Francine Gervais

Targeting soluble Aβ peptide with Tramiprosate for the treatment of brain amyloidosis

Amyloid beta-peptide (Abeta) is a major constituent of senile plaques in Alzheimers disease (AD). Neurotoxicity results from the conformational transition of Abeta from random-coil to beta-sheet and its oligomerization. Among a series of ionic compounds able to interact with soluble Abeta, Tramiprosate (3-amino-1-propanesulfonic acid; 3APS; Alzhemedtrade mark) was found to maintain Abeta in a non-fibrillar form, to decrease Abeta(42)-induced cell death in neuronal cell cultures, and to inhibit amyloid deposition. Tramiprosate crosses the murine blood-brain barrier (BBB) to exert its activity. Treatment of TgCRND8 mice with Tramiprosate resulted in significant reduction (approximately 30%) in the brain amyloid plaque load and a significant decrease in the cerebral levels of soluble and insoluble Abeta(40) and Abeta(42) (approximately 20-30%). A dose-dependent reduction (up to 60%) of plasma Abeta levels was also observed, suggesting that Tramiprosate influences the central pool of Abeta, changing either its efflux or its metabolism in the brain. We propose that Tramiprosate, which targets soluble Abeta, represents a new and promising therapeutic class of drugs for the treatment of AD.

Killing of Mycobacterium smegmatis by macrophages from genetically susceptible and resistant mice.

The bactericidal function of macrophages was investigated in congenic mice expressing the phenotype of susceptibility (B10.A, Bcgs) or resistance (B10.A.Bcgr) to mycobacterial infection. When splenic and peritoneal macrophages from these two mouse strains were infected in vitro with Mycobacterium smegmatis, the Bcgr macrophages were shown to inactivate M. smegmatis more efficiently than their Bcgs congenic counterparts. The mechanisms of this superior antimycobacterial activity was studied further. Addition of catalase did not abolish killing to a significant degree in either allelic type of macrophage, suggesting that hydrogen peroxide production was not involved in the killing activity controlled by the Bcg gene. Activation of Beg macrophages by exposure to crude lymphokines rendered them equally as efficient as their Bcgr counterparts in their capacity to destroy M. smegmatis. This finding suggests that both the genetically resistant and susceptible macrophages have the potential to kill M. smegmatis in vitro. This potential is expressed constitutively by the Bcgr but not Bcga macrophages and can be induced, by lymphokine treatment, in the Bcga macrophages. In a final set of experiments, the macrophage killing of M. smegmatis was evaluated as a test system to type for the Bcg gene allelic type in vitro, using a set of AXB and BXA recombinant inbred strains of mice. Results obtained show that typing of AXB/BXA recombinant inbred strains for the trait of bactericidal activity vs. M. smegmatis in vitro revealed a perfect match with the strain distribution pattern of resistance/susceptibility to Mycobacterium bovis BCG in vivo.

Susceptibility to a mouse acquired immunodeficiency syndrome is influenced by theH-2

The development of a mouse acquired immunodeficiency syndrome (MAIDS) induced following LP-BM5 MuLV infection depends on host genetic factors. Susceptible mice, such as C57BL/6J mice, develop a profound impairment of lymphoproliferative response to mitogens and hyperplasia of lymphoid organs and succumb to infection within 6 months. These changes do not occur in resistant mice, such as A/J mice. Resistance to MAIDS is a dominant trait since (C57BL/6JxA/J)F1 hybrid mice did not develop any immune dysfunctions following infection. Genetic regulation of the trait of resistance/susceptibility to MAIDS was determined in AXB/BXA recombinant inbred (RI) mouse strains (derived from resistant A/J and susceptible C57BL/6J progenitors). Two different criteria were used to determine their resistance or susceptibility to developing MAIDS: the gross pathologic evaluation of lymphoid organs at 13–15 weeks of infection, and survival. RI mouse strains segregated into two non-overlapping groups. The first group did not develop any significant pathology, and these mouse strains were considered as resistant to MAIDS. The second group showed the virus-induced pathological changes as well as an immunological dysfunction as seen in C57BL/6J progenitor mice, and these strains were thus considered as susceptible to MAIDS. This bimodal strain distribution pattern of resistance/susceptibility to MAIDS among the RI strains suggests that this phenotype is controlled by a single gene. Linkage analysis with other allelic markers showed a strong association between resistance/susceptibility to MAIDS and theH-2 complex. Possession of theH-2b haplotype derived from C57BL/6J mice was associated with susceptibility to MAIDS, while theH-2a haplotype conferred resistance to the disease. This finding was confirmed by demonstrating thatH-2a congenics on the susceptible C57BL/10 background were as resistant to MAIDS as A/J mice which donated theH-2a locus. Gene(s) within theH-2 complex thus represent the major regulatory mechanism of resistance/susceptibility to MAIDS.

Bee venom melittin blocks neutrophil O2− production

Bee vemon (BV) is used in folk medicine to treat arthritis. It has antiinflammatory effects in animal models of rheumatic disease. We have studied the effects of BV on human neutrophil production of superoxide (O2−) and hydrogen peroxide, finding potent, nontoxic, dose-dependent production inhibition. Melittin, the major fraction of BV (50–70%) shows high-affinity calmodulin binding Kd 3 nM). Drugs which bind calmodulin, such as trifluoperazine, inhibit O2− production by human neutrophils. For these reasons we have investigated the effect of melittin and other BV peptides on O2− production by human peripheral blood leukocytes. We show that melittin inhibited O2− production both pre- and poststimulation in contrast to other BV fractions which were without effect. Oxygen radicals and their derivatives from inflammatory cells are implicated in the tissue damage occurring during inflammation. The inhibition is due to a direct effect on cells, and not indicator medium, dismutation, toxic or scavenging effects. We propose that melittin may serve as a prototype small (mol wt 1280), cationic, amphipathic, calmodulin-binding, membrane-active, superoxide-production-inhibiting peptide, providing a model for peptides which could have a role in in vivo regulation of radical production.

Bee venom inhibits superoxide production by human neutrophils

Investigation of the antiinflammatory properties of bee venom demonstrates that it inhibits production of superoxide anion by human neutrophils in a potent, selective, nontoxic, dose-dependent fashion, both pre- and poststimulation by particulale and soluble activators of the neutrophil oxidative metabolism burst. The effect is not due to receptor competition, superoxide dismutase, and/or catalase activity, scavenging, or indicator media effects. These findings may explain the antiinflammatory effects of whole bee venom in experimental systems, its widespread use in folk medicine, and lead to the development of potent, new antiinflammatory substances for therapeutic use in man.

Genetic and physical mapping of the mouse host resistance locus Lgn1

lDepartment of Biochemistry, McGill University, Montreal, Canada, H3G-1Y6 2Department of Genetics, Faculty of Veterinary Medicine, University of Liege, 4000 Liege, Belgium 3Genetique Medicale, Hopital Salnte-Justine, Montreal, Quebec, Canada, H3T-1C5 4Center for the Study of Host Resistance, Montreal General Hospital, Montreal, Canada, H3G 1A4 5Department of Microbiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807 Japan

Proteoglycans and Amyloidogenic Proteins in Peripheral Amyloidosis

Amyloidogenic proteins have the characteristic of adopting a β-sheet conformation and assembling into fibrils. Although similar in fibrillar appearance, each type of peripheral amyloid deposits differs in the nature of the amyloidogenic protein forming fibrils. Other elements, known as the common structural elements of the amyloid deposits, also contribute to amyloidogenic process in vivo. Among these elements, heparan sulfate proteoglycans (HSPGs) have been shown to bind to different types of amyloidogenic proteins and to promote the formation of β-sheet secondary structure. Once fibrils are formed, HSPGs protect the fibrils from proteolytic degradation, which lead to the accumulation of the deposits in the targeted organs. Understanding the regulation of protein folding by proteoglycans can lead to the development of low molecular weight compounds, which bind to the amyloidogenic proteins prior to their organization as fibrils. Such binding would interfere with the natural association of amyloidogenic protein with HSPGs and maintain the amyloid protein in a non-fibrillar structure (either random coil or a mix of α-helix and β-sheet structure). It would also favor their clearance, and thereby inhibit or completely block the formation of amyloid deposits. Since HSPGs interact with several types of amyloidogenic proteins, such an approach may be beneficial for the treatment of systemic and localized types of amyloidosis.

Amyloid-enhancing factor: production and response in amyloidosis-susceptible and -resistant mouse strains.

Genetic variations in the development of casein‐induced amyloidosis exist among inbred strains of mice: CBA/J and C57BL/6J mice are susceptible, while A/J strain mice are resistant to this disease. Amyloidosis is usually induced by daily injections of an inflammatory stimulus for 2‐3 wk. The deposition of amyloid in experimental animals can be accelerated by injection of a material called amyloid‐enhancing factor (AEF); when injected concomitantly with an inflammatory stimulus, AEF provokes appearance of amyloidosis as early as 2 days after injection. AEF is extracted from amyloid laden or from normal organs (although in small amount).

The Effect of the Non-Steroidal Anti-Inflammatory Drug Etodolac on Macrophage Migration In Vitro and In Vivo

The possible mode of action of Etodolac, a potent anti-inflammatory drug, has been investigated. The effect of Etodolac on macrophage inflammatory depressed the influx of inflammatory macrophages into peritoneal cavity following stimulation with a sterile irritant. This decrease in macrophage accumulation in vivo correlated with the effect of Etodolac on the macrophage chemotaxis in vitro. Etodolac was also capable of reducing the macrophage ability to migrate towards a chemoattractant. In vivo Etodolac should reduce the amount of damage produced at the site of chronic inflammation since fewer macrophages would migrate to the inflammatory sites.

Bone marrow cell response following induction of acute inflammation in different strains of mice

The magnitude of the macrophage inflammatory response differs among inbred mouse strains. Mice of the A/J strain respond poorly to sterile inflammatory stimuli while those of the C57BL/6 strain show a strong response. Inflammatory macrophages found at the site of inflammation are the product of bone marrow (BM) myeloid stem cells. Mice of the A/J strain were found to have half the number of BM nucleated cells per femur than those of the C57BL/6 strain. The lower BM cellularity may be one reason for the poor macrophage inflammatory response observed in A/J mouse strain. Using A×B/B×A recombinant inbred mouse strains, we determined that the number of nucleated cells per femur found in normal mice was not a determining factor of the magnitude of the macrophage inflammatory response. One additional explanation for the poor macrophage inflammatory response in mice of the A/J strain is their deficiency in the C5 component of complement. Using a C5-sufficient A/J.C5 congenic strain, we have previously shown that the presence of C5 on the A/J background improved their inflammatory response. We compared A/J and A/J.C5 mouse strains to determine whether or not C5 had an impact on the BM cell response to inflammatory stimulus. The presence of C5 on the A/J background could contribute to the improvement of the inflammatory response in mice of the A/J.C5 strain by inducing a greater number of nucleated cells to exit the BM compartment early following induction of inflammation.