New insights into the pathogenesis and treatment of chlamydial infections

Chlamydiae are obligate intracellular Gram-negative bacteria with a unique biphasic developmental cycle, alternating between infectious elementary bodies and replicative reticulate bodies. However, when exposed to stressful conditions such as iron deprivation and IFN-gamma exposure, they fail to complete their developmental cycle generating morphologically aberrant reticulate bodies called persistent forms, which remain viable but non-infectious inside the host-cell for a long time and are difficult to eradicate with antibiotics. Chlamydiae cause a broad spectrum of diseases. Chlamydia pneumoniae causes community-acquired pneumonia and other respiratory tract infections, while Chlamydia trachomatis is the leading cause of sexually transmitted diseases all over the world and of trachoma in developing countries. More importantly, these pathogens may cause chronic sequelae. In fact, C. pneumoniae infections may be associated to atherosclerosis, whereas C. trachomatis infections lead to ectopic pregnancy, obstructive infertility and reactive arthritis. These sequelae could result from the inflammatory state induced by the persistent forms. In our research, we studied in vitro different aspects of chlamydial pathogenesis and treatment in C. pneumoniae and C. trachomatis, achieving the following results. In C. pneumoniae, in order to investigate the atherogenic process, we set up a model of foam cell induction by means of macrophages infection. In this model, we highlighted for the first time the C. pneumoniae-dependent production of IL-17A, a cytokine recently reported as proatherogenic. Moreover, we investigated the protective effects of resveratrol, a natural polyphenol known to exert antioxidant, cholesterol-lowering and anti-inflammatory effects. Resveratrol is able to avoid foam cell formation in macrophages exposed to high levels of lipoproteins, with possible applications in the prevention of atherosclerosis. In C. trachomatis, we assessed the antichlamydial activity of the essential oil of Mentha suaveolens, in an effort to find out new means to prevent sexually transmitted diseases

The yhiM gene codes for an inner membrane protein involved in GABA export in Escherichia coli

In order to survive the exposure to acid pH, Escherichia coli activates molecular circuits leading from acid tolerance to extreme acid resistance (AR). The activation of the different circuits involves several global and specific regulators affecting the expression of membrane, periplasmic and cytosolic proteins acting at different levels to dampen the harmful consequences of the uncontrolled entry of protons intracellularly. Many genes coding for the structural components of the AR circuits (protecting from pH ≤ 2.5) and their specific transcriptional regulators cluster in a genomic region named AFI (acid fitness island) and respond in the same way to global regulators (such as RpoS and H-NS) as well as to anaerobiosis, alkaline, cold and respiratory stresses, in addition to the acid stress. Notably some genes coding for structural components of AR, though similarly regulated, are non-AFI localised. Amongst these the gadBC operon, coding for the major structural components of the glutamate-based AR system, and the ybaS gene, coding for a glutaminase required for the glutamine-based AR system. The yhiM gene, a non-AFI gene, appears to belong to this group. We mapped the transcription start of the 1.1 kb monocistronic yhiM transcript: it is an adenine residue located 22 nt upstream a GTG start codon. By real-time PCR we show that GadE and GadX equally affect the expression of yhiM under oxidative growth conditions. While YhiM is partially involved in the RpoS-dependent AR, we failed to detect a significant involvement in the glutamate- or glutamine-dependent AR at pH ≤ 2.5. However, when grown in EG at pH 5.0, the yhiM mutant displays impaired GABA export, whereas when YhiM is overexpressed, an increases of GABA export in EG medium in the pH range 2.5–5.5 is observed. Our data suggest that YhiM is a GABA transporter with a physiological role more relevant at mildly acidic pH, but not a key component of AR at pH < 2.5

Chlamydia pneumoniae and oxidative stress in cardiovascular disease. State of the art and prevention strategies.

Chlamydia pneumoniae, a pathogenic bacteria responsible for respiratory tract infections, is known as the most implicated infectious agent in atherosclerotic cardiovascular diseases (CVDs). Accumulating evidence suggests that C. pneumoniae-induced oxidative stress may play a critical role in the pathogenesis of CVDs. Indeed, the overproduction of reactive oxygen species (ROS) within macrophages, endothelial cells, platelets and vascular smooth muscle cells (VSMCs) after C. pneumoniae exposure, has been shown to cause low density lipoprotein oxidation, foam cell formation, endothelial dysfunction, platelet adhesion and aggregation, and VSMC proliferation and migration, all responsible for the typical pathological changes of atherosclerotic plaque. The aim of this review is to improve our insight into C. pneumoniae-induced oxidative stress in order to suggest potential strategies for CVD prevention. Several antioxidants, acting on multi-enzymatic targets related to ROS production induced by C. pneumoniae, have been discussed. A future strategy for the prevention of C. pneumoniae-associated CVDs will be to target chlamydial HSP60, involved in oxidative stress

Acute Delta Hepatitis in Italy spanning three decades (1991–2019): Evidence for the effectiveness of the hepatitis B vaccination campaign

Updated incidence data of acute Delta virus hepatitis (HDV) are lacking worldwide. Our aim was to evaluate incidence of and risk factors for acute HDV in Italy after the introduction of the compulsory vaccination against hepatitis B virus (HBV) in 1991. Data were obtained from the National Surveillance System of acute viral hepatitis (SEIEVA). Independent predictors of HDV were assessed by logistic-regression analysis. The incidence of acute HDV per 1-million population declined from 3.2 cases in 1987 to 0.04 in 2019, parallel to that of acute HBV per 100,000 from 10.0 to 0.39 cases during the same period. The median age of cases increased from 27 years in the decade 1991-1999 to 44 years in the decade 2010-2019 (p &lt; .001). Over the same period, the male/female ratio decreased from 3.8 to 2.1, the proportion of coinfections increased from 55% to 75% (p = .003) and that of HBsAg positive acute hepatitis tested for by IgM anti-HDV linearly decreased from 50.1% to 34.1% (p &lt; .001). People born abroad accounted for 24.6% of cases in 2004-2010 and 32.1% in 2011-2019. In the period 2010-2019, risky sexual behaviour (O.R. 4.2; 95%CI: 1.4-12.8) was the sole independent predictor of acute HDV; conversely intravenous drug use was no longer associated (O.R. 1.25; 95%CI: 0.15-10.22) with this. In conclusion, HBV vaccination was an effective measure to control acute HDV. Intravenous drug use is no longer an efficient mode of HDV spread. Testing for IgM-anti HDV is a grey area requiring alert. Acute HDV in foreigners should be monitored in the years to come

RESVERATROL IN CHLAMYDIA PNEUMONIAE-INDUCED FOAM CELL FORMATION AND INTERLEUKIN-17A SYNTHESIS

The involvement of Chlamydia pneumoniae in the pathogenesis of atherosclerosis has been suggested by numerous seroepidemiological, in vivo and in vitro studies. In particular, it has been shown that C. pneumoniae is able to promote the accumulation of low-density lipoproteins into macrophages, thus facilitating foam cell formation. The aim of our study was to investigate the effects of resveratrol on macrophage-derived foam cell formation induced by C. pneumoniae, examining its underlying biochemical mechanisms. Our results showed a relevant decrease in the number of foam. cells, in the production of thiobarbituric acid reactive substances, superoxide anion and IL-17A while treating C. pneumoniae infected macrophages with resveratrol. Furthermore, the inhibition of Peroxisome Proliferator-Activated Receptors gamma by a specific antagonist (GW 9662), in presence of resveratrol and C. pneumoniae, enhanced intracellular lipid and cholesterol accumulation and the subsequent foam cell formation. In conclusion, the main result of our study is the evidence of an antiatherogenic effect of resveratrol on macrophage-derived foam cell formation and IL-17A production induced by C. pneumoniae

The elusive but pathogenic peptidoglycan of chlamydiae

Chlamydia species cause a broad spectrum of diseases in humans including severe chronic sequelae related to persistent forms. Despite the lack of detectable amounts of peptidoglycan, several studies suggest the presence of small quantities of peptidoglycan or its derivative at least in some stages of the growth cycle. Based on recent discovery in Chlamydiae of the aminotransferase pathway for biosynthesis of meso-diaminopimelic acid, we demonstrated the up-regulation of the gene (cp0259) encoding L,L-diaminopimelate aminotransferase in chlamydial persistent forms. This finding may be important in the search for target molecules to diagnose and treat Chlamydia-associated chronic diseases. Copyright © by BIOLIFE s.a.s

Aspetti patogenetici delle infezioni da Chlamydiae

Negli ultimi anni le infezioni da Chlamydiae hanno destato un crescente interesse nella comunità scientifica, dal momento che oltre ad essere responsabili delle tradizionali patologie acute (infezioni genitali da parte di Chlamydia trachomatis; infezioni respiratorie da parte di C. pneumoniae e C. psittaci) sono state coinvolte in una serie di sequelae croniche di grande impatto sulla salute pubblica, tra le quali l'aterosclerosi. Lo scopo della nostra ricerca è stato quello di studiare gli aspetti patogenetici delle infezioni da Chlamydiae e a tal fine abbiamo allestito modelli in vitro di infezione con C. trachomatis e C. pneumoniae su linee cellulari epiteliali (HeLa ed HEp‑2) e linee macrofagiche J774A.1

Effects of Mentha suaveolens Essential Oil on Chlamydia trachomatis

Chlamydia trachomatis, the most common cause of sexually transmitted bacterial infection worldwide, has a unique biphasic developmental cycle alternating between the infectious elementary body and the replicative reticulate body. C. trachomatis is responsible for severe reproductive complications including pelvic inflammatory disease, ectopic pregnancy, and obstructive infertility. The aim of our study was to evaluate whether Mentha suaveolens essential oil (EOMS) can be considered as a promising candidate for preventing C. trachomatis infection. Specifically, we investigated the in vitro effects of EOMS towards C. trachomatis analysing the different phases of chlamydial developmental cycle. Our results demonstrated that EOMS was effective towards C. trachomatis, whereby it not only inactivated infectious elementary bodies but also inhibited chlamydial replication. Our study also revealed the effectiveness of EOMS, in combination with erythromycin, towards C. trachomatis with a substantial reduction in the minimum effect dose of antibiotic. In conclusion, EOMS treatment may represent a preventative strategy since it may reduce C. trachomatis transmission in the population and, thereby, reduce the number of new chlamydial infections and risk of developing of severe sequelae

Short-term "in vivo" study on cellular DNA damage induced by acrylic Andresen activator in oral mucosa cells

Objectives: To analyse through comet assay and micronucleus test the viability and DNA damage occurred in buccal mucosa epithelial cells after a short-term exposure to Andresen activator resin monomers. Setting and Sample Population: Test group consisting of 26 subjects was treated with Andresen activator; 16 subjects who had never undergone orthodontic treatment were enrolled in the control group. Material &amp; Methods: Buccal mucosa samples were collected before treatment and after 7, 15, 30, 60 and 90&nbsp;days. The analyses performed on the cells included the following: cellular viability, comet assay and micronucleus test. Mean&nbsp;\ub1&nbsp;SD were calculated for cellular viability, tail moment, tail intensity, tail length, micronuclei, binuclear and bud cells. Significance (P&nbsp;&lt;&nbsp;0.05) was evaluated with Dunnett's test. Results: Cellular viability did not change during observational time, and its trend was similar to the controls. Tail moment and tail intensity significantly increased after 30 and 60&nbsp;days, respectively, whereas tail length remained unchanged over time in the test group; the same parameters did not change in the control group. In the test group, micronuclei, binuclear and bud cells significantly increased after 30, 60 and 90&nbsp;days, respectively. Conclusion: The resin monomers of the Andresen activator cause genotoxic effects detectable through comet assay and micronucleus test, but they do not produce clear cytotoxic effects after a 90&nbsp;days exposure