Paulo Vieira Damasco

Regulation of inflammatory chemokine receptors on blood T cells associated to the circulating versus liver chemokines in dengue fever

Little is known about the role of chemokines/chemokines receptors on T cells in natural DENV infection. Patients from DENV-2 and -3- outbreaks were studied prospectively during the acute or convalescent phases. Expression of chemokine receptor and activation markers on lymphocyte subpopulations were determined by flow cytometry analysis, plasma chemokine ligands concentrations were measured by ELISA and quantification of CCL5/RANTES+ cells in liver tissues from fatal dengue cases was performed by immunochemistry. In the acute DENV-infection, T-helper/T-cytotoxic type-1 cell (Th1/Tc1)-related CCR5 is significantly higher expressed on both CD4 and CD8 T cells. The Th1-related CXCR3 is up-regulated among CD4 T cells and Tc2-related CCR4 is up-regulated among CD8 T cells. In the convalescent phase, all chemokine receptor or chemokine ligand expression tends to reestablish control healthy levels. Increased CCL2/MCP-1 and CCL4/MIP-1β but decreased CCL5/RANTES levels were observed in DENV-patients during acute infection. Moreover, we showed an increased CD107a expression on CCR5 or CXCR3-expressing T cells and higher expression of CD29, CD44HIGH and CD127LOW markers on CCR4-expressing CD8 T cells in DENV-patients when compared to controls. Finally, liver from dengue fatal patients showed increased number of cells expressing CCL5/RANTES in three out of four cases compared to three death from a non-dengue patient. In conclusion, both Th1-related CCR5 and CXCR3 among CD4 T cells have a potential ability to exert cytotoxicity function. Moreover, Tc1-related CCR5 and Tc2-related CCR4 among CD8 T cells have a potential ability to exert effector function and migration based on cell markers evaluated. The CCR5 expression would be promoting an enhanced T cell recruitment into liver, a hypothesis that is corroborated by the CCL5/RANTES increase detected in hepatic tissue from dengue fatal cases. The balance between protective and pathogenic immune response mediated by chemokines during dengue fever will be discussed.

Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 microg/ml) to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 microg/ml) and azithromycin (MIC90 0.064 microg/ml) were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 microg/ml) to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74%) showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

Prior Dengue Virus Exposure Shapes T Cell Immunity to Zika Virus in Humans

ABSTRACT While progress has been made in characterizing humoral immunity to Zika virus (ZIKV) in humans, little is known regarding the corresponding T cell responses to ZIKV. Here, we investigate the kinetics and viral epitopes targeted by T cells responding to ZIKV and address the critical question of whether preexisting dengue virus (DENV) T cell immunity modulates these responses. We find that memory T cell responses elicited by prior infection with DENV or vaccination with tetravalent dengue attenuated vaccines (TDLAV) recognize ZIKV-derived peptides. This cross-reactivity is explained by the sequence similarity of the two viruses, as the ZIKV peptides recognized by DENV-elicited memory T cells are identical or highly conserved in DENV and ZIKV. DENV exposure prior to ZIKV infection also influences the timing and magnitude of the T cell response. ZIKV-reactive T cells in the acute phase of infection are detected earlier and in greater magnitude in DENV-immune patients. Conversely, the frequency of ZIKV-reactive T cells continues to rise in the convalescent phase in DENV-naive donors but declines in DENV-preexposed donors, compatible with more efficient control of ZIKV replication and/or clearance of ZIKV antigen. The quality of responses is also influenced by previous DENV exposure, and ZIKV-specific CD8 T cells from DENV-preexposed donors selectively upregulated granzyme B and PD1, unlike DENV-naive donors. Finally, we discovered that ZIKV structural proteins (E, prM, and C) are major targets of both the CD4 and CD8 T cell responses, whereas DENV T cell epitopes are found primarily in nonstructural proteins. IMPORTANCE The issue of potential ZIKV and DENV cross-reactivity and how preexisting DENV T cell immunity modulates Zika T cell responses is of great relevance, as the two viruses often cocirculate and Zika virus has been spreading in geographical regions where DENV is endemic or hyperendemic. Our data show that memory T cell responses elicited by prior infection with DENV recognize ZIKV-derived peptides and that DENV exposure prior to ZIKV infection influences the timing, magnitude, and quality of the T cell response. Additionally, we show that ZIKV-specific responses target different proteins than DENV-specific responses, pointing toward important implications for vaccine design against this global threat.

Pyogenic Liver Abscess Due to Rhodococcus equi in an Immunocompetent Host

ABSTRACT A case of pyogenic liver abscess (PLA) due to Rhodococcus equi in an immunocompetent individual was successfully treated by combining surgery and antibiotics. The R. equi-targeted antimicrobial agents erythromycin and rifampin were used only after surgical resection of the lesion and identification of the infective organism.

Metalloproteinases are produced during dengue fever and MMP9 is associated with severity

Dengue fever is an ancient infectious viral disease nthat is characterized by an acute and benign febrile ninfection in most cases. Eventually, during defervescence nonset, disease may evolve into severe clinical nmanifestations such as coagulation and/or haemodynamic ndisorders, caused mainly by an increase of vascular npermeability

Regulation of T lymphocyte apoptotic markers is associated to cell activation during the acute phase of dengue.

Dengue fever, a public health problem in Brazil, may present severe clinical manifestations as result of an increased vascular permeability and coagulation disorders. T cell activation is a critical event for an effective immune response against infection, including the production of cytokines. We aim to reveal mechanisms that modulate the virus-cell interaction, with an emphasis on cell death. Apoptosis is involved in lymphocyte homeostasis, contributes to the clearance of virus-infected cells but also may play a role in the pathogenesis. Phosphatidylserine exposure on CD8T lymphocytes from dengue patients support early apoptotic processes and loss of genomic integrity, observed by DNA fragmentation in T lymphocytes and indicating late apoptosis. These T cells express activation and cytotoxic phenotypes as revealed by CD29 and CD107a upregulation. Higher frequencies of CD95 were detected in T lymphocytes mainly in those with the cytotoxic profile (CD107a+) and lower levels of anti-apoptotic molecule Bcl-2, suggesting that both CD4+ and CD8+ T cell subsets are more susceptible to apoptosis during acute dengue. The analysis of apoptosis-related protein expression profile showed that not only molecules with pro- but also those with anti-apoptotic functions are overexpressed, indicating that survival mechanisms could be possibly protecting cells against apoptosis caused by viral, immune, oxidative and/or genotoxic stresses. These observations led us to propose that in dengue patients there is an association between T cell susceptibility to apoptosis and the activation state. The mechanisms for understanding the immunopathogenesis during dengue infection are discussed.

First Report of the East-Central South African Genotype of Chikungunya Virus in Rio de Janeiro, Brazil

Background: Chikungunya virus (CHIKV) is an arbovirus that causes an acute febrile syndrome with a severe and debilitating arthralgia. In Brazil, the Asian and East-Central South African (ECSA) genotypes are circulating in the north and northeast of the country, respectively. In 2015, the first autochthonous cases in Rio de Janeiro, Brazil were reported but until now the circulating strains have not been characterized. Therefore, we aimed here to perform the molecular characterization and phylogenetic analysis of CHIKV strains circulating in the 2016 outbreak occurred in the municipality of Rio de Janeiro. Methods: The cases analyzed in this study were collected at a private Hospital, from April 2016 to May 2016, during the chikungunya outbreak in Rio de Janeiro, Brazil. All cases were submitted to the Real Time RT-PCR for CHIKV genome detection and to anti-CHIKV IgM ELISA. Chikungunya infection was laboratorially confirmed by at least one diagnostic method and, randomly selected positive cases (n=10), were partially sequenced (CHIKV E1 gene) and analyzed. Results: The results showed that all the samples grouped in ECSA genotype branch and the molecular characterization of the fragment did not reveal the A226V mutation in the Rio de Janeiro strains analyzed, but a K211T amino acid substitution was observed for the first time in all samples and a V156A substitution in two of ten samples. Conclusions: Phylogenetic analysis and molecular characterization reveals the circulation of the ECSA genotype of CHIKV in the city of Rio de Janeiro, Brazil and two amino acids substitutions (K211T and V156A) exclusive to the CHIKV strains obtained during the 2016 epidemic, were reported.

Characterization of clinical and immunological features in patients coinfected with dengue virus and HIV

The pathogenesis of dengue in subjects coinfected with HIV remains largely unknown. We investigate clinical and immunological parameters in coinfected DENV/HIV patients. According to the new dengue classification, most coinfected DENV/HIV patients presented mild clinical manifestations of dengue infection. Herein, we show that DENV/HIV coinfected patients had higher CD8 T cells percentages reflected as a lower CD4/CD8 ratio. Furthermore, CCR5 expression on CD4 T cells and CD107a expression on both T subsets were significantly higher in coinfected patients when compared with monoinfected DENV and HIV individuals respectively. Increased inflammatory response was observed in treated HAART coinfected patients despite undetectable HIV load. These data indicate that DENV infection may influence the clinical profile and immune response in individuals concomitantly infected with HIV.

Trimethoprim-sulfamethoxazole and fluoroquinolones Resistant Escherichia Coli in Community-Acquired and Nosocomial Urinary Tract Infections in Rio De Janeiro, Brazil

To investigate the multidrug resistance (MDR) patterns of Escherichia coli causative of urinary tract infections (UTI) in patients attending a tertiary university hospital of Rio de Janeiro, Brazil. Antibiotic susceptibility testing was performed by the disk diffusion method. MDR, extensively-resistance (XDR) and pan-resistance (PDR) were defined by using recently described criteria. Retrospective analyses of clinical, microbiological and demographic features of outpatients and inpatients with UTI (n=416) were also performed. High antibiotic resistance rates for trimethoprimsulfamethoxazole - SXT-TMP (n=177; 46.7%) and fluoroquinolones - FQ [n=117; norfloxacin (27%) and ciprofloxacin (26.8%) – (FQ) were demonstrated for E. coli strains isolated from community and healthcare-onsets. Risk factors associated with UTIs due to MDR E. coli isolates included prior three-month hospitalization (OR: 2.4; CI 95%: 1.3-4.4; p<0.005), presence of neurogenic bladder (OR: 3.7; CI 95% :1.7-8.3; p<0.01 ) and kidney transplantation (OR: 3.1; CI 95%:1-0.5; p<0.04). A high prevalence of community-acquired and nosocomial urinary tract infections due SXT-TMP/ FQ resistant E. coli strains was observed in Rio de Janeiro metropolitan area, Brazil. According to IDSA Guidelines, initial empirical therapy for community-associated UTI with SXT-TMP and FQ should be avoided in Rio de Janeiro. Nitrofurantoin, amoxicillin/clavulanic, piperacillin/tazobactam or gentamicin associations were effective for the empiric therapy for community-acquired and healthcare-associated UTIs, respectively.

Tissue factor expression on monocytes from patients with severe dengue fever.

Dengue fever is a public health problem worldwide. The majority of dengue cases have a mild self-limited clinical course, whereas a small proportion progress to severe disease that is characterised by homeostatic abnormalities, including plasma leakage and bleeding [1]. The mechanisms leading to severe illness are not well understood but they are thought to involve an intricate interplay between virus, vascular cells, and inappropriate host immune responses. Mononuclear phagocytes are considered main targets for dengue virus replication. The infection of monocytes may induce inflammatory mediators and is the source of viral dissemination in the initial phase of the disease [2]. Tissue factor (TF) is a 47-kD protein that initiates the clotting cascade and is increasingly recognized at the interface of blood coagulation and inflammation [3,4]. Activation of coagulation by TF is frequently observed in the sepsis syndrome and has been proposed to play a role in certain viral hemorrhagic fevers [4]. TF binds to factor VII (FVII)/FVIIa and the binary TF/FVIIa complex initiates the coagulation cascade upon activation of factors IX and X, which leads to thrombin generation and platelet activation. Under physiological conditions TF is absent in blood. However, upon cytokine stimulation some cells – in particular monocytes and endothelial cells – may express this molecule [5]. Coagulation abnormalities occur during viral hemorrhagic fevers such Ebola and dengue [6,7]. Moreover, dendritic cells and macrophages are susceptible to Ebola virus, leading to TF upregulation, fibrin generation, and microthrombosis [7]. Dengue hemorrhagic fever, a severe form of dengue fever, is associated with increased TF plasma levels but the cellular origin remains speculative [6]. In the present investigation dengue infected patients (n=33) and healthy individuals (controls, n=11) were enrolled. Patients were assisted at two Brazilian Health Centres (Hospital Universitário Professora Esterian Corsini, UFMS, MS, and Hospital Universitário Pedro Ernesto, UERJ, RJ). All patients had a clinical diagnosis of dengue infection according to the criteria of the World Health Organization /Brazilian Health Ministry. Nineteen patients were considered to have mild dengue fever because no warning signs (WS) were observed, only classical symptoms of dengue fever. Fourteen individuals were considered to have severe disease consisting of those who presented severe clinical manifestations such as haemoconcentration, thrombocytopenia (counts b50×10/L), plasma leakage or internal haemorrhages. Criteria were based in earlier studies [8]. Dengue virus infection was confirmed either by anti-dengue enzyme-linked immunoabsorbent assay (ELISA)-IgM, serotype specific reverse transcriptionpolymerase chain reaction (RT-PCR) or by virus isolation. The study was approved by Ethical Committees at FIOCRUZ (IPEC, FIOCRUZ CAAE 3723.0.000.009-08). Blood was collected after written informed consent.