tacrolimus and Mucormycosis

Isavuconazole has theoretical advantages over other mold-active triazoles for the treatment of invasive aspergillosis and mucormycosis after solid organ transplantation (SOT). The available clinical experience, nevertheless, is scarce.. We performed a retrospective study including all adult SOT recipients with proven or probable invasive mold disease (IMD) that received isavuconazole for ≥24 h as first-line or salvage therapy at 10 Spanish centers between September 2017 and November 2021. The primary efficacy outcome was clinical response (complete or partial resolution of attributable symptoms and findings) by weeks 6 and 12. Safety outcomes included the rates of treatment-emergent adverse events and premature isavuconazole discontinuation.. We included 81 SOT recipients that received isavuconazole for a median of 58.0 days because of invasive aspergillosis (n = 71) or mucormycosis (n = 10). Isavuconazole was used as first-line (72.8%) or salvage therapy due because of previous treatment-emergent toxicity (11.1%) or refractory IMD (7.4%). Combination therapy was common (37.0%), mainly with an echinocandin or liposomal amphotericin B. Clinical response by weeks 6 and 12 was achieved in 53.1% and 54.3% of patients, respectively, and was more likely when isavuconazole was administered as first-line single-agent therapy. At least 1 treatment-emergent adverse event occurred in 17.3% of patients, and 6.2% required premature discontinuation. Daily tacrolimus dose was reduced in two-thirds of patients by a median of 50.0%, although tacrolimus levels remained stable throughout the first month of therapy.. Isavuconazole is a safe therapeutic option for IMD in SOT recipients, with efficacy comparable to other patient groups.

Topics: Adult; Antifungal Agents; Aspergillosis; Fungi; Humans; Invasive Fungal Infections; Mucormycosis; Nitriles; Organ Transplantation; Retrospective Studies; Tacrolimus; Transplant Recipients; Triazoles

Renal transplant patients are at increased risk for mucormycosis. Diabetes, neutropenia, deferoxamine therapy, and immunosuppressive medications have been associated with increased risk of mucormycosis in studies of solid organ transplant recipients. To focus on renal transplant patients, the US Renal Data System (USRDS) was queried to determine the incidence and risk factors for mucormycosis.. All renal transplant patients in the USRDS from 1988 to 2015 were queried for a diagnosis of mucormycosis after the first transplant date using ICD-9 and ICD-10 codes. The International Classification of Diseases (ICD) codes, which currently exist in the ninth and tenth revisions, are a global system of classification used to code diagnoses, procedures, and symptoms. We defined proven mucormycosis by a histopathologic or fungal stain procedure code within 7 days of the diagnosis code. Logistic regression controlling for person-years at risk was used to examine demographic and clinical diagnosis risk factors for mucormycosis.. Of the 306,482 renal transplant patients, 222 (0.07%) had codes consistent with proven mucormycosis. The incidence of mucormycosis increased from 1990 to 2000 (peak 17.6 per 100,000 person-years) and subsequently demonstrated more variability. Hispanic ethnicity (OR=1.45), age 65 years or greater (OR=1.64), other or black race compared with white race (OR=1.96 and 1.74), cadaver or other donor type (OR=2.41), and receiving tacrolimus (OR=2.09) were associated with increased risk. Comorbidities associated with decreased risk of mucormycosis included female sex (OR=0.68), iron overload (OR=0.56), and receiving mycophenolate mofetil (OR=0.67) or azathioprine (OR=0.53).. In renal transplant patients, age, deceased donor graft transplant, tacrolimus administration, race other than white, and Hispanic ethnicity were associated with increased risk of mucormycosis. Unexpectedly, iron overload was protective. Mucormycosis is a rare infection in renal transplant patients which should be considered in patients with the above risk factors after more common infections have been ruled out.

Topics: Aged; Aged, 80 and over; Antifungal Agents; Female; Humans; Immunocompromised Host; Immunosuppressive Agents; Incidence; Iron Overload; Kidney Transplantation; Male; Middle Aged; Mucormycosis; Risk Factors; Tacrolimus; Transplant Recipients

Topics: Amino Acid Sequence; Antifungal Agents; Calcineurin; Calcineurin Inhibitors; Drug Design; Fungal Proteins; Host-Pathogen Interactions; Humans; Mucor; Mucormycosis; Sequence Alignment; Tacrolimus; Tacrolimus Binding Protein 1A

The environmentally ubiquitous fungus

Topics: Animals; Antifungal Agents; Disease Models, Animal; Drug Resistance, Fungal; Epigenesis, Genetic; Humans; Male; Mice; Mice, Inbred BALB C; Mucor; Mucormycosis; RNA Interference; Sirolimus; Tacrolimus

Mucormycosis-an emergent, deadly fungal infection-is difficult to treat, in part because the causative species demonstrate broad clinical antifungal resistance. However, the mechanisms underlying drug resistance in these infections remain poorly understood. Our previous work demonstrated that one major agent of mucormycosis, Mucor circinelloides, can develop resistance to the antifungal agents FK506 and rapamycin through a novel, transient RNA interference-dependent mechanism known as epimutation. Epimutations silence the drug target gene and are selected by drug exposure; the target gene is re-expressed and sensitivity is restored following passage without drug. This silencing process involves generation of small RNA (sRNA) against the target gene via core RNAi pathway proteins. To further elucidate the role of epimutation in the broad antifungal resistance of Mucor, epimutants were isolated that confer resistance to another antifungal agent, 5-fluoroorotic acid (5-FOA). We identified epimutant strains that exhibit resistance to 5-FOA without mutations in PyrF or PyrG, enzymes which convert 5-FOA into the active toxic form. Using sRNA hybridization as well as sRNA library analysis, we demonstrate that these epimutants harbor sRNA against either pyrF or pyrG, and further show that this sRNA is lost after reversion to drug sensitivity. We conclude that epimutation is a mechanism capable of targeting multiple genes, enabling Mucor to develop resistance to a variety of antifungal agents. Elucidation of the role of RNAi in epimutation affords a fuller understanding of mucormycosis. Furthermore, it improves our understanding of fungal pathogenesis and adaptation to stresses, including the evolution of drug resistance.

Topics: Antifungal Agents; Drug Resistance, Multiple, Fungal; Epigenesis, Genetic; Genes, Fungal; Humans; Mucor; Mucormycosis; Mutation; Orotate Phosphoribosyltransferase; Orotic Acid; Orotidine-5'-Phosphate Decarboxylase; RNA Interference; RNA, Fungal; Sirolimus; Tacrolimus

To evaluate the in vitro interactions of isavuconazole with immune suppressors (tacrolimus, cyclosporin A or sirolimus) against 30 Mucorales isolates belonging to the most common species responsible for mucormycosis in humans (Rhizopus arrhizus, Rhizopus delemar, Rhizopus microsporus, Lichtheimia corymbifera, Lichtheimia ramosa, Mucor circinelloides and Rhizomucor pusillus).. In vitro interaction was evaluated by a microdilution chequerboard technique.. Combination of isavuconazole with tacrolimus, cyclosporin A or sirolimus, was synergistic for 50%, 46% and 7% of the isolates, respectively. Antagonistic interaction was observed for 4% of the isolates for the combination with cyclosporin A (one R. arrhizus isolate) and for 32% of the isolates for the combination with sirolimus (six R. arrhizus isolates and three R. pusillus isolates).. These in vitro data show that calcineurin inhibitors are more likely than inhibitors of the mTOR pathway to enhance the activity of isavuconazole against Mucorales. These in vitro results warrant further animal experiments.

Topics: Antifungal Agents; Cyclosporine; Immunosuppressive Agents; Microbial Sensitivity Tests; Mucorales; Mucormycosis; Nitriles; Pyridines; Sirolimus; Tacrolimus; Triazoles

Mucorales are a group of basal fungi that includes the casual agents of the human emerging disease mucormycosis. Recent studies revealed that these pathogens activate an RNAi-based pathway to rapidly generate drug-resistant epimutant strains when exposed to stressful compounds such as the antifungal drug FK506. To elucidate the molecular mechanism of this epimutation pathway, we performed a genetic analysis in Mucor circinelloides that revealed an inhibitory role for the non-canonical RdRP-dependent Dicer-independent silencing pathway, which is an RNAi-based mechanism involved in mRNA degradation that was recently identified. Thus, mutations that specifically block the mRNA degradation pathway, such as those in the genes r3b2 and rdrp3, enhance the production of drug resistant epimutants, similar to the phenotype previously described for mutation of the gene rdrp1. Our genetic analysis also revealed two new specific components of the epimutation pathway related to the quelling induced protein (qip) and a Sad-3-like helicase (rnhA), as mutations in these genes prevented formation of drug-resistant epimutants. Remarkably, drug-resistant epimutant production was notably increased in M. circinelloides f. circinelloides isolates from humans or other animal hosts. The host-pathogen interaction could be a stressful environment in which the phenotypic plasticity provided by the epimutant pathway might provide an advantage for these strains. These results evoke a model whereby balanced regulation of two different RNAi pathways is determined by the activation of the RNAi-dependent epimutant pathway under stress conditions, or its repression when the regular maintenance of the mRNA degradation pathway operates under non-stress conditions.

Topics: Amino Acid Sequence; Drug Resistance, Fungal; Fungal Proteins; Gene Expression Regulation, Fungal; Host-Pathogen Interactions; Humans; Immunosuppressive Agents; Models, Genetic; Mucor; Mucormycosis; Mutation; RNA Interference; RNA Stability; RNA, Fungal; RNA, Messenger; Signal Transduction; Tacrolimus

Without proper treatment, the mortality of pulmonary mucormycosis is nearly 100%. Although the diagnosis is often made histologically, it can be suspected when patients have a reverse halo sign on computed tomography (CT) of the chest, along with the right clinical findings. We describe the case of a woman 7 months post renal transplant who presented with fevers, malaise, and chest pain. Her chest CT revealed a round, focal area of ground-glass attenuation surrounded by a complete rim of consolidation in the left upper lobe, consistent with the reverse halo sign. Pulmonary mucormycosis was diagnosed by transbronchial lung biopsy. She was successfully treated with combined medical and surgical therapies. In the context of this case, we provide a brief review of the diagnosis of pulmonary mucormycosis, with a focus on radiographic and pathologic findings.

Topics: Female; Graft Rejection; Humans; Immunocompromised Host; Immunosuppressive Agents; Kidney Transplantation; Lung Diseases, Fungal; Middle Aged; Mucormycosis; Mycophenolic Acid; Prednisone; Tacrolimus; Tomography, X-Ray Computed

Microorganisms evolve via a range of mechanisms that may include or involve sexual/parasexual reproduction, mutators, aneuploidy, Hsp90 and even prions. Mechanisms that may seem detrimental can be repurposed to generate diversity. Here we show that the human fungal pathogen Mucor circinelloides develops spontaneous resistance to the antifungal drug FK506 (tacrolimus) via two distinct mechanisms. One involves Mendelian mutations that confer stable drug resistance; the other occurs via an epigenetic RNA interference (RNAi)-mediated pathway resulting in unstable drug resistance. The peptidylprolyl isomerase FKBP12 interacts with FK506 forming a complex that inhibits the protein phosphatase calcineurin. Calcineurin inhibition by FK506 blocks M. circinelloides transition to hyphae and enforces yeast growth. Mutations in the fkbA gene encoding FKBP12 or the calcineurin cnbR or cnaA genes confer FK506 resistance and restore hyphal growth. In parallel, RNAi is spontaneously triggered to silence the fkbA gene, giving rise to drug-resistant epimutants. FK506-resistant epimutants readily reverted to the drug-sensitive wild-type phenotype when grown without exposure to the drug. The establishment of these epimutants is accompanied by generation of abundant fkbA small RNAs and requires the RNAi pathway as well as other factors that constrain or reverse the epimutant state. Silencing involves the generation of a double-stranded RNA trigger intermediate using the fkbA mature mRNA as a template to produce antisense fkbA RNA. This study uncovers a novel epigenetic RNAi-based epimutation mechanism controlling phenotypic plasticity, with possible implications for antimicrobial drug resistance and RNAi-regulatory mechanisms in fungi and other eukaryotes.

Topics: Calcineurin; Calcineurin Inhibitors; Drug Resistance, Fungal; Epigenesis, Genetic; Humans; Hyphae; Molecular Sequence Data; Mucor; Mucormycosis; Mutation; Phenotype; RNA Interference; Tacrolimus; Tacrolimus Binding Protein 1A

Many pathogenic fungi are dimorphic and switch between yeast and filamentous states. This switch alters host-microbe interactions and is critical for pathogenicity. However, in zygomycetes, whether dimorphism contributes to virulence is a central unanswered question. The pathogenic zygomycete Mucor circinelloides exhibits hyphal growth in aerobic conditions but switches to multi-budded yeast growth under anaerobic/high CO₂ conditions. We found that in the presence of the calcineurin inhibitor FK506, Mucor exhibits exclusively multi-budded yeast growth. We also found that M. circinelloides encodes three calcineurin catalytic A subunits (CnaA, CnaB, and CnaC) and one calcineurin regulatory B subunit (CnbR). Mutations in the latch region of CnbR and in the FKBP12-FK506 binding domain of CnaA result in hyphal growth of Mucor in the presence of FK506. Disruption of the cnbR gene encoding the sole calcineurin B subunit necessary for calcineurin activity yielded mutants locked in permanent yeast phase growth. These findings reveal that the calcineurin pathway plays key roles in the dimorphic transition from yeast to hyphae. The cnbR yeast-locked mutants are less virulent than the wild-type strain in a heterologous host system, providing evidence that hyphae or the yeast-hyphal transition are linked to virulence. Protein kinase A activity (PKA) is elevated during yeast growth under anaerobic conditions, in the presence of FK506, or in the yeast-locked cnbR mutants, suggesting a novel connection between PKA and calcineurin. cnaA mutants lacking the CnaA catalytic subunit are hypersensitive to calcineurin inhibitors, display a hyphal polarity defect, and produce a mixture of yeast and hyphae in aerobic culture. The cnaA mutants also produce spores that are larger than wild-type, and spore size is correlated with virulence potential. Our results demonstrate that the calcineurin pathway orchestrates the yeast-hyphal and spore size dimorphic transitions that contribute to virulence of this common zygomycete fungal pathogen.

Topics: Calcineurin; Cell Line; Fungal Proteins; Humans; Hyphae; Immunosuppressive Agents; Mucor; Mucormycosis; Protein Structure, Tertiary; Tacrolimus; Virulence Factors

We hypothesized that tacrolimus, an inhibitor of the calcineurin pathway, would enhance the in vivo activity of posaconazole against Rhizopus oryzae, the Mucorales species most commonly associated with mucormycosis.. We examined patterns of growth inhibition and fungicidal activity of posaconazole and tacrolimus, alone and in combination, against R. oryzae in vitro, using multiple methods (ie, hyphal metabolic and fluorescent vital dye reduction assays and measurement of chitin concentrations), and in vivo, using 2 mucormycosis models: an invertebrate model (Drosophila) and a nonlethal murine model of cutaneous mucormycosis.. Combinations of posaconazole and tacrolimus were synergistic in checkerboard assays for 4 clinical isolates of R. oryzae (48-hour fractional inhibitory concentration index, 0.187-0.281). Pharmacodynamic analysis of the combination revealed that the 90% effective concentration threshold of posaconazole activity against R. oryzae could be achieved with 2-fold lower drug concentrations (0.5-1 mg/L) when administered with tacrolimus (0.007-2 mg/L). In vivo, combination therapy was associated with improved survival in the fly model of mucormycosis (65% vs 57% posaconazole alone) and with significant reductions in cutaneous lesions and R. oryzae fungal burden, compared with animals that received posaconazole monotherapy, in the cutaneous model of mucormycosis.. Combination posaconazole-tacrolimus therapy displays synergism in vitro and improved antifungal efficacy in vivo in 2 phylogenetically distinct models of mucormycosis.

Topics: Animals; Antifungal Agents; Disease Models, Animal; Drosophila; Drug Synergism; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mucormycosis; Rhizopus; Tacrolimus; Treatment Outcome; Triazoles