Bartonella spp. Bacteremia in Blood Donors from Campinas,Brazil

Bartonella species are blood-borne, re-emerging organisms, capable of causing prolonged infection with diverse disease manifestations, from asymptomatic bacteremia to chronic debilitating disease and death. This pathogen can survive for over a month in stored blood. However, its prevalence among blood donors is unknown, and screening of blood supplies for this pathogen is not routinely performed. We investigated Bartonella spp. prevalence in 500 blood donors from Campinas, Brazil, based on a cross-sectional design. Blood samples were inoculated into an enrichment liquid growth medium and sub-inoculated onto blood agar. Liquid culture samples and Gram-negative isolates were tested using a genus specific ITS PCR with amplicons sequenced for species identification. Bartonella henselae and Bartonella quintana antibodies were assayed by indirect immunofluorescence. B. henselae was isolated from six donors (1.2%). Sixteen donors (3.2%) were Bartonella-PCR positive after culture in liquid or on solid media, with 15 donors infected with B. henselae and one donor infected with Bartonella clarridgeiae. Antibodies against B. henselae or B. quintana were found in 16% and 32% of 500 blood donors, respectively. Serology was not associated with infection, with only three of 16 Bartonella-infected subjects seropositive for B. henselae or B. quintana. Bartonella DNA was present in the bloodstream of approximately one out of 30 donors from a major blood bank in South America. Negative serology does not rule out Bartonella spp. infection in healthy subjects. Using a combination of liquid and solid cultures, PCR, and DNA sequencing, this study documents for the first time that Bartonella spp. bacteremia occurs in asymptomatic blood donors. Our findings support further evaluation of Bartonella spp. transmission which can occur through blood transfusions.     

Glucagon signalling in the dorsal vagal complex is sufficient and necessary for high‐protein feeding to regulate glucose homeostasis in vivo

High‐protein feeding acutely lowers postprandial glucose concentration compared to low‐protein feeding, despite a dichotomous rise of circulating glucagon levels. The physiological role of this glucagon rise has been largely overlooked. We here first report that glucagon signalling in the dorsal vagal complex (DVC) of the brain is sufficient to lower glucose production by activating a Gcgr–PKA–ERK–K_ATP channel signalling cascade in the DVC of rats in vivo. We further demonstrate that direct blockade of DVC Gcgr signalling negates the acute ability of high‐ vs. low‐protein feeding to reduce plasma glucose concentration, indicating that the elevated circulating glucagon during high‐protein feeding acts in the brain to lower plasma glucose levels. These data revise the physiological role of glucagon and argue that brain glucagon signalling contributes to glucose homeostasis during dietary protein intake.     

A scaffoldless technique for self-generation of three-dimensional keratinospheroids on liquid crystal surfaces

We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment.     

Prevalence of Bartonella henselae and Borrelia burgdorferi Sensu Lato DNA in Ixodes ricinus Ticks in Europe

Bartonella spp. can cause persistent bloodstream infections in humans and animals. To determine whether Bartonella henselae is present in questing Ixodes ricinus ticks, we analyzed the prevalence of B. henselae DNA among tick stages compared to the prevalence of DNA from Borrelia burgdorferi sensu lato, the pathogen most frequently transmitted by ticks. B. henselae DNA was present with a prevalence of up to ∼40% in tick populations sampled in four European sites (Eberdingen, Germany; Klasdorf, Germany; Lembach, France; and Madeira, Portugal). The odds of detecting B. henselae DNA in nymphal ticks was ∼14-fold higher than in adult ticks. No tick was found to be coinfected with B. henselae and B. burgdorferi sensu lato. Taken together, our data indicate that ticks might serve as a vector for the transmission of B. henselae to humans.In immunocompetent patients, Bartonella henselae infections often result in cat scratch disease (CSD), a self-limiting but often prolonged lymphadenitis; immunocompromised patients (e.g., AIDS patients) can suffer from vasculoproliferative disorders (bacillary angiomatosis, peliosis hepatis [1]). Cats are a confirmed reservoir host of B. henselae transmitting the pathogen by cat scratches or bites.Several Bartonella species (e.g., B. henselae, B. quintana, and B. vinsonii) cause a persistent intraerythrocytic bacteremia in their respective mammalian reservoir hosts (7). B. henselae was detected in the peripheral blood of a wide range of mammals including domestic (e.g., cats, dogs, and horses) and wild animals (e.g., porpoise, lions, cheetahs, and wild felids). Obviously, such an asymptomatic, persistent bacteremia with B. henselae represents an important factor for the spread of the pathogens via blood-sucking arthropods. Mechanistic details determining the intraerythrocytic presence of Bartonella spp. have been investigated in detail in a B. tribocorum rat infection model mimicking Trench fever (a human disease caused by B. quintana); here, the pathogen persists several weeks in the circulating blood in an immunoprivileged intraerythrocytic niche (28).Cat fleas are well established vectors for B. henselae (1). However, transmission by other arthropods, in particular ticks, has been suggested: B. henselae DNA was detected in questing Ixodes pacificus and I. persulcatus ticks in North America, Eastern Europe, and Russia, respectively (4, 13, 14, 22, 25) and in I. ricinus ticks feeding on people or domestic animals in Central Europe (24, 26). DNA of various Bartonella spp. has also been detected in keds, biting flies, and mites (reviewed in reference 2). Recently, ticks (I. ricinus) were experimentally infected with B. henselae. Inoculation of cats with salivary glands of infected ticks resulted in a B. henselae bacteremia (5). Nevertheless, controversial data about the prevalence of Bartonella spp. in ticks and their role as vectors for B. henselae exist (29).Here, we present data on the prevalence of B. henselae and Lyme disease spirochetes in 654 questing ticks (I. ricinus) collected at four locations in Europe, suggesting that ticks might serve as potential vectors for the transmission of B. henselae to humans.     

Eicosapentaenoic acid and docosahexaenoic acid reduce interleukin-1β-mediated cartilage degradation

Introduction  

In inflammatory joint disease, such as osteoarthritis (OA), there is an increased level of proinflammatory cytokines, such as interleukin (IL)-1β. These cytokines stimulate the production of matrix metalloproteinases (MMPs), which leads to the degradation of the cartilage extracellular matrix and the loss of key structural components such as sulphated glycosaminoglycan (sGAG) and collagen II. The aim of this study was to examine the therapeutic potential of n-3 polyunsaturated fatty acids (PUFAs) in an in vitro model of cartilage inflammation.