Lourdes Lledó

Mesenteric Th1 polarization and monocyte TNF-α production: First steps to systemic inflammation in rats with cirrhosis†

A systemic inflammatory state with increased circulating tumor necrosis factor alpha (TNF‐α) has been related to the bacterial infection susceptibility and hemodynamic derangement of patients with cirrhosis. We compared the activation status of immune cell subpopulations defined by 4‐color cytometry in mesenteric and peripheral lymph nodes and blood of rats with CCl4‐cirrhosis to define the immune response initiation site, the T‐cell and monocyte contribution to pro‐inflammatory cytokine production, as well as the pathogenic role of enteric bacteria in the cirrhosis immune response. Th1 cells and monocytes were expanded in the mesenteric nodes (P < .001) and blood (P < .001) of rats with cirrhosis, and activated to produce interferon gamma (P < .0001) and TNF‐α (P < .0001), respectively. The greater numbers of recently activated CD134+ Th cells in mesenteric nodes compared with blood, the correlation between their numbers in mesenteric nodes and blood (r = 0.66, P < .001), and the expansion of activated CD45RC− Th cells, which are unable to re‐enter lymph nodes, in mesenteric nodes but not in blood or axillary nodes points to mesenteric nodes as the origin site of activated Th cells. Abrogation of bacterial translocation by bowel decontamination reduced the number of activated Th cells and monocytes, and normalized interferon gamma production by Th cells and TNF‐α production by monocytes in mesenteric nodes and blood, respectively. In conclusion, in cirrhosis, enteric bacteria start off an orchestrated immune response cascade in mesenteric nodes involving Th1 polarization and monocyte activation to TNF‐α production. Later, the recirculation of these activated effector immune cells into blood promotes systemic inflammation. (HEPATOLOGY 2005;42:411–419.)

Obeticholic acid reduces bacterial translocation and inhibits intestinal inflammation in cirrhotic rats.

BACKGROUND & AIMS In advanced cirrhosis, gut bacterial translocation is the consequence of intestinal barrier disruption and leads to bacterial infection. Bile acid abnormalities in cirrhosis could play a role in the integrity of the intestinal barrier and the control of microbiota, mainly through the farnesoid X receptor. We investigated the long-term effects of the farnesoid X receptor agonist, obeticholic acid, on gut bacterial translocation, intestinal microbiota composition, barrier integrity and inflammation in rats with CCl4-induced cirrhosis with ascites. METHODS Cirrhotic rats received a 2-week course of obeticholic acid or vehicle starting once ascites developed. We then determined: bacterial translocation by mesenteric lymph node culture, ileum expression of antimicrobial peptides and tight junction proteins by qPCR, fecal albumin loss, enteric bacterial load and microbiota composition by qPCR and pyrosequencing of ileum mucosa-attached contents, and intestinal inflammation by cytometry of the inflammatory infiltrate. RESULTS Obeticholic acid reduced bacterial translocation from 78.3% to 33.3% (p<0.01) and upregulated the expression of the farnesoid X receptor-associated gene small heterodimer partner. Treatment improved ileum expression of antimicrobial peptides, angiogenin-1 and alpha-5-defensin, tight junction proteins zonulin-1 and occludin, and reduced fecal albumin loss and liver fibrosis. Enteric bacterial load normalized, and the distinctive mucosal microbiota of cirrhosis was reduced. Gut immune cell infiltration was reduced and inflammatory cytokine and Toll-like receptor 4 expression normalized. CONCLUSIONS In ascitic cirrhotic rats, obeticholic acid reduces gut bacterial translocation via several complementary mechanisms at the intestinal level. This agent could be used as an alternative to antibiotics to prevent bacterial infection in cirrhosis.

Molecular detection of hemoprotozoa and Rickettsia species in arthropods collected from wild animals in the Burgos Province, Spain

Limited information on the presence of bacterial and hematozoan infections in parasitic arthropods from Spain is available. In an attempt to address this issue, the prevalence of Theileria, Babesia, Hepatozoon, and Rickettsia species was investigated by polymerase chain reaction plus sequencing. In a survey for zoonotic pathogens in ectoparasites, 42 wild animals (which included rodents, carnivores, Sciuridae, and Cervidae) were captured in Burgos (Spain). A total of 256 arthropods (including 107 ticks, 76 fleas, and 73 mites) were collected from these mammals. Molecular diagnostic results showed that (i) Rickettsia felis was found in fleas (two Ctenocephalides felis), (ii) Hepatozoon sp. infected some fleas (two Ctenophtalmus sp. and a DNA pool of Ceratophyllus sciurorum) and Acari (one Neotrombicula sp.), and (iii) Theileria annae was found in Ixodes ricinus and I. hexagonus (each a single infected specimen). All microorganisms and parasites were genetically identical to pathogens already described in Spain or elsewhere. Infected arthropods were recovered from beech marten, bank vole, squirrel, wood mouse, and red fox. Our findings emphasize the potential risk for transmission of rickettsias to humans (namely, R. felis) in Burgos, since C. felis is capable to seek out humans for feeding. No hemoprotozoa with proven significance as human pathogens were found in the survey. However, finding T. annae in ticks recovered from wild canids suggests possible links of sylvatic and domestic cycles for some Piroplasmida.

Critical role of the liver in the induction of systemic inflammation in rats with preascitic cirrhosis

Systemic activation of the inflammatory immune system contributes to the progression of cirrhosis with ascites. Immune cells become activated after interacting at the mesenteric lymph nodes (MLNs) with bacteria translocated from the gut, and thereafter reach the bloodstream through recirculation. It is unknown whether systemic activation of the immune system is present in pre‐ascitic cirrhosis, in which gut bacterial translocation has not been described. The purpose of this study was to determine whether systemic activation of the immune system initiates in rats with compensated carbon tetrachloride (CCl4)‐induced cirrhosis, and if so to establish the activation site of immune cells. We studied the activation status of immune cells in peripheral blood, MLNs, and hepatic lymph nodes (HLNs). Systemic inflammation was present in rats with cirrhosis, as shown by expansion (P < 0.01) of circulating total and inflammatory monocytes and recently activated CD134+ T helper (Th) cells. The same populations of cells were increased (P < 0.01) in MLNs and HLNs. Bacterial translocation was absent in rats with cirrhosis or control rats, but bacterial DNA fragments were present in the MLNs of 54% of rats with cirrhosis. The liver was the source of activated immune cells present in the blood, as shown by the direct correlation between activated Th cells in the blood and HLNs, but not in MLNs, and the normalization by gut decontamination with antibiotics of activated cells in MLNs, but not in the blood or HLNs. Conclusion: In experimental cirrhosis, systemic activation of the immune system occurs before ascites development and is driven by recirculation of cells activated in HLNs. In addition, in compensated cirrhosis, bacterial DNA fragments reach the MLNs, where they elicit a local inflammatory response. (HEPATOLOGY 2010;52:2086‐2095)

Independent lineage of lymphocytic choriomeningitis virus in wood mice (Apodemus sylvaticus), Spain.

To clarify the presence of lymphocytic choriomeningitis virus (LCMV) in Spain, we examined blood and tissue specimens from 866 small mammals. LCMV RNA was detected in 3 of 694 wood mice (Apodemus sylvaticus). Phylogenetic analyses suggest that the strains constitute a new evolutionary lineage. LCMV antibodies were detected in 4 of 10 rodent species tested.

Prevalence of antibodies to Rickettsia typhi in an area of the center of Spain.

It was the aim of the present work to evaluate Rickettsia typhi antibody prevalence in ‘Comunidad Autónoma de Madrid’ (CAM), an area in the centre of Spain. A total of 640 serum samples from the general population were tested by an indirect immunofluorescence assay. Specific R. typhi antibodies were found in 44 (6.8%) of the samples. The present survey results demonstrate the occurrence of R. typhi human infections in this area.

Prevalence of ectoparasitic arthropods on wild animals and cattle in the Las Merindades area (Burgos, Spain)

This paper reports the prevalence of ectoparasitic arthropods in sampled groups of wild (n = 128; 16 species) and domestic (n = 69; 3 species) animals in the Las Merindades area of the Province of Burgos, Spain. The study revealed that wild animals were more infested and with a wider variety of ectoparasites than domestic animals. The parasitic prevalence was 67% for wild animals and 48% for livestock. In this way, 39% of animals were infected by ticks. Ixodes ricinus and Ixodes hexagonus were the most prevalent species whereas Dermacentor reticulatus showed affinity for the fox and wolf. The overall prevalence of parasitisation by fleas was 27%. Ctenophthalmus spp. showed the wider range host in wild animals, while Pulex irritans was the most frequent specie found. The parasitic prevalences by lice (Trichodectes melis, Trichodectes canis and Trichodectes mustelae) and by mite (Neotrombicula spp., Laelaps agilis and Sarcoptes scabiei) were 4% and 12%, respectively. In both cases only wild animals were found parasited.

Hantavirus infections in Spain: analysis of sera from the general population and from patients with pneumonia, renal disease and hepatitis.

BACKGROUND Hantaviruses are rodent borne viruses in the family Bunyaviridae that cause significant morbidity in large areas of Europe. There are only a few reports available on hantavirus infections from Spain. Although the results of these earlier studies indicated the presence of hantavirus infections, no confirmative or serotype-specific analyses have been performed. OBJECTIVES To investigate whether hantaviruses cause human infection/disease in Spain. STUDY DESIGN Ten thousand, four hundred and eighteen serum samples from the general population and 599 sera from 492 patients with potential hantavirus infections (renal disease, pneumonia or hepatitis) were initially screened by immunofluorescence assay (IFA) using Hantaan, Seoul and Puumala hantavirus antigens. Altogether 193 suspicious samples (165 from healthy people and 28 from patients) were selected for confirmation by quality-assured assays. RESULTS AND CONCLUSIONS Of the 165 pre-screened serum samples from healthy individuals, only five could be confirmed by IFA for hantavirus-reactive antibodies (using Dobrava, Saaremaa, Hantaan or Puumala virus antigens). In addition, one serum was found weakly positive for hantavirus-reactive IgG by ELISA using recombinant Saaremaa virus (SAAV) nucleocapsid (N) antigen, and subsequently confirmed by immunoblotting. Thus, the results indicated a low (0.06%) total antibody prevalence to hantaviruses in Spain. Of 28 pre-screened serum samples from hospitalized patients, eight reacted as positive or showed border-line reactivities for hantavirus-specific IgM by ELISA using recombinant Saaremaa and Puumala virus N antigens. The IFA/ELISA reactive/border-line samples were subsequently analyzed by a focus reduction neutralization test, which revealed low titers (1:80) against SAAV in two samples from a patient with hepatic disease. The nature of the hantavirus(es) potentially involved remain, however, unknown, since none of the positive samples showed neutralizing titers of the expected range to any of the known European hantaviruses.

Infección por hantavirus y otros virus transmitidos por roedores

Bajo el termino “robovirus” (rodent-borne viruses) se engloban virus pertenecientes a las familias Bunyaviridae (genero Hantavirus ) y Arenaviridae que ocasionalmente se transmiten al hombre a partir de roedores, sus reservorios naturales. Los hantavirus causan dos enfermedades humanas: la fiebre hemorragica con sindrome renal y el sindrome pulmonar por hantavirus. Los arenavirus causan en el hombre fiebres hemorragicas o enfermedad aguda del sistema nervioso central. Este articulo presenta una revision sobre los aspectos relativos a la biologia, epidemiologia, patogenia, manifestaciones clinicas, diagnostico, tratamiento y prevencion de las infecciones por hantavirus y, de forma mas concisa, por arenavirus.

Screening of the prevalence of antibodies to Borrelia burgdorferi in Madrid province, Spain

It was the aim of the present study to evaluate Borrelia burgdorferi antibody prevalence in the province of Madrid, located in central Spain. A total of 1825 serum samples from the general population were tested by an indirect immunofluorescence assay. Specific B. burgdorferi antibodies were found in 63 (3.45%) of the samples. Statistical differences were found according to sex.