Abstract Kupffer cells (KCs) are thought to mediate hepatocyte injury via their production of proinflammatory cytokines and reactive oxygen species in response to stress. In this study, we depleted KCs from the liver to examine their role in total warm hepatic ischemia/reperfusion (I/R) injury with bowel congestion. We injected 8-wk-old C57BL/10J mice with liposome-encapsulated clodronate 48 h before 35 min of hepatic ischemia with bowel congestion, followed by 6 or 24 h of reperfusion. KC-depleted animals had a higher mortality rate than diluent-treated animals and a 10-fold elevation in transaminase levels that correlated with increases in centrilobular necrosis. There was extensive LPS binding to the endothelial cells, which correlated with an upregulation of endothelial adhesion molecules in the KC-depleted animals versus diluent-treated animals. There was an increase in the levels of proinflammatory cytokines in KC-depleted animals, and a concomitant decrease in IL-10 levels. When KC-depleted mice were treated with recombinant IL-10, their liver damage profile in response to I/R was similar to diluent-treated animals, and endothelial cell adhesion molecules and proinflammatory cytokine levels decreased. KCs are protective in the liver subjected to total I/R with associated bowel congestion and are not deleterious as previously thought. This protection appears to be due to KC secretion of the potent anti-inflammatory cytokine IL-10.
The susceptibility of congenitally immunodeficient mice to a nonencapsulated strain of Cryptococcus neoformans (strain M7) was evaluated. Gnotobiotic mice with defined congenital defects in innate immunity (beige) or cell-mediated immunity (athymic) or with combined defects in innate and cellular immunity (beige athymic) were i.v. challenged with C. neoformans M7. The nonencapsulated strain of C. neoformans produced a persistant low-grade infection in the brains of all immunodeficient and immunocompetent mice used in this study. Immunocompetent mice (nu/+;bg/+) and immunodeficient bg/bg mice readily cleared nonencapsulated cryptococci from their kidneys, liver, lungs, and spleen. In contrast to nu/+ mice, nu/nu mice had a reduced capacity to clear nonencapsulated cryptococci from their kidneys and liver after i.v. challenge. Both bg/bg–nu/nu and bg/bg–nu/+ mice developed a low-grade infection in their kidneys, liver, lungs, and spleen, which was maintained throughout the 21-day study. Persistent infections were not due to reversion to an encapsulated state. These data indicate that a capsule may not always be necessary for C. neoformans to survive, in vivo, in tissues of immunodeficient and immunocompetent mice. Key words: Cryptococcus neoformans, capsule, immunodeficient mice.
Candida albicans, an increasingly common opportunistic pathogenic fungus, frequently causes disease in immunodeficient but not immunocompetent hosts. Clarifying the role of the phagocytic cells that participate in resistance to candidiasis not only is basic to understanding how the host copes with this dimorphic pathogen but also will expedite the development of innovative prophylactic and therapeutic approaches for treating the multiple clinical presentations that candidiasis encompasses. In this review, we present evidence that a diverse population of mononuclear phagocytes, in different states of activation and differentiation and from a variety of host species, can phagocytize C. albicans blastoconidia via an array of opsonic and nonopsonic mechanisms and can kill C. albicans blastoconidia and hyphae by means of oxygen-dependent and -independent mechanisms. Reactive nitrogen intermediates should now be added to the well-established candidacidal reactive oxygen intermediates of macrophages. Furthermore, what were thought to be two independent pathways, i.e., nitric oxide and superoxide anion, have now been shown to combine to form a potent macrophage candidacidal molecule, peroxynitrite. In contrast to monocytes and neutrophils, which are important in resistance to early stages of C. albicans infections, more differentiated macrophages activated by cytokines such as gamma interferon participate in the acquired resistance of hosts with C. albicans-specific, cell-mediated immunity. Evidence presented in this review demonstrates that mononuclear phagocytes, in some instances in the absence of other professional phagocytes such as neutrophils, play an import role in resistance to systemic and mucosal candidiasis.
Phospholipase D1 (PLD1) mutants of Candida albicans are defective in important in vivo and in vitro virulence factors. PLD1 mutants colonize the murine alimentary tract as well as PLD1 sufficient strains. In comparison to PLD1 sufficient strains, the PLD1 mutants: (i) are unable to survive in internal organs after intravenous challenge; (ii) do not decrease the body weights of mice after oral challenge; and (iii) are not lethal for immunodeficient mice after oral challenge. In vitro, the PLD1 mutants show a drastically reduced capacity to penetrate epithelial monolayers and they fail to develop hyphae when grown on solid Spider medium. The morphogenic switch from yeast to hyphae is controlled by multiple parallel signaling pathways that couple specific stimuli to the regulation of several transcription factors. Our data suggest that PLD1 functions in at least one of these pathways regulating morphogenesis in vitro and that while the mutants are able to form hyphae in vivo, the hyphae are defective in their ability to cause oroesophageal and gastric candidiasis and to kill the C. albicans-colonized mice.
To investigate whether host immunocompetence influences hydrolytic gene expression, we compared secretory aspartyl proteinase gene (SAP) and phospholipase B gene (PLB) expression during gastric candidiasis in immunocompetent and defined immunodeficient gnotobiotic mice, by reverse-transcription polymerase chain reaction. The use of immunodeficient gnotobiotic mice with combined defects in T cells and natural killer cells enabled a comprehensive study of virulence gene expression in various mucosal sites during lethal oroesophageal (tongue, palate, and esophagus) and gastric candidiasis. All 10 SAP and both PLB genes were expressed in both immunocompetent and specific immunodeficient mice, which suggests that the absence of important components of the host defense did not alter gene expression during gastric candidiasis. Although similar patterns of gene expression were evident in different oral tissues, we detected specific differences between Candida albicans-infected oroesophageal and gastric tissues and differences at various time points during the progression of gastric candidiasis.
The capacity of aerobic and anaerobic bacteria to survive on cotton swabs placed into a dry gassed-out CO2-filled tube (DGT), dry sterile aerobic tube (DAT), and a tube containing a modified Stuarts' transport medium (MST), was assessed. Pseudomonas aeruginosa increased in numbers by 2 and 3 logs when stored in MST and DAT, respectively. The viability of P. aeruginosa, although retarded when compared to MSA and DAT, was not adversely affected by the CO2 environment in the DGT. The MST maintained relatively constant numbers of Streptococcus pyogenes during the 48-h storage period. The DAT and the DGT were unable to maintain the viability of S. pyogenes. Staphylococcus aureus, when stored in a DGT, DAT, or MST, was maintained in relatively constant numbers throughout the entire storage period. Of the four anaerobic bacteria evaluated (Bacteroides fragilis ssp. thetaiotaomicron, Bacteroides melaninogenicus ssp. asaccharolyticus, Fusobacterium nucleatum, and Peptostreptococcus anaerobius), only B. fragilis ssp. thetaiotamicron survived the 48-h storage period in the DGT. Under these test conditions the DGT did not adequately maintain the viability of the majority of anaerobic bacteria tested (when held on cotton swabs). However, the MST did maintain the viability of all species tested for at least the first 2 h of storage.
Mucosal and disseminated candidiasis in gnotobiotic SCID mice Get access E. Balish, E. Balish Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Jensen, J. Jensen Search for other works by this author on: Oxford Academic PubMed Google Scholar T. Warner, T. Warner Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Brekke, J. Brekke Search for other works by this author on: Oxford Academic PubMed Google Scholar B. Leonard B. Leonard Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Medical and Veterinary Mycology, Volume 31, Issue 2, March 1993, Pages 143–154, https://doi.org/10.1080/02681219380000161 Published: 01 March 1993 Article history Accepted: 28 October 1992 Published: 01 March 1993
Several blood and serum chemistry values were serially determined over a 2-yr period on 17 purebred beagle dogs from the same closed, inbred colony. Seven of these dogs were germfree, and 10 had a conventional bacterial flora. Seven of those with a conventional flora were confined in germfree-type isolators; 3 were housed in a routine manner in a conventional animal facility. The germfree dogs were found to have significantly lower red blood cell, white blood cell, neutrophil, and band cell counts lower levels of alpha-2 and gamma globulins, and higher amounts of cholesterol and alkaline phosphatase than the 2 sets of conventional dogs. In most other respects, the blood and serum chemistry values of the germfree dogs were similar to those of the conventional dogs and to previously reported values for normal beagles.
