Influenza A Virus as a Predisposing Factor for Cryptococcosis

Interactions among microorganisms open up a new world for anti-infectious therapy

The human microbiome, containing bacteria, fungi, and viruses, is a community that coexists peacefully with humans most of the time, but with the potential to cause disease under certain conditions. When the environment changes or certain stimuli are received, microbes may interact with each other, causing or increasing the severity of disease in a host. With the appropriate methods, we can make these microbiota work for us, creating new applications for human health. This review discusses the wide range of interactions between microorganisms that result in an increase in susceptibility to, severity of, and mortality of diseases, and also briefly introduces how microorganisms interact with each other directly or indirectly. The study of microbial interactions and their mechanisms has revealed a new world of treatments for infectious disease. The regulation of the balance between intestinal flora, the correct application of probiotics, and the development of effective drugs by symbiosis all demonstrate the great contributions of the microbiota to human health and its powerful potential value. Consequently, the study of interactions between microorganisms plays an essential role in identifying the causes of diseases and the development of treatments.

Immune evasion by Cryptococcus gattii in vaccinated mice coinfected with C. neoformans

Cryptococcus neoformans and C. gattii, the etiologic agents of cryptococcosis, cause over 100,000 deaths worldwide every year, yet no cryptococcal vaccine has progressed to clinical trials. In preclinical studies, mice vaccinated with an attenuated strain of C. neoformans deleted of three cryptococcal chitin deacetylases (Cn-cda1Δ2Δ3Δ) were protected against a lethal challenge with C. neoformans strain KN99. While Cn-cda1Δ2Δ3Δ extended the survival of mice infected with C. gattii strain R265 compared to unvaccinated groups, we were unable to demonstrate fungal clearance as robust as that seen following KN99 challenge. In stark contrast to vaccinated mice challenged with KN99, we also found that R265-challenged mice failed to induce the production of protection-associated cytokines and chemokines in the lungs. To investigate deficiencies in the vaccine response to R265 infection, we developed a KN99-R265 coinfection model. In unvaccinated mice, the strains behaved in a manner which mirrored single infections, wherein only KN99 disseminated to the brain and spleen. We expanded the coinfection model to Cn-cda1Δ2Δ3Δ-vaccinated mice. Fungal burden, cytokine production, and immune cell infiltration in the lungs of vaccinated, coinfected mice were indicative of immune evasion by C. gattii R265 as the presence of R265 neither compromised the immunophenotype established in response to KN99 nor inhibited clearance of KN99. Collectively, these data indicate that R265 does not dampen a protective vaccine response, but rather suggest that R265 remains largely undetected by the immune system.

Secondary Streptococcus pneumoniae infection increases morbidity and mortality during murine cryptococcosis

Microorganisms that cause pneumonia and translocate to the central nervous system (CNS) are responsible for high mortality worldwide. The fungus Cryptococcus gattii (Cg) and the bacteria Streptococcus pneumoniae (Sp) target the same infection organs. This study aimed to investigate the consequences of secondary Sp infection during murine cryptococcosis. Mice infected with Sp after Cg showed significantly increased lethality and a drop in scores of motor behaviour, neuropsychiatric status and autonomous function. Previous Cg infection favoured Sp multiplication in the lungs, causing intense inflammation and necrosis, with further increased bacterial translocation to the spleen, liver and brain. This phenotype was associated with increased platelet-activating factor receptor (Pafr) gene expression, reduced M1 macrophage recruitment, and high levels of proinflammatory mediators. Strategies to overcome early mortality (i.e., infection of Pafr-/- mice, treatment with IL-1 inhibitor or corticoid) were insufficient to revert this phenotype. These results suggest that Cg infection makes the lung microenvironment favourable for Sp colonization and dissemination. Altogether, it leads to an exacerbated and ineffective inflammatory response, decisive for the increased morbidity and mortality during coinfection. In conclusion, our results highlight the importance of more studies addressing coinfections and their consequences in the host, aiming to establish more effective therapeutical strategies.

Dysregulated pulmonary inflammatory responses exacerbate the outcome of secondary aspergillosis following influenza

IMPORTANCE

Severe influenza is a risk factor for fatal invasive pulmonary aspergillosis; however, the mechanistic basis for the lethality is unclear. Utilizing an influenza-associated pulmonary aspergillosis (IAPA) model, we found that mice infected with influenza A virus followed by Aspergillus fumigatus had 100% mortality when superinfected during the early stages of influenza but survived at later stages. While superinfected mice had dysregulated pulmonary inflammatory responses compared to controls, they had neither increased inflammation nor extensive fungal growth. Although influenza-infected mice had dampened neutrophil recruitment to the lungs following subsequent challenge with A. fumigatus, influenza did not affect the ability of neutrophils to clear the fungi. Our data suggest that the lethality seen in our model of IAPA is multifactorial with dysregulated inflammation being a greater contributor than uncontrollable microbial growth. If confirmed in humans, our findings provide a rationale for clinical studies of adjuvant anti-inflammatory agents in the treatment of IAPA.

Proteasome inhibition as a therapeutic target for the fungal pathogen Cryptococcus neoformans

The current therapeutic challenges for treating fungal diseases demand new approaches and new drugs. A promising strategy involves combination therapy with agents of distinct mechanisms of action to increase fungicidal activity and limit the impact of mutations leading to resistance. In this study, we evaluated the antifungal potential of bortezomib by examining the inhibition of proteasome activity, cell proliferation, and capsule production by Cryptococcus neoformans, the causative agent of fungal meningoencephalitis. Chemical genetic screens with collections of deletion mutants identified potential druggable targets for combination therapy with bortezomib. In vitro assays of combinations of bortezomib with flucytosine, chlorpromazine, bafilomycin A1, copper sulfate, or hydroxyurea revealed antifungal effects against C. neoformans. Furthermore, combination treatment with bortezomib and flucytosine in a murine inhalation model of cryptococcosis resulted in the improvement of neurological functions and reduced fungal replication and dissemination, leading to a delay in disease progression. This study therefore highlights the utility of chemical genetic screens to identify new therapeutic approaches as well as the antifungal potential of proteasome inhibition. IMPORTANCE Fungal diseases of humans are difficult to treat, and there is a clear need for additional antifungal drugs, better diagnostics, effective vaccines, and new approaches to deal with emerging drug resistance. Fungi are challenging to control because they share many common biochemical functions with their mammalian hosts and it is therefore difficult to identify fungal-specific targets for drug development. One approach is to employ existing antifungal drugs in combination with agents that target common cellular processes at levels that are (ideally) not toxic for the host. We pursued this approach in this study by examining the potential of the clinically approved proteasome inhibitor bortezomib to influence the proliferation and virulence of Cryptococcus neoformans. We found that the combination of bortezomib with the anti-cryptococcal drug flucytosine improved the survival of infected mice, thus demonstrating the potential of this strategy for antifungal therapy.

The Th2 Response and Alternative Activation of Macrophages Triggered by Strongyloides venezuelensis Is Linked to Increased Morbidity and Mortality Due to Cryptococcosis in Mice

Cryptococcosis is a systemic mycosis that causes pneumonia and meningoencephalitis. Strongyloidiasis is a chronic gastrointestinal infection caused by parasites of the genus Strongyloides. Cryptococcosis and strongyloidiasis affect the lungs and are more prevalent in the same world regions, i.e., Africa and tropical countries such as Brazil. It is undeniable that those coincidences may lead to the occurrence of coinfections. However, there are no studies focused on the interaction between Cryptococcus spp. and Strongyloides spp. In this work, we aimed to investigate the interaction between Strongyloides venezuelensis (Sv) and Cryptococcus gattii (Cg) in a murine coinfection model. Murine macrophage exposure to Sv antigens reduced their ability to engulf Cg and produce reactive oxygen species, increasing the ability of fungal growth intracellularly. We then infected mice with both pathogens. Sv infection skewed the host's response to fungal infection, increasing lethality in a murine coinfection model. In addition to increased NO levels and arginase activity, coinfected mice presented a classic Th2 anti-Sv response: eosinophilia, higher levels of alternate activated macrophages (M2), increased concentrations of CCL24 and IL-4, and lower levels of IL-1β. This milieu favored fungal growth in the lungs with prominent translocation to the brain, increasing the host's tissue damage. In conclusion, our data shows that primary Sv infection promotes Th2 bias of the pulmonary response to Cg-infection and worsens its pathological outcomes.

Staphylococcus aureus triggers a protective inflammatory response against secondary Cryptococcus gattii infection in a murine model

Prior infections can provide protection or enhance susceptibility to a subsequent infection through microorganism's interaction or host immunomodulation. Staphylococcus aureus (SA) and Cryptococcus gattii (CG) cause lungs infection, but it is unclear how they interact in vivo. This study aimed to study the effects of the primary SA lung infection on secondary cryptococcosis caused by CG in a murine model. The mice's survival, fungal burden, behavior, immune cells, cytokines, and chemokines were quantified to evaluate murine cryptococcosis under the influence of a previous SA infection. Further, fungal-bacterial in vitro interaction was studied in a culture medium and a phagocytosis assay. The primary infection with SA protects animals from the subsequent CG infection by reducing lethality, improving behavior, and impairing the fungal proliferation within the host. This phenotype was associated with the proinflammatory antifungal host response elicited by the bacteria in the early stage of cryptococcosis. There was no direct inhibition of CG by SA, although the phagocytic activity of macrophages was reduced. Identifying mechanisms involved in this protection may lead to new approaches for preventing and treating cryptococcosis.

Dysregulated Pulmonary Inflammatory Responses Exacerbate the Outcome of Secondary Aspergillosis Following Influenza

Inhalation of airborne conidia of the ubiquitous fungus Aspergillus fumigatus commonly occurs but invasive aspergillosis is rare except in profoundly immunocompromised persons. Severe influenza predisposes patients to invasive pulmonary aspergillosis by mechanisms that are poorly defined. Using a post-influenza aspergillosis model, we found that superinfected mice had 100% mortality when challenged with A. fumigatus conidia on days 2 and 5 (early stages) of influenza A virus infection but 100% survival when challenged on days 8 and 14 (late stages). Influenza-infected mice superinfected with A. fumigatus had increased levels of the pro-inflammatory cytokines and chemokines IL-6, TNFα, IFNβ, IL-12p70, IL-1α, IL-1β, CXCL1, G-CSF, MIP-1α, MIP-1β, RANTES and MCP-1. Surprisingly, on histopathological analysis, superinfected mice did not have greater lung inflammation compared with mice infected with influenza alone. Mice infected with influenza had dampened neutrophil recruitment to the lungs following subsequent challenge with A. fumigatus , but only if the fungal challenge was executed during the early stages of influenza infection. However, influenza infection did not have a major effect on neutrophil phagocytosis and killing of A. fumigatus conidia. Moreover, minimal germination of conidia was seen on histopathology even in the superinfected mice. Taken together, our data suggest that the high mortality rate seen in mice during the early stages of influenza-associated pulmonary aspergillosis is multifactorial, with a greater contribution from dysregulated inflammation than microbial growth.

Importance

Severe influenza is a risk factor for fatal invasive pulmonary aspergillosis; however, the mechanistic basis for the lethality is unclear. Utilizing an influenza-associated pulmonary aspergillosis (IAPA) model, we found that mice infected with influenza A virus followed by A. fumigatus had 100% mortality when superinfected during the early stages of influenza but survived at later stages. While superinfected mice had dysregulated pulmonary inflammatory responses compared to controls, they had neither increased inflammation nor extensive fungal growth. Although influenza-infected mice had dampened neutrophil recruitment to the lungs following subsequent challenge with A. fumigatus , influenza did not affect the ability of neutrophils to clear the fungi. Our data suggest that the lethality seen in our model IAPA is multifactorial with dysregulated inflammation being a greater contributor than uncontrollable microbial growth. If confirmed in humans, our findings provide a rationale for clinical studies of adjuvant anti-inflammatory agents in the treatment of IAPA.

Lidocaine inhibits influenza a virus replication by up-regulating IFNα4 via TBK1-IRF7 and JNK-AP1 signaling pathways

Influenza A viruses (IAV), significant respiratory pathogenic agents, cause seasonal epidemics and global pandemics in intra- and interannual cycles. Despite effective therapies targeting viral proteins, the continuous generation of drug-resistant IAV strains is challenging. Therefore, exploring novel host-specific antiviral treatment strategies is urgently needed. Here, we found that lidocaine, widely used for local anesthesia and sedation, significantly inhibited H1N1(PR8) replication in macrophages. Interestingly, its antiviral effect did not depend on the inhibition of voltage-gated sodium channels (VGSC), the main target of lidocaine for anesthesia. Lidocaine significantly upregulated early IFN-I, interferon α4 (IFNα4) mRNA, and protein levels, but not those of early IFNβ in mouse RAW 264.7 cell line and human THP-1 derived macrophages. Knocking out IFNα4 by CRISPR-Cas9 partly reversed lidocaine's inhibition of PR8 replication in macrophages. Mechanistically, lidocaine upregulated IFNα4 by activating TANK-binding kinase 1 (TBK1)-IRF7 and JNK-AP1 signaling pathways. These findings indicate that lidocaine has an incredible antiviral potential by enhancing IFN-I signaling in macrophages. In conclusion, our results indicate the potential auxiliary role of lidocaine for anti-influenza A virus therapy and even for anti-SARS-CoV-2 virus therapy, especially in the absence of a specific medicine.

The Dynamics of Cryptococcus neoformans Cell and Transcriptional Remodeling during Infection

The phenotypic plasticity of Cryptococcus neoformans is widely studied and demonstrated in vitro, but its influence on pathogenicity remains unclear. In this study, we investigated the dynamics of cryptococcal cell and transcriptional remodeling during pulmonary infection in a murine model. We showed that in Cryptococcus neoformans, cell size reduction (cell body ≤ 3 µm) is important for initial adaptation during infection. This change was associated with reproductive fitness and tissue invasion. Subsequently, the fungus develops mechanisms aimed at resistance to the host’s immune response, which is determinant for virulence. We investigated the transcriptional changes involved in this cellular remodeling and found an upregulation of transcripts related to ribosome biogenesis at the beginning (6 h) of infection and a later (10 days) upregulation of transcripts involved in the inositol pathway, energy production, and the proteasome. Consistent with a role for the proteasome, we found that its inhibition delayed cell remodeling during infection with the H99 strain. Altogether, these results further our understanding of the infection biology of C. neoformans and provide perspectives to support therapeutic and diagnostic targets for cryptococcosis.

Cryptococcosis among hospitalised patients with COVID-19: A multicentre research network study

It is unclear if there is an association between COVID-19 and cryptococcosis. Therefore, this study aimed to describe the clinical features, risk factors, and outcomes associated with cryptococcosis in hospitalised patients with COVID-19. The objectives of this study were to determine the incidence of and examine factors associated with cryptococcosis after a diagnosis of COVID-19. We used TriNetX to identify and sort patients 18 years and older hospitalised with COVID-19 into two cohorts based on the presence or absence of a diagnosis of cryptococcosis following diagnosis of COVID-19. Outcomes of interest included the incidence of cryptococcosis following the diagnosis of COVID-19 as well as the proportion of patients in each group who had underlying comorbidities, received immunomodulatory therapy, required ICU admission or mechanical ventilation (MV), or died. Propensity score matching was used to adjust for confounding. Among 212,479 hospitalised patients with COVID-19, 65 developed cryptococcosis. The incidence of cryptococcosis following COVID-19 was 0.022%. Patients with cryptococcosis were more likely to be male and have underlying comorbidities. Among cases, 32% were people with HIV. Patients with cryptococcosis were more likely to have received tocilizumab (p < .0001) or baricitinib (p < .0001), but not dexamethasone (p = .0840). ICU admission (38% vs 29%), MV (23% vs 11%), and mortality (36% vs 14%) were significantly higher among patients with cryptococcosis. Mortality remained elevated after adjusted propensity score matching. Cryptococcosis occurred most often in hospitalised patients with COVID-19 who had traditional risk factors, comparable to findings in patients without COVID-19. Cryptococcosis was associated with increased ICU admission, MV, and mortality.

COVID-19-associated Cryptococcus infection (CACI): a review of literature and clinical pearls

Background

Cryptococcal infection has been increasingly reported in patients with COVID-19 infection, but the epidemiological factors, presentation, diagnostic certainty, and outcome have not been well-described.

Methods

We reviewed the published cases of COVID-19-associated Cryptococcus infections (CACI) to shed the light on the burden of this infection.

Results

We identified 13 patients with confirmed cryptococcal infection. Cryptococcus infection was primarily seen in patients with severe COVID-19 disease who received corticosteroids therapy and admitted to the intensive care unit. Pulmonary CACI was the most common reported infection followed by cryptococcal meningitis.

Conclusion

In light of the high mortality rate, clinicians should maintain a high clinical suspicion of CACI in critically ill patients.

Pathogenesis of Respiratory Viral and Fungal Coinfections

Individuals suffering from severe viral respiratory tract infections have recently emerged as "at risk" groups for developing invasive fungal infections. Influenza virus is one of the most common causes of acute lower respiratory tract infections worldwide. Fungal infections complicating influenza pneumonia are associated with increased disease severity and mortality, with invasive pulmonary aspergillosis being the most common manifestation. Strikingly, similar observations have been made during the current coronavirus disease 2019 (COVID-19) pandemic. The copathogenesis of respiratory viral and fungal coinfections is complex and involves a dynamic interplay between the host immune defenses and the virulence of the microbes involved that often results in failure to return to homeostasis. In this review, we discuss the main mechanisms underlying susceptibility to invasive fungal disease following respiratory viral infections. A comprehensive understanding of these interactions will aid the development of therapeutic modalities against newly identified targets to prevent and treat these emerging coinfections.

The Salivary Microbiota, Cytokines, and Metabolome in Patients with Ankylosing Spondylitis Are Altered and More Proinflammatory than Those in Healthy Controls

The pathogenesis of ankylosing spondylitis (AS) remains unclear but appears to be associated with heredity and the environment. The mouth links the external environment to the gut and lungs. In the present study, compared to that observed in healthy controls (HCs), AS saliva was depleted of Bacilli such as Streptococcus, enriched with Clostridia such as Veillonellaceae, and enriched with opportunistic pathogens from Proteobacteria such as Brucella spp. and Campylobacter concisus. AS saliva was enriched with 16 cytokines related to inflammation, such as soluble IL-6 receptor α (sIL-6Rα), interleukin 2 (IL-2), IL-10, IL-11, IL-12p40, IL-12p70, IL-20, IL-26, IL-27, IL-28A, IL-29, alpha 2 interferon (IFN-α2), IFN-β, and matrix metalloproteinase 3 (MMP-3). AS saliva was also enriched with hazardous compounds, such as cadaverine and putrescine. AS-altered salivary bacteria, compounds, and cytokines are closely linked with disease indicators. Oral cleaning reduced the levels of proinflammatory cytokines and hazardous compounds in AS saliva compared with HC saliva. AS saliva induced the production of more proinflammatory cytokines, such as IL-12p70 and IL-8, by THP-1 monocyte-derived macrophages, than did HC saliva. The results highlight the importance of salivary microbes, cytokines, and compounds in the development and treatment of AS and provide new ideas for the pathogenesis and treatment of AS.

IMPORTANCE Ankylosing spondylitis (AS) affects as much as 0.32% of the population in some districts and causes work disability in one-third of these patients. Microbes are considered to play important roles in AS pathogenesis, and the mouth links the environment to the lungs and the gut. Our results showed that opportunistic pathogens such as Brucella and Campylobacter are enriched in the saliva of AS patients with ankylosing spondylitis. In addition, proinflammatory cytokines and hazardous materials such as putrescine were also enriched in the saliva of AS patients.[AQ1 sentence edit] Interestingly, the opportunistic pathogens and hazardous materials detected in the saliva of AS patients were associated with disease indexes. The saliva of AS patients was shown to induce immune cells to secrete proinflammatory cytokines in vitro. Reducing the levels of salivary microbes can significantly reduce the hazardous materials present in the saliva of AS patients. Our results provide a new perspective on the potential role of salivary microbes, cytokines, and hazardous compounds in the pathogenesis and treatment of AS.

N-acetylcysteine reduces amphotericin B deoxycholate nephrotoxicity and improves the outcome of murine cryptococcosis

Cryptococcosis is a life-threatening fungal infection, and its current treatment is toxic and subject to resistance. Drug repurposing represents an interesting approach to find drugs to reduce the toxicity of antifungals. In this study, we evaluated the combination of N-acetylcysteine (NAC) with amphotericin B (AMB) for the treatment of cryptococcosis. We examined the effects of NAC on fungal morphophysiology and on the macrophage fungicidal activity 3 and 24 hours post inoculation. The therapeutic effects of NAC combination with AMB were investigated in a murine model with daily treatments regimens. NAC alone reduced the oxidative burst generated by AMB in yeast cells, but did not inhibit fungal growth. The combination NAC + AMB decreased capsule size, zeta potential, superoxide dismutase activity and lipid peroxidation. In macrophage assays, NAC + AMB did not influence the phagocytosis, but induced fungal killing with different levels of oxidative bursts when compared to AMB alone: there was an increased reactive oxygen species (ROS) after 3 hours and reduced levels after 24 hours. By contrast, ROS remained elevated when AMB was tested alone, demonstrating that NAC reduced AMB oxidative effects without influencing its antifungal activity. Uninfected mice treated with NAC + AMB had lower concentrations of serum creatinine and glutamate-pyruvate transaminase in comparison to AMB. The combination of NAC + AMB was far better than AMB alone in increasing survival and reducing morbidity in murine-induced cryptococcosis, leading to reduced fungal burden in lungs and brain and also lower concentrations of pro-inflammatory cytokines in the lungs. In conclusion, NAC + AMB may represent an alternative adjuvant for the treatment of cryptococcosis.

Posaconazole for prevention of invasive pulmonary aspergillosis in critically ill influenza patients (POSA-FLU): a randomised, open-label, proof-of-concept trial

PURPOSE

Influenza-associated pulmonary aspergillosis (IAPA) is a frequent complication in critically ill influenza patients, associated with significant mortality. We investigated whether antifungal prophylaxis reduces the incidence of IAPA.

METHODS

We compared 7 days of intravenous posaconazole (POS) prophylaxis with no prophylaxis (standard-of-care only, SOC) in a randomised, open-label, proof-of-concept trial in patients admitted to an intensive care unit (ICU) with respiratory failure due to influenza (ClinicalTrials.gov, NCT03378479). Adult patients with PCR-confirmed influenza were block randomised (1:1) within 10 days of symptoms onset and 48 h of ICU admission. The primary endpoint was the incidence of IAPA during ICU stay in patients who did not have IAPA within 48 h of ICU admission (modified intention-to-treat (MITT) population).

RESULTS

Eighty-eight critically ill influenza patients were randomly allocated to POS or SOC. IAPA occurred in 21 cases (24%), the majority of which (71%, 15/21) were diagnosed within 48 h of ICU admission, excluding them from the MITT population. The incidence of IAPA was not significantly reduced in the POS arm (5.4%, 2/37) compared with SOC (11.1%, 4/36; between-group difference 5.7%; 95% CI - 10.8 to 21.7; p = 0.32). ICU mortality of early IAPA was high (53%), despite rapid antifungal treatment.

CONCLUSION

The higher than expected incidence of early IAPA precludes any definite conclusion on POS prophylaxis. High mortality of early IAPA, despite timely antifungal therapy, indicates that alternative management strategies are required. After 48 h, still 11% of patients developed IAPA. As these could benefit from prophylaxis, differentiated strategies are likely needed to manage IAPA in the ICU.

Gut mycobiota alterations in patients with COVID-19 and H1N1 infections and their associations with clinical features

The relationship between gut microbes and COVID-19 or H1N1 infections is not fully understood. Here, we compared the gut mycobiota of 67 COVID-19 patients, 35 H1N1-infected patients and 48 healthy controls (HCs) using internal transcribed spacer (ITS) 3-ITS4 sequencing and analysed their associations with clinical features and the bacterial microbiota. Compared to HCs, the fungal burden was higher. Fungal mycobiota dysbiosis in both COVID-19 and H1N1-infected patients was mainly characterized by the depletion of fungi such as Aspergillus and Penicillium, but several fungi, including Candida glabrata, were enriched in H1N1-infected patients. The gut mycobiota profiles in COVID-19 patients with mild and severe symptoms were similar. Hospitalization had no apparent additional effects. In COVID-19 patients, Mucoromycota was positively correlated with Fusicatenibacter, Aspergillus niger was positively correlated with diarrhoea, and Penicillium citrinum was negatively correlated with C-reactive protein (CRP). In H1N1-infected patients, Aspergillus penicilloides was positively correlated with Lachnospiraceae members, Aspergillus was positively correlated with CRP, and Mucoromycota was negatively correlated with procalcitonin. Therefore, gut mycobiota dysbiosis occurs in both COVID-19 patients and H1N1-infected patients and does not improve until the patients are discharged and no longer require medical attention.

Lv et al. associate the gut mycobiota with clinical features and the bacterial microbiota by comparing COVID-19 patients to those infected with H1N1 and healthy controls. They find that gut mycobiota dysbiosis occurs in both COVID-19 patients and those infected with H1N1 and that it does not improve until patients no longer require medical attention, providing insights into a better healthcare guideline.

Hypervirulence and cross-resistance to a clinical antifungal are induced by an environmental fungicide in Cryptococcus gattii

The increasing human population requires ongoing efforts in food production. This is frequently associated with an increased use of agrochemicals, leading to environmental contamination and altering microbial communities, including human fungal pathogens that reside in the environment. Cryptococcus gattii is an environmental yeast and is one of the etiological agents of cryptococcosis. Benomyl (BEN) is a broad-spectrum fungicide used on several crops. To study the effects of agrochemicals on fungal pathogens, we first evaluated the susceptibility of C. gattii to BEN and the interactions with clinical antifungals. Antagonistic interaction between BEN and fluconazole was seen and was strain- and concentration-dependent. We then induced BEN-resistance by culturing strains in increasing drug concentrations. One strain demonstrated to be more resistant and showed increased multidrug efflux pump gene (MDR1) expression and increased rhodamine 6G efflux, leading to cross-resistance between BEN and fluconazole. Morphologically, BEN-adapted cells had a reduced polysaccharide capsule; an increased surface/volume ratio; increased growth rate in vitro and inside macrophages and also higher ability in crossing an in vitro model of blood-brain-barrier. BEN-adapted strain demonstrated to be hypervirulent in mice, leading to severe symptoms of cryptococcosis, early mortality and higher fungal burden in the organs, particularly the brain. The parental strain was avirulent in murine model. In vivo cross-resistance between BEN and fluconazole was observed, with mice infected with the adapted strain unable to present any improvement in survival and behavior when treated with this antifungal. Furthermore, BEN-adapted cells cultured in drug-free media maintained the hypervirulent and cross-resistant phenotype, suggesting a persistent effect of BEN on C. gattii. In conclusion, exposure to BEN induces cross-resistance with fluconazole and increases the virulence of C. gattii. Altogether, our results indicate that agrochemicals may lead to unintended consequences on non-target species and this could result in severe healthy problems worldwide.

17-β-Estradiol increases macrophage activity through activation of the G-protein-coupled estrogen receptor and improves the response of female mice to Cryptococcus gattii

Cryptococcus gattii (Cg) is one of the agents of cryptococcosis, a severe systemic mycosis with a higher prevalence in men than women, but the influence of the female sex hormone, 17-β-estradiol (E2), on cryptococcosis remains unclear. Our study shows that female mice presented delayed mortality, increased neutrophil recruitment in bronchoalveolar lavage fluid, and reduced fungal load after 24 hr of infection compared to male and ovariectomised female mice (OVX). E2 replacement restored OVX female survival. Female macrophages have more efficient fungicidal activity, which was increased by E2 and reversed by the antagonist of G-protein-coupled oestrogen receptor (GPER), which negatively modulates PI3K activation. Furthermore, E2 induces a reduction in Cg cell diameter, cell charge, and antioxidant peroxidase activity. In conclusion, female mice present improved control of Cg infection, and GPER is important for E2 modulation of the female response.

Viral infection triggers interferon-induced expulsion of live Cryptococcus neoformans by macrophages

Cryptococcus neoformans is an opportunistic human pathogen, which causes serious disease in immunocompromised hosts. Infection with this pathogen is particularly relevant in HIV+ patients, where it leads to around 200,000 deaths per annum. A key feature of cryptococcal pathogenesis is the ability of the fungus to survive and replicate within the phagosome of macrophages, as well as its ability to be expelled from host cells via a novel non-lytic mechanism known as vomocytosis. Here we show that cryptococcal vomocytosis from macrophages is strongly enhanced by viral coinfection, without altering phagocytosis or intracellular proliferation of the fungus. This effect occurs with distinct, unrelated human viral pathogens and is recapitulated when macrophages are stimulated with the anti-viral cytokines interferon alpha or beta (IFNα or IFNβ). Importantly, the effect is abrogated when type-I interferon signalling is blocked, thus underscoring the importance of type-I interferons in this phenomenon. Lastly, our data help resolve previous, contradictory animal studies on the impact of type I interferons on cryptococcal pathogenesis and suggest that secondary viral stimuli may alter patterns of cryptococcal dissemination in the host.

Central Nervous System Cryptococcal Infections in Non-HIV Infected Patients

Central nervous system (CNS) cryptococcosis in non-HIV infected patients affects solid organ transplant (SOT) recipients, patients with malignancy, rheumatic disorders, other immunosuppressive conditions and immunocompetent hosts. More recently described risks include the use of newer biologicals and recreational intravenous drug use. Disease is caused by Cryptococcus neoformans and Cryptococcus gattii species complex; C. gattii is endemic in several geographic regions and has caused outbreaks in North America. Major virulence determinants are the polysaccharide capsule, melanin and several ‘invasins’. Cryptococcal plb1, laccase and urease are essential for dissemination from lung to CNS and crossing the blood–brain barrier. Meningo-encephalitis is common but intracerebral infection or hydrocephalus also occur, and are relatively frequent in C. gattii infection. Complications include neurologic deficits, raised intracranial pressure (ICP) and disseminated disease. Diagnosis relies on culture, phenotypic identification methods, and cryptococcal antigen detection. Molecular methods can assist. Preferred induction antifungal therapy is a lipid amphotericin B formulation (amphotericin B deoxycholate may be used in non-transplant patients) plus 5-flucytosine for 2–6 weeks depending on host type followed by consolidation/maintenance therapy with fluconazole for 12 months or longer. Control of raised ICP is essential. Clinicians should be vigilant for immune reconstitution inflammatory syndrome.

A Higher Rate of Pulmonary Fungal Infection in Chronic Obstructive Pulmonary Disease Patients with Influenza in a Large Tertiary Hospital

BACKGROUND

Influenza is considered a self-limiting disease. However, in patients with chronic obstructive pulmonary disease (COPD), it may result in serious outcomes during the flu season.

OBJECTIVES

The aims of this retrospective study were to explore the characteristics of hospitalized patients with COPD complicated by influenza and determine the factors affecting the prognosis of these patients.

METHOD

Demographic and clinical data were collected for 278 patients totally from the West China Hospital between January 1, 2016 and February 28, 2018.

RESULTS

Among the patients with influenza, the positive fungal culture rate, and the rates of antifungal drug and systemic corticosteroids use were higher for those with COPD than for those without COPD. Respiratory failure was more common in patients with influenza and COPD than in patients with influenza only, while the proportion of severe cases was higher among the former than among the latter. Among the patients with COPD, the positive fungal culture rate, particularly for Aspergillus, and the rate of systemic corticosteroids use were higher for those with influenza than for those without influenza. Multivariate analysis revealed that a COPD history of >20 years and smoking for >20 pack-years were independent factors for susceptibility of COPD patients to influenza.

CONCLUSIONS

Aspergillus infection seems to be more common in patients with influenza and COPD. In addition, COPD complicated by influenza during the seasonal outbreak can easily progress to a severe disease state. Heavy smokers and patients with a prolonged COPD history are more likely to be infected by influenza.

Pulmonary Iron Limitation Induced by Exogenous Type I IFN Protects Mice from Cryptococcus gattii Independently of T Cells

Cryptococcus neoformans and Cryptococcus gattii cause fatal infection in immunodeficient and immunocompetent individuals. While these fungi are sibling species, C. gattii infects very few AIDS patients, while C. neoformans infection is an AIDS-defining illness, suggesting that the host response to HIV selects C. neoformans over C. gattii. We used a viral mimic molecule (pICLC) to stimulate the immune response, and pICLC treatment improved mouse outcomes from both species. pICLC-induced action against C. neoformans was due to activation of well-defined immune pathways known to deter C. neoformans, whereas these immune pathways were dispensable for pICLC treatment of C. gattii. Since these immune pathways are eventually destroyed by HIV/AIDS, our data help explain why the antiviral immune response in AIDS patients is unable to control C. neoformans infection but is protective against C. gattii. Furthermore, pICLC induced tighter control of iron in the lungs of mice, which inhibited C. gattii, thus suggesting an entirely new mode of nutritional immunity activated by viral signals.

Cryptococcus neoformans causes deadly mycosis primarily in AIDS patients, whereas Cryptococcus gattii infects mostly non-HIV patients, even in regions with high burdens of HIV/AIDS and an established environmental presence of C. gattii. As HIV induces type I IFN (t1IFN), we hypothesized that t1IFN would differentially affect the outcome of C. neoformans and C. gattii infections. Exogenous t1IFN induction using stabilized poly(I·C) (pICLC) improved murine outcomes in either cryptococcal infection. In C. neoformans-infected mice, pICLC activity was associated with C. neoformans containment and classical Th1 immunity. In contrast, pICLC activity against C. gattii did not require any immune factors previously associated with C. neoformans immunity: T, B, and NK cells, IFN-γ, and macrophages were all dispensable. Interestingly, C. gattii pICLC activity depended on β-2-microglobulin, which impacts iron levels among other functions. Iron supplementation reversed pICLC activity, suggesting C. gattii pICLC activity requires iron limitation. Also, pICLC induced a set of iron control proteins, some of which were directly inhibitory to cryptococcus in vitro, suggesting t1IFN regulates iron availability in the pulmonary air space fluids. Thus, exogenous induction of t1IFN significantly improves the outcome of murine infection by C. gattii and C. neoformans but by distinct mechanisms; the C. gattii effect was mediated by iron limitation, while the effect on C. neoformans infection was through induction of classical T-cell-dependent immunity. Together this difference in types of T-cell-dependent t1IFN immunity for different Cryptococcus species suggests a possible mechanism by which HIV infection may select against C. gattii but not C. neoformans.

The status of cryptococcosis in Latin America

Cryptococcosis is a life-threatening fungal infection caused by the encapsulated yeasts Cryptococcus neoformans and C. gattii, acquired from the environment. In Latin America, as occurring worldwide, C. neoformans causes more than 90% of the cases of cryptococcosis, affecting predominantly patients with HIV, while C. gattii generally affects otherwise healthy individuals. In this region, cryptococcal meningitis is the most common presentation, with amphotericin B and fluconazole being the antifungal drugs of choice. Avian droppings are the predominant environmental reservoir of C. neoformans, while C. gattii is associated with several arboreal species. Importantly, C. gattii has a high prevalence in Latin America and has been proposed to be the likely origin of some C. gattii populations in North America. Thus, in the recent years, significant progress has been made with the study of the basic biology and laboratory identification of cryptococcal strains, in understanding their ecology, population genetics, host-pathogen interactions, and the clinical epidemiology of this important mycosis in Latin America.