The matrix metalloproteinase inhibitor RS-130830 attenuates brain injury in experimental pneumococcal meningitis.

BACKGROUND Pneumococcal meningitis (PM) is characterized by high mortality and morbidity including long-term neurofunctional deficits. Neuropathological correlates of these sequelae are apoptosis in the hippocampal dentate gyrus and necrosis in the cortex. Matrix metalloproteinases (MMPs) play a critical role in the pathophysiology of PM. RS-130830 (Ro-1130830, CTS-1027) is a potent partially selective inhibitor of MMPs of a second generation and has been evaluated in clinical trials as an anti-arthritis drug. It inhibits MMPs involved in acute inflammation but has low activity against MMP-1 (interstitial collagenase), MMP-7 (matrilysin) and tumour necrosis factor α converting enzyme (TACE). METHODS A well-established infant rat model of PM was used where live Streptococcus pneumoniae were injected intracisternally and antibiotic treatment with ceftriaxone was initiated 18 h post infection (hpi). Treatment with RS-130830 (75 mg/kg bis in die (bid) i.p., n = 40) was started at 3 hpi while control littermates received the vehicle (succinylated gelatine, n = 42). RESULTS Cortical necrosis was significantly attenuated in animals treated with RS-130830, while the extent of hippocampal apoptosis was not influenced. At 18 hpi, concentrations of interleukin (IL)-1β and IL-10 were significantly lower in the cerebrospinal fluid of treated animals compared to controls. RS-130830 significantly reduced weight loss and leukocyte counts in the cerebrospinal fluid of survivors of PM. CONCLUSION This study identifies MMP inhibition, specifically with RS-130830, as an efficient strategy to attenuate disease severity and cortical brain injury in PM.

Role of two UDP-Glycosyltransferases from the L group of arabidopsis in resistance against pseudomonas syringae

The role of the salicylic acid (SA) glycosides SA 2-O-β-D-glucose (SAG), SA glucose ester (SGE) and the glycosyl transferases UGT74F1 and UGT74F2 in the establishment of basal resistance of Arabidopsis against Pseudomonas syringae pv tomato DC3000 (Pst) was investigated. Both mutants altered in the corresponding glycosyl transferases (ugt74f1 and ugt74f2) were affected in their basal resistance against Pst. The mutant ugt74f1 showed enhanced susceptibility, while ugt74f2 showed enhanced resistance against the same pathogen. Both mutants have to some extent, altered levels of SAG and SGE compared to wild type plants, however, in response to the infection, ugt74f2 accumulated higher levels of free SA until 24 hpi compared to wild type plants while ugt74f1 accumulated lower SA levels. These SA levels correlated well with reduced expression in PR1 and EDS1 in ugt74f1. In contrast, ugt74f2 has enhanced expression of Enhanced Disease Susceptibility 1 (EDS1) but a strong reduction in the expression of several jasmonate (JA)-dependent genes. Bacterial infection interfered with the expression of Fatty Acid Desaturase (FAD), Lipoxygenase2 (LOX2), carboxyl methyltransferase1 (BSMT1) and 9-cis-epoxycarotenoid dioxygenase (NCED3) genes in ugt74f1, thus promoting an antagonistic effect with SA-signalling and leading to enhanced bacterial growth. UGT74F2 might be a target for bacterial effectors since bacterial mutants affected in effector synthesis were impaired in inducing UGT74F2 expression. These results suggest that UGT74F2 negatively influences the accumulation of free SA, hence leading to an increased susceptibility due to reduced SA levels and increased expression of the JA and ABA markers LOX-2, FAD and NCED-3.

Besnoitia besnoiti lytic cycle in vitro and differences in invasion and intracellular proliferation among isolates

Background Bovine besnoitiosis, caused by the protozoan Besnoitia besnoiti, reduces productivity and fertility of affected herds. Besnoitiosis continues to expand in Europe and no effective control tools are currently available. Experimental models are urgently needed. Herein, we describe for the first time the kinetics of standardised in vitro models for the B. besnoiti lytic cycle. This will aid to study the pathogenesis of the disease, in the screening for vaccine targets and drugs potentially useful for the treatment of besnoitiosis. Methods We compared invasion and proliferation of one B. tarandi (from Finland) and seven B. besnoiti isolates (Bb-Spain1, Bb-Spain2, Bb-Israel, Bb-Evora03, Bb-Ger1, Bb-France, Bb-Italy2) in MARC-145 cell culture. Host cell invasion was studied at 4, 6, 8 and 24 h post infection (hpi), and proliferation characteristics were compared at 24, 48, 72, 96, 120, and 144 hpi. Results In Besnoitia spp., the key parameters that determine the sequential adhesion-invasion, proliferation and egress steps are clearly distinct from those in the related apicomplexans Toxoplasma gondii and Neospora caninum. Besnoitia spp. host cell invasion is a rather slow process, since only 50 % of parasites were found intracellular after 3–6 h of exposure to host cells, and invasion still took place after 24 h. Invasion efficacy was significantly higher for Bb-France, Bb-Evora03 and Bb-Israel. In addition, the time span for endodyogeny to take place was as long as 18–35 h. Bb-Israel and B. tarandi isolates were most prolific, as determined by the tachyzoite yield at 72 hpi. The total tachyzoite yield could not be predicted neither by invasion-related parameters (velocity and half time invasion) nor by proliferation parameters (lag phase and doubling time (dT)). The lytic cycle of Besnoitia was asynchronous as evidenced by the presence of three different plaque-forming tachyzoite categories (lysis plaques, large and small parasitophorous vacuoles). Conclusions This study provides first insights into the lytic cycle of B. besnoiti isolates and a standardised in vitro model that allows screening of drug candidates for the treatment of besnoitiosis.