Journal of Microbiology

Journal Articles

Increased susceptibility against Cryptococcus neoformans of lupus mouse models (pristane-induction and FcGRIIb deficiency) is associated with activated macrophage, regardless of genetic background: Saowapha Surawut , Jiradej Makjaroen , Arthid Thim-uam , Jutamas Wongphoom , Tanapat Palaga , Prapaporn Pisitkun , Ariya Chindamporn , Asada Leelahavanichkul; J. Microbiol. 2019;57(1):45-53. Published online November 19, 2018; DOI: https://doi.org/10.1007/s12275-019-8311-8

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Abstract: The severity of cryptococcosis in lupus from varying geneticbackgrounds might be different due to the heterogeneity of lupus-pathogenesis. This study explored cryptococcosis in lupus mouse models of pristane-induction (normal geneticbackground) and FcGRIIb deficiency (genetic defect). Because the severity of lupus nephritis, as determined by proteinuria and serum creatinine, between pristane and FcGRIIb-/- mice were similar at 6-month-old, Cryptococcus neoformans was intravenously administered in 6-month-old mice and were age-matched with wild-type. Indeed, the cryptococcosis disease severity, as evaluated by mortality rate, internal-organ fungal burdens and serum cytokines, between pristane and FcGRIIb-/- mice was not different. However, the severity of cryptococcosis in wild-type was less severe than the lupus mice. On the other hand, phagocytosis activity of peritoneal macrophages from lupus mice (pristane and FcGRIIb-/-) was more predominant than the wild-type without the difference in macrophage killing-activity among these groups. In addition, the number of active T helper cells (Th-cell) in the spleen, including Th-cells with intracellular IFN-γ, from lupus mice (pristane and FcGRIIb-/-) was higher than wildtype. Moreover, these active Th-cells were even higher after 2 weeks of cryptococcal infection. These data support enhanced macrophage activation through prominent Th-cells in both lupus models. In conclusion, an increased susceptibility of cryptococcosis in both lupus models was independent to genetic background. This might due to Th-cell enhanced macrophage phagocytosis with the interference of macrophage killing activity from Cryptococcal immune-evasion properties.

The in vitro and in vivo efficacy of fluconazole in combination with farnesol against Candida albicans isolates using a murine vulvovaginitis model: Aliz Bozó , Marianna Domán , László Majoros , Gábor Kardos , István Varga , Renátó Kovács; J. Microbiol. 2016;54(11):753-760. Published online October 29, 2016; DOI: https://doi.org/10.1007/s12275-016-6298-y

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Abstract: Farnesol is a quorum-sensing molecule that inhibits biofilm formation in Candida albicans. Previous in vitro data suggest that, in combination with certain antifungals, farnesol may have an adjuvant anti-biofilm agent. However, the in vivo efficacy of farnesol is very questionable. Therefore, the in vitro and in vivo activity of fluconazole combined with farnesol was evaluated against C. albicans biofilms using fractional inhibitory concentration index (FICI) determination, time-kill experiments and a murine vulvovaginitis model. The median biofilm MICs of fluconazole-sensitive C. albicans isolates ranged between 4 -> 512 mg/L and 150–300 μM for fluconazole and farnesol, respectively. These values were 512 -> 512 mg/L and > 300 μM for fluconazole-resistant clinical isolates. Farnesol decreased the median MICs of fluconazole by 2-64-fold for biofilms. Based on FICI, synergistic interaction was observed only in the case of the sessile SC5314 reference strain (FICIs: 0.16–0.27). In time-kill studies, only the 512 mg/L fluconazole and 512 mg/L fluconazole + 75 μM farnesol reduced biofilm mass significantly at each time point in the case of all isolates. The combination reduced the metabolic activity of biofilms for all isolates in a concentration- and time-dependent manner. Our findings revealed that farnesol alone was not protective in a murine vulvovaginitis model. Farnesol was not beneficial in combination with fluconazole for fluconazole-susceptible isolates, but partially increased fluconazole activity against one fluconazole- resistant isolate, but not the other one.

Research Support, Non-U.S. Gov'ts

Newly Identified CpG ODNs, M5-30 and M6-395, Stimulate MouseNewly Identified CpG ODNs, M5-30 and M6-395, Stimulate Mouse Immune Cells to Secrete TNF-α and Enhance Th1-Mediated Immunity: Sun-Shim Choi , Eunkyung Chung , Yu-Jin Jung; J. Microbiol. 2010;48(4):512-517. Published online August 20, 2010; DOI: https://doi.org/10.1007/s12275-010-0053-6

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Abstract: Bacterial CpG motifs are known to induce both innate and adaptive immunity in infected hosts via toll-like receptor 9 (TLR9). Because small oligonucleotides (ODNs) mimicking bacterial CpG motifs are easily synthesized, they have found use as immunomodulatory agents in a number of disease models. We have developed a novel bioinformatics approach to identify effective CpG ODN sequences and evaluate their function as TLR9 ligands in a murine system. Among the CpG ODNs we identified, M5-30 and M6-395 showed significant ability to stimulate TNF-α and IFN-γ production in a mouse macrophage cell line and mouse splenocytes, respectively. We also found that these CpG ODNs activated cells through the canonical NF-κB signaling pathway. Moreover, both CpG ODNs were able to induce Th1-mediated immunity in Mycobacterium tuberculosis (Mtb)-infected mice. Our results demonstrate that M5-30 and M6-395 function as TLR9-specific ligands, making them useful in the study of TLR9 functionality and signaling in mice.

In Vivo Studies with a Candida tropicalis Isolate Exhibiting Paradoxical Growth In Vitro in the Presence of High Concentration of Caspofungin: Sedigh Bayegan , Laszlo Majoros , Gabor Kardos , Adam Kemény-Beke , Cecilia Miszti , Renato Kovacs , Rudolf Gesztelyi; J. Microbiol. 2010;48(2):170-173. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-010-9221-y

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Abstract: We investigated the activity of caspofungin against a Candida tropicalis clinical isolate showing paradoxical growth in vitro. BALB/c mice immunosuppressed by cyclophosphamide were infected intraperitoneally using 107 CFU/mouse. Caspofungin was administered intraperitoneally once daily for 5 days or as a single dose using the following doses: 0.12, 0.25, 1, 2, 3, 5, and 15 mg/kg. The single dose of caspofungin was effective only at 5 and 15 mg/kg concentrations (100% survival). Five-day caspofungin treatment led to 100% survival at doses of 1 mg/kg or higher. Caspofungin treatment significantly decreased the number of viable yeasts in the peritoneal lavage samples as well as in the infected abscesses at doses 1, 3, 5, and 15 mg/kg caspofungin as compared to the untreated control (P<0.001 in all cases), and even to the group treated with 0.12 mg/kg caspofungin (P<0.05 in all cases). At 2 mg/kg caspofungin dose, sterilization of the internal organs was reproducibly incomplete, suggesting that the role of paradoxical growth in the late clinical failure cannot be excluded.

Comparative Analysis of Immune Responses to Mycobacterium abscessus Infection and Its Antigens in Two Murine Models: Bo-Young Jeon , Jeongyeon Kwak , Seung-Sub Lee , SangNae Cho , Chul Jae Won , Jin Man Kim , Sung Jae Shin; J. Microbiol. 2009;47(5):633-640. Published online October 24, 2009; DOI: https://doi.org/10.1007/s12275-009-0139-1

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Abstract: Mycobacterium abscessus has been identified as an emerging pulmonary pathogen in humans. Because little is known regarding immune responses elicited by M. abscessus or its antigens, immunological responses were studied in two murine models subjected to intravenous (high-dose or systemic infection) or pulmonary (low-dose or local infection) inoculation with M. abscessus ATCC 19977. An overall comparison between the two models showed similar patterns of bacterial survival and host immune responses. The colonization of M. abscessus was the highest at 5 days post-infection (dpi) and its elimination was positively correlated with cell-mediated immunity in both challenges. However, an inverse relationship was observed between progressive inflammation and mycobacterial colonization levels in mice infected with a high dose at 14 dpi. Regarding antigens, culture filtrate (CF) of M. abscessus strongly induced IFN-γ secretion, whereas cellular extract (CE) antigen elicited strong antibody responses. The antibody response to M. abscessus antigens in mice subjected to low-dose infection increased when the cellular immune response decreased over 14 dpi. However, the antibody response for the high-dose infection increased promptly after the infection. In comparison of cytokine expression in lung homogenates after M. abscessus infection, Th1 and Th2 cytokines increased simultaneously in the high-dose infection, whereas only cell-mediated immunity developed in the low-dose pulmonary infection. These findings not only enhance our understanding of the immune response to M. abscessus infection according to systemic or pulmonary infection, but may also aid in immunological diagnosis and vaccine development.

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