Cytokines in candidiasis and aspergillosis

Circulatory Inflammatory Proteins as Early Diagnostic Biomarkers for Invasive Aspergillosis in Patients with Hematologic Malignancies-an Exploratory Study

OBJECTIVES

Invasive aspergillosis (IA) is a major cause of mortality in immunocompromised patients and it is difficult to diagnose because of the lack of reliable highly sensitive diagnostics. We aimed to identify circulating immunological markers that could be useful for an early diagnosis of IA.

METHODS

We collected longitudinally serum samples from 33 cases with probable/proven IA and two matched control cohorts without IA (one with microbiological and clinical evidence of bacterial or viral non-fungal pneumonia and one without evidence of infection, all matched for neutropenia, primary underlying disease, and receipt of corticosteroids/other immunosuppressants) at a tertiary university hospital. In addition, samples from an independent cohort (n = 20 cases of proven/probable IA and 20 matched controls without infection) were obtained. A panel of 92 circulating proteins involved in inflammation was measured by proximity extension assay. A random forest model was used to predict the development of IA using biomarkers measured before diagnosis.

RESULTS

While no significant differences were observed between IA cases and infected controls, concentrations of 30 inflammatory biomarkers were different between cases and non-infected controls, of which nine were independently replicated: PD-L1, MMP-10, Interleukin(IL)-10, IL-15RA, IL-18, IL-18R1, CDCP1, CCL19 and IL-17C. From the differential abundance analysis of serum samples collected more than 10 days before diagnosis and at diagnosis, increased IL-17C concentrations in IA patients were replicated in the independent cohort.

CONCLUSIONS

An increased circulating concentration of IL-17C was detected both in the discovery and independent cohort, both at the time of diagnosis and in samples 10 days before the diagnosis of IA, suggesting it should be evaluated further as potential (early) biomarker of infection.

Immunomodulatory Effects of the Pea Defensin Psd1 in the Caco-2/Immune Cells Co-Culture upon Candida albicans Infection

Candidiasis is one of the most common fungal diseases that can pose a threat to life in immunodeficient individuals, particularly in its disseminated form. Not only fungal invasion but also fatal infection-related inflammation are common causes of systemic candidiasis. In this study, we investigated in vitro immunomodulatory properties of the antifungal pea defensin Psd1 upon Candida albicans infection. Using the real-time PCR, we showed that Psd1 inhibited the antimicrobial peptide HBD-2 and pro-inflammatory cytokines IL-1 and IL-8 downregulation at mRNA level in epithelium cells caused by C. albicans infection. By using the Caco-2/immune cells co-culture upon C. albicans infection and the multiplex xMAP assay, we demonstrated that this pathogenic fungus induced a pronounced host defense response; however, the cytokine responses were different in the presence of dendritic cells or monocytes. We revealed that Psd1 at a low concentration (2 µM) had a pronounced immunomodulatory effect on the Caco-2/immune cells co-culture upon fungal infection. Thus, we hypothesized that the pea defensin Psd1 might be an effective agent in the treatment of candidiasis not only due to its antifungal activity, but also owing to its ability to modulate a protective immune response upon infection.

The Role of B-Cells and Antibodies against Candida Vaccine Antigens in Invasive Candidiasis

Systemic candidiasis is an invasive fungal infection caused by members of the genus Candida. The recent emergence of antifungal drug resistance and increased incidences of infections caused by non-albicans Candida species merit the need for developing immune therapies against Candida infections. Although the role of cellular immune responses in anti-Candida immunity is well established, less is known about the role of humoral immunity against systemic candidiasis. This review summarizes currently available information on humoral immune responses induced by several promising Candida vaccine candidates, which have been identified in the past few decades. The protective antibody and B-cell responses generated by polysaccharide antigens such as mannan, β-glucan, and laminarin, as well as protein antigens like agglutinin-like sequence gene (Als3), secreted aspartyl proteinase (Sap2), heat shock protein (Hsp90), hyphally-regulated protein (Hyr1), hyphal wall protein (Hwp1), enolase (Eno), phospholipase (PLB), pyruvate kinase (Pk), fructose bisphosphate aldolase (Fba1), superoxide dismutase gene (Sod5) and malate dehydrogenase (Mdh1), are outlined. As per studies reviewed, antibodies induced in response to leading Candida vaccine candidates contribute to protection against systemic candidiasis by utilizing a variety of mechanisms such as opsonization, complement fixation, neutralization, biofilm inhibition, direct candidacidal activity, etc. The contributions of B-cells in controlling fungal infections are also discussed. Promising results using anti-Candida monoclonal antibodies for passive antibody therapy reinforces the need for developing antibody-based therapeutics including anti-idiotypic antibodies, single-chain variable fragments, peptide mimotopes, and antibody-derived peptides. Future research involving combinatorial immunotherapies using humanized monoclonal antibodies along with antifungal drugs/cytokines may prove beneficial for treating invasive fungal infections.

The Host Immune Response to Scedosporium/Lomentospora

Infections caused by the opportunistic pathogens Scedosporium/Lomentospora are on the rise. This causes problems in the clinic due to the difficulty in diagnosing and treating them. This review collates information published on immune response against these fungi, since an understanding of the mechanisms involved is of great interest in developing more effective strategies against them. Scedosporium/Lomentospora cell wall components, including peptidorhamnomannans (PRMs), α-glucans and glucosylceramides, are important immune response activators following their recognition by TLR2, TLR4 and Dectin-1 and through receptors that are yet unknown. After recognition, cytokine synthesis and antifungal activity of different phagocytes and epithelial cells is species-specific, highlighting the poor response by microglial cells against L. prolificans. Moreover, a great number of Scedosporium/Lomentospora antigens have been identified, most notably catalase, PRM and Hsp70 for their potential medical applicability. Against host immune response, these fungi contain evasion mechanisms, inducing host non-protective response, masking fungal molecular patterns, destructing host defense proteins and decreasing oxidative killing. In conclusion, although many advances have been made, many aspects remain to be elucidated and more research is necessary to shed light on the immune response to Scedosporium/Lomentospora.

Increased mRNA expression of key cytokines among suspected cases of Pneumocystis jirovecii infection

Background

Pneumocystis pneumonia (PCP) is a fatal infectious disease caused by Pneumocystis jirovecii (PJP). The major factor relevant to morbidity and mortality seems to be the host inflammatory reaction. The objective of this study was to evaluate the role of IL-2, IL-4, IL-10, and IL-13 cytokine mRNA expression among suspected P. jirovecii infection.

Methods

This was a cross-sectional analytical study undertaken in Aseer region, Saudi Arabia. One hundred suspected PCP cases and 100 healthy controls were included in the study. Basic clinical manifestations, radiological findings, microbiological and immunological findings were extracted from the hospital records from January 2019 to August 2019, Pneumocystis detection was done by immune-fluorescent staining (IFAT, Gomorimethanamine silver staining (GMSS), Giemsa staining, Toluidine blue O (TBO), and Pneumocystis RT-PCR.

Results

Increased more than 5 fold, 3 fold, 4 fold, and 7 fold of IL-2, IL-4, IL-10, and IL-13 mRNA expression were observed in PCP cases compared to controls. Higher expression of IL-2 mRNA was connected with crept, wheezing and chest X-ray findings like central perihilar infiltrate, patchy infiltrate, consolidation, hilar lymphadenopathy, pneumothorax, pleural effusion which showed higher expression compared to counterpart (p< 0.0001). Higher expression of IL-4 mRNA was found to be significantly associated with weight loss (p=0.002), dyspnea (p=0.003), crept (p=0.01), and chest X-ray findings (p< 0.0001). Significantly increased expression of IL-10 mRNA was observed to be associated with weight loss, dyspnea, night sweats, wheezing, and different findings of chest X-ray compared to their counterparts, whereas, IL-13 mRNA was observed in cases with fever. Suspected cases of PCP confirmed positive by IFTA with higher IL-2, IL-4, and IL-10 mRNA expression compared to negative cases. RT-PCR confirmed PCP cases had significantly higher expression of IL-2, IL-4, and IL-10 as well as IL-13 mRNA compared to negative cases. Positive detected cases by GMSS showed higher IL-2, IL-10 mRNA expression, while Giemsa showed only higher IL-4 mRNA expression compared to negative cases.

Conclusion

Confirmed cases of P. jirovecii showed higher IL-2, IL-4, IL-10, and IL-13 mRNA expression comparatively to negative cases. Increased expression of cytokines may be indicative of infection severity and could help in patients’ management.

The Absence of NOD1 Enhances Killing of Aspergillus fumigatus Through Modulation of Dectin-1 Expression

One of the major life-threatening infections for which severely immunocompromised patients are at risk is invasive aspergillosis (IA). Despite the current treatment options, the increasing antifungal resistance and poor outcome highlight the need for novel therapeutic strategies to improve outcome of patients with IA. In the current study, we investigated whether and how the intracellular pattern recognition receptor NOD1 is involved in host defense against Aspergillus fumigatus. When exploring the role of NOD1 in an experimental mouse model, we found that Nod1^−/− mice were protected against IA and demonstrated reduced fungal outgrowth in the lungs. We found that macrophages derived from bone marrow of Nod1^−/− mice were more efficiently inducing reactive oxygen species and cytokines in response to Aspergillus. Most strikingly, these cells were highly potent in killing A. fumigatus compared with wild-type cells. In line, human macrophages in which NOD1 was silenced demonstrated augmented Aspergillus killing and NOD1 stimulation decreased fungal killing. The differentially altered killing capacity of NOD1 silencing versus NOD1 activation was associated with alterations in dectin-1 expression, with activation of NOD1 reducing dectin-1 expression. Furthermore, we were able to demonstrate that Nod1^−/− mice have elevated dectin-1 expression in the lung and bone marrow, and silencing of NOD1 gene expression in human macrophages increases dectin-1 expression. The enhanced dectin-1 expression may be the mechanism of enhanced fungal killing of Nod1^−/− cells and human cells in which NOD1 was silenced, since blockade of dectin-1 reversed the augmented killing in these cells. Collectively, our data demonstrate that NOD1 receptor plays an inhibitory role in the host defense against Aspergillus. This provides a rationale to develop novel immunotherapeutic strategies for treatment of aspergillosis that target the NOD1 receptor, to enhance the efficiency of host immune cells to clear the infection by increasing fungal killing and cytokine responses.

The Major Chromoblastomycosis Etiologic Agent Fonsecaea pedrosoi Activates the NLRP3 Inflammasome

Fonsecaea pedrosoi is the main etiologic agent of chromoblastomycosis (CBM), one of the most prevalent subcutaneous mycosis in tropical and subtropical countries. CBM is a poorly characterized chronic infection that commonly starts after transcutaneous inoculation of conidia and saprophytic hyphae of F. pedrosoi. Recently, we have shown that unlike conidia, hyphae and muriform cells (the parasitic morphotype) of F. pedrosoi promotes an intense inflammatory response pattern in vivo, which comprises the production of an inflammasome-derived cytokine, IL-1β. Nonetheless, the mechanisms underlying IL-1β production and maturation upon F. pedrosoi infection and its functional output in the course of CBM remains unknown. We show here that F. pedrosoi hyphae, differently from conidia, induce IL-1β secretion in both bone marrow-derived dendritic cells and macrophages. Using inhibitors and knockout cells, we demonstrated that the mechanisms underlying IL-1β production by hyphae-infected macrophages were dependent on dectin-1, -2, and -3 receptors and the Syk-NF-kB signaling pathway. Furthermore, F. pedrosoi promoted a NLRP3-dependent inflammasome activation, which required potassium efflux, reactive oxygen species production, phagolysosomal acidification, and cathepsin B release as triggers. IL-1β processing and release was mediated primarily by caspase-1 and, to a lesser extent, by caspase-8-dependent cleavage. Finally, we showed using a murine CBM model that F. pedrosoi elicits a NLRP3-regulated IL-1β and interleukin-18 release in vivo, but without NLRP3 inflammasome activation interfering in the course of the experimental infection.

Plasma Levels of IFN-γ, IL-4, IL-6 and IL-17 in HIV-Positive Patients With Oral Candidiasis

BACKGROUND

Cell-mediated immunity (CMI) by CD4 + Th (T helper)-type cells is the predominant host defense mechanism against Oral Candidiasis (OC) in HIV-infected individuals. Weakened CMI and depletion of CD4 + T cells are the main factor contributing to the output of OC in HIV-positive individuals. The cytokines produced by Th1, Th2 and Th17 cells play a role in mediating an increased susceptibility to OC during HIV infection.

OBJECTIVES

The present study investigated plasma concentration of IFN-γ, IL-4, IL-6 and IL-17 in HIV-1 patients suffering from OC.

PATIENTS AND METHODS

In total, 98 samples in four groups (HIV-positive and HIV-negative persons with and without OC) were obtained from the oral cavities and cultured on Sabouraud's dextrose agar and CHROMagar. Also blood samples were obtained to assess plasma level of IFN-γ, IL-4, IL-6 and IL-17 using ELISA technique.

RESULTS

There was a statistically significant difference in the plasma concentration of IFN-γ, IL-6 and IL-17 but not about IL-4. Our findings suggest a significant interaction between fungal infection and HIV on expression of assessed cytokines.

CONCLUSIONS

Fungal infection and HIV alone and together could seriously alter immune system function as assessed by measuring the levels of the plasma cytokines. Therefore, these results provide important new information relative to the putative immune-based factors associated with resistance and/or susceptibility to OC in HIV-positive persons.

Interferon-gamma production by human neutrophils upon stimulation by IL-12, IL-15 and IL-18 and challenge with Paracoccidioides brasiliensis

Paracoccidiodomycosis is a systemic mycosis caused by the fungus Paracoccidioides brasiliensis (Pb), which is endemic in Latin America. The host innate immune response against the fungus has been well characterized and several studies have shown the important role played by phagocytic cells. Our laboratory has studied the relationship between human neutrophils (PMNs)/Pb, focusing the effector mechanisms of these cells against the fungus. However, in last years, studies have shown that in addition to their phagocytic and killer functions, PMNs can modulate and instruct the immune response, since these cells have been shown to produce and release several cytokines. Thus, we evaluated whether PMNs stimulated with Pb can modulate the immune response to a Th1 phenotype through the production of IFN-γ, as well as the role of "pattern-recognition receptors" (PRRs) such as TLR2, TLR4 and Dectin-1 in this production. Furthermore, we asked whether activation of the cells with the cytokines IL-12, IL-15 and IL-18 could result in increased levels of this cytokine. Peripheral blood PMNs obtained from 20 healthy donors were nonactivated or activated with IL-12, IL-15 or IL-18 in different concentrations and challenged with strain 18 Pb (Pb18) for 2 h, 4 h, 12 h, 24 h and 48 h and evaluated for IFN-γ production, by ELISA. In other experiments, PMNs were treated with monoclonal antibodies anti-TLR2, TLR4 and Dectin-1, challenged with Pb and evaluated for IFN-γ production. We found that Pb induces human PMNs to produce IFN-γ, probably by binding to TLR4 and Dectin-1 receptors expressed by these cells. Moreover, IFN-γ levels were significantly increased when cells were activated with each of the tested cytokines or a combination of two of them, being the association IL-12 plus IL-15 the most effective. The results support our hypothesis that during infection by Pb, human PMNs modulate the adaptive immune response to a Th1 response pattern, via IFN-γ production.

Mouse bone marrow-derived dendritic cells can phagocytize the Sporothrix schenckii, and mature and activate the immune response by secreting interleukin-12 and presenting antigens to T lymphocytes

In sporotrichosis, dermal dendritic cells were considered to participate in induction of the immune responses against Sporothrix schenckii infection. However, it is still unclear whether and how dermal dendritic cells were involved in the progress. To clarify the pathogenic role of dermal dendritic cells (DC) in sporotrichosis, we examined the phagocytosis, maturation stages, cytokine production and antigen-presenting ability of mouse bone marrow-derived DC after stimulation with S. schenckii. By analysis of flow cytometry, electron microscope and confocal microscope, mouse bone marrow-derived DC were proved to be able to phagocytize the S. schenckii. The increased expression of CD40, CD80 and CD86 on the surface of S. schenckii-pulsed mouse bone marrow-derived DC was detected by flow cytometer, indicating that the S. schenckii-pulsed mouse bone marrow-derived DC underwent the maturation program. The secretory enhancement of interleukin (IL)-12, but not IL-4, was found in S. schenckii-pulsed mouse bone marrow-derived DC, suggesting the possible activation of T-helper 1 prone immune responses. Furthermore, S. schenckii-pulsed mouse bone marrow-derived DC were demonstrated to be capable of inducing the proliferation of T lymphocytes from BALB/c mice that were pre-sensitized with S. schenckii. Together, all the results implied that dermal DC may participate in the induction of immune responses against S. schenckii infection in sporotrichosis.

Th1 and Th2 cytokines in a self-healing primary pulmonary Aspergillus flavus infection in BALB/c mice

Studies with non-immunocompromised mice have demonstrated that Aspergillus flavus is more virulent than almost all other Aspergillus species. However, the type of immune response this fungus induces in mammals has not been investigated thoroughly. The study was carried out to analyze the sequential pathogenesis of pulmonary A. flavus infection and the role of cytokines in host response in BALB/c mice. Two distinct phases were observed in mice: First, an intense rate of clearance of A. flavus occurred, most likely through recruited neutrophils and the resident alveolar macrophages with concurrent release of pro-inflammatory cytokines and second, fungal and cellular debris were cleaned by recruited monocytes, pro-inflammatory cytokine production rapidly decreased and infection self-healed. The pro-inflammatory cytokine IFN-γ demonstrated an upward trend up to 24h PI followed by a steady decline. The titers of TNF-α (a pro-inflammatory Th1 cytokine) were, however, inversely related to the titers of IL-10 an anti-inflammatory Th2 cytokine. The anti-inflammatory cytokine IL-4 showed slightly decreasing trend between 12 and 48 h PI, beyond that it again reached to the titers observed at 6h PI. The infected mice produced signs of Th1 type response with self healing capabilities.

Exogenous interferon-gamma immunotherapy for invasive fungal infections in kidney transplant patients

The incidence of invasive fungal infections (IFIs) in nonneutropenic solid organ transplant patients is increasing. We report our clinical experience with the use of interferon-gamma (IFN-gamma) immunotherapy in seven renal transplant patients who developed life threatening, disseminated IFIs refractory to conventional antifungal drug therapy. The infections were all microbiologically and histologically proven. The rapid cure of these disseminated infections with exogenous IFN-gamma injections was not associated with impaired kidney allograft function despite the use of liposomal amphotericin B in all cases. No clinical toxicity from the IFN-gamma immunotherapy was seen and no IFI relapsed during long-term follow-up. Our experience is both uncontrolled and in patients with unpredictable fungal infection-related outcomes. However, compared to standard approaches, the accelerated cure of life threatening, disseminated IFIs with 6 weeks of combination antifungal drug therapy and IFN-gamma immunotherapy saved lives, retained allograft function and led to substantial cost savings in this small patient group.

Current research on the immune response to experimental sporotrichosis

Sporotrichosis is often manifested as a chronic granulomatous infection and the monocytes/macrophages play a central role in the host defense system. Surface components of Sporothrix schenckii have been characterized and suggestions have been made as to their possible role in pathogenicity. Ergosterol peroxide, cell-wall compounds (alkali-insoluble fraction-F1 and lipid extract-LEY), and exoantigen from the yeast form of the fungus have been characterized as virulence factors, activating both innate, by cytotoxins linked to the activation of reactive oxygen and nitrogen species (H2O2 and NO), and adaptive immune response to produce cytokines Th1 and Th2 profile. In this study, preliminary results have demonstrated that, in systemic sporotrichosis, TLR-4 triggers the innate immune response, activating an oxidative burst. These data represent the first report of the participation of TLR-4 in murine sporotrichosis, in the presence of lipids from the cell wall of S. schenckii. These results taken together may open new perspectives of study leading to an antifungal agent that could be used to benefit the entire population.

Pathogenesis of mucosal biofilm infections: challenges and progress

Living-tissue biofilms remained unrecognized until very recently, mainly as a result of traditional microbial sampling techniques or histologic processing, which disrupt the spatial organization of the tissue microorganisms. Thus, the biofilm nature of certain mucosal infections was frequently unintentionally missed or disregarded. To a large extent, the study of human tissue biofilms is still in its infancy. However, with the advent of newer methodologies, such as fluorescent in situ hybridization and endoscopic confocal laser scanning microscopy, which combine the identification of microbes with in situ, direct visualization of their relationships with each other and with their substratum, mucosal tissue biofilms are becoming easier to study and, thus, their role in human infections is becoming more apparent. This review summarizes the challenges in the study of tissue biofilms, proposes two inflammation-centered - albeit opposite - pathogenetic models of mucosal tissue biofilm infections and suggests directions for future research and novel therapeutic approaches.

Fungal infections in primary immunodeficiencies

Patients with phagocytic, cellular, combined and other primary immunodeficiencies exhibit immune deficits that confer increased susceptibility to fungal infections. A number of yeasts and moulds, most commonly Candida and Aspergillus but also Cryptococcus, Histoplasma, Paecilomyces, Scedosporium, Trichosporon, Penicillium and other, rarely isolated, fungal organisms, have been variably implicated in causing disease in patients with chronic granulomatous disease, severe combined immunodeficiency, chronic mucocutaneous candidiasis, hyper-IgE syndrome, myeloperoxidase deficiency, leukocyte adhesion deficiency, defects in the interferon-gamma/interleukin-12 axis, DiGeorge syndrome, X-linked hyper-IgM syndrome, Wiskott-Aldrich syndrome and common variable immunodeficiency. Differences in the spectrum of fungal pathogens as well as in the incidence and clinical presentation of the infections may be observed among patients, depending upon different immune disorders. Fungal infections in these individuals may occasionally be the presenting clinical manifestation of a primary immunodeficiency and can cause significant morbidity and potentially fatal outcome if misdiagnosed or mistreated. A high degree of suspicion is needed and establishment of diagnosis should actively be pursued using appropriate imaging, mycological and histological studies. A number of antifungal agents introduced over the last fifteen years, such as the lipid formulations of amphotericin B, the second-generation triazoles, and the echinocandins, increase the options for medical management of these infections. Surgery may also be needed in some cases, while the role of adjunctive immunotherapy has not been systematically evaluated. The low incidence of primary immunodeficiencies in the general population complicates single-center prospective or retrospective clinical studies aiming to address diagnostic or therapeutic issues pertaining to fungal infections in these patients.

Effect of interleukin-10 on the Paracoccidioides brasiliensis killing by gamma-interferon activated human neutrophils

Paracoccidioidomycosis, a deep mycosis endemic in Latin America, is a chronic granulomatous disease caused by the fungus Paracoccidioides brasiliensis. Phagocytic cells play a critical role against this fungus, and several studies have shown the effects of activator and suppressive cytokines on macrophage and monocyte functions. However, studies on polymorphonuclear neutrophils (PMNs), that are the first cells recruited to the infection sites, are scarcer. Thus, the objective of this paper was to assess whether interleukin-10 (IL-10), a potent anti-inflammatory cytokine, is able to block the activity of IFN-gamma-activated human PMNs upon P. brasiliensis intracellular killing, in vitro. The results showed that IFN-gamma-activated PMNs have an effective fungicidal activity against the fungus. This activity was associated with the release of high levels of H(2)O(2), the metabolite involved in phagocytic cells antifungal activities. However, the concomitant incubation of these cells with IFN-gamma and IL-10 significantly blocked IFN-gamma activation. As a consequence, PMNs killing activity and H(2)O(2) release were inhibited. Together, our results show the importance of PMNs exposure to activator or suppressor cytokines in the early stages of paracoccidioidomycosis infection.

Functional characteristics of neutrophils and mononuclear cells from tuberculosis patients stimulated in vitro with heat killed M. tuberculosis

BACKGROUND

The major protective immune response against intracellular bacteria, such as Mycobacterium tuberculosis, is a cell-mediated immunity involving neutrophils (PMNs) and peripheral mononuclear cells (MCs), contributing to the clearance of this microorganism and the resolution of the infection. This study was addressed to evaluate PMNs and MCs for their bactericidal function.

METHODS

The sample comprised 14 tuberculosis (TB) inpatients (HIV-), and 10 healthy controls (HCo). Peripheral PMNs and MCs were separated by Ficoll-Hypaque and cultured in RPMI with or without heat-killed Mycobacterium tuberculosis (HK Mtb). Respiratory burst (RB), CD11b, IL-8 and TNFalpha receptor expression were assessed by flow cytometry in cells undergoing stimulation or not. Presence of IL-8 and TNFalpha in cell culture supernatants was determined by ELISA.

RESULTS

TB patients had a lower RB response than HCo for both cell types (MCs, p <0.05, PMNs, p <0.01) regardless of HK Mtb stimulation. Compared to HCo, PMNs and MCs from TB patients presented a reduced CD11b expression, with the two subject groups showing a decrease in this marker expression following HK. Mtb was added to both cell cultures. Whereas fewer IL-8 and TNFalpha receptors were found when studying MCs and PMNs from TB patients, antigen stimulation significantly raised the expression for both cytokine receptors. Culture supernatants from MCs and PMNs of TB patients contained increased amounts of IL-8 and TNFalpha.

CONCLUSIONS

The present findings may provide some explanation as to the different roles played by PMNs and MCs in TB immunopathology.

Paracoccidioides brasiliensiskilling by IFN-γ, TNF-α and GM-CSF activated human neutrophils: role for oxygen metabolites

Paracoccidioidomycosis, a deep mycosis endemic in Latin America, is a chronic granulomatous disease caused by the fungus Paracoccidioides brasiliensis. Phagocytic cells play a critical role against the fungus and several papers show the effects of activator and suppressive cytokines on macrophage and monocyte functions. However, the studies focusing on polymorphonuclear neutrophils (PMNs) antifungal functions are scarcer. Thus, the objective of the present paper was to assess the capacity of human PMNs to kill virulent P. brasiliensis strain in vitro, before and after priming with different cytokines. Moreover, the involvement of oxygen metabolites in this activity was evaluated. Nonactivated cells failed to exhibit antifungal activity. However, when these cells were IFN-gamma, TNF-alpha or GM-CSF activated, a significative fungicidal activity was detected. This process was significantly inhibited when P. brasiliensis challenge occurred in presence of catalase (CAT - a scavenger of H2O2) and superoxide dismutase (SOD - a scavenger of superoxide anion). From these results it is concluded that cytokines activation is required for P. brasiliensis killing by human PMNs, and that H2O2 and superoxide anion participate as effectors molecules in this process.

Expression of immunomodulatory genes in human monocytes induced by voriconazole in the presence of Aspergillus fumigatus

We assessed the effect of voriconazole (VRC) on the expression and release of selected cytokines and chemokines in the THP-1 human monocytic cell line in response to Aspergillus fumigatus hyphal fragments (HF) by cDNA microarray analysis, reverse transcriptase (RT) PCR, and enzyme-linked immunosorbent assay. Stimulation of THP-1 cells by HF alone caused a significant up-regulation of CCL4 (MIP1B) and CCL16, while CCL2 (MCP1) was down-regulated. By comparison, in the presence of VRC, a large number of genes such as CCL3 (MIP1A), CCL4 (MIP1B), CCL5 (RANTES), CCL7 (MCP3), CCL11 (EOTAXIN), CCL15 (MIP1Delta), CXCL6, and CXCL13 were strongly up-regulated in THP-1 cells challenged by HF, whereas CCL20 (MIP3A) and CCL21 (MIP2) were down-regulated. Among five genes differentially expressed in THP-1 cells, IL12A, IL12B, and IL-16 were down-regulated whereas IL-11 and TGFB1 were significantly up-regulated in the presence of VRC. The inflammation-related genes IFNgamma, IL1R1, and TNFA were also up-regulated in THP-1 cells exposed to HF only in the presence of VRC. RT-PCR of four selected genes validated the results of microarrays. The release of interleukin 1beta (IL-1beta) and IL-12 was significantly increased from monocytes stimulated either by HF alone (P < 0.05) or in the presence of VRC (P < 0.01 and P < 0.05, respectively). In contrast, tumor necrosis factor alpha release from monocytes was enhanced only in the presence of VRC (P < 0.01). The chemokines monocyte chemoattractant protein 1 and macrophage inflammatory protein 1beta were decreased under both conditions (P < 0.01). These results demonstrate that in the presence of VRC, HF induces a more pronounced profile of gene expression in THP-1 cells than HF alone, potentially leading to more-efficient host resistance to A. fumigatus.

Influence of leflunomide on gastrointestinal Candida albicans infection induced in naive and arthritic newborn mice

Mucosal Candida albicans infection in immunocompromised individuals being treated with recently advanced drugs can progress to systemic disease. One such medication applied in patients with rheumatoid arthritis is leflunomide. The object of the present study was to investigate the effect of leflunomide on a model of gastrointestinal (g.i.) C. albicans infection induced in naïve or arthritic mice and on the host resistance to systemic re-infection. Newborn mice were orally inoculated with 1 x 10(5) colony forming units (CFU) of C. albicans and at age of 5 weeks they were treated with 5 mg/kg or 20 mg/kg of leflunomide for 10 consecutive days. Both doses elevated the yeast colonization of the stomach, without the dissemination into the internal organs. This was in parallel with the enhanced delayed type hypersensitivity (DTH) reaction to the yeast. Contrary to that, leflunomide caused a shift to Th2 reactivity by prevalence of IL-4 to IFN-gamma and a suppression of anti-Candida antibody synthesis by a higher dose. It might be supposed that infection increased autoimmune response in arthritic mice, according to stimulated DTH reaction to collagen. The administration of leflunomide during the simultaneous development of infection and arthritis diminished anti-Candida and anti-collagen antibody synthesis compared to untreated infected arthritic mice. The improved survival of arthritic infected animals against severe systemic re-infection was not changed after administration of leflunomide to re-infected arthritic mice. We can conclude that although leflunomide influenced cytokine secretion and suppressed anti-Candida antibody production it neither provokes a progression from gastrointestinal to systemic C. albicans infection nor increases the susceptibility to severe C. albicans re-infection of arthritic mice.

Cytokine profiling of pulmonary aspergillosis

Aspergillus fumigatus is ubiquitous and yet causes invasive, chronic and allergic disease of the lung. Chronic cavitary pulmonary aspergillosis (CCPA) is a slowly destructive form of pulmonary aspergillosis, without immunocompromise. We hypothesized that CCPA cytokine gene polymorphisms would differ from patients with allergic bronchopulmonary aspergillosis (ABPA) and uninfected controls. We have profiled functional cytokine gene polymorphisms for interleukin (IL)-10, IL-15, transforming growth factors (TGF)-beta1, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma in patients with CCPA (n = 24) who were compared with other forms of aspergillosis (mostly ABPA) (n = 15) and with ethnically matched controls (n = 65-330). Results are described with reference to the high-producing genotype in each case. Susceptibility to aspergillosis (all patients compared with normal controls) was associated with higher frequency of the IL-15 +13689*A allele (OR = 2.37, P = 0.0028) and A/A genotype (chi(2) = 10.31, P < 0.001), with a lower frequency of the TNF-alpha-308*A/A genotype (chi(2) = 11.05, P < 0.01). Within the aspergillosis patients, CCPA is associated with lower frequency of the IL-10 -1082*G allele (OR = 0.38, P = 0.0006) and G/G genotype (chi(2) = 22.45, P < 0.001) and with a lower frequency of the TGF-beta1 +869 *T allele (OR +0.42, P < 0.0029) and T/T genotype (chi(2) = 17.82, P < 0.001) compared with non-CCPA patients and normal controls. Patients infected with Aspergillus appear to be higher producers of IL-15, a Th2-promoting cytokine, and lower producers of TNF-alpha, a cytokine central in protective responses. CCPA occurs in patients who are genetically lower producers of both IL-10 and TGF-beta1. As these cytokines are regulatory and anti-inflammatory, CCPA may be a consequence of poor inflammatory response control in the lung.

Manipulating immunity against Aspergillus fumigatus

Efficient response to Aspergillusfumigatus requires different mechanisms. Polymorphonuclear neutrophils (PMNs) are the predominant immune cells in the acute stage of most fungal infections and play a crucial role in determining the type of pathology associated with fungal infections in different clinical settings. Dendritic cells (DC) are able to decode the fungus-associated information and translate it into different T helper (Th) and regulatory (Treg) cell responses. Functionally distinct Treg cells are activated after exposure to Aspergillus conidia. Early in infection, inflammation/Th1 reactivity is controlled by Treg cells suppressing PMNs and the immunogenic program of DC. The levels of IFN-γ produced in this phase set the subsequent adaptive stage by conditioning the indoleamine 2, 3-dioxygenase (IDO)-dependent tolerogenic program of DC and the subsequent activation of tolerogenic Treg cells, which inhibit Th2 cells and prevent allergy to the fungus. Knowledge of the immunopathogenesis of Aspergillus infections may pave the way to promising strategies for immunotherapy.

Cytokines and fungal infections

The very poor outcome of invasive fungal infections (IFI) in patients with haematological malignancies or recipients of haematopoietic stem cell transplantation is largely attributed to their compromised host defence mechanisms. The restoration or augmentation of immune responses in these patients is now considered as one of the cornerstones of effective antifungal therapy. Major advances in the field of experimental immunology have provided insight on the important regulatory role of cytokines in both innate and adaptive immunity to fungal pathogens. Preclinical studies have convincingly demonstrated that immunomodulation with cytokines can enhance the antifungal activity of neutrophils and monocytes/macrophages as well as upregulate protective T-helper type 1 adaptive immune responses. Evidence on the clinical use of cytokines in immunocompromised hosts with IFI is, however, still scant and inconclusive. The present review summarizes experimental and clinical data on the role of cytokines in the immune response to fungal pathogens and on their potential use for prevention or treatment of fungal infections. Implications for future research are also briefly discussed.

Antifungal effect and possible mode of activity of a compound from the marine sponge Dysidea herbacea

OBJECTIVES

Assessment of antifungal activity of a compound isolated from the marine sponge Dysidea herbacea against the fungal pathogens Candida (primarily C. albicans) and Aspergillus (primarily A. fumigatus) species, and investigations of the possible mode of activity of the compound.

METHODS

Freeze dried sponges were extracted with EtOAc-MeOH. Bioassay guided separation was used to identify the active compound. Antifungal activity was assessed in vitro by a modified NCCLS technique. For determination of the possible mode of activity of the compound we tested the effect on fungal cellular morphology (light, scanning and transmission electron microscopy) and possible site of activity in the fungal cells, such as cell membrane (ion leakage kinetics) as well as toxicity (cytotoxicity tests).

RESULTS AND CONCLUSIONS

The active compound was determined to be 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy) phenol. This compound exhibited in vitro activity against the tested fungal pathogens. The experiments on the mode of activity revealed that there are significant changes in fungal cell morphology, as demonstrated by scanning and transmission electron microscopy. The compound, apparently, affects the fungal cell membrane, expressed primarily in leakage of potassium ions from the fungal cells. Two other bromo diphenyl ethers were also found to be active. Further experiments in in vivo models are planned.

Immunogenicity and protective effect of recombinant enolase ofCandidaalbicansin a murine model of systemic candidiasis

Enolase, a 46-kDa glycolytic enzyme, is an immunodominant antigen of the opportunistic pathogen Candida albicans. A recombinant 6 x His-tagged enolase was studied, in conjunction with interleukin-12 (IL-12), as an adjuvant for cytokine induction favouring protection in a murine model of haematogenous candidiasis. Mice immunized with enolase plus IL-12 showed increased antibody titres against enolase, as well as increased median survival time and decreased fungal burden in kidneys, in comparison to non-immunized or IL-12-treated mice. This increased survival was attributable to enolase-induced cell-mediated immunity as it also occurred in B-cell-deficient mice. Enolase immunization stimulated a predominant T-helper-1 (Th1) cytokine pattern in splenic cells and induced production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) by purified CD4+ T cells. However, despite the elevation of immunogenicity, recombinant enolase induced only a modest protection against disseminated candidiasis, suggesting a form of protection likely attributable to the induction of a Th1 cell-mediated immune response.

Polyene and cytokine treatment of experimental aspergillosis

The aim of the present study was to assess the efficacy of amphotericin B (AMB), AMB-intralipid admixture (AMB-IL) or nystatin-IL formulation (Ny-IL) in combination with granulocyte colony stimulating factor (G-CSF) in treatment of experimental murine aspergillosis. ICR mice were immunosuppressed by cyclophosphamide and 3 days later inoculated intravenously (i.v.) with Aspergillus fumigatus. Treatment was initiated 2 h later and administered for 5 consecutive days (polyenes, i.v.; G-CSF, intraperitoneally). Combination therapy, particularly G-CSF with AMB or AMB-IL, significantly increased the survival rate (up to 87.3%) and prolonged the mean survival time (MST) (up to 28.8 days) in comparison to untreated controls (0% survival, MST 6.7 days) and to treatment with polyenes alone (up to 51.5% survival, MST 18.4 days). These data indicate that combination therapy could be beneficial for management of disseminated aspergillosis in humans.

Interleukin-18 and gamma interferon production by oral epithelial cells in response to exposure to Candida albicans or lipopolysaccharide stimulation

Oral candidiasis is a collective name for a group of disorders caused by the dimorphic fungus Candida albicans. Host defenses against C. albicans essentially fall into two categories: specific immune mechanisms and local oral mucosal epithelial cell defenses. Since oral epithelial cells secrete a variety of cytokines and chemokines in response to oral microorganisms and since C. albicans is closely associated with oral epithelial cells as a commensal organism, we wanted to determine whether interleukin-18 (IL-18) and gamma interferon (IFN-gamma) were produced by oral epithelial cells in response to C. albicans infection and lipopolysaccharide (LPS) stimulation. Our results showed that IL-18 mRNA and protein were constitutively expressed by oral epithelial cells and were down-regulated by Candida infections but increased following LPS stimulation. Both C. albicans and LPS significantly decreased pro-IL-18 (24 kDa) levels and increased active IL-18 (18 kDa) levels. This effect was IL-1beta-converting-enzyme dependent. The increase in active IL-18 protein levels promoted the production of IFN-gamma by infected cells. No effect was obtained with LPS. Although produced only at an early stage, secreted IFN-gamma seemed to be a preferential response by oral epithelial cells to C. albicans growth. These results provide additional evidence for the contribution of oral epithelial cells to local (direct contact) and systemic (IL-18 and IFN-gamma production) defense against exogenous stimulation such as C. albicans infection or LPS stimulation.

Non-redundant role of the long pentraxin PTX3 in anti-fungal innate immune response

Pentraxins are a superfamily of conserved proteins that are characterized by a cyclic multimeric structure. The classical short pentraxins, C-reactive protein (CRP) and serum amyloid P component (SAP), are acute-phase proteins produced in the liver in response to inflammatory mediators. Short pentraxins regulate innate resistance to microbes and the scavenging of cellular debris and extracellular matrix components. In contrast, long pentraxins have an unrelated, long amino-terminal domain coupled to the carboxy-terminal pentraxin domain, and differ, with respect to short pentraxins, in their gene organization, chromosomal localization, cellular source, and in their stimuli-inducing and ligand-recognition ability. To investigate the in vivo function of the long pentraxin PTX3, we generated mice deficient in Ptx3 by homologous recombination. Ptx3-null mice were susceptible to invasive pulmonary aspergillosis. Ptx3 binds selected microbial agents, including conidia of Aspergillus fumigatus, and we found that susceptibility of Ptx3-null mice was associated with defective recognition of conidia by alveolar macrophages and dendritic cells, as well as inappropriate induction of an adaptive type 2 response. Thus, the long pentraxin Ptx3 is a secreted pattern-recognition receptor that has a non-redundant role in resistance to selected microbial agents, in particular to the opportunistic fungal pathogen Aspergillus fumigatus.