Nasal administration of Lactococcus lactis improves local and systemic immune responses against Streptococcus pneumoniae

Lactococcus lactis NZ9000 is a non-pathogenic non-invasive bacterium extensively used for the delivery of antigens and cytokines at the mucosal level. However, there are no reports concerning the per se immunomodulatory capacity of this strain. The aim of the present study was to investigate the intrinsic immunostimulating properties of the nasal administration of L. lactis NZ9000 in a pneumococcal infection model. Mice were preventively treated with L. lactis (2, 5 or 7 days with 10(8) cells/day per mouse) and then challenged with Streptococcus pneumoniae. The local and the systemic immune responses were evaluated. Our results showed that nasal administration of L. lactis for 5 days (LLN5d) increased the clearance rate of S. pneumoniae from lung and prevented the dissemination of pneumococci into blood. This effect coincided with an upregulation of the innate and specific immune responses in both local and systemic compartments. LLN5d increased phagocyte activation in lung, blood and bone marrow, determined by NBT and peroxidase tests. Anti-pneumococcal immunoglobulin (Ig)A in bronchoalveolar lavages (BAL) and IgG in BAL and serum were increased in the LLN5d group. Lung tissue injury was reduced by LLN5d treatment as revealed by histopathological examination and albumin concentration and lactate dehydrogenase activity in BAL. The adjuvant effect of L. lactis in our infection model would be an important advantage for its use as a delivery vehicle of pneumococcal proteins and nasal immunization with recombinant L. lactis emerges as an effective route of vaccination for both systemic and mucosal immunity against pneumococcal infection.     

Factors that affect the re-attachment of Chondracanthus chamissoi (Rhodophyta, Gigartinales) thalli

Vegetative reproduction of Chondracanthus chamissoi by means of fragmentation and re-attachment of thalli is considered an effective strategy for maintaining natural populations of this species. Here, we evaluate the effects of (1) time of drifting thallus, (2) type of substratum, and (3) photon flux density, on the re-attachment capacity of thallus fragments of C. chamissoi. The results show that re-attachment decreases with the time after detachment, and was higher at the lower photon flux densities tested (10 and 40 μmol photons m⁻²s⁻¹), and on calcareous substratum. Secondary attachment discs are formed along the entire surface of the fragment.     

Synthesis and evaluation of quinazoline derivatives as phosphodiesterase 7 inhibitors

The latest scientific findings concerning PDE7 and PDE4 inhibition suggest that selective small-molecule inhibitors of both enzymes could provide a novel approach to treat a variety of immunological diseases. In this context, we describe a new series of quinazoline derivatives from quinazolin-4-thiones which include a substituted biphenyl fragment. Some of these compounds show inhibitory potencies at sub-micromolar levels against the catalytic domain of PDE7.     

Human-Induced Trophic Cascades along the Fecal Detritus Pathway

Human presence and activity in tropical forest is thought to exert top-down regulation over the various ‘green-world’ pathways of plant-based foodwebs. However, these effects have never been explored for the ‘brown-world’ pathways of fecal-detritus webs. The strong effects of humans on tropical game mammals are likely to indirectly influence fecal detritivores (including Scarabaeine dung beetles), with subsequent indirect impacts on detrivore-mediated and plant-facilitating detrital processes. Across a 380-km gradient of human influence in the western Brazilian Amazon, we conducted the first landscape-level assessment of human-induced cascade effects on the fecal detritus pathway, by coupling data on human impact, game mammal and detritivore community structure, and rate measurements of a key detritus process (i.e. dung beetle-mediated secondary seed dispersal). We found evidence that human impact indirectly influences both the diversity and biomass of fecal detritivores, but not detritivore-mediated processes. Cascade strength varied across detritivore groups defined by species'' traits. We found smaller-bodied dung beetles were at higher risk of local decline in areas of human presence, and that body size was a better predictor of cascade structure than fecal resource manipulation strategy. Cascade strength was also stronger in upland, unflooded forests, than in seasonally flooded forests. Our results suggest that the impact of human activity in tropical forest on fecal-detritus food web structure is mediated by both species'' traits and habitat type. Further research will be required to determine the conditions under which these cascade effects influence fecal-detritus web function.     

Metformin Induces Apoptosis through AMPK-Dependent Inhibition of UPR Signaling in ALL Lymphoblasts

The outcome of patients with resistant phenotypes of acute lymphoblastic leukemia (ALL) or those who relapse remains poor. We investigated the mechanism of cell death induced by metformin in Bp- and T-ALL cell models and primary cells, and show that metformin effectively induces apoptosis in ALL cells. Metformin activated AMPK, down-regulated the unfolded protein response (UPR) demonstrated by significant decrease in the main UPR regulator GRP78, and led to UPR-mediated cell death via up-regulation of the ER stress/UPR cell death mediators IRE1α and CHOP. Using shRNA, we demonstrate that metformin-induced apoptosis is AMPK-dependent since AMPK knock-down rescued ALL cells, which correlated with down-regulation of IRE1α and CHOP and restoration of the UPR/GRP78 function. Additionally rapamycin, a known inhibitor of mTOR-dependent protein synthesis, rescued cells from metformin-induced apoptosis and down-regulated CHOP expression. Finally, metformin induced PIM-2 kinase activity and co-treatment of ALL cells with a PIM-1/2 kinase inhibitor plus metformin synergistically increased cell death, suggesting a buffering role for PIM-2 in metformin’s cytotoxicity. Similar synergism was seen with agents targeting Akt in combination with metformin, supporting our original postulate that AMPK and Akt exert opposite regulatory roles on UPR activity in ALL. Taken together, our data indicate that metformin induces ALL cell death by triggering ER and proteotoxic stress and simultaneously down-regulating the physiologic UPR response responsible for effectively buffering proteotoxic stress. Our findings provide evidence for a role of metformin in ALL therapy and support strategies targeting synthetic lethal interactions with Akt and PIM kinases as suitable for future consideration for clinical translation in ALL.     

Identification of Candida albicans heat shock proteins and Candida glabrata and Candida krusei enolases involved in the response to oxidative stress

In the past two decades, Candida species have become the second leading cause of invasive mycosis in immunocompromised patients. In order to colonize their hosts, these microorganisms express adhesins and cell wall proteins that allow them to adhere and neutralize the reactive oxygen species produced by phagocytic cells during the respiratory burst. However, the precise mechanism by which Candida cell wall proteins change their expression in response to oxidative stress has not been described. In an attempt to understand this change in response to oxidative stress, in this study, three Candida species, namely, C. albicans, C. glabrata and C. krusei, were exposed to increasing concentrations of H₂O₂ and induced cell wall proteins were identified by two-dimensional gel electrophoresis and peptide mass fingerprinting. Sequence analysis of differential proteins led to the identification of two heat-shock proteins in C. albicans, two enolases in C. glabrata and one enolase in C. krusei. Enolases may be involved in the protection of pathogenic cells against oxidative stress as suggested by the decrease in their expression when they were exposed to high concentrations of H₂O₂. To our knowledge, this is the first demonstration that expression of these proteins changes in response to oxidative stress in different Candida species. This knowledge can eventually facilitate both an early diagnosis and a more efficient treatment of this mycosis.     

Bovine babesiosis: Cattle protected in the field with a frozen vaccine containing Babesia bovis and Babesia bigemina cultured in vitro with a serum-free medium

An attenuated live vaccine containing Babesia bovis and B. bigemina cultured in vitro with a serum-free medium was assessed for its clinical protection conferred of naïve cattle, under natural tick-challenge in a high endemicity zone to Babesia spp. Three groups of six animals were treated as follows: group I (GI) received a vaccine derived from parasites cultured with a free-serum medium; group II (GII) were immunized with the standard vaccine, with parasites cultured in a medium supplemented with 40% (v/v) bovine serum; and a control group (GIII) inoculated with non-infected bovine erythrocytes. Inocula were administered by IM route. Experimental animals were kept during 23 days after vaccination in a cattle farm free of ticks and Babesia spp. Thereafter, cattle were moved to a high endemicity farm for natural exposure to Babesia spp. transmitted by Rhipicephalus microplus ticks. Protection against clinical babesiosis was observed in bovines belonging to GI (100%) and GII (83.33%), while the control animals (GIII) were not protected, and showed severe clinical signs, closely related to babesiosis, were observed for at least three consecutive days during the challenge. These were fever, anemia, which were measured simultaneously, and circulating parasites were detected by optic light microscopy. All cattle showed B. bovis and B. bigemina in stained blood films during the challenge; B. bovis antibody titers were higher than those to B. bigemina in GI and GII, and lower titers were determined in GIII. The protective capacity of the vaccine derived from B. bovis and B. bigemina cultured in vitro in a serum-free medium was demonstrated.