Effects of Porphyromonas gingivalis on the activation of mouse macrophages by lipopolysaccharide

Porphyromonas gingivalis (PG) is a micro-organism that is suggested to play an etiologic role in acute and chronic periodontitis. The present study was undertaken to evaluate the question whether PG is capable of inducing interleukin (IL)-1beta, IL-6, macrophage inflammatory protein (MIP)-2, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production in macrophages. Furthermore, the effect of PG on the activation of macrophages by Escherichia coli-lipopolysaccharide (LPS) was studied. The cytokines were analyzed by detection of specific mRNA. The mRNA was amplified by RT-PCR and semi-quantitatively analyzed by high performance liquid chromatography and densitometrically, respectively. These studies demonstrate that LPS was more active than PG in inducing mRNA expression of IL-1beta, IL-6, MIP-2 and GM-CSF. Moreover, PG reduced the mRNA expression of the macrophages stimulated with LPS, especially the IL-1beta and IL-6 mRNA expression was decreased.

DNA analysis for phospholipase A2 coding sequences of Mycoplasma hominis isolated from women with a normal pregnancy and women with a pregnancy complicated by preterm labour

A possible cause of preterm labour is an increased synthesis of prostaglandins by a phospholipase A2 (PLA2) activity. PLA2 activity has been detected in Mycoplasma hominis. The aim of this study was to test whether chromosomal DNA of M. hominis contains sequences coding for PLA2. M. hominis was cultured in specimens from 5 women with normal pregnancy and 4 in preterm labour. Using sequence alignment, primer pairs for the active part of PLA2 of different species were designed for PCR analysis. No sequences coding for PLA2 could be amplified. Whatever its role in preterm labour, M. hominis is not involved in causing an increase of prostaglandin synthesis.

A simple technique to isolate DNA and supernatant of genital Mycoplasma hominis and Ureaplasma urealyticum

Vaginal colonization with Mycoplasma hominis and Ureaplasma urealyticum has been implicated as a cause of prematurity. Several mechanisms to induce preterm labor have been discussed. The investigation of expressed and secreted enzymes requires a feasible method for culturing and further processing of these bacteria. We describe a simple technique for culturing of Mycoplasma hominis and Ureaplasma urealyticum without contamination with other microorganisms and isolating DNA and supernatant. PCR amplification of a chromosomal Mycoplasma fragment was performed as positive control.

[Primary vitrectomy in endophthalmitis]

From January 1994 to January 1996, 18 patients underwent vitrectomy as a result of endophthalmitis. All patients received intraocular and systemic antibiotics in accordance with the first group of patients in the Endophthalmitis Vitrectomy Study. The aim of this retrospective study was to analyze the visual outcome of surgical treatment.

METHODS

Data from 18 consecutive patients, 11 women and 7 men, with the diagnosis of endophthalmitis as indication for vitrectomy were evaluated. The patients' ages ranged from 14 to 93 years (mean 66.6 +/- 21.3). Postoperative follow-up ranged from 6 weeks to 10 months.

RESULTS

Endophthalmitis resulted from cataract surgery with implantation of an intraocular lens in 14 patients and from ocular trauma in 2 patients. Endophthalmitis followed the resection of posterior capsule fibrosis in 1 patient. Another patient suffered from endogenous endophthalmitis. Positive cultures were obtained in 12 patients. The most frequent causative organisms were coagulase-negative Staphylococcus (n = 7) and Streptococcus species (n = 4). Visual outcome: 13 of 18 patients (72%) gained a visual acuity of 20/400 or better at the final examination after vitrectomy. Four patients (22%) reached a visual acuity of 20/50 or better. Two eyes were enucleated. Good functional outcome was achieved in 2 patients with streptococcal infection (20/200; 30/50).

CONCLUSION

Vitrectomy in combination with intraocular antibiotics is a suitable method for the treatment of endophthalmitis and results in preservation of ambulatory vision in 72% of patients. Vitrectomy in endophthalmitis can result in good functional outcome even in the case of infections with streptococcal species.

Legionella pneumophila heat-shock protein-induced increase of interleukin-1 beta mRNA involves protein kinase C signalling in macrophages

Heat-shock proteins (hsp) are chaperon molecules important in protein folding and assembly. Furthermore, they may have functions in immunoregulatory processes, like T-cell stimulation and antigen presentation, which are not yet fully understood. It has been shown that several hsp of various species and family derivations modulate functions in macrophage immunity by directly increasing cytokine production. In the present study we showed that the 60,000 MW hsp of Legionella pneumophila (Lp-hsp 60) increased cellular steady-state levels of interleukin-1 beta (IL-1 beta) mRNA measured by quantitative reverse transcription-polymerase chain reaction and Northern blotting as well as IL-1 secretion, when added to cultures of thioglycollate-elicited mouse peritoneal macrophages in vitro. The level of mRNA increased in a dose-dependent manner with a minimum effective concentration of 0.5 microgram/ml and peaked 3 hr after stimulation. Lp-hsp 60-coated latex beads also increased IL-1 beta mRNA levels in the presence of cytochalasin D, which inhibits bead uptake but permits binding, indicating that binding to the macrophage surface was sufficient for induction. Accumulation of IL-1 beta mRNA was completely blocked by pretreatment with the protein kinase C (PKC) inhibitor, H7, but not decreased by prior treatment with cycloheximide. The cell lysates of macrophages stimulated with Lp-hsp 60 showed an increased PKC activity measured by phosphorylation of PKC pseudosubstrate. The IL-1 bioactivity in culture supernatants after 24 hr of stimulation with Lp-hsp 60 was increased in a dose-dependent manner but at hsp concentrations in excess of those needed to increase mRNA. Thus, the present study demonstrates that Lp-hsp 60 rapidly increases the steady-state level of IL-1 beta mRNA, possibly through a cell surface receptor system involving a PKC-dependent signalling pathway.

Quantitative reverse transcription-PCR analysis of Legionella pneumophila-induced cytokine mRNA in different macrophage populations by high-performance liquid chromatography

Cytokine production in macrophages infected by bacteria is critical for the course of infection. However, it is not known how infection of macrophages with opportunistic bacteria leads to cytokine production in different populations of cells. Since it is possible that cytokine genes may be differentially regulated by attachment rather than by active infection, the levels of various cytokine mRNAs were measured in alveolar macrophages (AMs), peritoneal resident macrophages (RMs), and peritoneally elicited macrophages (EMs) interacting with Legionella pneumophila by using cytochalasin D-treated macrophages and a newly developed quantitative reverse transcription-PCR procedure with high-performance liquid chromatographic analysis to determine cytokine mRNA formation. Increased levels of interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, and macrophage inflammatory protein 2 mRNAs were quantitated in the macrophages responding to L. pneumophila attachment in vitro. Using this technique, we showed that the three different macrophage populations responded differently to bacterial attachment. We found that the levels of IL-6 and granulocyte-macrophage colony-stimulating factor mRNAs induced by the attachment of L. pneumophila to AMs were significantly lower than the levels in RMs but similar to the levels in EMs. Furthermore, the levels of MIP-2 mRNA in the AMs were found to be higher than those in the RMs, but similar levels were found in EMs. IL-1 beta mRNA levels were higher in both AMs and RMs than in EMs, but tumor necrosis factor alpha levels were not different among the three macrophage populations examined. Thus, the responses of macrophages to bacterial attachment in terms of cytokine mRNA levels were readily quantitated by the reverse transcription-PCR assay. However, the results obtained showed different levels of responsiveness of distinct macrophage populations to L. pneumophila attachment, and this could be related to the characteristic nature of the macrophage type examined.

Bacterial heat shock proteins directly induce cytokine mRNA and interleukin-1 secretion in macrophage cultures

Bacterial heat shock proteins (hsp) have been shown to be important immunogens stimulating both T cells and B cells. However, little is known concerning the direct interactions between hsp and macrophages. In this study, we demonstrated that treatment of macrophage cultures with purified bacterial hsp, including Legionella pneumophila hsp60, Escherichia coli GroEL, Mycobacterium tuberculosis hsp70, Mycobacterium leprae hsp65, and Mycobacterium bovis BCG hsp65, increased the steady-state levels of cytokine mRNA for interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor as well as supernatant IL-1 secretion. This effect was shown not to be due to contamination of the hsp preparations with bacterial lipopolysaccharide. However, not all hsp induced cytokines; M. tuberculosis hsp10 showed minimal activity in our study. These results suggest that bacterial hsp might modulate immunity by rapidly and directly increasing cytokine production in macrophages.