CD4 lymphocytes in the blood of HIV(+) individuals migrate rapidly to lymph nodes and bone marrow: support for homing theory of CD4 cell depletion

Recent studies have provided evidence that macrophages from Th1-prone mouse strains respond with an M1 profile, and macrophages from Th2-prone mouse strains respond with an M2 profile, characterized by the dominant production of NO or TGF-beta 1, respectively. We have shown that peritoneal macrophages from IL-12p40 gene knockout mice have a bias toward the M2 profile, spontaneously secreting large amounts of TGF-beta 1 and responding to rIFN-gamma with weak NO production. Moreover, IL-12p40KO macrophages are more permissive to Trypanosoma cruzi replication than their wild-type littermate cells. Prolonged incubation with rIL-12 fails to reverse the M2 polarization of IL-12p40KO macrophages. However, TGF-beta 1 is directly implicated in sustaining the M2 profile because its inhibition increases NO release from IL-12p40KO macrophages. IFN-gamma deficiency is apparently not the reason for TGF-beta 1 up-regulation, because rIFN-gamma KO macrophages produce normal amounts of this cytokine. These findings raise the possibility that IL-12 has a central role in driving macrophage polarization, regulating their intrinsic ability to respond against intracellular parasites.     

Application of inter-simple sequence repeat PCR to mouse models: assessment of genetic alterations in carcinogenesis

Genomic instability is believed to play a significant role in cancer development by facilitating tumor progression and tumor heterogeneity. Inter-simple sequence repeat (inter-SSR) PCR has been proved to be a fast and reproducible technique for quantitation of genomic instability (amplifications, deletions, translocations, and insertions) in human sporadic tumors. However, the use of inter-SSR PCR in animal models of cancer has never been described. This new technique has been adapted in our laboratory for the analysis of spontaneous and induced mouse tumors. We established the best PCR conditions for each microsatellite-anchored primer and critically evaluated the reproducibility of the band patterns. We also studied the variation of the fingerprints between and within various inbred mouse strains, including wild-derived lines. Tumor-specific alterations were detected as gains, losses, or intensity changes in bands when compared with matched normal DNA. We quantitated the extent of alterations by dividing the number of altered bands in the tumor by the total number of bands in normal DNA (instability index). By means of inter-SSR PCR, we successfully analyzed genomic alterations in various mouse tumors, including spontaneous thymic lymphomas developed in Msh2 knockout mice as well as chemically induced squamous cell carcinomas and thymic lymphomas. Instability index values ranged between 0 and 9%, the highest levels observed in N-methyl-N-nitrosourea-induced thymic lymphomas generated in Trp53 (p53) nullizygote (-/-) mice. We report here, for the first time, the use of inter-SSR PCR to detect somatic mutations in mouse tumoral DNA, including laser-capture microdissected, methanol-fixed tissues. These PCR-based fingerprints provide a novel approach to assessing the number and onset of mutational events in mouse tumors and will help to understand better the mechanisms of carcinogenesis in mouse models.     

Drosophila dSAP18 is a nuclear protein that associates with chromosomes and the nuclear matrix, and interacts with pinin, a protein factor involved in RNA splicing

SAP18 is a highly conserved protein that was proposed to be involved in multiple cellular processes from autophagy to gene regulation and mRNA processing. In this paper we show that, in Drosophila, dSAP18 is a predominantly nuclear protein that associates to both chromosomes and the nuclear matrix. dSAP18 becomes nuclear early during development, at the onset of cellularization, and remains so all through embryo development. dSAP18 is also nuclear in salivary glands, ovaries and cultured S2 cells. Here we also show that dSAP18 forms a complex with the Drosophila homolog of pinin (dPnn), a protein factor involved in mRNA splicing. dSAP18-dPnn interaction was confirmed in vivo, through co-immunoprecipitation experiments, as well as in vitro, through GST pull-down assays. These results are discussed in the context of the possible functions played by SAP18.     

Antimicrobial resistance of Salmonella serotypes isolated from slaughter-age pigs and environmental samples

The aim of this study was to determine the antimicrobial resistance patterns of Salmonella strains isolated from slaughter-age pigs and environmental samples collected at modern swine raising facilities in Brazil. Seventeen isolates of six serotypes of Salmonella enterica subsp. enterica were isolated out of 1,026 collected samples: Salmonella Typhimurium (1), Salmonella Agona (5), Salmonella Sandiego (5), Salmonella Rissen (1), Salmonella Senftenberg (4), and Salmonella Javiana (1). Resistance patterns were determined to extended-spectrum penicillin (ampicillin), broad-spectrum cephalosporins (cefotaxime and ceftriaxone), aminoglycosides (streptomycin, neomycin, gentamicin, amikacin, and tobramycin), narrow-spectrum quinolone (nalidixic acid), broad-spectrum quinolone (ciprofloxacin and norfloxacin), tetracycline, trimethoprim, and chloramphenicol. Antimicrobial resistance patterns varied among serotypes, but isolates from a single serotype consistently showed the same resistance profile. All isolates were resistant to tetracycline, streptomycin, and nalidixic acid. One isolate, Salmonella Rissen, was also resistant to cefotaxime and tobramycin. All serotypes were susceptible to ceftriaxone, norfloxacin, ciprofloxacin, ampicillin, gentamicin, and chloramphenicol. The high resistance to tetracycline and streptomycin may be linked to their common use as therapeutic drugs on the tested farms. No relation was seen between nalidixic acid and fluoroquinolone resistance.     

Seroprevalence of human herpesvirus-8 in blood donors from different geographical regions of Argentina, Brazil, and Chile

Human herpesvirus-8 (HHV-8) causes Kaposi's sarcoma (KS) and lymphoproliferative disorders in both HIV-infected and uninfected patients. HHV-8 has a worldwide occurrence but infection rates vary according to a combination of geographic and behavioral risks. The main transmission route seems to be sexual, nevertheless, nasal secretions, saliva, blood, and organ graft have been proposed. HHV-8 was postulated as a new infectious agent for screening in blood donors. The aim of this study was to evaluate the prevalence of antibodies against HHV-8 antigens in blood donors of South America. Serum samples from 2,470 blood donors from Argentina, Brazil, and Chile corresponding to five geographic regions were studied by indirect immunofluorescence assay (IFA). Seroprevalence rate was 3.7% (92/2,470; 95% CI 2.9-4.5) in the entire blood donor population distributed as follows: Argentina, 4.0% (Buenos Aires city, 4.3%; Bahia Blanca, 2.4%; and Córdoba, 4.0%), Campinas (Brazil), 2.8%; and Santiago de Chile, 3.0%. There was no difference (P>0.05) between men and women or age related, except in Brazil where positive cases were 30-49-year-old males. The present study, which includes different geographical areas of multiple countries from South America, has not been done before. The results show similar prevalence rates among the studied zones corresponding to low-prevalence regions. South America is a large sub-continent with a wide spectrum of population and geographical characteristics, thus, more HHV-8 prevalence studies should be necessary to establish possible regional differences.     

Changed accumbal responsiveness to alcohol in rats pre-treated with nicotine or the cannabinoid receptor agonist WIN 55,212-2

Alcohol, nicotine, and cannabinoid acutely increase the activity of the mesolimbic dopamine (DA) pathway. Although polysubstance consumption is a common pattern of abuse in humans, little is known about dopamine release following pre-exposure to these drugs. The purpose of this study was to test whether alcohol-induced dopamine release into the nucleus accumbens (NAc) shell is modified by different pre-treatments: water (i.g.), alcohol (1 g/kg, i.g.), nicotine (0.4 mg/kg, s.c.), and WIN 55,212-2 (1 mg/kg, s.c.). Male Wistar rats were treated (i.g.) for 14 days with either water or alcohol. In the following 5 days rats were injected (s.c.) with vehicle, nicotine, or WIN 55,212-2. Finally, a cannula was surgically implanted into the NAc shell and alcohol-induced extracellular dopamine release was monitored in freely moving rats. Alcohol (1 g/kg; i.g.) only increased the release of dopamine when animals were previously treated with water. This DA increase was markedly inhibited by (subchronic) treatment (5 days) with nicotine or WIN 55-212-2 as well as by previous (chronic) exposure to alcohol (14 days). These data demonstrate that pre-treatment with nicotine and the cannabinoid agonist WIN 55,212-2 is able to change the sensitivity of the NAc shell in response to a moderate dose of alcohol. Therefore, cannabinoid and nicotine exposure may have important implications on the rewarding effects of alcohol, because these drugs lead to long-lasting changes in accumbal dopamine transmission.     

Immune responses induced by the Leishmania (Leishmania) donovani A2 antigen,but not by the LACK antigen,are protective against experimental Leishmania (Leishmania) amazonensis infection

Leishmania amazonensis is one of the major etiologic agents of a broad spectrum of clinical forms of leishmaniasis and has a wide geographical distribution in the Americas, which overlaps with the areas of transmission of many other Leishmania species. The LACK and A2 antigens are shared by various Leishmania species. A2 was previously shown to induce a potent Th1 immune response and protection against L. donovani infection in BALB/c mice. LACK is effective against L. major infection, but no significant protection against L. donovani infection was observed, in spite of the induction of a potent Th1 immune response. In an attempt to select candidate antigens for an American leishmaniasis vaccine, we investigated the protective effect of these recombinant antigens (rLACK and rA2) and recombinant interleukin-12 (rIL-12) against L. amazonensis infection in BALB/c mice. As expected, immunization with either rA2-rIL-12 or rLACK-rIL-12 induced a robust Th1 response prior to infection. However, only the BALB/c mice immunized with rA2-rIL-12 were protected against infection. Sustained gamma interferon (IFN-gamma) production, high levels of anti-A2 antibodies, and low levels of parasite-specific antibodies were detected in these mice after infection. In contrast, mice immunized with rLACK-rIL-12 displayed decreased levels of IFN-gamma and high levels of both anti-LACK and parasite-specific antibodies. Curiously, the association between rA2 and rLACK antigens in the same vaccine completely inhibited the rA2-specific IFN-gamma and humoral responses and, consequently, the protective effect of the rA2 antigen against L. amazonensis infection. We concluded that A2, but not LACK, fits the requirements for a safe vaccine against American leishmaniasis.     

Tuning of innate immunity and polarized responses by decoy receptors

After the identification of the interleukin (IL)-1 type II receptor as the prototype, decoy receptors have been identified for a number of members of the IL-1/IL-18, TNF, IL-10 and IL-13 receptor families. Moreover, the silent receptor D6 is a promiscuous decoy and scavenger receptor of inflammatory chemokines. The IL-1 decoy receptor is regulated by pro- and anti-inflammatory signals and its levels may serve as a readout of the activation of anti-inflammatory pathways, for instance by glucocorticoid hormones. Decoy receptors represent a strategy to tune inflammatory and polarized adaptive responses.