Bone marrow granulocytes downregulate IL-1ß and TNF production and the microbicidal activity of inflammatory macrophages.

Macrophages play critical roles in inflammation and defense against pathogens, as well as in the return to tissue homeostasis. Macrophage subpopulations displaying antagonistic phenotypes are generally classified as proinflammatory M1, implicated in antipathogen and antitumoral activities, or as anti-inflammatory M2, associated with tissue repair. Granulocytic and monocytic myeloid-derived suppressor cells recruited from the bone marrow to tissues and phagocytosis of apoptotic neutrophils can attenuate macrophage microbicidal activity. Here, we showed that bone marrow neutrophils, but not thioglycollate-recruited neutrophils, directly suppress the responses of macrophages that were previously committed to an inflammatory phenotype. Cocultures of inflammatory macrophages with bone marrow CD11b+Ly6Ghi granulocytes led to reduced release of IL-1ß, TNF-α, and IL-6 by macrophages after lipopolysaccharide stimulation. The suppressive activity was unrelated to granulocyte apoptosis or to secreted factors and required cell-to-cell contact. The suppressive effect was paralleled by reduction in the nuclear levels of the NF-κB p65 subunit, but not of the p50 subunit. Furthermore, bone marrow granulocytes decreased the phagocytic activity of macrophages and their capacity to kill intracellular Escherichia coli. Taken together, these results show that bone marrow granulocytes can function as suppressors of the proinflammatory activity and microbial-killing responses of macrophages.

Identification of a phylogenetically distinct orthobunyavirus from group C.

Apeu virus (APEUV) (family Bunyaviridae, genus Orthobunyavirus) was plaque purified and characterised by serological and molecular analysis. Neutralising assays confirmed cross-reactivity between purified APEUV clones and the Caraparu virus complex of group C orthobunyaviruses. Partial sequencing of the L, M and S segments of one APEUV clone (APEUV-CL5) was carried out. A phylogenetic tree constructed with the L amino acid sequences clustered APEUV-CL5 within the genus Orthobunyavirus, confirming its serological classification. Analysis of M segment sequences clustered APEUV-CL5 in the Caraparu virus complex (Group C), in agreement with serological tests and previous molecular characterisation. However, the sequence of the nucleocapsid gene (N) gave low identity values when compared to those of the group C viruses. The phylogenetic tree based on N nucleotide sequences clustered APEUV-CL5 next to the California and Bwamba groups. This remarkable S nucleotide variability suggests that APEUV-CL5 could be a genetic reassortant and that this evolutionary mechanism is present in the history of the group C viruses.

MMP-2 and MMP-9 plasma levels are potential biomarkers for indeterminate and cardiac clinical forms progression in chronic Chagas disease.

One of the major challenges in chronic Chagas disease is to understand the mechanisms that predict the clinical evolution from asymptomatic to severe cardiac clinical forms. Our cohort consisted of twenty-eight Chagas disease patients followed for twenty years. Plasma levels of MMP-2 and MMP-9 gelatinases and TIMPs were evaluated by multiplexed immunoassay at two points in time with an average interval of six years. MMP-2 plasma levels, but not MMP-9, increased in cardiac patients over time. TIMP-1 levels diminished in cardiac patients, while TIMP-3 dropped in asymptomatic patients in the course of the evaluated interval. An inversion of time lines was observed relative to the clinical asymptomatic and cardiac forms for MMP-2. Receiver Operating Characteristic (ROC) curve analysis identified MMP-2 as a biomarker to distinguish asymptomatic from cardiac clinical forms, while MMP-9 is a biomarker that segregates infected from non-infected patients. We have pointed out that MMP-2 and MMP-9 together can predict clinical evolution in Chagas disease. MMP-2 was suggested as a biomarker for fibrosis replacement in early remodeling and a sensitive predictor for initial changes in asymptomatic patients that may evolve into the cardiac clinical form. MMP-9 seems to be a biomarker for late fibrosis and severe cardiac remodeling in cardiac patients.

Modulation of glutathione intracellular levels alters the spontaneous proliferation of lymphocyte from HTLV-1 infected patients.

The human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus associated with neoplasias and inflammatory diseases, such as adult T-cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1-infected individuals present a spontaneous T lymphocyte proliferation. This phenomenon is related to the HTLV-1-proviral load and the persistence of the infection. Viral proteins induce many cellular mediators, which can be associated with the abnormal cellular proliferation. The intracellular levels of glutathione (GSH) are important to modulate the cellular proliferation. The aim of this study was to investigate the correlation between the modulation of intracellular GSH levels and the spontaneous lymphocyte proliferation during the HTLV-1 infection. Intracellular GSH level can be modulated by using dl-buthionine-[S,R]-sulfoximine (BSO, GSH synthesis inhibitor) and N-acetylcysteine (NAC, peptide precursor). Our results demonstrated that BSO was capable of inducing a decrease in the spontaneous proliferation of PBMC derived from HTLV-1 carriers. On the other hand, the GSH precursor induces an increase in mitogen-stimulated cellular proliferation in infected and uninfected individuals. Similar results were observed by the inhibition of ABCC1/MRP1 protein, augmenting the mitogen-induced proliferation. This effect can be related with an increase in the GSH levels since ABCC1/MRP1 transports GSH to the extracellular medium. There was a significant difference on the expression of CD69 and CD25 molecules during the lymphocyte activation. We did not observe any alterations on CD25 expression induced by BSO or NAC. However, our results demonstrated that NAC treatment induced an increase in CD69 expression on unstimulated CD8(+) T lymphocytes obtained from HTLV-1 infected individuals, healthy donors and HTLV carriers. Therefore, our results suggest that the cellular proliferation promoted by the infection with HTLV-1 and the activation phenotype of CD8(+) T lymphocytes can be regulated by changing the intracellular GSH levels; suggesting the modulation of these intracellular levels as a new approach for the treatment of pathologies associated with the HTLV-1 infection.

Sequence and phylogenetic analysis of the large (L) segment of the Tahyna virus genome.

The Tahyna virus (TAHV) is an important human pathogen in the Bunyaviridae family. To date, only the S and M segments of this virus have been sequenced, but the sequence of the L segment hasn't been established yet. In this study, we sequenced 963 nucleotides of the L segment of TAHV, comprising pre-motif A and motif A in region 3 of the RNA polymerase gene.

Caraparu virus (group C Orthobunyavirus): sequencing and phylogenetic analysis based on the conserved region 3 of the RNA polymerase gene.

Here, for the first time, we report the nucleotide sequence of Caraparu virus (CARV) L segment and the analysis of the RNA polymerase region 3 encoded by this segment. The 1,404 bp nucleotide sequence shares the highest identity with Bunyamwera, La Crosse, Oropouche, and Akabane virus sequences. The amino acid sequence was deduced and aligned with sequences from members of the Bunyaviridae family and used for phylogenetic analysis. The CARV clustered in the Orthobunyavirus genus. The premotif A and motifs A-E are present in the region 3 of the Bunyaviridae family, were also conserved in CARV L protein, as well as other conserved regions among Orthobunyavirus genus.