scholarly journals Bet-hedging antimicrobial strategies in macrophage phagosome acidification drive the dynamics of Cryptococcus neoformans intracellular escape mechanisms

2021 ◽  
Author(s):  
Quigly Dragotakes ◽  
Ella Jacobs ◽  
Lia Sanchez Ramirez ◽  
Olivia Insun Yoon ◽  
Caitlin Perez-Stable ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cryptococcus Neoformans ◽  
Stochastic Dynamics ◽  
Macrophage Polarization ◽  
Polarization State ◽  
Fluorescent Microscopy ◽  
Fungal Growth ◽  
Cell Stress ◽  
Fungal Cell ◽  
Oxidative Stresses

The fungus Cryptococcus neoformans is a major human pathogen with a remarkable intracellular survival strategy that includes exiting macrophages through non-lytic exocytosis (Vomocytosis) and transferring between macrophages (Dragotcytosis) by a mechanism that involves sequential events of non-lytic exocytosis and phagocytosis. Vomocytosis and Dragotcytosis are fungal driven processes, but their triggers are not understood. We hypothesized that the dynamics of Dragotcytosis could inherit the stochasticity of phagolysosome acidification and that Dragotcytosis was triggered by fungal cell stress. Consistent with this view, fungal cells involved in Dragotcytosis reside in phagolysosomes characterized by low pH and/or high oxidative stress. Using fluorescent microscopy, qPCR, live cell video microscopy, and fungal growth assays we found that the that mitigating pH or oxidative stress abrogated Dragotcytosis frequency, that ROS susceptible mutants of C. neoformans underwent Dragotcytosis more frequently. Dragotcytosis initiation was linked to phagolysosomal pH and oxidative stresses and correlated with the macrophage polarization state. Dragotcytosis manifested stochastic dynamics thus paralleling the dynamics of phagosomal acidification, which correlated with the inhospitality of phagolysosomes in differently polarized macrophages. Hence, randomness in phagosomal acidification randomly created a population of inhospitable phagosomes where fungal cell stress triggered stochastic C. neoformans non-lytic exocytosis dynamics to escape a non-permissive intracellular macrophage environment.

scholarly journals The Cch1-Mid1 High-Affinity Calcium Channel Contributes to the Virulence of Cryptococcus neoformans by Mitigating Oxidative Stress

2015 ◽  
Vol 14 (11) ◽  
pp. 1135-1143 ◽  
Author(s):  
Kiem Vu ◽  
Jennifer M. Bautos ◽  
Angie Gelli
Keyword(s):  
Oxidative Stress ◽  
Cryptococcus Neoformans ◽  
Defense Mechanisms ◽  
Pathogenic Fungi ◽  
Growth Defect ◽  
Compensatory Mechanism ◽  
General Role ◽  
Content Type ◽  
High Affinity ◽  
Oxidative Stresses

ABSTRACT Pathogenic fungi have developed mechanisms to cope with stresses imposed by hosts. For Cryptococcus spp., this implies active defense mechanisms that attenuate and ultimately overcome the onslaught of oxidative stresses in macrophages. Among cellular pathways within Cryptococcus neoformans ' arsenal is the plasma membrane high-affinity Cch1-Mid1 calcium (Ca 2+ ) channel (CMC). Here we show that CMC has an unexpectedly complex and disparate role in mitigating oxidative stress. Upon inhibiting the Ccp1-mediated oxidative response pathway with antimycin, strains of C. neoformans expressing only Mid1 displayed enhanced growth, but this was significantly attenuated upon H 2 O 2 exposure in the absence of Mid1, suggesting a regulatory role for Mid1 acting through the Ccp1-mediated oxidative stress response. This notion is further supported by the interaction detected between Mid1 and Ccp1 (cytochrome c peroxidase). In contrast, Cch1 appears to have a more general role in promoting cryptococci survival during oxidative stress. A strain lacking Cch1 displayed a growth defect in the presence of H 2 O 2 without BAPTA [(1,2-bis(2-aminophenoxy)ethane- N , N , N ′, N ′-tetraacetic acid, cesium salt] or additional stressors such as antimycin. Consistent with a greater contribution of Cch1 to oxidative stress tolerance, an intracellular growth defect was observed for the cch1 Δ strain in the macrophage cell line J774A.1. Interestingly, while the absence of either Mid1 or Cch1 significantly compromises the ability of C. neoformans to tolerate oxidative stress, the absence of both Mid1 and Cch1 has a negligible effect on C. neoformans growth during H 2 O 2 stress, suggesting the existence of a compensatory mechanism that becomes active in the absence of CMC.

scholarly journals Human Antibodies against a Purified Glucosylceramide from Cryptococcus neoformans Inhibit Cell Budding and Fungal Growth

2000 ◽  
Vol 68 (12) ◽  
pp. 7049-7060 ◽  
Author(s):  
Marcio L. Rodrigues ◽  
Luiz R. Travassos ◽  
Kildare R. Miranda ◽  
Anderson J. Franzen ◽  
Sonia Rozental ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
High Performance ◽  
Fungal Growth ◽  
Fungal Cell ◽  
Human Antibodies ◽  
Different Strains ◽  
Immunofluorescence Labeling

ABSTRACT A major ceramide monohexoside (CMH) was purified from lipidic extracts of Cryptococcus neoformans. This molecule was analyzed by high-performance thin-layer chromatography (HPTLC), gas chromatography coupled with mass spectrometry, and fast atom bombardment-mass spectrometry. The cryptococcal CMH is a β-glucosylceramide, with the carbohydrate residue attached to 9-methyl-4,8-sphingadienine in amidic linkage to 2-hydroxyoctadecanoic acid. Sera from patients with cryptococcosis and a few other mycoses reacted with the cryptococcal CMH. Specific antibodies were purified from patients' sera by immunoadsorption on the purified glycolipid followed by protein G affinity chromatography. The purified antibodies to CMH (mainly immunoglobulin G1) bound to different strains and serological types of C. neoformans, as shown by flow cytofluorimetry and immunofluorescence labeling. Transmission electron microscopy of yeasts labeled with immunogold-antibodies to CMH and immunostaining of isolated cell wall lipid extracts separated by HPTLC showed that the cryptococcal CMH predominantly localizes to the fungal cell wall. Confocal microscopy revealed that the β-glucosylceramide accumulates mostly at the budding sites of dividing cells with a more disperse distribution at the cell surface of nondividing cells. The increased density of sphingolipid molecules seems to correlate with thickening of the cell wall, hence with its biosynthesis. The addition of human antibodies to CMH to cryptococcal cultures of both acapsular and encapsulated strains of C. neoformans inhibited cell budding and cell growth. This process was complement-independent and reversible upon removal of the antibodies. The present data suggest that the cryptococcal β-glucosylceramide is a fungal antigen that plays a role on the cell wall synthesis and yeast budding and that antibodies raised against this component are inhibitory in vitro.

scholarly journals Effect of Cytokine Interplay on Macrophage Polarization during Chronic Pulmonary Infection with Cryptococcus neoformans

2011 ◽  
Vol 79 (5) ◽  
pp. 1915-1926 ◽  
Author(s):  
Shikha Arora ◽  
Michal A. Olszewski ◽  
Tiffany M. Tsang ◽  
Roderick A. McDonald ◽  
Galen B. Toews ◽  
...  
Keyword(s):  
Fungal Infection ◽  
Cryptococcus Neoformans ◽  
Pulmonary Infection ◽  
Macrophage Polarization ◽  
Polarization State ◽  
Interleukin 4 ◽  
Activation Markers ◽  
Content Type ◽  
Th1 And Th2 Cytokines ◽  
Ifn Γ

ABSTRACTThe immune response toCryptococcus neoformansfollowing pulmonary infection of C57BL/6 wild-type (WT) mice results in the development of persistent infection with characteristics of allergic bronchopulmonary mycosis (ABPM). To further clarify the role of Th1/Th2 polarizing cytokines in this model, we performed kinetic analysis of cytokine responses and compared cytokine profiles, pathologies, and macrophage (Mac) polarization status inC. neoformans-infected WT, interleukin-4-deficient (IL-4−/−), and gamma interferon-deficient (IFN-γ−/−) C57BL/6 mice. Results show that cytokine expression in the infected WT mice is not permanently Th2 biased but changes dynamically over time. Using multiple Mac activation markers, we further demonstrate that IL-4 and IFN-γ regulate the polarization state of Macs in this model. A higher IL-4/IFN-γ ratio leads to the development of alternatively activated Macs (aaMacs), whereas a higher IFN-γ/IL-4 ratio leads to the generation of classically activated Macs (caMacs). WT mice that coexpress IL-4 and IFN-γ during fungal infection concurrently display both types of Mac polarization markers. Concurrent stimulation of Macs with IFN-γ and IL-4 results in an upregulation of both sets of markers within the same cells, i.e., formation of an intermediate aaMac/caMac phenotype. These cells express both inducible nitric oxide synthase (important for clearance) and arginase (associated with chronic/progressive infection). Together, our data demonstrate that the interplay between Th1 and Th2 cytokines supports chronic infection, chronic inflammation, and the development of ABPM pathology inC. neoformans-infected lungs. This cytokine interplay modulates Mac differentiation, including generation of an intermediate caMac/aaMac phenotype, which in turn may support chronic “steady-state” fungal infection and the resultant ABPM pathology.

scholarly journals Macrophage M1/M2 Polarization Dynamically Adapts to Changes in Cytokine Microenvironments in Cryptococcus neoformans Infection

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Michael J. Davis ◽  
Tiffany M. Tsang ◽  
Yafeng Qiu ◽  
Jeremy K. Dayrit ◽  
Joudeh B. Freij ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Macrophage Polarization ◽  
Polarization State ◽  
Marker Genes ◽  
M2 Macrophage ◽  
Content Type ◽  
Cryptococcal Infection ◽  
M2 Polarization ◽  
Polarized Cells ◽  
Ifn Γ

ABSTRACTThe outcome of cryptococcal pneumonia correlates with local macrophage polarization status, as M1 and M2 polarization marks protective and nonprotective responses, respectively. Overall, pulmonary macrophage polarization status changes over time during a cryptococcal infection. This could have been caused by repolarization of individual macrophages or by a replacement of M2-polarized cells by new M1-polarized cells. To explore the ability of macrophages to change between polarization states, we conducted a series of experiments usingin vitromacrophages. Coculture of macrophages withCryptococcus neoformansresulted in development of a weak M1-like phenotype, with modestly increased inducible nitric oxide synthase (iNOS) but lacking interleukin 6 (IL-6) induction. TheC. neoformans-induced M1-like polarization state was plastic, as macrophages stimulated first withC. neoformansand then with gamma interferon (IFN-γ) or IL-4 expressed mRNA polarization patterns similar to those stimulated with cytokines alone. To further evaluate macrophage polarization plasticity, cytokine stimulatory conditions were established which fully polarized macrophages. IFN-γ and IL-4 stimulation differentially induced complete M1 and M2 polarization, defined by differential expression of marker mRNA panels, surface marker expression, and tumor necrosis factor alpha (TNF-α) protein production. Switching IFN-γ- to IL-4-stimulating conditions, and vice versa, resulted in uniform changes in profiles of polarization marker genes consistent with the most recent cytokine environment. Furthermore, the ability of sequentially stimulated macrophages to inhibitC. neoformansreflected the most recent polarizing condition, independent of previous polarization. Collectively, these data indicate that M1/M2 macrophage polarization phenotypes are highly plastic to external signals, and interventions which therapeutically repolarize macrophages could be beneficial for treatment of cryptococcosis.IMPORTANCEOur studies reveal how a major opportunistic fungal pathogen,Cryptococcus neoformans, interacts with macrophages, immune cells which can ingest and kill invading pathogens. Macrophages play a crucial role in the pathogenesis of cryptococcal infection, as their polarization phenotype determines the outcome of the battle between the infected host andC. neoformans. This study suggests that dynamic changes in polarization of macrophages at the level of individual cells are an important characteristic ofin vivocryptococcosis, as they occur throughout the natural course of infection. We demonstrate that macrophages can rapidly and uniformly reverse their polarization phenotype in response to dynamic signaling conditions and lose or regain their fungicidal function. Demonstrating importance of these pathways may become a cornerstone for novel therapeutic strategies for treatment of cryptococcosis in both immunocompromised and immunocompetent patients.

Alpha-1-Antichymotrypsin: a Common Player for Type 2 Diabetes and Alzheimer's Disease

2020 ◽  
Vol 16 ◽  
Author(s):  
Nataly Guzmán-Herrera ◽  
Viridiana C. Pérez-Nájera ◽  
Luis A. Salazar-Olivo
Keyword(s):  
Oxidative Stress ◽  
Alzheimer’S Disease ◽  
Type 2 Diabetes ◽  
Alzheimer's Disease ◽  
Regulatory Networks ◽  
Therapeutic Strategies ◽  
Oxidative Stresses ◽  
Bibliographic Search ◽  
And Oxidative Stress

Background: Numerous studies have shown a significant association between type 2 diabetes mellitus (T2D) and Alzheimer's disease (AD), two pathologies affecting millions of people worldwide. Chronic inflammation and oxidative stress are two conditions common to these diseases also affecting the activity of the serpin alpha-1-antichymotrypsin (ACT), but a possible common role for this serpin in T2D and AD remains unclear. Objective: To explore the possible regulatory networks linking ACT to T2D and AD. Materials and Methods: A bibliographic search was carried out in PubMed, Med-line, Open-i, ScienceDirect, Scopus and SpringerLink for data indicating or suggesting association among T2D, AD, and ACT. Searched terms like “alpha-1-antichymotrypsin”, “type 2 diabetes”, “Alzheimer's disease”, “oxidative stress”, “pro-inflammatory mediators” among others were used. Moreover, common therapeutic strategies between T2D and AD as well as the use of ACT as a therapeutic target for both diseases were included. Results: ACT has been linked with development and maintenance of T2D and AD and studies suggest their participation through activation of inflammatory pathways and oxidative stress, mechanisms also associated with both diseases. Likewise, evidences indicate that diverse therapeutic approaches are common to both diseases. Conclusion: Inflammatory and oxidative stresses constitute a crossroad for T2D and AD where ACT could play an important role. In-depth research on ACT involvement in these two dysfunctions could generate new therapeutic strategies for T2D and AD.

scholarly journals Recurrent Indoor Environmental Pollution and Its Impact on Health and Oxidative Stress of the Textile Workers in Bangladesh

2020 ◽  
Vol 14 ◽  
pp. 117863022093839
Author(s):  
Tania Rahman ◽  
Ar-Rafi Md. Faisal ◽  
Tahura Khanam ◽  
Hossain Uddin Shekhar
Keyword(s):  
Oxidative Stress ◽  
Ascorbic Acid ◽  
Occupational Health ◽  
Environmental Pollution ◽  
Control Area ◽  
Textile Workers ◽  
Control Subjects ◽  
Oxidative Stresses ◽  
Healthy Control ◽  
Textile Industries

Perennial indoor environmental pollution in the textile industrial area is a potential health hazard for workers engaged in this line of work, resulting in mental aberration to severe health risks. This study was designed to investigate the indoor environmental quality of textile industries and correlate its effect on the occupational health and well-being of the textile workers by measuring plasma oxidative stress status in textile workers and healthy control subjects. Environmental samples were collected from 15 textile industries located in Dhaka division, and 30 volunteer textile workers and 30 volunteer office workers (control) aged 18 to 57 years participated in the study. The concentration of plasma ascorbic acid (P-ASC), plasma malondialdehyde (P-MDA), and plasma conjugated diene (P-CD) was measured in both groups. The noise level (78.0 ± 0.68 dB) and the formaldehyde level (141.80 ± 4.47 µg/m3) were found to be significantly higher in the indoor environmental area compared with those in the control area (70.17 ± 0.25 dB and 108.0 ± 0.76 µg/m3, respectively). Furthermore, the daily average concentration of suspended particulate matters (PMs), that is, PM2.5 (322.2 ± 13.46 µg/m3) and PM10 (411.0 ± 17.57 µg/m3), was also found to be significantly higher in the indoor environmental air compared with that in the control area (78.59 ± 1.66 and 174.0 ± 2.33 µg/m3, respectively). The levels of P-MDA (0.37 ± 0.03 nmol/L) and P-CD (14.74 ± 0.61 nmol/L) were significantly increased, whereas the level of P-ASC level (0.46 ± 0.04 mg/dL) was markedly decreased in the textile workers compared with the healthy control subjects (0.18 ± 0.01 nmol/L of P-MDA, 10.04 ± 0.44 nmol/L of P-CD, and 1.29 ± 0.06 mg/dL of P-ASC). The textile plants were found to have significantly elevated levels of indoor environmental pollutants compared with those in the control area, and the textile workers were significantly exposed to oxidative stresses compared with the control subjects. The use of noise pads and high-efficiency air filters is perhaps highly instrumental to put an end to this prevailing situation. Moreover, to overcome the oxidative stresses among workers, supplementation of antioxidant vitamins (ie, ascorbic acid and/or vitamin E) may be beneficial. In addition, to prevent serious health-related issues, proper precautions should be taken to protect the occupational health of the textile workers.

scholarly journals Critical Role of Zinc as Either an Antioxidant or a Prooxidant in Cellular Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Sung Ryul Lee
Keyword(s):  
Oxidative Stress ◽  
Zinc Deficiency ◽  
Metal Binding ◽  
Inflammatory Responses ◽  
Binding Capacity ◽  
Critical Role ◽  
Cellular Systems ◽  
Oxidative Stresses ◽  
Dual Action

Zinc is recognized as an essential trace metal required for human health; its deficiency is strongly associated with neuronal and immune system defects. Although zinc is a redox-inert metal, it functions as an antioxidant through the catalytic action of copper/zinc-superoxide dismutase, stabilization of membrane structure, protection of the protein sulfhydryl groups, and upregulation of the expression of metallothionein, which possesses a metal-binding capacity and also exhibits antioxidant functions. In addition, zinc suppresses anti-inflammatory responses that would otherwise augment oxidative stress. The actions of zinc are not straightforward owing to its numerous roles in biological systems. It has been shown that zinc deficiency and zinc excess cause cellular oxidative stress. To gain insights into the dual action of zinc, as either an antioxidant or a prooxidant, and the conditions under which each role is performed, the oxidative stresses that occur in zinc deficiency and zinc overload in conjunction with the intracellular regulation of free zinc are summarized. Additionally, the regulatory role of zinc in mitochondrial homeostasis and its impact on oxidative stress are briefly addressed.

scholarly journals RTT109 AND Fun30 proteins mediate epigenetic regulation of the DNA damage response pathway in C. albicans

2021 ◽  
Author(s):  
Prashant Kumar Maurya ◽  
Pramita Garai ◽  
Kaveri Goel ◽  
Himanshu Bhatt ◽  
Aarti Goyal ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Regulation Of Gene Expression ◽  
Repair Pathway ◽  
Fungal Cell ◽  
Opportunistic Fungi ◽  
Damage Response ◽  
H3 Acetylation ◽  
Dna Damage Response Pathway

Fun30, an ATP-dependent chromatin remodeller, from S. cerevisiae mediates both regulation of gene expression as well as DNA damage response/repair. In this paper, we have characterized the biochemical and physiological function of Fun30 from the opportunistic fungi, C. albicans. Biochemically, the protein shows DNA-stimulated ATPase activity. Physiologically, the protein co-regulates transcription of RTT109, TEL1, MEC1, and SNF2-genes that encode for proteins involved in DNA damage response and repair pathway. The expression of FUN30, in turn, is regulated by histone H3 acetylation catalysed by Rtt109 encoded by RTT109. The RTT109Hz/FUN30Hz mutant strain shows sensitivity to oxidative stress and resistance to MMS as compared to the wild type strain. Quantitative PCR showed that the sensitivity to oxidative stress results from downregulation of MEC1, RAD9, MRC1 and RAD5 expression; ChIP experiments showed Fun30 but not H3ac regulates the expression of these genes in response to oxidative stress. In contrast, on treatment with MMS, the expression of RAD9 is upregulated and this upregulation is co-regulated by both Fun30 and H3 acetylation catalysed by Rtt109. Thus, Fun30 and H3 acetylation mediate the response of the fungal cell to genotoxic agents in C. albicans by regulating the expression of DNA damage response and repair pathway genes.

scholarly journals Screening and Antifungal Activity of a β-Carboline Derivative against Cryptococcus neoformans and C. gattii

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Kátia Santana Cruz ◽  
Emerson Silva Lima ◽  
Marcia de Jesus Amazonas da Silva ◽  
Erica Simplício de Souza ◽  
Andreia Montoia ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Cryptococcus Neoformans ◽  
Active Compound ◽  
Cell Walls ◽  
Human Fibroblasts ◽  
Lead Compound ◽  
Fungal Cell ◽  
Fungal Cell Walls

Background. Cryptococcosis is a fungal disease of bad prognosis due to its pathogenicity and the toxicity of the drugs used for its treatment. The aim of this study was to investigate the medicinal potential of carbazole and β-carboline alkaloids and derivatives against Cryptococcus neoformans and C. gattii. Methods. MICs were established in accordance with the recommendations of the Clinical and Laboratory Standards Institute for alkaloids and derivatives against C. neoformans and C. gattii genotypes VNI and VGI, respectively. A single active compound was further evaluated against C. neoformans genotypes VNII, VNIII, and VNIV, C. gattii genotypes VGI, VGIII, and VGIV, Candida albicans ATCC 36232, for cytotoxicity against the MRC-5 lineage of human fibroblasts and for effects on fungal cells (cell wall, ergosterol, and leakage of nucleic acids). Results. Screening of 11 compounds revealed 8-nitroharmane as a significant inhibitor (MIC 40 μg/mL) of several C. neoformans and C. gattii genotypes. It was not toxic to fibroblasts (IC50 > 50 µg/mL) nor did it alter fungal cell walls or the concentration of ergosterol in C. albicans or C. neoformans. It increased leakage of substances that absorb at 260 nm. Conclusions. The synthetic β-carboline 8-nitroharmane significantly inhibits pathogenic Cryptococcus species and is interesting as a lead compound towards new therapy for Cryptococcus infections.

scholarly journals Laccase Expression in Murine Pulmonary Cryptococcus neoformans Infection

2005 ◽  
Vol 73 (5) ◽  
pp. 3124-3127 ◽  
Author(s):  
Javier Garcia-Rivera ◽  
Stephanie C. Tucker ◽  
Marta Feldmesser ◽  
Peter R. Williamson ◽  
Arturo Casadevall
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Lung Tissue ◽  
Immunogold Electron Microscopy ◽  
Cell Cytoplasm ◽  
Fungal Cell ◽  
Time Of Infection

ABSTRACT Cryptococcus neoformans laccase expression during murine infection was investigated in lung tissue by immunohistochemistry and immunogold electron microscopy. Laccase was detected in the fungal cell cytoplasm, cell wall, and capsule in vivo. The amount of laccase found in different sites varied as a function of the time of infection.

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