The high cAMP levels upregulate cAMP responsive genes and induce an antiapoptotic state in the endothelial cells, resulting in their proliferation [31]

The high cAMP levels upregulate cAMP responsive genes and induce an antiapoptotic state in the endothelial cells, resulting in their proliferation [31]. Proteobacteria [1,2]. Of the 24 species that comprise the genusBartonella, B. bacilliformis, B. henselae,andB. quintanainfections have been most commonly implicated in human disease andB. henselaeandB. quintanaaccount for the majority of morbidity and mortality among immunocompromised individuals [35]. == 3.BartonellaEpidemiology == Each of the majorBartonellaspecies implicated Mouse monoclonal to ABL2 in human disease has unique epidemiology. While the vast majority ofBartonellaspecies have an identified zoonotic reservoir such as domesticated animals and farm animals, the animal reservoir for bothB. quintanaandB. bacilliformishave not yet been identified. WhileB. bacilliformisis transmitted by the sand fly and the major vector forB quintanais the human body louse,B quintanahas also been found in rodent fleas, including rat fleas, and thus a potential for a rodent vector has been hypothesized [6,7]. B. henselaeoccurs throughout the world. It is a zoonosis transmitted from the natural reservoir, cats (Felis catus), usually via cat scratch or bite and less commonly by a vector such as cat fleas (Ctenocephalides felis) or ticks [8]. Cross-sectional studies have reported as much as 81% seropositivity point prevalence among cats in different regions of the world. Bacteremia is more prevalent in cats that are less than 1 year old [2]. Humans and dogs are accidental hosts. AlthoughB. quintanaoccurs worldwide, with improved sanitation and living conditions, disease caused byB. quintanahas dramatically decreased and now alpha-Boswellic acid occurs primarily in small epidemics in conditions characterized by crowding and poor sanitation. Humans are likely the natural reservoir forB. quintanawhich is spread by human body lice (Pediculus humanis corporis) [8]. Infected body lice excreta on human skin induce pruritis, and skin breakdown that follows scratching allows forB. quintana’spathway of invasion [9]. Wild rodents have also been identified as potential reservoirs [6,7]. B. bacilliformisis endemic in mountainous areas of Peru, Columbia, and Ecuador [10]. It is transmitted by theLutzomyiasandfly, but the animal reservoir has alpha-Boswellic acid yet to be identified. == 4.Bartonellaand the Human Immune System == == 4.1. Establishing Contamination: Evasion of the Immune System == Despite extensive knowledge about the disease syndromes caused byBartonellaspecies in humans, little is known about the humoral and cellular immune mechanisms involved in establishment and persistence ofBartonellainfection in humans. Experimental studies usingB. tribocoruminoculation onto an immune-competent rat model have shown that the brief bacteremia after inoculation is followed by a 35-day bacteremia-free window before resurgence of persistent intraerythrocytic bacteremia that lasts for 811 weeks [11]. This model highlights possible existence of a sanctuary site where the initial contamination gets established before persistent intraerythrocytic contamination manifests. So far, three such potential sanctuary sites include (a) extracellular matrix where high local bacterial replication may be achieved following initial contamination [11], (b) bone-marrow stem cells such as erythroid progenitor cells where CD34+ cells in the bone alpha-Boswellic acid marrow may be infected followed by release of infected erythrocytes into the blood stream [12] or endothelial progenitor cells which may also get infected in the bone marrow prior to their mobilization into circulation for endothelial repair [13], and, finally, alpha-Boswellic acid (c) mature endothelial cells [14]. == Bartonella alpha-Boswellic acid Has Several Characteristics That Lead to Immune Evasion == Bartonellalipopolysaccaride (LPS) is composed of a unique combination of Lipid A and long-chain fatty acids and likely contributes to the bacteria’s ability to evade the immune system [15]. Empiric data have shown thatBartonellainitially evades the innate immune system because its surface molecules are not recognized by TLR-4 on dendritic cells or macrophages, [16], thereby allowing for establishment of what might lead to persistent contamination. The LPS does not induce tumor necrosis factor alpha and has reduced stimulation of Toll-like receptor 2 (TLR2) and thus reduced endotoxicity [17,18]. The LPS.