis. C3H/HeJ mice are unresponsive to LPS. Six months after infection, severe atrophic gastritis had developed in the body mucosae of all infected C3H/He mice, with replacement of parietal and chief cells. Atrophy was associated with a loss of the H. felis from the antral mucosa. In contrast, no atrophy was seen in the infected C3H/HeJ non-LPS responder animals, and heavy colonization of the antrum remained. There were no significant differences between both the quantitative and qualitative serum immunoglobulin G (IgG) and salivary IgA levels in both strains of mice. The main difference between the two strains of long-term-infected mice was a lack of macrophage infiltration in the lamina propria. Immunization induced good protective immunity to challenge with viable H. felis. Helicobacter-induced, host-dependent gastritis is likely to be cell mediated. The C3H/He and C3H/HeJ mouse model provides an excellent opportunity to investigate the cellular basis of atrophic gastritis.

Unusually high susceptibility of NZR/Gd rats to bladder cancer induction by low doses of nitrosomethylurea

Inbred female rats of the NZR/Gd strain were exceptionally susceptible to nitrosomethylurea (NMU) toxicity after intravesical instillations. After only 1.0 mg NMU total given in 10 fractions, 100% of NZR rats developed malignant bladder tumours. Transitional cell carcinomas predominated (56%) when the NMU dose interval was 2 weeks, and most tumours were squamous carcinomas (57%) with a 1-week interval.