Hemolymph of triatomines presents fungistatic activity against Cryptococcus neoformans and improves macrophage function through MCP-I/TNF-α increase

Background:

Triatomines are blood-feeding arthropods belonging to the subfamily Triatominae (Hemiptera; Reduviidae), capable of producing immunomodulatory and water-soluble molecules in their hemolymph, such as antimicrobial peptides (AMPs). In this work, we evaluated the antifungal and immunomodulatory activity of the hemolymph of Meccus pallidipennis (MPH) and Rhodnius prolixus (RPH) against Cryptococcus neoformans.

Methods:

We assessed the activity of the hemolymph of both insects on fungal growth by a minimum inhibitory concentration (MIC) assay. Further, RAW 264.7 macrophages were cultivated with hemolymph and challenged with C. neoformans. Then, their phagocytic and killing activities were assessed. The cytokines MCP-1, IFN-γ, TNF-α, IL-10, IL-12, and IL-6 were measured in culture supernatants 4- and 48-hours post-infection.

Results:

Both hemolymph samples directly affected the growth rate of the fungus in a dose-dependent manner. Either MPH or RPH was capable of inhibiting fungal growth by at least 70%, using the lowest dilution (1:20). Treatment of RAW 264.7 macrophages with hemolymph of both insects was capable of increasing the production of MCP-I and TNF-α. In addition, when these cells were stimulated with hemolymph in the presence of C. neoformans, a 2- and a 4-fold increase in phagocytic rate was observed with MPH and RPH, respectively, when compared to untreated cells. For the macrophage killing activity, MPH decreased in approximately 30% the number of viable yeasts inside the cells compared to untreated control; however, treatment with RPH could not reduce the total number of viable yeasts. MPH was also capable of increasing MHC-II expression on macrophages. Regarding the cytokine production, MCP-I and TNF-α, were increased in the supernatant of macrophages treated with both hemolymphs, 4 and 48 hours after stimulation.

Conclusion:

These results suggested that hemolymph of triatomines may represent a source of molecules capable of presenting antifungal and immunomodulatory activity in macrophages during fungal infection.

Reverse vaccinology and subtractive genomics approaches for identifying common therapeutics against Mycobacterium leprae and Mycobacterium lepromatosis

BACKGROUND

Mycobacterium leprae and Mycobacterium lepromatosis are gram-positive bacterial pathogens and the causative agents of leprosy in humans across the world. The elimination of leprosy cannot be achieved by multidrug therapy alone, and highlights the need for new tools and drugs to prevent the emergence of new resistant strains.

METHODS

In this study, our contribution includes the prediction of vaccine targets and new putative drugs against leprosy, using reverse vaccinology and subtractive genomics. Six strains of Mycobacterium leprae and Mycobacterium lepromatosis (4 and 2 strains, respectively) were used for comparison taking Mycobacterium leprae strain TN as the reference genome. Briefly, we used a combined reverse vaccinology and subtractive genomics approach.

RESULTS

As a result, we identified 12 common putative antigenic proteins as vaccine targets and three common drug targets against Mycobacterium leprae and Mycobacterium lepromatosis. Furthermore, the docking analysis using 28 natural compounds with three drug targets was done.

CONCLUSIONS

The bis-naphthoquinone compound Diospyrin (CID 308140) obtained from indigenous plant Diospyros spp. showed the most favored binding affinity against predicted drug targets, which can be a candidate therapeutic target in the future against leprosy.

Synergic effect of simvastatin in combination with amphotericin B against environmental strains of Cryptococcus neoformans from northeastern Brazil: a prospective experimental study

BACKGROUND

Statins are used as cholesterol-lowering drugs and may also have direct antimicrobial effects.

OBJECTIVE

To evaluate synergic interactions between simvastatin and both amphotericin B and fluconazole, against environmental strains of Cryptococcus neoformans isolated from captive birds' droppings.

DESIGNAND SETTING

Experimental study conducted at Federal University of Piauí, Parnaíba, in collaboration with Federal University of Triângulo Mineiro, Uberaba, Brazil.

METHODS

Statin susceptibility tests of Cryptococcus neoformans samples were performed as prescribed in standards. Interactions of simvastatin with amphotericin and fluconazole were evaluated using the checkerboard microdilution method. Presence of these interactions was quantitatively detected through determining the fractional inhibitory concentration index (FICI).

RESULTS

Isolates of Cryptococcus neoformans were obtained from 30 of the 206 samples of dry bird excreta (14.5%) that were collected from pet shops and houses. Ten isolates were selected for susceptibility tests. All of them were susceptible to amphotericin and fluconazole. All presented minimum inhibitory concentration (MIC) > 128 µg/ml and, thus, were resistant in vitro to simvastatin. An in vitro synergic effect was shown through combined testing of amphotericin B and simvastatin, such that six isolates (60%) presented FICI < 0.500. Two isolates showed considerable reductions in MIC, from 1 µg/ml to 0.250 µg/ml. No synergic effect was observed through combining fluconazole and simvastatin.

CONCLUSION

These results demonstrate that simvastatin should be considered to be a therapeutic alternative, capable of potentiating the action of amphotericin B. However, further studies are necessary to clarify the real effect of simvastatin as an antifungal agent.

Cytokine patterns in a prospective cohort of HIV-infected patients with cryptococcal meningitis following initiation of antifungal and antiretroviral therapy

Cryptococcal meningitis (CM) is a life-threatening infection in HIV-infected patients, especially in resource-limited settings. Cytokine patterns in the cerebrospinal fluid (CSF) and sera may be related to clinical outcomes. This study aimed to evaluate cytokine patterns in the CSF and sera of HIV-infected patients with CM as well as the cytokines produced by peripheral blood mononuclear cells (PBMCs) when stimulated with LPS and cryptococcal GXM. CSF and serum levels of IL-2, IL-4, IL-8, IL-10, IL-12p40, IL-17A, INF-γ, TNF-α and CXCL-10 were measured in HIV-infected patients with CM (CM⁺ HIV⁺) at various time points. Cytokine levels were evaluated in the PBMC culture supernatants and the baseline values were compared to those of HIV-infected patients without CM (CM^- HIV⁺) and healthy controls (CM^- HIV^-). CSF cytokine levels at admission (n = 33) were higher than levels among the 23 survivors at week 2, but statistically significant differences were observed for IL-8 and IFN-γ (p<0.05). CSF and serum levels of IL-4 and IL-17A at week 10 (n = 16) were lower than the baseline values, whereas IL-2 levels increased compared to week 2 (p<0.05). At week 16 (n = 15), CSF and serum levels of IL-4, IL-10 and CXCL-10 were decreased compared to the baseline values (p<0.05). PBMCs from CM^- HIV^- individuals produced significantly higher levels of proinflammatory cytokines in response to LPS, with the exception of TNF-α, which showed higher levels among CM⁺ HIV⁺ patients. The PBMCs of CM patients produced higher levels of IL-4 than those of CM^- HIV^- patients in response to GXM stimulation, and levels progressively decreased during treatment (p<0.05). Then, a progressive shift in cytokine expression favoring a Th1 pattern was observed, which is crucial in controlling cryptococcal infection. A better understanding of the protective immune response against Cryptococcus neoformans will help to develop novel strategies to improve the outcomes of patients with cryptococcosis.

Paracoccidioidomycosis in Brazilian Patients With and Without Human Immunodeficiency Virus Infection

Paracoccidioidomycosis (PCM) is endemic to Latin America, where 10 million people may be infected with Paracoccidioides brasiliensis/Paracoccidioides lutzii and 1,600,000 individuals live with human immunodeficiency virus (HIV) infection. An epidemiological overlapping of these infections occurred early in acquired immunodeficiency syndrome era with nearly 180 published cases. This study presents epidemiological, clinical, and outcome profiles for 31 PCM patients with HIV infection diagnosed in a teaching hospital in Brazil, and includes an update of previously reported cases. Medical records were reviewed and data compared with 64 PCM patients without HIV infection. Of the 31 PCM patients with HIV infection, 23 (74.1%) were male, with a median age of 36.7 years, whereas of the 64 PCM, 45 (70.3%) were male, with a median age of 35.1 years. Both groups presented similar proportions for smoking and alcoholism. PCM patients with HIV infection presented more fever, weight loss, and the acute clinical form than the PCM patients who had more mucosal and respiratory involvement characterizing the chronic form. Most PCM patients with HIV infection exhibited overlapping symptoms from both clinical forms with median symptom duration of 4.5 months compared with 8.3 months for the PCM control. Patients received sulfonamides and/or itraconazole for a median of 15.7 and 16.7 months for PCM/HIV-infected and PCM, respectively. Relapses occurred more in PCM (12 [30%]) than PCM/HIV-infected (4 [14.8%]) patients, whose mortality rate was higher (10 [32.8%]) than PCM patients (8 [20%]). The cases of PCM/HIV infection confirm that HIV can interact with some endemic diseases without increasing their frequency, while changing their natural history, clinical presentation, and outcome. The data presented here are in agreement with those observed in other studies.

Cytokine profiles at admission can be related to outcome in AIDS patients with cryptococcal meningitis

Cryptococcal meningitis (CM) remains as common life-threatening AIDS-defining illness mainly in resource-limited settings. Previous reports suggested that baseline cytokine profiles can be associated to fungal burden and clinical outcome. This study aimed to evaluate the baseline cytokine profiles in AIDS patients with CM and its relation with the outcome at weeks 2 and 10. Thirty AIDS patients with CM diagnosed by cerebrospinal fluid (CSF) Cryptococcus neoformans positive culture, India ink stain and cryptococcal antigen test were prospectively evaluated. As controls, 56 HIV-infected patients without CM and 48 non-HIV individuals were included. Baseline CSF and sera levels of IL-2, IL-4, IL-8, IL-10, IL-12p40, IL-17A, INF-γ and TNF-α were measured by ELISA. Of 30 CM patients, 24 (80%) were male, median age of 38.1. The baseline CSF high fungal burden and positive blood culture were associated with a positive CSF culture at week 2 (p = 0.043 and 0.029). Most CSF and sera cytokines presented higher levels in CM patients than control subjects (p < 0.05). CSF levels of IL-8, IL-12p40, IL-17A, TNF-α, INF-γ and sera TNF-α were significantly higher among survivors at weeks 2 and 10 (p < 0.05). Patients with increased intracranial pression exhibited CSF IL-10 high levels and poor outcome at week 10 (p = 0.032). Otherwise, baseline CSF log10 IFN-γ and IL-17A were negatively correlated with fungal burden (r = -0.47 and -0.50; p = 0.0175 and 0.0094, respectively). The mortality rate was 33% (10/30) at week 2 and 57% (17/30) at week 10. The severity of CM and the advanced immunodeficiency at admission were related to a poor outcome in these patients. Otherwise, the predominant Th1 cytokines profile among survivors confirms its pivotal role to infection control and would be a prognostic marker in cryptococcal meningitis.

Clinical, epidemiological and outcome features of patients with cryptococcosis in Uberaba, Minas Gerais, Brazil

Nearly one million of cryptococcosis cases occur yearly around the world, involving mainly HIV-infected patients who are not receiving antiretroviral therapy (ART) or present poor adherence. This study aims to evaluate epidemiological, clinical and outcome aspects of patients with cryptococcosis from 1998-2010. Patients were prospectively recruited, and their medical and laboratory records were reviewed. A total of 131 cases were included, and of these, 119 (90.83%) had AIDS, 4 received a renal transplant, 2 presented systemic lupus erythematosus and 6 (4.6%) were apparently immunocompetent. Ninety-one (69.46%) were men, and the median age was 38.7 years. Cryptococcal meningitis (CM) was diagnosed in 103 (78.62%), whereas 28 (21.38%) had cryptococcal infection in other sites. Of patients with CM, 94 (91.26%) had AIDS being cryptococcosis the first defining illness in 61 (64.9%), while 37 (60.65%) of them presented simultaneously both diagnosis. Headache, altered mental status, papilledema and seizures at admission were significatively associated with a poor outcome. Of 163 different isolates, 155 (95.09%) were Cryptococcus neoformans and eight (4.88%) Cryptococcus gattii. Antifungal therapy was warranted in 8 (87.4%) patients with CM, but 46 (51.1%) died during the first days or weeks. Of 28 patients without CM, 21 (75%) received treatment, but 6 (28.6%) died. The poor outcome among this case series was similar to that reported from other developing countries, but it is paradoxal in Brazil where the ART is at free disposal in the public health services. Despite, at least 60-70% of patients present advanced immunosuppression when they receive the AIDS diagnosis.