Search

Moving from the earlier periods in which the lungs were believed to represent sterile environments, our knowledge on the lung microbiota has dramatically increased, from the first descriptions of the microbial communities inhabiting the healthy lungs and the definition of the ecological rules that regulate its composition, to the identification of the changes that occur in pathological conditions. Despite the limitations of lung as a microbiome reservoir due to the low microbial biomass and abundance, defining its microbial composition and function in the upper and lower airways may help understanding the impact on local homeostasis and its disruption in lung diseases. In particular, the understanding of the metabolic and immune significance of microbes, their presence or lack thereof, in health and disease states could be valuable in development of novel druggable targets in disease treatments. Next-generation sequencing has identified intricate inter-microbe association networks that comprise true mutualistic or antagonistic direct or indirect relationships in the respiratory tract. In this review, the tripartite interaction of bacteria, fungi and the mammalian host is addressed to provide an integrated view of the microbial-host cross-talk in lung health and diseases from an immune and metabolic perspective., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Garaci, Pariano, Nunzi, Costantini, Bellet, Antognelli, Russo and Romani.)

As a result of a long evolutionary history, serotonin plays a variety of physiological roles, including neurological, cardiovascular, gastrointestinal, and endocrine functions. While many of these activities can be accommodated within the serotoninergic activity, recent findings have revealed an unsuspected role of serotonin in orchestrating host and microbial dialogue at the tryptophan dining table, to the benefit of local and systemic homeostasis. Herein we review the dual role of serotonin at the host-microbe interface and discuss how unraveling the interconnections among the host and microbial pathways of tryptophan degradation may help to accommodate the versatility of serotonin in physiology and pathology., Competing Interests: Declaration of interests The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Aspergillus fumigatus is an environmental fungus recently included in the fungal high-priority pathogens by the World Health Organization. While immunodeficiency and/or pre-existing lung damage represent a well-recognized fertile ground for fungal growth, it is increasingly being recognized that severe viral infections may similarly favor A. fumigatus colonization and infection, as recently experienced in the Coronavirus disease 2019 (COVID-19) pandemic. Herein, in a murine model of COVID-19-associated pulmonary aspergillosis (CAPA), obtained by the concomitant exposure to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein and A. fumigatus conidia, we found that the microbial compound indole-3-aldehyde (3-IAld) was able to ameliorate CAPA by working at multiple levels during viral infection and fungal superinfection, including epithelial barrier protection, promotion of antiviral responses, and limiting viral replication. As a consequence, 3-IAld limited the pathogenic sequelae of fungal superinfection as revealed by the controlled fungal burden and restrained inflammatory pathology. These results point to indole compounds as potential agents to prevent CAPA.

Biological membrane-engineered lipid nanoparticles (LNP) have shown enormous potential as vehicles for drug delivery due to their outstanding biomimetic properties. To make these nanoparticles more adaptable to complex biological systems, several methods and cellular sources have been adopted to introduce biomembrane-derived moieties onto LNP and provide the latter with more functions while preserving their intrinsic nature. In this review, we focus on LNP decoration with specific regard to mRNA therapeutics and vaccines. The bio-engineering approach exploits a variety of biomembranes for functionalization, such as those derived from red blood cells, white blood cells, cancer cells, platelets, exosomes, and others. Biomembrane engineering could greatly enhance efficiency in targeted drug delivery, treatment, and diagnosis of cancer, inflammation, immunological diseases, and a variety of pathologic conditions. These membrane-modification techniques are expected to advance biomembrane-derived LNP into wider applications in the future., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Celiac disease (CD) is an autoimmune enteropathy resulting from an interaction between diet, genome, and immunity. Although many patients respond to a gluten-free diet, in a substantive number of individuals, the intestinal injury persists. Thus, other factors might amplify the ongoing inflammation. Candida albicans is a commensal fungus that is well adapted to the intestinal life. However, specific conditions increase Candida pathogenicity. The hypothesis that Candida may be a trigger in CD has been proposed after the observation of similarity between a fungal wall component and two CD-related gliadin T-cell epitopes. However, despite being implicated in intestinal disorders, Candida may also protect against immune pathologies highlighting a more intriguing role in the gut. Herein, we postulated that a state of chronic inflammation associated with microbial dysbiosis and leaky gut are favorable conditions that promote C. albicans pathogenicity eventually contributing to CD pathology via a mast cells (MC)-IL-9 axis. However, the restoration of immune and microbial homeostasis promotes a beneficial C. albicans -MC cross-talk favoring the attenuation of CD pathology to alleviate CD pathology and symptoms., (© 2024 Renga et al.)

Humans interact with a multitude of microorganisms in various ecological relationships, ranging from commensalism to pathogenicity. The same applies to fungi, long recognized for their pathogenic roles in infection-such as in invasive fungal diseases caused, among others, by Aspergillus fumigatus and Candida spp.-and, more recently, for their beneficial activities as an integral part of the microbiota. Indeed, alterations in the fungal component of the microbiota, or mycobiota, have been associated with inflammatory, infectious and metabolic diseases, and cancer. Whether acting as opportunistic pathogens or symbiotic commensals, fungi possess a complex enzymatic repertoire that intertwines with that of the host. In this metabolic cross-talk, fungal enzymes may be unique, thus providing novel metabolic opportunities to the host, or, conversely, produce toxic metabolites. Indeed, administration of fungal probiotics and fungi-derived products may be beneficial in inflammatory and infectious diseases, but fungi may also produce a plethora of toxic secondary metabolites, collectively known as mycotoxins. Fungal enzymes may also be homologues to human enzymes, but nevertheless embedded in fungal-specific metabolic networks, determined by all the interconnected enzymes and molecules, quantitatively and qualitatively specific to the network, such that the activity and metabolic effects of each enzyme remain unique to fungi. In this Opinion, we explore the concept that targeting this fungal metabolic unicity, either in opportunistic pathogens or commensals, may be exploited to develop novel therapeutic strategies. In doing so, we present our recent experience in different pathological settings that ultimately converge on relevant trans-kingdom metabolic differences., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Costantini, Pariano, Puccetti, Giovagnoli, Pampalone, Dindo, Cellini and Romani.)

Abstract: CPX-351, a liposomal combination of cytarabine plus daunorubicin, has been approved for the treatment of adults with newly diagnosed, therapy-related acute myeloid leukemia (AML) or AML with myelodysplasia-related changes, because it improves survival and outcome of patients who received hematopoietic stem cell transplant compared with the continuous infusion of cytarabine plus daunorubicin (referred to as "7 + 3" combination). Because gut dysbiosis occurring in patients with AML during induction chemotherapy heavily affects the subsequent phases of therapy, we have assessed whether the superior activity of CPX-351 vs "7 + 3" combination in the real-life setting implicates an action on and by the intestinal microbiota. To this purpose, we have evaluated the impact of CPX-351 and "7 + 3" combination on mucosal barrier function, gut microbial composition and function, and antifungal colonization resistance in preclinical models of intestinal damage in vitro and in vivo and fecal microbiota transplantation. We found that CPX-351, at variance with "7 + 3" combination, protected from gut dysbiosis, mucosal damage, and gut morbidity while increasing antifungal resistance. Mechanistically, the protective effect of CPX-351 occurred through pathways involving both the host and the intestinal microbiota, namely via the activation of the aryl hydrocarbon receptor-interleukin-22 (IL-22)-IL-10 host pathway and the production of immunomodulatory metabolites by anaerobes. This study reveals how the gut microbiota may contribute to the good safety profile, with a low infection-related mortality, of CPX-351 and highlights how a better understanding of the host-microbiota dialogue may contribute to pave the way for precision medicine in AML., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Multiple sclerosis is a debilitating autoimmune disease, characterized by chronic inflammation of the central nervous system. While the significance of the gut microbiome on multiple sclerosis pathogenesis is established, the underlining mechanisms are unknown. We found that serum levels of the microbial postbiotic tryptophan metabolite indole-3-carboxaldehyde (3-IAld) inversely correlated with disease duration in multiple sclerosis patients. Much like the host-derived tryptophan derivative L-Kynurenine, 3-IAld would bind and activate the Aryl hydrocarbon Receptor (AhR), which, in turn, controls endogenous tryptophan catabolic pathways. As a result, in peripheral lymph nodes, microbial 3-IAld, affected mast-cell tryptophan metabolism, forcing mast cells to produce serotonin via Tph1. We thus propose a protective role for AhR-mast-cell activation driven by the microbiome, whereby natural metabolites or postbiotics will have a physiological role in immune homeostasis and may act as therapeutic targets in autoimmune diseases., (© 2024. The Author(s).)

The Sertoli cells (SeCs) of the seminiferous tubules secrete a multitude of immunoregulatory and trophic factors to provide immune protection and assist in the orderly development of germ cells. Grafts of naked or encapsulated SeCs have been proved to represent an interesting therapeutic option in a plethora of experimental models of diseases. However, whether SeCs have immunosuppressive or immunomodulatory effects, which is imperative for their clinical translatability, has not been demonstrated. We directly assessed the immunopotential of intraperitoneally grafted microencapsulated porcine SeCs (MC-SeCs) in murine models of fungal infection ( Aspergillus fumigatus or Candida albicans ) or cancer (Lewis lung carcinoma/LLC or B16 melanoma cells). We found that MC-SeCs (i) provide antifungal resistance with minimum inflammatory pathology through the activation of the tolerogenic aryl hydrocarbon receptor/indoleamine 2,3-dioxygenase pathway; (ii) do not affect tumor growth in vivo; and (iii) reduce the LLC cell metastatic cancer spread associated with restricted Vegfr2 expression in primary tumors. Our results point to the fine immunoregulation of SeCs in the relative absence of overt immunosuppression in both infection and cancer conditions, providing additional support for the potential therapeutic use of SeC grafts in human patients., Competing Interests: The authors declare no conflicts of interest.

Patients with cystic fibrosis (PwCF) have recently experienced an unprecedented breakthrough with the adoption of modulator therapy in clinical practice. This remarkable achievement has led to the reconsideration of disease management as the increased life expectancy has gradually shifted the attention over a spectrum of extra-pulmonary manifestations that become prevalent in the aging population. It comes to be that complementary approaches that target patient co-morbidities are needed for the optimal clinical management of PwCF. A strategy would be to adjuvate the cystic fibrosis transmembrane conductance regulator (CFTR) in performing its functions in the different organs in which it is expressed. Solute carrier family 26 (SLC26) members appear ideal in this context. Indeed, they not only cooperate with CFTR in the organ-dependent regulation of ion fluxes but physically interact with it to reciprocally modulate their function. In this opinion, we summarize available evidence pointing to a physical and functional interaction between CFTR and SLC26 members, with a particular focus on SLC26A6 for its wider expression and broader anion selectivity, and then discuss how restoring the physical interaction between CFTR and SLC26A6 might be beneficial in the treatment of PwCF in the era of modulator therapy.

The progress in human disease treatment can be greatly advanced through the implementation of nanomedicine. This approach involves targeted and cell-specific therapy, controlled drug release, personalized dosage forms, wearable drug delivery, and companion diagnostics. By integrating cutting-edge technologies with drug delivery systems, greater precision can be achieved at the tissue and cellular levels through the use of stimuli-responsive nanoparticles, and the development of electrochemical sensor systems. This precision targeting - by virtue of nanotechnology - allows for therapy to be directed specifically to affected tissues while greatly reducing side effects on healthy tissues. As such, nanomedicine has the potential to transform the treatment of conditions such as cancer, genetic diseases, and chronic illnesses by facilitating precise and cell-specific drug delivery. Additionally, personalized dosage forms and wearable devices offer the ability to tailor treatment to the unique needs of each patient, thereby increasing therapeutic effectiveness and compliance. Companion diagnostics further enable efficient monitoring of treatment response, enabling customized adjustments to the treatment plan. The question of whether all the potential therapeutic approaches outlined here are viable alternatives to current treatments is also discussed. In general, the application of nanotechnology in the field of biomedicine may provide a strong alternative to existing treatments for several reasons. In this review, we aim to present evidence that, although in early stages, fully merging advanced technology with innovative drug delivery shows promise for successful implementation across various disease areas, including cancer and genetic or chronic diseases., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The recent Coronavirus Disease 2019 (COVID-19) pandemic has dramatically exposed our gap in understanding the pathogenesis of airborne infections. Within such a context, it is increasingly clear that the nasal cavity represents a critical checkpoint not only in the initial colonization phase but also in shaping any infectious sequelae . This is particularly relevant to COVID-19 in that the nasal cavity is characterized by high-level expression of the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) receptor, Angiotensin-Converting Enzyme 2 (ACE2), all along the respiratory tract. As part of the nasal mucosa, commensal microbes harbored by the nasal cavity likely are far more than just innocent bystanders in the interaction between SARS-CoV-2 and the local microenvironment. Yet the role of the qualitative composition of the nasal microbiome is unclear, as is its function, whether protective or not., Methods: In this study, individuals undergoing SARS-CoV-2 molecular testing at the Hospital of Perugia (Italy) were recruited, with their residual material from the nasopharyngeal swabs being collected for microbiome composition analysis and short-chain fatty acid (SCFA) measurements (by 16S rRNA sequencing and gas chromatography-mass spectrometry), respectively., Results: After stratification by age, gender, and viral load, the composition of the nasopharyngeal microbiome appeared to be influenced by age and gender, and SARS-CoV-2 infection further determined compositional changes. Notwithstanding this variability, a restricted analysis of female subjects-once SARS-CoV-2-infected-unraveled a shared expansion of Lachnospirales-Lachnospiraceae, irrespective of the viral load and age. This was associated with a reduction in the branched SCFA isobutanoic acid, as well as in the SCFAs with longer chains., Conclusions: Our results indicate that the nasopharyngeal microbiome is influenced by age, gender, and viral load, with consistent patterns of microbiome changes being present across specific groups. This may help in designing a personalized medicine approach in COVID-19 patients with specific patterns of nasal microbial communities., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

Cystic fibrosis (CF) is an autosomal recessive disorder characterized by respiratory failure due to a vicious cycle of defective Cystic Fibrosis Transmembrane conductance Regulator (CFTR) function, chronic inflammation and recurrent bacterial and fungal infections. Although the recent introduction of CFTR correctors/potentiators has revolutionized the clinical management of CF patients, resurgence of inflammation and persistence of pathogens still posit a major concern and should be targeted contextually. On the background of a network-based selectivity that allows to target the same enzyme in the host and microbes with different outcomes, we focused on sphingosine-1-phosphate (S1P) lyase (SPL) of the sphingolipid metabolism as a potential candidate to uniquely induce anti-inflammatory and antifungal activities in CF. As a feasibility study, herein we show that interfering with S1P metabolism improved the immune response in a murine model of CF with aspergillosis while preventing germination of Aspergillus fumigatus conidia. In addition, in an early drug discovery process, we purified human and A. fumigatus SPL, characterized their biochemical and structural properties, and performed an in silico screening to identify potential dual species SPL inhibitors. We identified two hits behaving as competitive inhibitors of pathogen and host SPL, thus paving the way for hit-to-lead and translational studies for the development of drug candidates capable of restraining fungal growth and increasing antifungal resistance., (© 2023. The Author(s).)

Hydroquinone, a potent toxic agent of cigarette smoke, damages retinal pigmented epithelial cells by triggering oxidative stress and mitochondrial dysfunction, two events causally related to the development and progression of retinal diseases. The inner mitochondrial membrane is enriched in cardiolipin, a phospholipid susceptible of oxidative modifications which determine cell-fate decision. Using ARPE-19 cell line as a model of retinal pigmented epithelium, we analyzed the potential involvement of cardiolipin in hydroquinone toxicity. Hydroquinone exposure caused an early concentration-dependent increase in mitochondrial reactive oxygen species, decrease in mitochondrial membrane potential, and rise in the rate of oxygen consumption not accompanied by changes in ATP levels. Despite mitochondrial impairment, cell viability was preserved. Hydroquinone induced cardiolipin translocation to the outer mitochondrial membrane, and an increase in the colocalization of the autophagosome adapter protein LC3 with mitochondria, indicating the induction of protective mitophagy. A prolonged hydroquinone treatment induced pyroptotic cell death by cardiolipin-mediated caspase-1 and gasdermin-D activation. Cardiolipin-specific antioxidants counteracted hydroquinone effects pointing out that cardiolipin can act as a mitochondrial "eat-me signal" or as a pyroptotic cell death trigger. Our results indicate that cardiolipin may act as a timer for the mitophagy to pyroptosis switch and propose cardiolipin-targeting compounds as promising approaches for the treatment of oxidative stress-related retinal diseases., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

The pathogenesis of coronavirus disease 2019 (COVID-19) is associated with a hyperinflammatory response. The mechanisms of SARS-CoV-2-induced inflammation are scantly known. Methylglyoxal (MG) is a glycolysis-derived byproduct endowed with a potent glycating action, leading to the formation of advanced glycation end products (AGEs), the main one being MG-H1. MG-H1 exerts strong pro-inflammatory effects, frequently mediated by the receptor for AGEs (RAGE). Here, we investigated the involvement of the MG-H1/RAGE axis as a potential novel mechanism in SARS-CoV-2-induced inflammation by resorting to human bronchial BEAS-2B and alveolar A549 epithelial cells, expressing different levels of the ACE2 receptor (R), exposed to SARS-CoV-2 spike protein 1 (S1). Interestingly, we found in BEAS-2B cells that do not express ACE2-R that S1 exerted a pro-inflammatory action through a novel MG-H1/RAGE-based pathway. MG-H1 levels, RAGE and IL-1β expression levels in nasopharyngeal swabs from SARS-CoV-2-positive and -negative individuals, as well as glyoxalase 1 expression, the major scavenging enzyme of MG, seem to support the results obtained in vitro. Altogether, our findings reveal a novel mechanism involved in the inflammation triggered by S1, paving the way for the study of the MG-H1/RAGE inflammatory axis in SARS-CoV-2 infection as a potential therapeutic target to mitigate COVID-19-associated pathogenic inflammation.

The aromatic amino acid L-tryptophan (Trp) is essentially metabolized along the host and microbial pathways. While much is known about the role played by downstream metabolites of each pathways in intestinal homeostasis, their role in lung immune homeostasis is underappreciated. Here we have examined the role played by the Trp hydroxylase/5-hydroxytryptamine (5-HT) pathway in calibrating host and microbial Trp metabolism during Aspergillus fumigatus pneumonia. We found that 5-HT produced by mast cells essentially contributed to pathogen clearance and immune homeostasis in infection by promoting the host protective indoleamine-2,3-dioxygenase 1/kynurenine pathway and limiting the microbial activation of the indole/aryl hydrocarbon receptor pathway. This occurred via regulation of lung and intestinal microbiota and signaling pathways. 5-HT was deficient in the sputa of patients with Cystic fibrosis, while 5-HT supplementation restored the dysregulated Trp partitioning in murine disease. These findings suggest that 5-HT, by bridging host-microbiota Trp partitioning, may have clinical effects beyond its mood regulatory function in respiratory pathologies with an inflammatory component., (© 2023. Springer Nature Limited.)

The recent COVID-19 pandemic has catalyzed the attention of the scientific community to the long-standing issue of lower respiratory tract infections. The myriad of airborne bacterial, viral and fungal agents to which humans are constantly exposed represents a constant threat to susceptible individuals and bears the potential to reach a catastrophic scale when the ease of inter-individual transmission couples with a severe pathogenicity. While we might be past the threat of COVID-19, the risk of future outbreaks of respiratory infections is tangible and argues for a comprehensive assessment of the pathogenic mechanisms shared by airborne pathogens. On this regard, it is clear that the immune system play a major role in dictating the clinical course of the infection. A balanced immune response is required not only to disarm the pathogens, but also to prevent collateral tissue damage, thus moving at the interface between resistance to infection and tolerance. Thymosin alpha1 (Tα1), an endogenous thymic peptide, is increasingly being recognized for its ability to work as an immunoregulatory molecule able to balance a derailed immune response, working as immune stimulatory or immune suppressive in a context-dependent manner. In this review, we will take advantage from the recent work on the COVID-19 pandemic to reassess the role of Tα1 as a potential therapeutic molecule in lung infections caused by either defective or exaggerated immune responses. The elucidation of the immune regulatory mechanisms of Tα1 might open a new window of opportunity for the clinical translation of this enigmatic molecule and a potential new weapon in our arsenal against lung infections., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Hypoxia contributes to the exaggerated yet ineffective airway inflammation that fails to oppose infections in cystic fibrosis (CF). However, the potential for impairment of essential immune functions by HIF-1α (hypoxia-inducible factor 1α) inhibition demands a better comprehension of downstream hypoxia-dependent pathways that are amenable for manipulation. We assessed here whether hypoxia may interfere with the activity of AhR (aryl hydrocarbon receptor), a versatile environmental sensor highly expressed in the lungs, where it plays a homeostatic role. We used murine models of Aspergillus fumigatus infection in vivo and human cells in vitro to define the functional role of AhR in CF, evaluate the impact of hypoxia on AhR expression and activity, and assess whether AhR agonism may antagonize hypoxia-driven inflammation. We demonstrated that there is an important interferential cross-talk between the AhR and HIF-1α signaling pathways in murine and human CF, in that HIF-1α induction squelched the normal AhR response through an impaired formation of the AhR:ARNT (aryl hydrocarbon receptor nuclear translocator)/HIF-1β heterodimer. However, functional studies and analysis of the AhR genetic variability in patients with CF proved that AhR agonism could prevent hypoxia-driven inflammation, restore immune homeostasis, and improve lung function. This study emphasizes the contribution of environmental factors, such as infections, in CF disease progression and suggests the exploitation of hypoxia:xenobiotic receptor cross-talk for antiinflammatory therapy in CF.

The environmental light/dark cycle has left its mark on the body's physiological functions to condition not only our inner biology, but also the interaction with external cues. In this scenario, the circadian regulation of the immune response has emerged as a critical factor in defining the host-pathogen interaction and the identification of the underlying circuitry represents a prerequisite for the development of circadian-based therapeutic strategies. The possibility to track down the circadian regulation of the immune response to a metabolic pathway would represent a unique opportunity in this direction. Herein, we show that the metabolism of the essential amino acid tryptophan, involved in the regulation of fundamental processes in mammals, is regulated in a circadian manner in both murine and human cells and in mouse tissues. By resorting to a murine model of pulmonary infection with the opportunistic fungus Aspergillus fumigatus , we showed that the circadian oscillation in the lung of the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO)1, generating the immunoregulatory kynurenine, resulted in diurnal changes in the immune response and the outcome of fungal infection. In addition, the circadian regulation of IDO1 drives such diurnal changes in a pre-clinical model of cystic fibrosis (CF), an autosomal recessive disease characterized by progressive lung function decline and recurrent infections, thus acquiring considerable clinical relevance. Our results demonstrate that the circadian rhythm at the intersection between metabolism and immune response underlies the diurnal changes in host-fungal interaction, thus paving the way for a circadian-based antimicrobial therapy., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Developing therapeutics for inflammatory diseases is challenging due to physiological mucosal barriers, systemic side effects, and the local microbiota. In the search for novel methods to overcome some of these problems, drug delivery systems that improve tissue-targeted drug delivery and modulate the microbiota are highly desirable. Microbial metabolites are known to regulate immune responses, an observation that has resulted in important conceptual advances in areas such as metabolite pharmacology and metabolite therapeutics. Indeed, the doctrine of "one molecule, one target, one disease" that has dominated the pharmaceutical industry in the 20th century is being replaced by developing therapeutics which simultaneously manipulate multiple targets through novel formulation approaches, including the multitarget-directed ligands. Thus, metabolites may not only represent biomarkers for disease development, but also, being causally linked to human diseases, an unexploited source of therapeutics. We have shown the successful exploitation of this approach: by deciphering how signaling molecules, such as the microbial metabolite, indole-3-aldehyde, and the repurposed drug anakinra, interact with the aryl hydrocarbon receptor may pave the way for novel therapeutics in inflammatory human diseases, for the realization of which drug delivery platforms are instrumental.

Inflammation is a key pathological driver in cystic fibrosis (CF). Current therapies are ineffective in treating and preventing the escalation of inflammatory events often exacerbated by superimposed infection. In this work, we propose a novel treatment based on the pulmonary administration of anakinra, a non-glycosylated recombinant form of IL-1Ra. An inhalable dry powder of anakinra was successfully developed to meet the specific needs of lung drug delivery. The new formulation was investigated in vitro for aerodynamic performances and activity and in vivo for its pharmacological profile, including the pharmacokinetics, treatment schedule, antimicrobial and anti-inflammatory activity and systemic toxicity. The protein was structurally preserved inside the formulation and retained its pharmacological activity in vitro immediately after preparation and over time when stored at ambient conditions. Anakinra when delivered to the lungs showed an improved and extended therapeutic efficacy in CF models in vivo as well as higher potency compared to systemic delivery. Peripheral side effects were significantly reduced and correlated with lower serum levels compared to systemic treatment. These findings provide proof-of-concept demonstration for anakinra repurposing in CF through the pulmonary route., Competing Interests: Declaration of Competing Interest The authors declare that an Italian Patent Application n. 102022000007844 has been submitted on April 21st, 2022., (Copyright © 2022. Published by Elsevier B.V.)

Aspergillus fumigatus is a ubiquitous mold that can cause severe infections in immunocompromised patients, typically manifesting as invasive pulmonary aspergillosis (IPA). Adaptive and innate immune cells that respond to A. fumigatus are present in the endogenous repertoire of patients with IPA but are infrequent and cannot be consistently isolated and expanded for adoptive immunotherapy. Therefore, we gene-engineered A. fumigatus -specific chimeric antigen receptor (Af-CAR) T cells and demonstrate their ability to confer antifungal reactivity in preclinical models in vitro and in vivo. We generated a CAR targeting domain AB90-E8 that recognizes a conserved protein antigen in the cell wall of A. fumigatus hyphae. T cells expressing the Af-CAR recognized A. fumigatus strains and clinical isolates and exerted a direct antifungal effect against A. fumigatus hyphae. In particular, CD8 + Af-CAR T cells released perforin and granzyme B and damaged A. fumigatus hyphae. CD8 + and CD4 + Af-CAR T cells produced cytokines that activated macrophages to potentiate the antifungal effect. In an in vivo model of IPA in immunodeficient mice, CD8 + Af-CAR T cells localized to the site of infection, engaged innate immune cells, and reduced fungal burden in the lung. Adoptive transfer of CD8 + Af-CAR T cells conferred greater antifungal efficacy compared to CD4 + Af-CAR T cells and an improvement in overall survival. Together, our study illustrates the potential of gene-engineered T cells to treat aggressive infectious diseases that are difficult to control with conventional antimicrobial therapy and support the clinical development of Af-CAR T cell therapy to treat IPA.

It is becoming increasingly clear that the communities of microorganisms that populate the surfaces exposed to the external environment, termed microbiota, are key players in the regulation of pathogen-host cross talk affecting the onset as well as the outcome of infectious diseases. We have performed a multicenter, prospective, observational study in which nasal and oropharyngeal swabs were collected for microbiota predicting the risk of invasive fungal infections (IFIs) in patients with hematological malignancies. Here, we demonstrate that the nasal and oropharyngeal microbiota are different, although similar characteristics differentiate high-risk from low-risk samples at both sites. Indeed, similar to previously published results on the oropharyngeal microbiota, high-risk samples in the nose were characterized by low diversity, a loss of beneficial bacteria, and an expansion of potentially pathogenic taxa, in the presence of reduced levels of tryptophan (Trp). At variance with oropharyngeal samples, however, low Trp levels were associated with defective host-derived kynurenine production, suggesting reduced tolerance mechanisms at the nasal mucosal surface. This was accompanied by reduced levels of the chemokine interleukin-8 (IL-8), likely associated with a reduced recruitment of neutrophils and impaired fungal clearance. Thus, the nasal and pharyngeal microbiomes of hematological patients provide complementary information that could improve predictive tools for the risk of IFI in hematological patients.

Alterations of the microbiome occur in inflammatory and autoimmune diseases, a finding consistent with the role of the microbiome in the maintenance of the immune system homeostasis. In this regard, L-tryptophan (Trp) metabolites, of both host and microbial origin, act as important regulators of host-microbial symbiosis by acting as aryl hydrocarbon receptor (AhR) ligands. The intestinal and respiratory barriers are very sensitive to AhR activity, suggesting that AhR modulation could be a therapeutic option to maintain the integrity of the epithelial barrier, which has substantial implications for health even beyond the mucosal site. A number of studies have highlighted the capacity of AhR to respond to indoles and indolyl metabolites, thus positioning AhR as a candidate indole receptor. However, the context-and ligand-dependent activity of AhR requires one to resort to suitable biopharmaceutical formulations to enable site-specific drug delivery in order to achieve therapeutic effectiveness, decrease unwanted toxicities and prevent off-target effects. In this review, we highlight the dual activity of the microbial metabolite indole-3-aldehyde at the host-microbe interface and its ability to orchestrate host pathophysiology and microbial symbiosis and discuss how its proper clinical development may turn into a valuable therapeutic strategy in local and distant inflammatory diseases.

Background: Despite the great success, the therapeutic benefits of immune checkpoint inhibitors (ICIs) in cancer immunotherapy are limited by either various resistance mechanisms or ICI-associated toxic effects including gastrointestinal toxicity. Thus, novel therapeutic strategies that provide manageable side effects to existing ICIs would enhance and expand their therapeutic efficacy and application. Due to its proven role in cancer development and immune regulation, gut microbiome has gained increasing expectation as a potential armamentarium to optimize immunotherapy with ICI. However, much has to be learned to fully harness gut microbiome for clinical applicability. Here we have assessed whether microbial metabolites working at the interface between microbes and the host immune system may optimize ICI therapy., Methods: To this purpose, we have tested indole-3-carboxaldehyde (3-IAld), a microbial tryptophan catabolite known to contribute to epithelial barrier function and immune homeostasis in the gut via the aryl hydrocarbon receptor (AhR), in different murine models of ICI-induced colitis. Epithelial barrier integrity, inflammation and changes in gut microbiome composition and function were analyzed. AhR, indoleamine 2,3-dioxygenase 1, interleukin (IL)-10 and IL-22 knockout mice were used to investigate the mechanism of 3-IAld activity. The function of the microbiome changes induced by 3-IAld was evaluated on fecal microbiome transplantation (FMT). Finally, murine tumor models were used to assess the effect of 3-IAld treatment on the antitumor activity of ICI., Results: On administration to mice with ICI-induced colitis, 3-IAld protected mice from intestinal damage via a dual action on both the host and the microbes. Indeed, paralleling the activation of the host AhR/IL-22-dependent pathway, 3-IAld also affected the composition and function of the microbiota such that FMT from 3-IAld-treated mice protected against ICI-induced colitis with the contribution of butyrate-producing bacteria. Importantly, while preventing intestinal damage, 3-IAld did not impair the antitumor activity of ICI., Conclusions: This study provides a proof-of-concept demonstration that moving past bacterial phylogeny and focusing on bacterial metabolome may lead to a new class of discrete molecules, and that working at the interface between microbes and the host immune system may optimize ICI therapy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Autophagy selectively degrades aggregation-prone misfolded proteins caused by defective cellular proteostasis. However, the complexity of autophagy may prevent the full appreciation of how its modulation could be used as a therapeutic strategy in disease management. Here, we define a molecular pathway through which recombinant IL-1 receptor antagonist (IL-1Ra, anakinra) affects cellular proteostasis independently from the IL-1 receptor (IL-1R1). Anakinra promoted H2O2-driven autophagy through a xenobiotic sensing pathway involving the aryl hydrocarbon receptor that, activated through the indoleamine 2,3-dioxygenase 1-kynurenine pathway, transcriptionally activated NADPH oxidase 4 independent of the IL-1R1. By coupling the mitochondrial redox balance to autophagy, anakinra improved the dysregulated proteostasis network in murine and human cystic fibrosis. We anticipate that anakinra may represent a therapeutic option in addition to its IL-1R1-dependent antiinflammatory properties by acting at the intersection of mitochondrial oxidative stress and autophagy with the capacity to restore conditions in which defective proteostasis leads to human disease.

Cystic fibrosis (CF) is an autosomal recessive disorder that affects multiple organs, although a decline in respiratory function represents the major cause of morbidity and mortality. The airways of CF patients are characterized by a chronic inflammatory state to which the receptor for advanced glycation end-products greatly contributes. Glyoxalase 1 (GLO1) is the major enzyme metabolizing methylglyoxal, a potent precursor of advanced glycation end-products. Its role in CF has never been investigated. We herein resorted to murine and human preclinical models of CF to define the contribution of GLO1 to inflammatory pathology. We found that the expression and activity of GLO1, measured by real-time PCR and Western blot or a specific spectrophotometric assay, respectively, are defective in mice and human bronchial cells from CF patients exposed to Aspergillus fumigatus , a common pathogen in CF, but could be restored upon blockade of interleukin-1 receptor signaling by anakinra in mice. This study suggests that GLO1 contributes to pathology in CF and may be potentially targeted to mitigate inflammation.

A tryptophan metabolite of microbial origin, indole-3-carboxaldehyde (3-IAld), has been recently identified as a Janus molecule that, acting at the host-pathogen interface and activating the aryl hydrocarbon receptor, can result as a potential candidate to treat infections as well as diseases with an inflammatory and/or immune component. In this work, an inhaled dry powder of 3-IAld was developed and evaluated for its efficacy, compared to oral and intranasal administration using an aspergillosis model of infection and inflammation. The obtained inhalable dry powder was shown to: i) be suitable to be delivered for pulmonary administration, ii) possess good toxicological safety, and iii) be superior to other administration modalities (oral and intranasal) in reducing disease scores by acting on infection and inflammation. This study supports the use of 3-IAld inhalable dry powders as a potential novel therapeutic tool to target inflammation and infection in pulmonary diseases., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The microbiome, i.e., the communities of microbes that inhabit the surfaces exposed to the external environment, participates in the regulation of host physiology, including the immune response against pathogens. At the same time, the immune response shapes the microbiome to regulate its composition and function. How the crosstalk between the immune system and the microbiome regulates the response to fungal infection has remained relatively unexplored. We have previously shown that strict anaerobes protect from infection with the opportunistic fungus Aspergillus fumigatus by counteracting the expansion of pathogenic Proteobacteria. By resorting to immunodeficient mouse strains, we found that the lung microbiota could compensate for the lack of B and T lymphocytes in Rag1 -/- mice by skewing the composition towards an increased abundance of protective anaerobes such as Clostridia and Bacteroidota. Conversely, NSG mice, with major defects in both the innate and adaptive immune response, showed an increased susceptibility to infection associated with a low abundance of strict anaerobes and the expansion of Proteobacteria. Further exploration in a murine model of chronic granulomatous disease, a primary form of immunodeficiency characterized by defective phagocyte NADPH oxidase, confirms the association of lung unbalance between anaerobes and Proteobacteria and the susceptibility to aspergillosis. Consistent changes in the lung levels of short-chain fatty acids between the different strains support the conclusion that the immune system and the microbiota are functionally intertwined during Aspergillus infection and determine the outcome of the infection.

Fungal infections represent a global problem, notably for immunocompromised patients in hospital, COVID-19 patient wards and care home settings, and the ever-increasing emergence of multidrug resistant fungal strains is a sword of Damocles hanging over many healthcare systems. Azoles represent the mainstay of antifungal drugs, and their mode of action involves the binding mode of these molecules to the fungal lanosterol 14α-demethylase target enzyme. In this study, we have prepared and characterized four novel organometallic derivatives of the frontline antifungal drug fluconazole ( 1a-4a ). Very importantly, enzyme inhibition and chemogenomic profiling demonstrated that lanosterol 14α-demethylase, as for fluconazole, was the main target of the most active compound of the series, ( N -(ferrocenylmethyl)-2-(2,4-difluorophenyl)-2-hydroxy- N -methyl-3-(1 H -1,2,4-triazol-1-yl)propan-1-aminium chloride, 2a ). Transmission electron microscopy (TEM) studies suggested that 2a induced a loss in cell wall integrity as well as intracellular features ascribable to late apoptosis or necrosis. The impressive activity of 2a was further confirmed on clinical isolates, where antimycotic potency up to 400 times higher than fluconazole was observed. Also, 2a showed activity towards azole-resistant strains. This finding is very interesting since the primary target of 2a is the same as that of fluconazole, emphasizing the role played by the organometallic moiety. In vivo experiments in a mice model of Candida infections revealed that 2a reduced the fungal growth and dissemination but also ameliorated immunopathology, a finding suggesting that 2a is active in vivo with added activity on the host innate immune response., Competing Interests: The authors declare no competing financial interests., (This journal is © The Royal Society of Chemistry.)

Primary sclerosing cholangitis (PSC) is a long-term liver disease characterized by a progressive course of cholestasis with liver inflammation and fibrosis. Intestinal barrier dysfunction has been implicated in the pathogenesis of PSC. According to the "leaky gut" hypothesis, gut inflammation alters the permeability of the intestinal mucosa, with the translocation of gut-derived products that enter the enterohepatic circulation and cause hepatic inflammation. Thus, the administration of molecules that preserve epithelial barrier integrity would represent a promising therapeutic strategy. Indole-3-carboxaldehyde (3-IAld) is a microbial-derived product working at the interface between the host and the microbiota and is able to promote mucosal immune homeostasis in a variety of preclinical settings. Herein, by resorting to a murine model of PSC, we found that 3-IAld formulated for localized delivery in the gut alleviates hepatic inflammation and fibrosis by modulating the intestinal microbiota and activating the aryl hydrocarbon receptor-IL-22 axis to restore mucosal integrity. This study points to the therapeutic potential of 3-IAld in liver pathology.

Inflammation plays a major role in the pathophysiology of cystic fibrosis (CF), a multisystem disease. Anti-inflammatory therapies are, therefore, of interest in CF, provided that the inhibition of inflammation does not compromise the ability to fight pathogens. Here, we assess whether indole-3-aldehyde (3-IAld), a ligand of the aryl hydrocarbon receptor (AhR), may encompass such an activity. We resorted to biopharmaceutical technologies in order to deliver 3-IAld directly into the lung, via dry powder inhalation, or into the gut, via enteric microparticles, in murine models of CF infection and inflammation. We found the site-specific delivery of 3-IAld to be an efficient strategy to restore immune and microbial homeostasis in CF organs, and mitigate lung and gut inflammatory pathology in response to fungal infections, in the relative absence of local and systemic inflammatory toxicity. Thus, enhanced delivery to target organs of AhR agonists, such as 3-IAld, may pave the way for the development of safe and effective anti-inflammatory agents in CF.

Inflammasomes are powerful cytosolic sensors of environmental stressors and are critical for triggering interleukin-1 (IL-1)-mediated inflammatory responses. However, dysregulation of inflammasome activation may lead to pathological conditions, and the identification of negative regulators for therapeutic purposes is increasingly being recognized. Anakinra, the recombinant form of the IL-1 receptor antagonist, proved effective by preventing the binding of IL-1 to its receptor, IL-1R1, thus restoring autophagy and dampening NLR family pyrin domain containing 3 (NLRP3) activity. As the generation of mitochondrial reactive oxidative species (ROS) is a critical upstream event in the activation of NLRP3, we investigated whether anakinra would regulate mitochondrial ROS production. By profiling the activation of transcription factors induced in murine alveolar macrophages, we found a mitochondrial antioxidative pathway induced by anakinra involving the manganese-dependent superoxide dismutase (MnSOD) or SOD2. Molecularly, anakinra promotes the binding of SOD2 with the deubiquitinase Ubiquitin Specific Peptidase 36 (USP36) and Constitutive photomorphogenesis 9 (COP9) signalosome, thus increasing SOD2 protein longevity. Functionally, anakinra and SOD2 protects mice from pulmonary oxidative inflammation and infection. On a preclinical level, anakinra upregulates SOD2 in murine models of chronic granulomatous disease (CGD) and cystic fibrosis (CF). These data suggest that protection from mitochondrial oxidative stress may represent an additional mechanism underlying the clinical benefit of anakinra and identifies SOD2 as a potential therapeutic target.