Expression and regulation of immune-modulatory enzyme indoleamine 2,3-dioxygenase (IDO) by human airway epithelial cells and its effect on T cell activation

The New Paradigm: The Role of Proteins and Triggers in the Evolution of Allergic Asthma

Epithelial barrier damage plays a central role in the development and maintenance of allergic inflammation. Rises in the epithelial barrier permeability of airways alter tissue homeostasis and allow the penetration of allergens and other external agents. Different factors contribute to barrier impairment, such as eosinophilic infiltration and allergen protease action-eosinophilic cationic proteins' effects and allergens' proteolytic activity both contribute significantly to epithelial damage. In the airways, allergen proteases degrade the epithelial junctional proteins, allowing allergen penetration and its uptake by dendritic cells. This increase in allergen-immune system interaction induces the release of alarmins and the activation of type 2 inflammatory pathways, causing or worsening the main symptoms at the skin, bowel, and respiratory levels. We aim to highlight the molecular mechanisms underlying allergenic protease-induced epithelial barrier damage and the role of immune response in allergic asthma onset, maintenance, and progression. Moreover, we will explore potential clinical and radiological biomarkers of airway remodeling in allergic asthma patients.

Kynurenine Pathway in Respiratory Diseases

The kynurenine pathway is the primary route for tryptophan catabolism and has received increasing attention as its association with inflammation and the immune system has become more apparent. This review provides a broad overview of the kynurenine pathway in respiratory diseases, from the initial observations to the characterization of the different cell types involved in the synthesis of kynurenine metabolites and the underlying immunoregulatory mechanisms. With a focus on respiratory infections, the various attempts to characterize the kynurenine/tryptophan (K/T) ratio as an inflammatory marker are reviewed. Its implication in chronic lung inflammation and its exacerbation by respiratory pathogens is also discussed. The emergence of preclinical interventional studies targeting the kynurenine pathway opens the way for the future development of new therapies.

Correlation between immune-related Tryptophan-Kynurenine pathway and severity of severe pneumonia and inflammation-related polyunsaturated fatty acids

BACKGROUND

Immune dysfunction and oxidative stress caused by severe pneumonia can lead to multiple organ dysfunction and even death, causing a significant impact on health and the economy. Currently, great progress has been made in the diagnosis and treatment of this disease, but the mortality rate remains high (approximately 50%). Therefore, there is still potential for further exploration of the immune response mechanisms against severe pneumonia.

OBJECTIVE

This study analyzed the difference in serum metabolic profiles between patients with severe pneumonia and health individuals through metabolomics, aiming to uncover the correlation between the Tryptophan-Kynurenine pathway and the severity of severe pneumonia, as well as N-3/N-6 polyunsaturated fatty acids (PUFAs).

METHODS

In this study, 44 patients with severe pneumonia and 37 health controls were selected. According to the changes in the disease symptoms within the 7 days of admission, the patients were divided into aggravation (n = 22) and remission (n = 22) groups. Targeted metabolomics techniques were performed to quantify serum metabolites and analyze changes between groups.

RESULTS

Metabolomics analysis showed that serum kynurenine and kynurenine/tryptophan (K/T) were significantly increased and tryptophan was significantly decreased in patients with severe pneumonia; HETE and HEPE in lipids increased significantly, while eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), α-linolenic acid (linolenic acid, α-LNA), arachidonic acid (ARA), Dihomo-γ-linolenic acid (DGLA), and 13(s)-hydroperoxylinoleic acid (HPODE) decreased significantly. Additionally, the longitudinal comparison revealed that Linolenic acid, DPA, and Tryptophan increased significantly in the remission group, while and kynurenine and K/T decreased significantly. In the aggravation group, Kynurenine and K/T increased significantly, while ARA, 8(S)-hydroxyeicosatetraenoic acid (HETE), 11(S)-HETE, and Tryptophan decreased significantly. The correlation analysis matrix demonstrated that Tryptophan was positively correlated with DGLA, 12(S)-hydroxyeicosapentaenoic acid (HEPE), ARA, EPA, α-LNA, DHA, and DPA. Kynurenine was positively correlated with 8(S)-HETE and negatively correlated with DHA. Additionally, K/T was negatively correlated with DGLA, ARA, EPA, α-LNA, DHA, and DPA.

CONCLUSION

This study revealed that during severe pneumonia, the Tryptophan-Kynurenine pathway was activated and was positively correlated with the disease progression. On the other hand, the activation of the Tryptophan-Kynurenine pathway was negatively correlated with N-3/N-6 PUFAs.

Protease allergens as initiators-regulators of allergic inflammation

Tremendous progress in the last few years has been made to explain how seemingly harmless environmental proteins from different origins can induce potent Th2-biased inflammatory responses. Convergent findings have shown the key roles of allergens displaying proteolytic activity in the initiation and progression of the allergic response. Through their propensity to activate IgE-independent inflammatory pathways, certain allergenic proteases are now considered as initiators for sensitization to themselves and to non-protease allergens. The protease allergens degrade junctional proteins of keratinocytes or airway epithelium to facilitate allergen delivery across the epithelial barrier and their subsequent uptake by antigen-presenting cells. Epithelial injuries mediated by these proteases together with their sensing by protease-activated receptors (PARs) elicit potent inflammatory responses resulting in the release of pro-Th2 cytokines (IL-6, IL-25, IL-1β, TSLP) and danger-associated molecular patterns (DAMPs; IL-33, ATP, uric acid). Recently, protease allergens were shown to cleave the protease sensor domain of IL-33 to produce a super-active form of the alarmin. At the same time, proteolytic cleavage of fibrinogen can trigger TLR4 signaling, and cleavage of various cell surface receptors further shape the Th2 polarization. Remarkably, the sensing of protease allergens by nociceptive neurons can represent a primary step in the development of the allergic response. The goal of this review is to highlight the multiple innate immune mechanisms triggered by protease allergens that converge to initiate the allergic response.

Multi-OMICs analysis reveals metabolic and epigenetic changes associated with macrophage polarization

Macrophages (MФ) are an essential immune cell for defense and repair that travel to different tissues and adapt based on local stimuli. A critical factor that may govern their polarization is the crosstalk between metabolism and epigenetics. However, simultaneous measurements of metabolites, epigenetics, and proteins (phenotype) have been a major technical challenge. To address this, we have developed a novel triomics approach using mass spectrometry to comprehensively analyze metabolites, proteins, and histone modifications in a single sample. To demonstrate this technique, we investigated the metabolic-epigenetic-phenotype axis following polarization of human blood–derived monocytes into either ‘proinflammatory M1-’ or ‘anti-inflammatory M2-’ MФs. We report here a complex relationship between arginine, tryptophan, glucose, and the citric acid cycle metabolism, protein and histone post-translational modifications, and human macrophage polarization that was previously not described. Surprisingly, M1-MФs had globally reduced histone acetylation levels but high levels of acetylated amino acids. This suggests acetyl-CoA was diverted, in part, toward acetylated amino acids. Consistent with this, stable isotope tracing of glucose revealed reduced usage of acetyl-CoA for histone acetylation in M1-MФs. Furthermore, isotope tracing also revealed MФs uncoupled glycolysis from the tricarboxylic acid cycle, as evidenced by poor isotope enrichment of succinate. M2-MФs had high levels of kynurenine and serotonin, which are reported to have immune-suppressive effects. Kynurenine is upstream of de novo NAD⁺ metabolism that is a necessary cofactor for Sirtuin-type histone deacetylases. Taken together, we demonstrate a complex interplay between metabolism and epigenetics that may ultimately influence cell phenotype.

Precision Medicine in Lung Cancer Theranostics: Paving the Way from Traditional Technology to Advance Era

Precision medicine for lung cancer theranostics is an advanced model combining prevention, diagnosis, and treatment for individual or specific population diseases to match individual patient differences. It involves collection and integration of genome, transcriptome, proteome, and metabolome features of lung cancer patients, combined with clinical characteristics. Subsequently, large data and artificial intelligence (AI) analysis have emerged to identify the most suitable therapeutic targets and personal treatment strategies for treatment of patients with lung cancer. We review the development and challenges associated with diagnosis and therapy of lung cancer from traditional technology, including immunotherapy prediction markers, liquid biopsy, surgery, and tumor immune microenvironment and patient-derived xenograft models, to AI in the era of precision medicine. AI has improved precision medicine and the predictive ability and accuracy of patient outcomes. Finally, we discuss some opportunities and challenges for lung cancer theranostics. Precision medicine in lung cancer can help us find the optimum treatment dose and time for a specific patient, which can advance the development of lung cancer therapeutics.

Kynurenine pathway in Coronavirus disease (COVID‐19): Potential role in prognosis

Background

It is known that inflammatory responses play an important role in the pathophysiology of COVID‐19.

Aims

In this study, we aimed to examine the role of kynurenine (KYN) metabolism on the severity of COVID‐19 disease AQ5.

Materials & Methods

Seventy COVID‐19 patients of varying severity and 30 controls were included in the study. In addition to the classical laboratory parameters, KYN, tryptophan (TRP), kynurenic acid (KYNA), 3 hydroxykynurenine (3OHKYN), quinolinic acid (QA), and picolinic acid (PA) were measured with mass spectrometry.

Results

TRP, KYN, KYN:TRP ratio, KYNA, 3OHKYN, PA, and QA results were found to be significantly different in COVID‐19 patients (p < 0.001 for all). The KYN:TRP ratio and PA of severe COVID‐19 patients was statistically higher than that of mild‐moderate COVID‐19 patients (p < 0.001 for all). When results were examined, statistically significant correlations with KYN:TRP ratio, IL‐6, ferritin, and procalcitonin were only found in COVID‐19 patients. ROC analysis indicated that highest AUC values were obtained by KYN:TRP ratio and PA (0.751 vs 0.742). In determining the severity of COVID‐19 disease, the odd ratios (and confidence intervals) of KYN:TRP ratio and PA levels that were adjusted according to age, gender, and comorbidity were determined to be 1.44 (1.1–1.87, p = 0.008) and 1.06 (1.02–1.11, p = 0.006), respectively.

Discussion & Conclusion

According to the results of this study, KYN metabolites play a role in the pathophysiology of COVID‐19, especially KYN:TRP ratio and PA could be markers for identification of severe COVID‐19 cases.

Human Oral Epithelial Cells Suppress T Cell Function via Prostaglandin E2 Secretion

The oral mucosa is constantly exposed to a plethora of stimuli including food antigens, commensal microbiota and pathogens, requiring distinct immune responses. We previously reported that human oral epithelial cells (OECs) suppress immune responses to bacteria, using H413 and TR146 OEC lines and primary OECs in co-culture with dendritic cells (DCs) and T cells (OEC-conditioned cells). OECs reduced DCs expression of CD80/CD86 and IL-12/TNFα release and impaired T cell activation. Here, we further evaluated the immunosuppression by these OECs and investigated the underlying mechanisms. OEC-conditioned DCs did not induce CD4 T cell polarization towards Treg, judging by the absence of FoxP3 expression. OECs also repressed T-bet/IFNγ expression in CD4 and CD8 T cells activated by DCs or anti-CD3/CD28 antibodies. This inhibition depended on OEC:T cell ratio and IFNγ repression occurred at the transcriptional level. Time-lapse experiments showed that OECs inhibited early steps of T cell activation, consistent with OECs inability to suppress T cells stimulated with PMA/ionomycin. Blocking CD40/CD40L, CD58/CD2 and PD-L1/PD-1 interactions with specific antibodies did not disrupt T cell suppression by OECs. However, preventing prostaglandin E2 (PGE2) synthesis or blocking PGE2 binding to the cognate EP2/EP4 receptors, restored IFNγ and TNFα production in OEC-conditioned T cells. Finally, treating OECs with poly(I:C), which simulates viral infections, limited T cell suppression. Overall, these results point to an inherent ability of OECs to suppress immune responses, which can nonetheless be eluded when OECs are under direct assault.

MicroRNA-511-3p Mediated Modulation of the Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Controls LPS-Induced Inflammatory Responses in Human Monocyte Derived DCs

The peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor expressed in dendritic cells (DCs), where it exerts anti-inflammatory responses against TLR4-induced inflammation. Recently, microRNA-511 (miR-511) has also emerged as a key player in controlling TLR4-mediated signalling and in regulating the function of DCs. Interestingly, PPARγ has been previously highlighted as a putative target of miR-511 activity; however, the link between miR-511 and PPARγ and its influence on human DC function within the context of LPS-induced inflammatory responses is unknown. Using a selection of miR-511-3p-specific inhibitors and mimics, we demonstrate for the first time that knockdown or overexpression of miR-511-3p inversely correlates with PPARγ mRNA levels and affects its transcriptional activity following treatment with rosiglitazone (RSG; PPARγ agonist), in the presence or absence of LPS. Additionally, we show that PPARγ-mediated suppression of DC activation and pro-inflammatory cytokine production in miR-511-3p knockdown DCs is abrogated following overexpression of miR-511-3p. Lastly, PPARγ activation suppressed LPS-mediated induction of indoleamine 2,3-dioxygenase (IDO) activity in DCs, most likely due to changes in miR-511-3p expression. Our data thus suggests that PPARγ-induced modulation of DC phenotype and function is influenced by miR-511-3p expression, which may serve as a potential therapeutic target against inflammatory diseases.

Mining for Active Molecules in Probiotic Supernatant by Combining Non-Targeted Metabolomics and Immunoregulation Testing

Chronic respiratory diseases such as asthma are highly prevalent in industrialized countries. As cases are expected to rise, there is a growing demand for alternative therapies. Our recent research on the potential benefits of probiotics suggests that they could prevent and reduce the symptoms of many diseases by modulating the host immune system with secreted metabolites. This article presents the first steps of the research that led us to identify the immunoregulatory bioactivity of the amino acid d-Trp reported in our previous study. Here we analyzed the cell culture metabolic footprinting of 25 commercially available probiotic strains to associate metabolic pathway activity information with their respective immune modulatory activity observed in vitro. Crude probiotic supernatant samples were processed in three different ways prior to untargeted analysis in positive and negative ionization mode by direct infusion ESI-FT-ICR-MS: protein precipitation and solid phase extraction (SPE) using HLB and CN-E sorbent cartridges. The data obtained were submitted to multivariate statistical analyses to distinguish supernatant samples into the bioactive and non-bioactive group. Pathway analysis using discriminant molecular features showed an overrepresentation of the tryptophan metabolic pathway for the bioactive supernatant class, suggesting that molecules taking part in that pathway may be involved in the immunomodulatory activity observed in vitro. This work showcases the potential of metabolomics to drive product development and novel bioactive compound discovery out of complex biological samples in a top-down manner.

Increased Kynurenine Indicates a Fatal Course of COVID-19

(1) Background: An inefficient immune response accompanied by an overwhelming inflammatory reaction is involved in severe courses of COVID-19. Kynurenine (KYN) has important immune-modulatory functions and may contribute to a failure in controlling SARS-CoV-2. The present study aims to explore biomarkers that hint at a fatal outcome of COVID-19 early on. (2) Methods: We established a cohort of 148 hospitalized COVID-19 patients for this study. Thirty-one patients died due to a severe COVID-19 course, and 117 recovered within 90 days. We built a biobank by collecting left-over material from these patients whenever blood arrived at the central laboratory of our University hospital for analysis of routine markers. The scientific laboratory analysis comprised KYN, Tryptophan (TRP), KYN/TRP ratio, ferritin, interleukin-6 (IL-6), C-reactive protein (CRP), creatinine, N-terminal pro-natriuretic peptide (NTproBNP), troponin T (TnT), fibrinogen, D-Dimer, prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin (AT), protein C, protein S, factor XIII, lupus aPTT, angiotensin-2, vitamin D metabolites, and telomeres in all COVID-19 patients. Basic clinical characteristics and anteceding diseases including cardiovascular, oncologic, renal, hypertension, pulmonary, metabolic (diabetes, obesity) were recorded in a database together with the laboratory data. (3) Results: At the time of diagnosis of SARS-CoV-2 infection those patients who deceased within 90 days afterwards due to COVID-19, had a significantly higher age, higher KYN, KYN/TRP ratio, ferritin, creatinine, and NTproBNP values than SARS-CoV-2 patients who survived COVID-19 along the same time span. In a Kaplan-Meier analysis the variables age, KYN, ferritin, D-Dimer, TnT, NTproBNP, and creatinine showed a significant influence on survival time. Gender, however, showed no influence. In a combined Cox regression analysis KYN had the highest hazard ratio (1.188, 95% CI: 1.071-1.319) followed by age (1.041, 95% CI: 1.011-1.073). In a ROC analysis, KYN values above the cut off limit of 4.82 nmol/l (as specified by Youden index) had a sensitivity of 82% (95% CI: 66-95%) and a specificity of 72% (95% CI: 65-82%) to predict COVID-19 related death within 90 days observation time. (4) Conclusions: Kynurenine is a promising blood biomarker to predict an increased risk of mortality in SARS-CoV-2 infected people already at the time of the first positive SARS-CoV-2 verification detected in these persons.

Immune Tolerance in the Oral Mucosa

The oral mucosa is a site of intense immune activity, where a large variety of immune cells meet to provide a first line of defense against pathogenic organisms. Interestingly, the oral mucosa is exposed to a plethora of antigens from food and commensal bacteria that must be tolerated. The mechanisms that enable this tolerance are not yet fully defined. Many works have focused on active immune mechanisms involving dendritic and regulatory T cells. However, epithelial cells also make a major contribution to tolerance by influencing both innate and adaptive immunity. Therefore, the tolerogenic mechanisms concurring in the oral mucosa are intertwined. Here, we review them systematically, paying special attention to the role of oral epithelial cells.

Comparative metabolomics analysis of bronchial epithelium during barrier establishment after allergen exposure

Background

Several studies have shown a correlation between an altered metabolome and respiratory allergies. The epithelial barrier hypothesis proposes that an epithelial barrier dysfunction can result in allergic diseases development. Der p 1 allergen from house dust mite is a renowned epithelial barrier disruptor and allergy initiator due to its cysteine‐protease activity. Here, we compared the metabolic profile of the bronchial epithelium exposed or not to Der p 1 during barrier establishment to understand its active role in allergy development.

Methods

Calu‐3 cells were cultivated in air‐liquid interface cultures and exposed to either Der p 1 or Ole e 1 allergens during barrier establishment. The comparative metabolomics analysis of apical and basolateral media were performed using liquid chromatography and capillary electrophoresis both coupled to mass spectrometry.

Results

We showed that epithelial barrier disruption by Der p 1 was associated with a specific metabolic profile, which was highly dependent on the state of the epithelium at the time of contact. Moreover, an apical‐basolateral distribution of the metabolites was also observed, indicating a compartmentalization of the response with differential metabolic patterns. A number of metabolites were changed by Der p 1, mainly related to amino acids metabolism, such as L‐arginine, L‐kynurenine and L‐methionine.

Conclusion

This work is the first report on the metabolic response in human bronchial epithelial cells associated with cysteine‐protease Der p 1 activity, which could contribute to allergy development. Moreover, it supports a reformulated epithelial barrier hypothesis that might help to explain allergies and their increasing prevalence.

Type-1 immunity and endogenous immune regulators predominate in the airway transcriptome during chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) remains the major complication limiting long-term survival among lung transplant recipients (LTRs). Limited understanding of CLAD immunopathogenesis and a paucity of biomarkers remain substantial barriers for earlier detection and therapeutic interventions for CLAD. We hypothesized the airway transcriptome would reflect key immunologic changes in disease. We compared airway brush-derived transcriptomic signatures in CLAD (n = 24) versus non-CLAD (n = 21) LTRs. A targeted assessment of the proteome using concomitant bronchoalveolar lavage (BAL) fluid for 24 cytokines/chemokines and alloimmune T cell responses was performed to validate the airway transcriptome. We observed an airway transcriptomic signature of differential genes expressed (DGEs) in CLAD marked by Type-1 immunity and striking upregulation of two endogenous immune regulators: indoleamine 2, 3 dioxygenase 1 (IDO-1) and tumor necrosis factor receptor superfamily 6B (TNFRSF6B). Advanced CLAD staging was associated with a more intense airway transcriptome signature. In a validation cohort using the identified signature, we found an area under the curve (AUC) of 0.77 for CLAD LTRs. Targeted proteomic analyses revealed a predominant Type-1 profile with detection of IFN-γ, TNF-α, and IL-1β as dominant CLAD cytokines, correlating with the airway transcriptome. The airway transcriptome provides novel insights into CLAD immunopathogenesis and biomarkers that may impact diagnosis of CLAD.

Decreased IDO1-dependent tryptophan metabolism in aged lung during influenza

Influenza epidemics remain a leading cause of morbidity and mortality worldwide. In the current study, we investigated the impact of chronological ageing on tryptophan metabolism in response to influenza infection.Examination of metabolites present in plasma collected from critically ill patients identified tryptophan metabolism as an important metabolic pathway utilised specifically in response to influenza. Using a murine model of influenza infection to further these findings illustrated that there was decreased production of kynurenine in aged lung in an indoleamine-pyrrole 2,3-dioxygenase-dependent manner that was associated with increased inflammatory and diminished regulatory responses. Specifically, within the first 7 days of influenza, there was a decrease in kynurenine pathway mediated metabolism of tryptophan, which resulted in a subsequent increase in ketone body catabolism in aged alveolar macrophages. Treatment of aged mice with mitoquinol, a mitochondrial targeted antioxidant, improved mitochondrial function and restored tryptophan metabolism.Taken together, our data provide additional evidence as to why older persons are more susceptible to influenza and suggest a possible therapeutic to improve immunometabolic responses in this population.

Increased kynurenine-to-tryptophan ratio in the serum of patients infected with SARS-CoV2: An observational cohort study

Immune dysregulation is a hallmark of patients infected by SARS-CoV2 and the balance between immune reactivity and tolerance is a key determinant of all stages of infection, including the excessive inflammatory state causing the acute respiratory distress syndrome. The kynurenine pathway (KP) of tryptophan (Trp) metabolism is activated by pro-inflammatory cytokines and drives mechanisms of immune tolerance. We examined the state of activation of the KP by measuring the Kyn:Trp ratio in the serum of healthy subjects (n = 239), and SARS-CoV2-negative (n = 305) and -positive patients (n = 89). Patients were recruited at the Emergency Room of St. Andrea Hospital (Rome, Italy). Kyn and Trp serum levels were assessed by HPLC/MS-MS. Compared to healthy controls, both SARS-CoV2-negative and -positive patients showed an increase in the Kyn:Trp ratio. The increase was larger in SARS-CoV2-positive patients, with a significant difference between SARS-CoV2-positive and -negative patients. In addition, the increase was more prominent in males, and positively correlated with age and severity of SARS-CoV2 infection, categorized as follows: 1 = no need for intensive care unit (ICU); 2 ≤ 3 weeks spent in ICU; 3 ≥ 3 weeks spent in ICU; and 4 = death. The highest Kyn:Trp values were found in SARS-CoV2-positive patients with severe lymphopenia. These findings suggest that the Kyn:Trp ratio reflects the level of inflammation associated with SARS-CoV2 infection, and, therefore, might represent a valuable biomarker for therapeutic intervention.

Serum Proteomics in COVID-19 Patients: Altered Coagulation and Complement Status as a Function of IL-6 Level

Over 5 million people around the world have tested positive for the beta coronavirus SARS-CoV-2 as of May 29, 2020, a third of which are in the United States alone. These infections are associated with the development of a disease known as COVID-19, which is characterized by several symptoms, including persistent dry cough, shortness of breath, chills, muscle pain, headache, loss of taste or smell, and gastrointestinal distress. COVID-19 has been characterized by elevated mortality (over 100 thousand people have already died in the US alone), mostly due to thromboinflammatory complications that impair lung perfusion and systemic oxygenation in the most severe cases. While the levels of pro-inflammatory cytokines such as interleukin-6 (IL-6) have been associated with the severity of the disease, little is known about the impact of IL-6 levels on the proteome of COVID-19 patients. The present study provides the first proteomics analysis of sera from COVID-19 patients, stratified by circulating levels of IL-6, and correlated to markers of inflammation and renal function. As a function of IL-6 levels, we identified significant dysregulation in serum levels of various coagulation factors, accompanied by increased levels of antifibrinolytic components, including several serine protease inhibitors (SERPINs). These were accompanied by up-regulation of the complement cascade and antimicrobial enzymes, especially in subjects with the highest levels of IL-6, which is consistent with an exacerbation of the acute phase response in these subjects. Although our results are observational, they highlight a clear increase in the levels of inhibitory components of the fibrinolytic cascade in severe COVID-19 disease, providing potential clues related to the etiology of coagulopathic complications in COVID-19 and paving the way for potential therapeutic interventions, such as the use of pro-fibrinolytic agents. Raw data for this study are available through ProteomeXchange with identifier PXD020601.

Developing immune-regulatory materials using immobilized monosaccharides with immune-instructive properties

New strategies for immune modulation have shown real promise in regenerative medicine as well as the fight against autoimmune diseases, allergies, and cancer. Dendritic cells (DCs) are gatekeepers of the immune system and their ability in shaping the adaptive immune responses makes DCs ideal targets for immune modulation. Carbohydrates are abundant in different biological systems and are known to modulate DC phenotype and function. However, how simple monosaccharides instruct DC function is less well understood. In this study, we used a combinatorial array of immobilized monosaccharides to investigate how they modulate DC phenotype and function and crucially the impact of such changes on downstream adaptive immune responses. Our data show that a selection of monosaccharides significantly suppress lipopolysaccharide-induced DC activation as evidenced by a reduction in CD40 expression, IL-12 production, and indoleamine 2,3-dioxygenase activity, while inducing a significant increase in IL-10 production. These changes are indicative of the induction of an anti-inflammatory or regulatory phenotype in DCs, which was further confirmed in DC-T cell co-cultures where DCs cultured on the 'regulatory' monosaccharide-coated surfaces were shown to induce naïve T cell polarization toward regulatory phenotype. Our data also highlighted a selection of monosaccharides that are able to promote mixed Treg and Th17 cell differentiation, a T cell phenotype expected to be highly immune suppressive. These data show the potential immunomodulatory effects of immobilized monosaccharides in priming DCs and skewing T cell differentiation toward an immune-regulatory phenotype. The ability to fine-tune immune responses using these simple carbohydrate combinations (e.g. as coatings for existing materials) can be utilized as novel tools for immune modulation with potential applications in regenerative medicine, implantable medical devices, and wound healing where reduction of inflammatory responses and maintaining immune homeostasis are desirable.

A dissection of SARS‑CoV2 with clinical implications (Review)

We are being confronted with the most consequential pandemic since the Spanish flu of 1918‑1920 to the extent that never before have 4 billion people quarantined simultaneously; to address this global challenge we bring to the forefront the options for medical treatment and summarize SARS‑CoV2 structure and functions, immune responses and known treatments. Based on literature and our own experience we propose new interventions, including the use of amiodarone, simvastatin, pioglitazone and curcumin. In mild infections (sore throat, cough) we advocate prompt local treatment for the naso‑pharynx (inhalations; aerosols; nebulizers); for moderate to severe infections we propose a tried‑and‑true treatment: the combination of arginine and ascorbate, administered orally or intravenously. The material is organized in three sections: i) Clinical aspects of COVID‑19; acute respiratory distress syndrome (ARDS); known treatments; ii) Structure and functions of SARS‑CoV2 and proposed antiviral drugs; iii) The combination of arginine‑ascorbate.

COVID-19 infection alters kynurenine and fatty acid metabolism, correlating with IL-6 levels and renal status

BACKGROUNDReprogramming of host metabolism supports viral pathogenesis by fueling viral proliferation, by providing, for example, free amino acids and fatty acids as building blocks.METHODSTo investigate metabolic effects of SARS-CoV-2 infection, we evaluated serum metabolites of patients with COVID-19 (n = 33; diagnosed by nucleic acid testing), as compared with COVID-19-negative controls (n = 16).RESULTSTargeted and untargeted metabolomics analyses identified altered tryptophan metabolism into the kynurenine pathway, which regulates inflammation and immunity. Indeed, these changes in tryptophan metabolism correlated with interleukin-6 (IL-6) levels. Widespread dysregulation of nitrogen metabolism was also seen in infected patients, with altered levels of most amino acids, along with increased markers of oxidant stress (e.g., methionine sulfoxide, cystine), proteolysis, and renal dysfunction (e.g., creatine, creatinine, polyamines). Increased circulating levels of glucose and free fatty acids were also observed, consistent with altered carbon homeostasis. Interestingly, metabolite levels in these pathways correlated with clinical laboratory markers of inflammation (i.e., IL-6 and C-reactive protein) and renal function (i.e., blood urea nitrogen).CONCLUSIONIn conclusion, this initial observational study identified amino acid and fatty acid metabolism as correlates of COVID-19, providing mechanistic insights, potential markers of clinical severity, and potential therapeutic targets.FUNDINGBoettcher Foundation Webb-Waring Biomedical Research Award; National Institute of General and Medical Sciences, NIH; and National Heart, Lung, and Blood Institute, NIH.

Cytotoxicity of Standardized Curcuminoids Mixture against Epithelial Ovarian Cancer Cell Line SKOV-3

Herbal medicine has been in use for centuries for a wide variety of ailments; however, the efficacy of its therapeutic agents in modern medicine is currently being studied. Curcuminoids are an example of natural agents, widely used due to their potential contribution in the prevention and treatment of cancer. In this study, the three main compounds of curcuminoids—curcumin, desmethoxycurcumin, and bisdesmethoxycurcumin—were determined by reversed-phase high performance liquid chromatography (HPLC) to quantify total content in a mixture. Subsequently, the effect of the three curcuminoids, employed as one sample, was evaluated, to study the proliferation, apoptosis, cell cycle, and migration of the human ovarian cancer cell line SKOV-3. The results reveal that curcuminoids inhibit the proliferation of SKOV-3 cells with concentration- and time-dependent mechanisms. The morphological analysis of the treated SKOV-3 cells showed a typical apoptotic phenotype—cell shrinkage and membrane blebbing in a dose-dependent manner. In addition, flow cytometry demonstrated an increase in apoptosis with an IC50 of 30 µM curcuminoids. The migration of SKOV-3 cells was also inhibited, reflected by a decrease in wound area. Furthermore, the curcuminoids were found to have no stimulation effect on the expression of cytokines TNF-α and IL-10. These results suggest that a curcuminoid mixture can effectively suppress epithelial cancer cell growth in vitro by inducing cellular changes and apoptosis.

The Cross-Talk between miR-511-3p and C-Type Lectin Receptors on Dendritic Cells Affects Dendritic Cell Function

MicroRNAs are small, noncoding RNAs that function as posttranscriptional modulators of gene expression by binding target mRNAs and inhibiting translation. They are therefore crucial regulators of several biological as well as immunological events. Recently, miR-511-3p has been implicated in the development and differentiation of APCs, such as dendritic cells (DCs), and regulating several human diseases. Interestingly, miR-511-3p is embedded within the human MRC1 gene that encodes the mannose receptor. In this study, we sought to examine the impact of miR-511-3p up- or downregulation on human DC surface phenotype, cytokine profile, immunogenicity (using IDO activity as a surrogate), and downstream T cell polarization. Using gene silencing and a selection of microRNA mimics, we could successfully suppress or induce the expression of miR-511-3p in DCs. Consequently, we show for the first time, to our knowledge, that inhibition and/or overexpression of miR-511-3p has opposing effects on the expression levels of two key C-type lectin receptors, namely the mannose receptor and DC-specific ICAM 3 nonintegrin at protein and mRNA levels, thereby affecting C-type lectin receptor-induced modulation of IDO activity in DCs. Furthermore, we show that downregulation of miR-511-3p drives an anti-inflammatory DC response characterized by IL-10 production. Interestingly, the miR-511-3p^low DCs also promoted IL-4 secretion and suppressed IL-17 in cocultures with autologous T cells. Together, our data highlight the potential role of miR-511 in regulating DC function and downstream events leading to Th polarization and immune modulation.

Contribution of IDO to human respiratory syncytial virus infection

IDO is an enzyme that participates in the degradation of tryptophan (Trp), which is an essential amino acid necessary for vital cellular processes. The degradation of Trp and the metabolites generated by the enzymatic activity of IDO can have immunomodulating effects, notably over T cells, which are particularly sensitive to the absence of Trp and leads to the inhibition of T cell activation, cell death, and the suppression of T cell effector functions. Noteworthy, T cells participate in the cellular immune response against the human respiratory syncytial virus (hRSV) and are essential for viral clearance, as well as the total recovery of the host. Furthermore, inadequate or non‐optimal polarization of T cells is often seen during the acute phase of the disease caused by this pathogen. Here, we discuss the capacity of hRSV to exploit the immunosuppressive features of IDO to reduce T cell function, thus acquiring relevant aspects during the biology of the virus. Additionally, we review studies on the influence of IDO over T cell activation and its relationship with hRSV infection.

Transcriptomic and proteomic host response to Aspergillus fumigatus conidia in an air-liquid interface model of human bronchial epithelium

Aspergillus fumigatus (A. fumigatus) is a wide-spread fungus that is a potent allergen in hypersensitive individuals but also an opportunistic pathogen in immunocompromised patients. It reproduces asexually by releasing airborne conidiospores (conidia). Upon inhalation, fungal conidia are capable of reaching the airway epithelial cells (AECs) in bronchial and alveolar tissues. Previous studies have predominantly used submerged monolayer cultures for studying this host-pathogen interaction; however, these cultures do not recapitulate the mucocililary differentiation phenotype of the in vivo epithelium in the respiratory tract. Thus, the aim of this study was to use well-differentiated primary human bronchial epithelial cells (HBECs) grown at the air-liquid interface (ALI) to determine their transcriptomic and proteomic responses following interaction with A. fumigatus conidia. We visualized conidial interaction with HBECs using confocal laser scanning microscopy (CLSM), and applied NanoString nCounter and shotgun proteomics to assess gene expression changes in the human cells upon interaction with A. fumigatus conidia. Western blot analysis was used to assess the expression of top three differentially expressed proteins, CALR, SET and NUCB2. CLSM showed that, unlike submerged monolayer cultures, well-differentiated ALI cultures of primary HBECs were estimated to internalize less than 1% of bound conidia. Nevertheless, transcriptomic and proteomic analyses revealed numerous differentially expressed host genes; these were enriched for pathways including apoptosis/autophagy, translation, unfolded protein response and cell cycle (up-regulated); complement and coagulation pathways, iron homeostasis, nonsense mediated decay and rRNA binding (down-regulated). CALR and SET were confirmed to be up-regulated in ALI cultures of primary HBECs upon exposure to A. fumigatus via western blot analysis. Therefore, using transcriptomics and proteomics approaches, ALI models recapitulating the bronchial epithelial barrier in the conductive zone of the respiratory tract can provide novel insights to the molecular response of bronchial epithelial cells upon exposure to A. fumigatus conidia.

Mechanism and prognostic value of indoleamine 2,3-dioxygenase 1 expressed in hepatocellular carcinoma

Indoleamine 2,3‐dioxygenase 1 (IDO1) is a tryptophan‐metabolizing enzyme that is widely distributed in normal or malignant tissues and contributes to immunologic tolerance and immune escape. However, in hepatocellular carcinoma (HCC), the characteristics and mechanism of IDO1 expression have not been well defined. In this study, IDO1 expression in tumor cells (T‐IDO1) was frequently detected (109/112) by immunohistochemistry in formalin‐fixed paraffin‐embedded specimens from HCC patients, and the expression patterns were mostly focal (102/109). Expression of T‐IDO1 was significantly associated with the infiltration of CD8+ T cells (P = .043), as well as younger age (<50 years old, P = .02). It was also found that IDO1 had diffuse expression in inflammatory cells in all specimens, which were defined as antigen‐presenting cells. Significant correlations among IDO1,IFNG, and CD8A transcriptional levels were observed in freshly resected HCC specimens; moreover, no constitutive IDO1 expression was detected in HCC cell lines until stimulated by interferon‐γ through the JAK2‐STAT1 signaling pathway, but not type I interferon. Survival analyses showed that increased T‐IDO1 and CD8+ T cell infiltration were significantly associated with superior overall survival (OS) (T‐IDO1, P = .003; CD8+ T cells, P = .004), and T‐IDO1 expression is an independent prognosis factor in both OS and disease‐free survival (OS, P = .007; disease‐free survival, P = .044). These findings indicated that T‐IDO1 expression in HCC is common and is dominantly driven by the host antitumor immune response, which is a favorable prognostic factor in HCC.

Indoleamine 2,3-Dioxygenase Expression Pattern in the Tumor Microenvironment Predicts Clinical Outcome in Early Stage Cervical Cancer

The indoleamine 2,3-dioxygenase (IDO) enzyme can act as an immunoregulator by inhibiting T cell function via the degradation of the essential amino acid tryptophan (trp) into kynurenine (kyn) and its derivates. The kyn/trp ratio in serum is a prognostic factor for cervical cancer patients; however, information about the relationship between serum levels and IDO expression in the tumor is lacking. IDO expression was studied in 71 primary and 14 paired metastatic cervical cancer samples by various immunohistochemical (IHC) techniques, including 7-color fluorescent multiparameter IHC, and the link between the concentration of IDO metabolites in serum, clinicopathological characteristics, and the presence of (proliferating) T cells (CD8, Ki67, and FoxP3) was examined. In addition, we compared the relationships between IDO1 and IFNG gene expression and clinical parameters using RNAseq data from 144 cervical tumor samples published by The Cancer Genome Atlas (TCGA). Here, we demonstrate that patchy tumor IDO expression is associated with an increased systemic kyn/trp ratio in cervical cancer (P = 0.009), whereas marginal tumor expression at the interface with the stroma is linked to improved disease-free (DFS) (P = 0.017) and disease-specific survival (P = 0.043). The latter may be related to T cell infiltration and localized IFNγ release inducing IDO expression. Indeed, TCGA analysis of 144 cervical tumor samples revealed a strong and positive correlation between IDO1 and IFNG mRNA expression levels (P < 0.001) and a significant association with improved DFS for high IDO1 and IFNG transcript levels (P = 0.031). Unexpectedly, IDO+ tumors had higher CD8⁺Ki67⁺ T cell rates (P = 0.004). Our data thus indicate that the serum kyn/trp ratio and IDO expression in primary tumor samples are not clear-cut biomarkers for prognosis and stratification of patients with early stage cervical cancer for clinical trials implementing IDO inhibitors. Rather, a marginal IDO expression pattern in the tumor dominantly predicts favorable outcome, which might be related to IFNγ release in the cervical tumor microenvironment.

Overexpression of indoleamine 2, 3-dioxygenase contributes to the repair of human airway epithelial cells inhibited by dexamethasone via affecting the MAPK/ERK signaling pathway

Indoleamine 2, 3-dioxygenase (IDO) catalyzes the degradation of trytophan, which serves a key role in immune suppression via regulating the production of several metabolites. The present study aimed to explore the effects and mechanisms of IDO in the repair of human airway epithelium suppressed by dexamethasone (DEX). Cell viability, proliferation and migration were evaluated using a Cell Counting Kit-8 (CCK-8), 5(6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling, and wound-healing assay, respectively. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot analysis and ELISA were performed to assess the levels of IDO, the mitogen-activated protein kinase (MAPK)/extracellular regulated kinase (ERK) pathway-related factors and epidermal growth factor (EGF) expression, respectively. The results revealed that overexpression of IDO enhanced the cell viability, and promoted the proliferation and migration of 16HBE cells which repair was inhibited by DEX. Furthermore, it was indicated that overexpression of IDO affected the MAPK/ERK pathway. In conclusion, overexpression of IDO promoted the human airway epithelium repair inhibited by DEX through affecting MAPK/ERK pathway. The present study implied that IDO may be a potential genetic therapeutic agent and supported the utilization of IDO in asthma.

[Immunotherapy in lung cancer: New concepts]

Improvements in knowledge about the complexity of the tumor microenvironment have paved the way for a revolution in lung cancer treatment with the emergence of immune checkpoint inhibitors. The immune checkpoints negatively regulate immune cells and lead to a dormant state: the immune cells are then unable to interact effectively with their targets. The immune checkpoint inhibitors are monoclonal antibodies that block immune checkpoints and permit reactivation of the immune response against the tumor. Although immune checkpoint inhibitors are effective as monotherapy, several other immune targets exist. The better understanding of the involvement of these new targets in the immune response against tumors is leading to the design of new compounds and new therapeutic approaches.

Expression of indoleamine 2,3-dioxygenase 1 as transcript and protein in the healthy and diseased equine endometrium

The enzyme indoleamine 2,3-dioxygenase 1 (IDO1) acts immunomodulatory and restricts bacterial growth. In the uterus of women and mice, it likely contributes to tissue homeostasis and disease pathogenesis. Pregnancy failure in mares is often caused by endometritis and endometrosis. The pathogenesis of nonsuppurative endometritis and endometrosis is still uncertain. To the authors' knowledge, no information on IDO1 expression in the equine endometrium is published. Aim of this study was to examine the presence of IDO1 as transcripts and proteins in the healthy and diseased endometrium of 25 mares and to determine its cellular expression. By PCR, IDO1 transcripts were detected in healthy (3 mares) and diseased endometria (22 mares). Western blot on 15 samples showed the concurrent presence of IDO1 proteins. Immunohistochemistry revealed its expression in macrophages and epithelial cells. Endometria of 21 mares showed an intense staining of glandular epithelia, whereas glands of the remaining 4 mares were negative or contained only few positive cells. Tissue samples of all mares showed a minimal to mild IDO1 expression in the surface epithelium and glandular ducts. Quantification of immunohistochemistry on biopsies of 6 mares collected at different stages of the same endometrial cycle indicated that the IDO1 expression is not influenced by the endometrial cycle. This study confirmed IDO1 expression also in the equine endometrium and suggests an immunomodulatory role of uterine macrophages and epithelial cells. A markedly reduced glandular IDO1 expression as detected in 4 mares may be associated with alterations of uterine immune defenses.

A Multifaceted Role of Tryptophan Metabolism and Indoleamine 2,3-Dioxygenase Activity in Aspergillus fumigatus-Host Interactions

Aspergillus fumigatus is the most prevalent filamentous fungal pathogen of humans, causing either severe allergic bronchopulmonary aspergillosis or often fatal invasive pulmonary aspergillosis (IPA) in individuals with hyper- or hypo-immune deficiencies, respectively. Disease is primarily initiated upon the inhalation of the ubiquitous airborne conidia—the initial inoculum produced by A. fumigatus—which are complete developmental units with an ability to exploit diverse environments, ranging from agricultural composts to animal lungs. Upon infection, conidia initially rely on their own metabolic processes for survival in the host’s lungs, a nutritionally limiting environment. One such nutritional limitation is the availability of aromatic amino acids (AAAs) as animals lack the enzymes to synthesize tryptophan (Trp) and phenylalanine and only produce tyrosine from dietary phenylalanine. However, A. fumigatus produces all three AAAs through the shikimate–chorismate pathway, where they play a critical role in fungal growth and development and in yielding many downstream metabolites. The downstream metabolites of Trp in A. fumigatus include the immunomodulatory kynurenine derived from indoleamine 2,3-dioxygenase (IDO) and toxins such as fumiquinazolines, gliotoxin, and fumitremorgins. Host IDO activity and/or host/microbe-derived kynurenines are increasingly correlated with many Aspergillus diseases including IPA and infections of chronic granulomatous disease patients. In this review, we will describe the potential metabolic cross talk between the host and the pathogen, specifically focusing on Trp metabolism, the implications for therapeutics, and the recent studies on the coevolution of host and microbe IDO activation in regulating inflammation, while controlling infection.

[Tryptophan metabolism in patients with primary immune thrombocytopenia with high dose of dexamethasone]

Objective: To test whether the tryptophan metabolism was abnormal in newly diagnosed ITP patients as well as in these patients after treatment with dexamethasone. Methods: Newly diagnosed patients with ITP between Jan 2014 and May 2015 were enrolled, including 14 females and 11 males, with a median age of 57 years and a median PLT count of 16 (0-32) ×10(9)/L. All patients were treated with oral dexamethasone. The expression levels of IDO mRNA and TTS mRNA in peripheral blood mononuclear cells (PBMC) were analyzed by real-time quantitative polymerase chain reaction. ELISA was used to test the concentrations of IDO and TTS in serum. The concentrations of plasma kynurenine and tryptophan were detected by high-pressure liquid chromatography. Samples from healthy individuals were tested as controls. Results: ①After dexamethasone treatment, 17 patients resulted in persistent remission, 2 cases were ineffective, and relapse occurred in 6 cases at a median follow-up of 11 (6-18) months. ②Before and after dexamethasone treatment, the relative expression of indoleamine2,3-dioxygenase (IDO) mRNA and tryptophanyl t-RNA synthetase (TTS) mRNA showed that there were significant decline in persistent remission group (2.54±0.86 vs 19.85±5.36, t=3.188, P=0.003; 0.68±0.19 vs 45.39±15.83, t=2.842, P=0.008) , compared with the normal control group, the difference was not statistically significant (t=2.313, P=0.027; t=1.127, P=0.268) . After treatment, the IDO concentration decreased [ (19.34±0.42) U/ml] and the TTS concentration was markedly increased [ (13.37±0.54) μg/L] in sustained remission group compared with that before treatment [ (21.91±0.37) U/ml] as well as that in normal controls. In particularly, abnormal tryptophan catabolism could be recovered in these 17 patients with persistent remission [Try: (19.85±5.36) μmol/L vs (19.65±4.55) μmol/L, t=1.027, P=0.311; Kyn: (0.56±0.26) μmol/L vs (0.58±0.23) μmol/L, t=2.075, P=0.448]. ③There was no obviously difference in the relative expression of IDO mRNA and TTS mRNA, the concentration of IDO and TTS and the abnormal tryptophan catabolism between before and after treatment of dexamethasone in patients without response and relapsed patients (all P>0.01) . Conclusion: The tryptophan catabolism was abnormal in ITP patients, and it could be recovered in patients with persistent remission.