Molecular and physiological roles of the adaptor protein CARD9 in immunity

A novel inherited CARD9 deficiency in an otherwise healthy woman with CNS candidiasis

Patients with caspase-associated recruitment domain-9 (CARD9) deficiency are more likely to develop invasive fungal disease that affect CNS. However, the understanding of how Candida invades and persists in CNS is still limited. We here reported a 24-year-old woman who were previously immunocompetent and diagnosed with CNS candidiasis. A novel autosomal recessive homozygous CARD9 mutation (c.184 + 5G > T) from this patient was identified using whole genomic sequencing. Furthermore, we extensively characterized the impact of this CARD9 mutation on the host immune response in monocytes, neutrophils and CD4 + T cells, using single cell sequencing and in vitro experiments. Decreased pro-inflammatory cytokine productions of CD14 + monocyte, impaired Th17 cell differentiation, and defective neutrophil accumulation in CNS were found in this patient. In conclusion, this study proposed a novel mechanism of CNS candidiasis development. Patients with CNS candidiasis in absence of known immunodeficiencies should be analyzed for CARD9 gene mutation as the cause of invasive fungal infection predisposition.

Transcription of NOD1 and NOD2 and their interaction with CARD9 and RIPK2 in IFN signaling in a perciform fish, the Chinese perch, Siniperca chuatsi

NOD1 and NOD2 as two representative members of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family play important roles in antimicrobial immunity. However, transcription mechanism of nod1 and nod2 and their signal circle are less understood in teleost fish. In this study, with the cloning of card9 and ripk2 in Chinese perch, the interaction between NOD1, NOD2, and CARD9 and RIPK2 were revealed through coimmunoprecipitation and immunofluorescence assays. The overexpression of NOD1, NOD2, RIPK2 and CARD9 induced significantly the promoter activity of NF-κB, IFNh and IFNc. Furthermore, it was found that nod1 and nod2 were induced by poly(I:C), type I IFNs, RLR and even NOD1/NOD2 themselves through the ISRE site of their proximal promoters. It is thus indicated that nod1 and nod2 can be classified also as ISGs due to the presence of ISRE in their proximal promoter, and their expression can be mechanistically controlled through PRR pathway as well as through IFN signaling in antiviral immune response.

Deep dermatophytosis caused by Trichophyton rubrum in an elderly patient with CARD9 deficiency: A case report and literature review

Deep dermatophytosis is an invasive and sometimes life-threatening fungal infection mainly reported in immunocompromised patients. However, a caspase recruitment domain-containing protein 9 (CARD9) deficiency has recently been reported to cause deep dermatophytosis. Herein, we report the first Japanese case of deep dermatophytosis associated with CARD9 deficiency. An 80-year-old Japanese man with tinea corporis presented with subcutaneous nodules on his left sole. Histopathological findings revealed marked epithelioid cell granulomas with filamentous fungal structures in the deep dermis and subcutis, and the patient was diagnosed with deep dermatophytosis. Despite antifungal therapy, the subcutaneous nodule on his left sole gradually enlarged, his left calcaneal bone was invaded, and the patient finally underwent amputation of his left leg. Genetic analysis revealed a homozygous CARD9 c.586 A > G (p. Lys196Glu) variant, suggesting a CARD9 deficiency. Here, we discuss the clinical features of CARD9 deficiency-associated deep dermatophytosis with a case report and review of the literature.

Regulatory roles of CARD9-BCL10-Rac1 (CBR) signalome in islet β-cell function in health and metabolic stress: Is there room for MALT1?

It is widely accepted that pancreatic islet β-cell failure and the onset of type 2 diabetes (T2DM) constitute an intricate interplay between the genetic expression of the disease and a host of intracellular events including increased metabolic (oxidative, endoplasmic reticulum) stress under the duress of glucolipotoxicity. Emerging evidence implicates unique roles for Caspase Recruitment Domain containing protein 9 (CARD9) in the onset of metabolic diseases, including obesity and insulin resistance. Mechanistically, CARD9 has been implicated in the regulation of p38MAPK and NFkB signaling pathways culminating in cellular dysfunction. Several regulatory factors, including B-cell lymphoma/leukemia 10 (BCL10) have been identified as modulators of CARD9 function in multiple cell types. Despite this evidence on regulatory roles of CARD9-BCL10 signalome in the onset of various pathological states, putative roles of this signaling module in islet β-cell dysfunction in metabolic stress remain less understood. This brief review is aimed at highlighting roles for CARD9 in islet β-cell function under acute (physiological insulin secretion) and long-term (cell dysfunction) exposure to glucose. Emerging roles of other signaling proteins, such as Rac1, BCL10 and MALT1 as contributors to CARD9 signaling in the islet β-cells are also reviewed. Potential avenues for future research toward the development of novel therapeutics for the prevention CARD9-BCL10-Rac1 (CBR) signalome-induced β-cell defects under metabolic stress are discussed.

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

Prognostic utility of TME-associated genes in pancreatic cancer

Background: Pancreatic cancer (PC) is a deadly disease. The tumor microenvironment (TME) participates in PC oncogenesis. This study focuses on the assessment of the prognostic and treatment utility of TME-associated genes in PC. Methods: After obtaining the differentially expressed TME-related genes, univariate and multivariate Cox analyses and least absolute shrinkage and selection operator (LASSO) were performed to identify genes related to prognosis, and a risk model was established to evaluate risk scores, based on The Cancer Genome Atlas (TCGA) data set, and it was validated by external data sets from the Gene Expression Omnibus (GEO) and Clinical Proteomic Tumor Analysis Consortium (CPTAC). Multiomics analyses were adopted to explore the potential mechanisms, discover novel treatment targets, and assess the sensitivities of immunotherapy and chemotherapy. Results: Five TME-associated genes, namely, FERMT1, CARD9, IL20RB, MET, and MMP3, were identified and a risk score formula constructed. Next, their mRNA expressions were verified in cancer and normal pancreatic cells. Multiple algorithms confirmed that the risk model displayed a reliable ability of prognosis prediction and was an independent prognostic factor, indicating that high-risk patients had poor outcomes. Immunocyte infiltration, gene set enrichment analysis (GSEA), and single-cell analysis all showed a strong relationship between immune mechanism and low-risk samples. The risk score could predict the sensitivity of immunotherapy and some chemotherapy regimens, which included oxaliplatin and irinotecan. Various latent treatment targets (LAG3, TIGIT, and ARID1A) were addressed by mutation landscape based on the risk model. Conclusion: The risk model based on TME-related genes can reflect the prognosis of PC patients and functions as a novel set of biomarkers for PC therapy.

Phaeohyphomycosis caused by Corynespora cassiicola, a plant pathogen worldwide

Although rare, trans-kingdom infection features an interesting infection biology concept, in which highly versatile pathogenic attributes allow successful infections in evolutionarily highly divergent species. Corynespora cassiicola is a phytopathogenic fungus and occasionally causes human infections. Herein, we report a phaeohyphomycosis case caused by C. cassiicola. Given that sporadic reports may contribute to a lack of awareness of the transmission route, clinical manifestations, and diagnostic and clinical management, we systematically reviewed the cases reported thus far. Nine patients were identified and included in the pooled analysis, 88.9% (8/9) of whom were reported after 2010. All patients were from Asian, African, and Latin American countries, among whom 77.8% (7/9) were farmers or lived in areas with active agriculture. Exposed body parts were the major affected infection area, and clinical manifestations were mainly non-specific inflammatory reactions. Although biochemical and morphological examinations confirmed the presence of fungal infection, molecular analysis was used for the final diagnosis, with 77.8% (7/9) being identified by internal transcribed spacer sequencing. Whereas voriconazole, terbinafine, and AmB, either alone or in combination, resulted in successful infection resolution in most cases (5/9; 55.5%), those suffering from invasive facial infections and CARD9 deficiency showed poor outcomes. Our patient is the third case of invasive facial infection caused by C. cassiicola and was successfully treated with intravenous LAmB followed by oral voriconazole combined with topical antifungal irrigation. Molecular identification of fungus and prompt antifungal treatment is pivotal in the clinical success of patients suspected to have phaeohyphomycosis. Moreover, as evidenced by our data, itraconazole treatment is not recommended.

CARD9 attenuates Aβ pathology and modifies microglial responses in an Alzheimer's disease mouse model

Recent advances have highlighted the importance of several innate immune receptors expressed by microglia in Alzheimer's disease (AD). In particular, mounting evidence from AD patients and experimental models indicates pivotal roles for TREM2, CD33, and CD22 in neurodegenerative disease progression. While there is growing interest in targeting these microglial receptors to treat AD, we still lack knowledge of the downstream signaling molecules used by these receptors to orchestrate immune responses in AD. Notably, TREM2, CD33, and CD22 have been described to influence signaling associated with the intracellular adaptor molecule CARD9 to mount downstream immune responses outside of the brain. However, the role of CARD9 in AD remains poorly understood. Here, we show that genetic ablation of CARD9 in the 5xFAD mouse model of AD results in exacerbated amyloid beta (Aβ) deposition, increased neuronal loss, worsened cognitive deficits, and alterations in microglial responses. We further show that pharmacological activation of CARD9 promotes improved clearance of Aβ deposits from the brains of 5xFAD mice. These results help to establish CARD9 as a key intracellular innate immune signaling molecule that regulates Aβ-mediated disease and microglial responses. Moreover, these findings suggest that targeting CARD9 might offer a strategy to improve Aβ clearance in AD.

Mesenchymal stem cells regulate M1 polarization of peritoneal macrophages through the CARD9-NF-κB signaling pathway in severe acute pancreatitis

BACKGROUND

Macrophages release large numbers of proinflammatory cytokines that trigger inflammatory cascade reactions, which promote the rapid development of severe acute pancreatitis (SAP) from local to systemic inflammation. The ability of mesenchymal stem cells (MSCs) to suppress inflammation is related to inhibition of M1 polarization of macrophages. Our previous studies revealed that caspase recruitment domain protein 9 (CARD9) was involved in SAP inflammation and activation of the CARD9-NF-κB signaling pathway plays an important proinflammatory role in SAP. At present, there is no effective treatment to control the inflammatory response in SAP. Therefore, the aim of the present study was to determine whether MSCs regulate the polarization of macrophages through the CARD9-NF-κB signaling pathway in SAP.

METHODS

Short hairpin RNA interference technology and coculture in vitro were used to assess the activation status of the CARD9-NF-κB signal pathway in macrophages. Furthermore, flow cytometry was used to determine the polarization state of macrophages.

RESULTS

The results showed MSCs inhibited CARD9 expression in vivo and in vitro (P < .05), alleviated inflammation induced by proinflammatory cytokines, and inhibited the phosphorylation of NF-κB in macrophages both in vivo and in vitro. Meanwhile, MSCs downregulated the CARD9-NF-κB signal pathway and inhibited M1 polarization of macrophages.

CONCLUSION

In conclusion, MSCs regulate M1 polarization of peritoneal macrophages through the CARD9-NF-κB signaling pathway in SAP and transplantation of MSCs presents an effective treatment option for SAP.

The combination of gemcitabine and ginsenoside Rh2 enhances the immune function of dendritic cells against pancreatic cancer via the CARD9-BCL10-MALT1 / NF-κB pathway

Cold tumor immune microenvironment (TIME) of pancreatic cancer (PC) with minimal dendritic cell (DC) and T cell infiltration can result in insufficient immunotherapy and chemotherapy. While gemcitabine (GEM) is a first-line chemotherapeutic drug for PC, its efficacy is reduced by immunosuppression and drug resistance. Ginsenoside Rh2 (Rh2) is known to have anti-cancer and immunomodulatory properties. Combining GEM with Rh2 may thus overcome immunosuppression and induce lasting anti-tumor immunity in PC. Here, we showed that after GEM-Rh2 therapy, there was significantly greater tumor infiltration by DCs. Caspase recruitment domain-containing protein 9 (CARD9), a central adaptor protein, was strongly up-regulated DCs with GEM-Rh2 therapy and promoted anti-tumor immune responses by DCs. CARD9 was found to be a critical target for Rh2 to enhance DC function. However, GEM-Rh2 treatment did not achieve the substantial anti-PC efficacy in CARD9^-/- mice as in WT mice. The adoptive transfer of WT DCs to DC-depleted PC mice treated with GEM-Rh2 elicited strong anti-tumor immune responses, although CARD9^-/- DCs were less effective than WT DCs. Our results showed that GEM-Rh2 may reverse cold TIME by enhancing tumor immunogenicity and decreasing the levels of immunosuppressive factors, reactivating DCs via the CARD9-BCL10-MALT1/ NF-κB pathway. Our findings suggest a potentially feasible and safe treatment strategy for PC, with a unique mechanism of action. Thus, Rh2 activation of DCs may remodel the cold TIME and optimize GEM chemotherapy for future therapeutic use.

Can circulating oxidative stress-related biomarkers be used as an early prognostic marker for COVID-19?

Background

Oxidative stress plays an important role in the pathogenesis of many diseases. This study aimed to investigate the relationship between nuclear factor kappa B (NF-κB) and oxidative stress and the severity of the disease in new COVID-19 patients, and, to compare the levels of NF-κB, oxidized LDL (oxLDL), and lectin-like oxidized-LDL receptor-1 (LOX-1) with oxygen saturation, which is an indicator of the severity parameters of the disease in COVID-19 patients.

Methods

In this prospective study, 100 COVID-19 patients and 100 healthy subjects were selected.

Results

LOX-1, NF-κB, and oxLDL were found to be higher in COVID-19 patients compared to the healthy subjects (p < 0.001 for all). According to the results of correlation analysis, it was found that there was no significant relationship between oxygen saturation and LOX-1, NF-κB and oxLDL parameters. There was significant relationship between oxLDL with LOX-1 and NF-κB in patients with COVID-19 disease. ROC analysis results of the highest discrimination power were oxLDL (AUC: 0.955, CI: 0.904-1.000; sensitivity: 77%, and specificity: 100%, for cutoff: 127.944 ng/l) indicating COVID-19.

Conclusion

Oxidative stress plays an essential role in COVID-19. NF-κB, oxLDL, and LOX-1 seem to represent good markers in COVID-19. Our study also showed that oxLDL has the highest power in distinguishing patients with COVID-19 from the healthy subjects.

CARD9 contributes to ovarian cancer cell proliferation, cycle arrest, and cisplatin sensitivity

BACKGROUND

Ovarian cancer recurrence and chemotherapy resistance are still urgent issues, and exploring the mechanisms of metastasis and chemotherapy resistance is beneficial to the development of therapeutic methods. Caspase recruitment domain family member 9 (CARD9) and homeobox B5 (HOXB5) are related and both are upregulated in ovarian cancer. This study aimed to define their functions in ovarian cancer cell proliferation, migration, and cisplatin sensitivity.

RESULTS

The levels of CARD9 were detected in acquired ovarian cancer tissues and cell lines. CARD9 was indeed abnormally upregulated in them. CARD9 knockdown significantly suppressed cell proliferation, colony formation, migration, cycle arrest, and cisplatin sensitivity. HOXB5 bound to the CARD9 promoter, and HOXB5 overexpression reversed the regulation by CARD9 knockdown in cells, as well as the activation of NF-κB signaling. This indicated that CARD9 was positively regulated by HOXB5 in ovarian cancer cells.

CONCLUSION

Together, CARD9 is involved in ovarian cancer cell proliferation, migration, and cisplatin sensitivity via NF-κB signaling after transcriptional activation by HOXB5.

Melatonin-Microbiome Two-Sided Interaction in Dysbiosis-Associated Conditions

Melatonin is a pineal indolamine, allegedly known as a circadian rhythm regulator, and an antioxidative and immunomodulatory molecule. In both experimental and clinical trials, melatonin has been shown to have positive effects in various pathologies, as a modulator of important biochemical pathways including inflammation, oxidative stress, cell injury, apoptosis, and energy metabolism. The gut represents one of melatonin's most abundant extra pineal sources, with a 400-times-higher concentration than the pineal gland. The importance of the gut microbial community-namely, the gut microbiota, in multiple critical functions of the organism- has been extensively studied throughout time, and its imbalance has been associated with a variety of human pathologies. Recent studies highlight a possible gut microbiota-modulating role of melatonin, with possible implications for the treatment of these pathologies. Consequently, melatonin might prove to be a valuable and versatile therapeutic agent, as it is well known to elicit positive functions on the microbiota in many dysbiosis-associated conditions, such as inflammatory bowel disease, chronodisruption-induced dysbiosis, obesity, and neuropsychiatric disorders. This review intends to lay the basis for a deeper comprehension of melatonin, gut microbiota, and host-health subtle interactions.

LC3-associated endocytosis and the functions of Rubicon and ATG16L1

LC3-associated endocytosis (LANDO) is a noncanonical function of the autophagy machinery, in which LC3 (microtubule-associated protein light chain) is conjugated to rab5-positive endosomes, using a portion of the canonical autophagy pathway. LANDO was initially discovered in a murine model of Alzheimer's disease as a critical regulator of amyloid-β receptor recycling in microglial cells, playing a protective role against neuronal loss and memory impairment. Recent evidence suggests an emerging role of LANDO in cytokine receptor signaling and innate immunity. Here, we discuss the regulation of two crucial effectors of LANDO, Rubicon and ATG16L1, and their impact on endocytosis, autophagy, and phagocytosis.

Triptolide promotes autophagy to inhibit mesangial cell proliferation in IgA nephropathy via the CARD9/p38 MAPK pathway

Background

Mesangial cell proliferation is the most basic pathological feature of immunoglobulin A nephropathy (IgAN); however, the specific underlying mechanism and an appropriate therapeutic strategy are yet to be unearthed. This study aimed to investigate the therapeutic effect of triptolide (TP) on IgAN and the mechanism by which TP regulates autophagy and proliferation of mesangial cells through the CARD9/p38 MAPK pathway.

Methods

We established a TP‐treated IgAN mouse model and produced IgA1‐induced human mesangial cells (HMC) and divided them into control, TP, IgAN, and IgAN+TP groups. The levels of mesangial cell proliferation (PCNA, cyclin D1, cell viability, and cell cycle) and autophagy (P62, LC3 II, and autophagy flux rate) were measured, with the autophagy inhibitor 3‐Methyladenine used to explore the relationship between autophagy and proliferation. We observed CARD9 expression in renal biopsies from patients and analyzed its clinical significance. CARD9 siRNA and overexpression plasmids were constructed to investigate the changes in mesangial cell proliferation and autophagy as well as the expression of CARD9 and p‐p38 MAPK/p38 MAPK following TP treatment.

Results

Administering TP was safe and effectively alleviated mesangial cell proliferation in IgAN mice. Moreover, TP inhibited IgA1‐induced HMC proliferation by promoting autophagy. The high expression of CARD9 in IgAN patients was positively correlated with the severity of HMC proliferation. CARD9/p38 MAPK was involved in the regulation of HMC autophagy and proliferation, and TP promoted autophagy to inhibit HMC proliferation by downregulating the CARD9/p38 MAPK pathway in IgAN.

Conclusion

TP promotes autophagy to inhibit mesangial cell proliferation in IgAN via the CARD9/p38 MAPK pathway.

A nucleation barrier spring-loads the CBM signalosome for binary activation

Immune cells activate in binary, switch-like fashion via large protein assemblies known as signalosomes, but the molecular mechanism of the switch is not yet understood. Here, we employed an in-cell biophysical approach to dissect the assembly mechanism of the CARD-BCL10-MALT1 (CBM) signalosome, which governs nuclear transcription factor-κB activation in both innate and adaptive immunity. We found that the switch consists of a sequence-encoded and deeply conserved nucleation barrier to ordered polymerization by the adaptor protein BCL10. The particular structure of the BCL10 polymers did not matter for activity. Using optogenetic tools and single-cell transcriptional reporters, we discovered that endogenous BCL10 is functionally supersaturated even in unstimulated human cells, and this results in a predetermined response to stimulation upon nucleation by activated CARD multimers. Our findings may inform on the progressive nature of age-associated inflammation, and suggest that signalosome structure has evolved via selection for kinetic rather than equilibrium properties of the proteins.

The innate immune system is the body’s first line of defence against pathogens. Although innate immune cells do not recognize specific disease-causing agents, they can detect extremely low levels of harmful organisms or substances. In response, they activate signals that lead to inflammation, which tells other cells that there is an infection. Innate immune cells are turned on in a switch-like fashion, becoming active very quickly after interacting with a pathogen. This is due to the action of signalosomes, large complexes made up of several proteins that clump together to form long chains that activate the cell.

But how do these large protein complexes assemble quick enough to create the switch-like activation observed in innate immune cells? To answer this question, Rodríguez Gama et al. focused on the CBM signalosome, which is involved in triggering inflammation through the activation of a protein called NF-kB.

First, Rodríguez Gama et al. used genetic tools to determine that activating the CBM signalosome drives a switch-like activation of NF-kB in cells. This means that individual cells in a population either become fully activated or not at all in response to minute amounts of harmful substances.

Once they had established this, Rodríguez Gama et al. wanted to know which protein in the CBM signalosome was responsible for the switch. They found that one of the proteins in the signalosome, called BCL10, has a ‘nucleation barrier’ encoded in its sequence. This means that it is very hard for BCL10 to start clumping together, but once it does, the clumps grow on their own. The nucleation barrier describes exactly how hard it is for these clumps to get started, and is determined by how disorganized the protein is.

When a pathogen ‘stimulates’ an immune cell, a tiny template is formed that lowers the nucleation barrier so that BCL10 can then aggregate itself together, leading to the switch-like behaviour observed. The nucleation barrier allows there to be more than enough BCL10 present in the cell at all times – ready to clump together at a moment’s notice – and this permits the cell to detect very low levels of a pathogen.

Rodríguez Gama et al. then tested whether BCL10 from other animals also has a nucleation barrier. They found that this feature is conserved from cnidarians, such as corals or jellyfish, to mammals, including humans. This suggests that the use of nucleation barriers to regulate innate immune signalling has existed for a long time throughout evolution.

The work by Rodríguez Gama et al. broadens our understanding of how the innate immune system senses and responds to extremely low levels of pathogens. That BCL10 is always ready to clump together suggests it may be a driving force for chronic and age-associated inflammation. Additionally, the findings of Rodríguez Gama et al. also offer insights into how other signalosomes may become activated, and offer the possibility of new drugs aimed at modifying nucleation barriers.

Invasive Rhinosinusitis Caused by Alternaria infectoria in a Patient with Autosomal Recessive CARD9 Deficiency and a Review of the Literature

Phaeohyphomycoses comprise a heterogeneous group of fungal infections caused by dematiaceous fungi and have primarily been reported in patients with underlying acquired immunodeficiencies, such as hematological malignancies or solid-organ transplants. Over the past decade, a growing number of patients with phaeohyphomycosis but otherwise healthy were reported with autosomal recessive (AR) CARD9 deficiency. We report a 28-year-old woman who presented with invasive rhinosinusitis caused by Alternaria infectoria. Following a candidate gene sequencing approach, we identified a biallelic loss-of-function mutation of CARD9, thereby further broadening the spectrum of invasive fungal diseases found in patients with inherited CARD9 deficiency. In addition, we reviewed 17 other cases of phaeohyphomycosis associated with AR CARD9 deficiency. Physicians should maintain a high degree of suspicion for inborn errors of immunity, namely CARD9 deficiency, when caring for previously healthy patients with phaeohyphomycosis, regardless of age at first presentation.

CARD9 Signaling, Inflammation, and Diseases

Caspase-recruitment domain 9 (CARD9) protein is expressed in many cells especially in immune cells, and is critically involved in the function of the innate and adaptive immune systems through extensive interactions between CARD9 and other signaling molecules including NF-κB and MAPK. CARD9-mediated signaling plays a central role in regulating inflammatory responses and oxidative stress through the productions of important cytokines and chemokines. Abnormalities of CARD9 and CARD9 signaling or CARD9 mutations or polymorphism are associated with a variety of pathological conditions including infections, inflammation, and autoimmune disorders. This review focuses on the function of CARD9 and CARD9-mediated signaling pathways, as well as interactions with other important signaling molecules in different cell types and the relations to specific disease conditions including inflammatory diseases, infections, tumorigenesis, and cardiovascular pathologies.

CARD9 Expression Pattern, Gene Dosage, and Immunodeficiency Phenotype Revisited

BACKGROUND

CARD9 deficiency is an autosomal recessive primary immunodeficiency underlying increased susceptibility to fungal infection primarily presenting as invasive CNS Candida and/or cutaneous/invasive dermatophyte infections. More recently, a rare heterozygous dominant negative CARD9 variant c.1434 + 1G > C was reported to be protective from inflammatory bowel disease.

OBJECTIVE

We studied two siblings carrying homozygous CARD9 variants (c.1434 + 1G > C) and born to heterozygous asymptomatic parents. One sibling was asymptomatic and the other presented with candida esophagitis, upper respiratory infections, hypogammaglobulinemia, and low class-switched memory B cells.

METHODS AND RESULTS

The CARD9 c.1434 + 1G > C variant generated two mutant transcripts confirmed by mRNA and protein expression: an out-of-frame c.1358-1434 deletion/ ~ 55 kDa protein (CARD9Δex.11) and an in-frame c.1417-1434 deletion/ ~ 61 kDa protein (CARD9Δ18 nt.). Neither transcript was able to form a complete/functional CBM complex, which includes TRIM62. Based on the index patient's CVID-like phenotype, CARD9 expression was tested and detected in lymphocytes and monocytes from humans and mice. The functional impact of different CARD9 mutations and gene dosage conditions was evaluated in heterozygous and homozygous c.1434 + 1 G > C members of the index family, and in WT (two WT alleles), haploinsufficiency (one WT, one null allele), and null (two null alleles) individuals. CARD9 gene dosage impacted lymphocyte and monocyte functions including cytokine generation, MAPK activation, T-helper commitment, transcription, plasmablast differentiation, and immunoglobulin production in a differential manner.

CONCLUSIONS

CARD9 exon 11 integrity is critical to CBM complex function. CARD9 is expressed and affects particular T and B cell functions in a gene dosage-dependent manner, which in turn may contribute to the phenotype of CARD9 deficiency.

CARD9 Deficiency Increases Hippocampal Injury Following Acute Neurotropic Picornavirus Infection but Does Not Affect Pathogen Elimination

Neurotropic viruses target the brain and contribute to neurologic diseases. Caspase recruitment domain containing family member 9 (CARD9) controls protective immunity in a variety of infectious disorders. To investigate the effect of CARD9 in neurotropic virus infection, CARD9^−/− and corresponding C57BL/6 wild-type control mice were infected with Theiler’s murine encephalomyelitis virus (TMEV). Brain tissue was analyzed by histology, immunohistochemistry and molecular analyses, and spleens by flow cytometry. To determine the impact of CARD9 deficiency on T cell responses in vitro, antigen presentation assays were utilized. Genetic ablation of CARD9 enhanced early pro-inflammatory cytokine responses and accelerated infiltration of T and B cells in the brain, together with a transient increase in TMEV-infected cells in the hippocampus. CARD9^−/− mice showed an increased loss of neuronal nuclear protein⁺ mature neurons and doublecortin⁺ neuronal precursor cells and an increase in β-amyloid precursor protein⁺ damaged axons in the hippocampus. No effect of CARD9 deficiency was found on the initiation of CD8⁺ T cell responses by flow cytometry and co-culture experiments using virus-exposed dendritic cells or microglia-enriched glial cell mixtures, respectively. The present study indicates that CARD9 is dispensable for the initiation of early antiviral responses and TMEV elimination but may contribute to the modulation of neuroinflammation, thereby reducing hippocampal injury following neurotropic virus infection.

TREM (Triggering Receptor Expressed on Myeloid Cells)-1 Inhibition Attenuates Neuroinflammation via PKC (Protein Kinase C) δ/CARD9 (Caspase Recruitment Domain Family Member 9) Signaling Pathway After Intracerebral Hemorrhage in Mice

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MALT1 as a promising target to treat lymphoma and other diseases related to MALT1 anomalies

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is a key adaptor protein that regulates the NF-κB pathway, in which MALT1 functions as a scaffold protein and protease to trigger downstream signals. The abnormal expression of MALT1 is closely associated with lymphomagenesis and other diseases, including solid tumors and autoimmune diseases. MALT1 is the only protease in the underlying pathogenesis of these diseases, and its proteolytic activity can be pharmacologically regulated. Therefore, MALT1 is a potential and promising target for anti-lymphoma and other MALT1-related disease treatments. Currently, the development of MALT1 inhibitors is still in its early stages. This review presents an overview of MALT1, particularly its X-ray structures and biological functions, and elaborates on the pathogenesis of diseases associated with its dysregulation. We then summarize previously reported MALT1 inhibitors, focusing on their molecular structure, biological activity, structure-activity relationship, and limitations. Finally, we propose future research directions to accelerate the discovery of novel MALT1 inhibitors with clinical applications. Overall, this review provides a comprehensive and systematic overview of MALT1-related research advances and serves as a theoretical basis for drug discovery and research.

Analysis of miRNA and mRNA reveals core interaction networks and pathways of dexamethasone-induced immunosuppression in chicken bursa of Fabricius

Stress-induced immunosuppression is a serious problem affecting the production value of poultry, but its specific molecular mechanism has not yet been elucidated. We selected 7-day-old Gushi cocks as test animals and successfully established a stress-induced immunosuppression model by injecting 2.0 mg/kg (body weight) dexamethasone (Dex). We then constructed six cDNA libraries and two small RNA libraries of Bursa of Fabricius from the control group and the Dex group. RNA-seq results revealed 21,028 transcripts including 3920 novel transcripts; 500 miRNAs including 68 novel miRNAs were identified. Correlation analysis of miRNA, target genes and mRNA results indicated that the gga-miR-15 family, gga-miR-103-3p, gga-miR-456-3p, and gga-miR-27b-3p, as core differentially expressed miRNAs, may potentially regulate multiple genes which are involved in immune-related pathways; and that the core genes Suppressor of IKBKE 1 (SIKE1) and high mobility group AT-hook 2 (HMGA2) are associated with the miR-17 family (gga-miR-20a-5p, gga-miR-20b-5p, gga-miR-106-5p, and gga-miR-17-5p) and gga-let -7 family (gga-let-7b, gga-let-7i, gga-let-7c-5p, and gga-let-7f-5p). The interaction networks of mRNAs of significantly enrichment pathways and PPI (protein-protein interaction) networks showed that IL6, IL1B, IL8L1, CCL5, SOCS3, SOCS1, ITGB5, GSTA3, SQLE, FDFT1, FN1, IL18, IL10, MAPK11 and MAPK12 are network core nodes and that most of them are strongly associated with immune response. One of the candidate miRNAs, gga-miR-20b-5p, may play an important role in stress-induced immunosuppression. Luciferase assay and over-expression experiments suggested that gga-miR-20b-5p negatively regulated the expression of target gene SIKE1. These results provide better understanding of the mechanism of stress-induced immunosuppression in Gushi chicken bursa, and provide novel targets for subsequent research to improve poultry anti-stress capability.

The Role of CARD9 Deficiency in Neutrophils

Neutrophils play a critical role in innate immune defense and directly contribute to infectious and autoimmune ailments. Great efforts are underway to better understand the nature of neutrophilic inflammation. Of note, CARD9, a myeloid cell-specific signaling protein that mainly expresses in macrophages and dendritic cells, is also present in neutrophils, emerging as a critical mediator for intercellular communication. CARD9-deficiency neutrophils display an increased susceptibility to fungal infection that primarily localize to the central nervous system, subcutaneous, and skin tissue. Additionally, CARD9-deficiency neutrophils are associated with some autoimmune diseases and even provide protection against a few bacteria. Here, the review summarizes recent preclinical and clinical advances that have provided a novel insight into the pathogenesis of CARD9 deficiency in neutrophils.

The role and mechanism of CARD9 gene polymorphism in diseases

CARD9 is a cytosolic adaptor in myeloid cells, has a critical role in inflammatory disorders, and provides a protective function against microbial pathogen, especially fungal infection. Recently, CARD9 polymorphisms are of interest, showing a positive correlation with the elevated risk of fungal infection, inflammatory bowel disease, and other autoimmune diseases. Mechanistically, CARD9 polymorphisms impair the activation of RelB, a subunit of non-canonical NF-κB, which lead to the reduced cytokine and chemokine production by innate immune cells. In addition, CARD9 polymorphisms show a defective neutrophil accumulation in infectious sites. Furthermore, CARD9 polymorphisms could alter the composition of the gut microbiome. In this review, we summarize the latest findings of CARD9 polymorphisms with respect to inflammatory diseases.

Zinc homeostasis plays an important role in the prevention of obesity-induced cardiac inflammation, remodeling and dysfunction

Obesity often leads to cardiovascular diseases, such as obesity-related cardiac hypertrophy (ORCH), due to chronic cardiac inflammation. Zinc is structurally and functionally essential for many transcription factors, therefore it not only has anti-inflammatory and anti-oxidative stress functions, but also has insulin-like function, however, its role in the development of obesity-associated cardiac pathogenesis and the potentially underlying mechanism(s) remains unclear. This review aims to summarize the available evidence on the role of zinc homeostasis in the prevention of ORCH. It was recently reported that when four-week old mice were fed either high fat diet (HFD) or normal diet containing deficient, adequate or supplemented zinc, HFD induced obesity and ORCH along with increased phosphorylation of p38 MAPK and increased expression of B-cell lymphoma/ leukemia 10 (BCL10) and caspase recruitment domain family member 9 (CARD9). These effects were further aggravated by zinc deficiency and significantly alleviated by zinc supplementation. Mechanistically administration of a p38 MAPK specific inhibitor in HFD-fed mice for 3 months did not affect HFD-induced obesity and increased expression of BCL10 and CARD9, but completely abolished HFD/obesity-induced cardiac hypertrophy and inflammation. In cultured cardiomyocytes, inhibition of BCL10 expression by siRNA prevented palmitate-induced increased p38 MAPK activation and atrial natriuretic peptide expression. Deletion of metallothionein abolished the protective effect of zinc on palmitate-induced up-regulation of BCL10 and phospho-p38 MAPK. Taken together with other recent studies, we concluded that HFD and zinc deficiency synergistically induce ORCH by increasing oxidative stress-mediated activation of BCL10/CARD9/p38 MAPK signaling. Zinc supplementation ameliorates ORCH through activation of metallothionein to repress oxidative stress-activated BCL10 expression and p38 MAPK activation.

Epidemiology and Diagnostic Perspectives of Dermatophytoses

Dermatophytoses affect about 25% of the world population, and the filamentous fungus Trichophyton rubrum is the main causative agent of this group of diseases. Dermatomycoses are caused by pathogenic fungi that generally trigger superficial infections and that feed on keratinized substrates such as skin, hair, and nails. However, there are an increasing number of reports describing dermatophytes that invade deep layers such as the dermis and hypodermis and that can cause deep infections in diabetic and immunocompromised patients, as well as in individuals with immunodeficiency. Despite the high incidence and importance of dermatophytes in clinical mycology, the diagnosis of this type of infection is not always accurate. The conventional methods most commonly used for mycological diagnosis are based on the identification of microbiological and biochemical features. However, in view of the limitations of these conventional methods, molecular diagnostic techniques are increasingly being used because of their higher sensitivity, specificity and rapidity and have become more accessible. The most widely used molecular techniques are conventional PCR, quantitative PCR, multiplex PCR, nested, PCR, PCR-RFLP, and PCR-ELISA. Another promising technique for the identification of microorganisms is the analysis of protein profiles by MALDI-TOF MS. Molecular techniques are promising but it is necessary to improve the quality and availability of the information in genomic and proteomic databases in order to streamline the use of bioinformatics in the identification of dermatophytes of clinical interest.

Primary Cutaneous Aspergillosis in a Patient with CARD9 Deficiency and Aspergillus Susceptibility of Card9 Knockout Mice

PURPOSE

We describe a case of primary cutaneous aspergillosis caused by Aspergillus fumigatus, and elucidate the underlying genetic and immunological mechanisms.

MATERIALS AND METHODS

Routine clinical and laboratory investigations were performed. Whole-exome sequencing of the patient's DNA suggested the presence of a CARD9 mutation, which was confirmed by Sanger sequencing. Innate and adaptive immunological responses of patient-derived CARD9-deficient cells were evaluated with ELISA and flow cytometry. Cutaneous and pulmonary aspergillosis models were established in Card9 knockout (KO) mice, which were compared with wild-type and immunosuppressed mice, to explore the pathogenesis and Aspergillus susceptibility.

RESULTS

A 45-year-old man presented with a 37-year history of skin lesions on his face. A diagnosis of primary cutaneous aspergillosis was made through histopathology, immunohistochemistry, and tissue culture. Sanger sequencing of CARD9 showed a homozygous frame-shift mutation (c.819_820insG, p.D274fsX60), which led to the lack of CARD9 expression. Peripheral blood mononuclear cells from the patient showed selective impairment of proinflammatory cytokines, and Th1-, Th17-, and Th22-associated responses upon fungus-specific stimulation. The cutaneous aspergillosis model established in Card9 KO mice presented with persistent infection, with fungal germs and short hyphae in tissue, consistent with the patient's lesions. Skin lesions in immunosuppressed mice were more severe, and led to death. Unlike our patient, Card9 KO mice were relatively susceptible to pulmonary aspergillosis, with reasons to be investigated.

CONCLUSIONS

This is, to our knowledge, the first report that links cutaneous aspergillosis to CARD9 mutation. This work enriches both the phenotypic spectrum of CARD9 deficiencies and the genetic background of cutaneous aspergillosis.

Caspase Recruitment Domain-Containing Protein 9 Expression is a Novel Prognostic Factor for Lung Adenocarcinoma

Purpose

Caspase recruitment domain-containing protein 9 (CARD9) is expressed at high levels in bone marrow cells and has a crucial role in innate immunity. Current studies indicate that CARD9 also plays a key role in tumor progression, but there are few reports on the role of CARD9 in lung cancer. The aim of this study was to clarify the role of CARD9 in lung adenocarcinoma.

Patients and Methods

Lung adenocarcinoma tumor samples from 74 patients who underwent complete resection at Kobe University Hospital from January 2014 to December 2014 were analyzed by immunohistochemistry. The role of CARD9 in cancer cells was analyzed using lung cancer cell lines treated with CARD9 siRNA.

Results

High expression of CARD9 was observed in 32.4% of tumors, and compared to low expression of CARD9, high expression was associated with poorer overall survival (P = 0.0365). Univariate and multivariate analyses showed that high expression of CARD9 was an independent prognostic factor. Knockdown of CARD9 in lung adenocarcinoma cells inhibited proliferation but did not increase apoptosis. In addition, CARD9 activated the NF-κB pathway in a lung adenocarcinoma cell line.

Conclusion

CARD9 was shown to be an independent prognostic factor of poor outcome for lung cancer and may represent a molecular target for treatment.

Role of CARD9 in inflammatory signal pathway of peritoneal macrophages in severe acute pancreatitis

Previous studies revealed that caspase recruitment domain protein 9 (CARD9) was involved in severe acute pancreatitis (SAP) inflammation and that interfering with its expression in vivo could inhibit inflammation. However, the specific mechanism is unknown. This study aimed to discover the related signal pathways of CARD9 in macrophages. SiRNA interference technology was used in vivo and in vitro to detect CARD9‐related signal pathways in peritoneal macrophages. Furthermore, Toll‐like receptor 4 (TLR4) and membrane‐associated C‐type lectin‐1 (Dectin‐1) pathways in macrophages were activated specially to looking for the upstream signal path of CARD9. Results showed up‐regulation of CARD9 expression in peritoneal macrophages of SAP rats (P < .05). CARD9 siRNA alleviated inflammatory cytokines, and inhibited the phosphorylation of NF‐κB and p38MAPK in peritoneal macrophages in vivo or in vitro. Meanwhile, CARD9 siRNA reduced the concentration of CARD9 and Bcl10 in peritoneal macrophages, and TLR4 and Dectin‐1 took part in CARD9 signal pathways in macrophages. In conclusion, there is an inflammation signal pathway comprised of TLR4/Dectin‐1‐CARD9‐NF‐κB/p38MAPK activated in macrophages in SAP. Blockade of CARD9 expression in macrophages can effectively alleviate SAP inflammation.

Comparative Analysis of Clinical and Environmental Strains of Exophiala spinifera by Long-Reads Sequencing and RNAseq Reveal Adaptive Strategies

Exophiala spinifera, a capsule-producing black yeast, is overrepresented as agent of disseminated infection in humans with inherited dysfunction of the CARD9 gene. In a review of published caspase recruitment domain-containing protein 9 (CARD9) deficiency cases, black fungi were linked to mutations other than those prevalent in yeast and dermatophyte cases, and were found to respond to a larger panel of cytokines. Here, we sequenced and annotated the genomes of BMU 08022 from a patient with CARD9 deficiency and two environmental strains, BMU 00051 and BMU 00047. We performed genomic and transcriptomic analysis for these isolates including published black yeasts genomes, using a combination of long-read (PACBIO) and short-read (Illumina) sequencing technologies with a hybrid assembly strategy. We identified the virulence factors, fitness, and the major genetic and gene expression differences between the strains with RNAseq technology. Genome assembly reached sub-chromosome level with between 12,043 and 12,130 predicted genes. The number of indels identified in the clinical strain was higher than observed in environmental strains. We identify a relatively large core genome of 9,887 genes. Moreover, substantial syntenic rearrangements of scaffolds I and III in the CARD9-related isolate were detected. Seventeen gene clusters were involved in the production of secondary metabolites. PKS-cluster 17 was consistently found to be absent in the clinical strain. Comparative transcriptome analysis demonstrated that 16 single-copy genes were significantly differentially expressed upon incubation in brain-heart infusion broth vs. Sabouraud glucose broth. Most of the single-copy genes upregulated with Brain Heart Infusion (BHI) were transporters. There were 48 unique genes differentially expressed exclusively to the clinical strain in two different media, including genes from various metabolic processes and transcriptional regulation. Up-regulated genes in the clinical strain with Gene Ontology (GO) enrichment are mainly involved in transmembrane transport, biosynthetic process and metabolic process. This study has provided novel insights into understanding of strain-differences in intrinsic virulence of the species and indicated that intraspecific variability may be related to habitat choice. This indicates that strains of E. spinifera are differentially prone to cause infection in susceptible patient populations, and provides clues for future studies exploring the mechanisms of pathogenic and adaptive strategies of black yeasts in immunodeficient patients.

Mendelian diseases of dysregulated canonical NF-κB signaling: From immunodeficiency to inflammation

NF-κB is a master transcription factor that activates the expression of target genes in response to various stimulatory signals. Activated NF-κB mediates a plethora of diverse functions including innate and adaptive immune responses, inflammation, cell proliferation, and NF-κB is regulated through interactions with IκB inhibitory proteins, which are in turn regulated by the inhibitor of κB kinase (IKK) complex. Together, these 3 components form the core of the NF-κB signalosomes that have cell-specific functions which are dependent on the interactions with other signaling molecules and pathways. The activity of NF-κB pathway is also regulated by a variety of post-translational modifications including phosphorylation and ubiquitination by Lys63, Met1, and Lys48 ubiquitin chains. The physiologic role of NF-κB is best studied in the immune system due to discovery of many human diseases caused by pathogenic variants in various proteins that constitute the NF-κB pathway. These disease-causing variants can act either as gain-of-function (GoF) or loss-of-function (LoF) and depending on the function of mutated protein, can cause either immunodeficiency or systemic inflammation. Typically, pathogenic missense variants act as GoF and they lead to increased activity in the pathway. LoF variants can be inherited as recessive or dominant alleles and can cause either a decrease or an increase in pathway activity. Dominantly inherited LoF variants often result in haploinsufficiency of inhibitory proteins. Here, we review human Mendelian immunologic diseases, which results from mutations in different molecules in the canonical NF-κB pathway and surprisingly present with a continuum of clinical features including immunodeficiency, atopy, autoimmunity, and autoinflammation.

CARD9 mediates T cell inflammatory response in Coxsackievirus B3-induced acute myocarditis

Cardiac inflammation in Coxsackievirus B3 (CVB3)-induced myocarditis is a consequence of viral-related cardiac injury and immune response. Caspase-associated recruitment domain 9 (CARD9) is a critical adaptor protein involved in transduction of signals from various innate pattern recognition receptors. In this study, the role of CARD9 in acute viral myocarditis was evaluated. CARD9^-/- and C57BL/6 mice were infected with CVB3. On day 7 postinfection, myocardial tissue and blood samples were collected and examined. After CARD9 knockout, mRNA and protein levels of transforming growth factor-β(TGF-β), interleukin-17A(IL-17A), and CARD domain of B-cell CLL/lymphoma 10(BCL-10) in the myocardium were markedly lower in CARD9^-/- mice than in C57BL/6 mice with CVB3-induced viral myocarditis. This trend was similar for the pathological scores for inflammation and serum levels of cytokines interleukin-6(IL-6), interleukin-10(IL-10), interferon -γ(IFN-γ), TGF-β, and IL-17A. These results suggest that the CARD9-mediated secretion of pro-inflammatory cytokines plays an important role in the immune response to acute viral myocarditis.

Role of oxidized LDL-induced "trained macrophages" in the pathogenesis of COVID-19 and benefits of pioglitazone: A hypothesis

BACKGROUND AND AIMS

Older adults and people who have cardiovascular disorders (their common pathogenetic mechanism is progressive atherosclerosis) are at higher risk for severe illness from COVID-19 (coronavirus disease 2019). Their common pathogenetic mechanism is progressive atherosclerosis in which oxLDL (oxidized LDL) plays major role. Receptor-mediated uptake of oxLDL by the monocyte-derived macrophages activates the long-term epigenetic reprogramming of innate immunity, which is termed "trained immunity." The aim of this work is to investigate the mechanisms and treatment possibilities that can control the activities of these specific macrophages.

METHODS

Search in Medline and PubMed relevant articles on the trained immunity and cytokine storm of COVID-19.

RESULTS AND CONCLUSIONS

When oxLDL-trained macrophages encounter SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) in the lung, it causes unregulated cytokine secretion, leading to the alveolar damage. Therefore, blocking macrophage training by pioglitazone, a thiazolidinedione, could control the hyperactivation that the virus would trigger.

The Role of CARD9 in Metabolic Diseases

Caspase recruitment domain containing protein 9 (CARD9) is an adaptor protein that plays a critical role in pattern recognition receptors (PRRs)-mediated activation of NF-?B and mitogen-activated protein kinase (MAPK). This elicits initiation of the pro-inflammatory cytokines and leads to inflammatory responses, which has been recognized as a critical contributor to chronic inflammation. Current researches demonstrate that CARD9 is strongly associated with metabolic diseases, such as obesity, insulin resistance, atherosclerosis and so on. In this review, we summarize CARD9 signaling pathway and the role of CARD9 in metabolic diseases.

CARD9 promotes autophagy in cardiomyocytes in myocardial ischemia/reperfusion injury via interacting with Rubicon directly

Autophagy in cardiomyocyte is involved in myocardial ischemia/reperfusion (M-I/R) injury. Caspase recruitment domain-containing protein 9 (CARD9) plays a critical role in cardiovascular diseases (CVDs) such as hypertension and cardiac fibrosis. However, its role in autophagy following M-I/R injury is yet to be fully elucidated. Here, we found that CARD9 expression increased in M-I/R mouse hearts, and in H9c2 or neonatal rat ventricular myocytes (NRVMs) in response to hypoxia/reoxygenation (H/R) or H₂O₂. CARD9^-/- mice exhibited a significant cardiac dysfunction following M-I/R injury (30 min of left ascending coronary (LAD) ischemia and 12 h of reperfusion) compared to wild-type (WT) mice. CARD9 deletion impaired autophagy during M-I/R in vivo and in vitro, evidenced by decrease of microtubule-associated protein 1 light chain 3 (LC3) lipidation and p62 accumulation. Conversely, CARD9 overexpression increased autophagic flux as indicated by enhanced expression of LC3 II/LC3 I and a reduction in p62. The protective effect of CARD9 on cardiomyocytes against H/R-induced oxidative stress was abolished by treatment with autophagy inhibitors, 3-methyladenine (3-MA) or Bafilomycin A1(BafA1). CARD9 interacted with RUN domain Beclin-1-interacting cysteine-rich-containing (Rubicon), a negative regulator of autophagy, and enhanced UV-irradiation-resistance-associated gene (UVRAG)-Beclin1-phosphatidylinositol 3-kinase catalytic subunit type 3 (PI3KC3) interaction and UVRAG-Vps16-mediated Rab7 activation to promote autophagosome formation, maturation, and endocytosis. Ablation of Rubicon by siRNA effectively prevented the detrimental effect of CARD9 knockdown on cardiomyocytes. These results suggest that CARD9 has protective effects on the myocardium against M-I/R injury by activating autophagy and restoring autophagic flux in vivo and in vitro.

Ets-2 deletion in myeloid cells attenuates IL-1α-mediated inflammatory disease caused by a Ptpn6 point mutation

The SHP-1 protein encoded by the Ptpn6 gene has been extensively studied in hematopoietic cells in the context of inflammation. A point mutation in this gene (Ptpn6^spin) causes spontaneous inflammation in mice, which has a striking similarity to neutrophilic dermatoses in humans. Recent findings highlighted the role of signaling adapters and kinases in promoting inflammation in Ptpn6^spin mice; however, the underlying transcriptional regulation is poorly understood. Here, we report that SYK is important for driving neutrophil infiltration and initiating wound healing responses in Ptpn6^spin mice. Moreover, we found that deletion of the transcription factor Ets2 in myeloid cells ameliorates cutaneous inflammatory disease in Ptpn6^spin mice through transcriptional regulation of its target inflammatory genes. Furthermore, Ets-2 drives IL-1α-mediated inflammatory signaling in neutrophils of Ptpn6^spin mice. Overall, in addition to its well-known role in driving inflammation in cancer, Ets-2 plays a major role in regulating IL-1α-driven Ptpn6^spin-mediated neutrophilic dermatoses. Model for the role of ETS-2 in neutrophilic inflammation in Ptpn6^spin mice. Mutation of the Ptpn6 gene results in SYK phosphorylation which then sequentially activates MAPK signaling pathways and activation of ETS-2. This leads to activation of ETS-2 target genes that contribute to neutrophil migration and inflammation. When Ets2 is deleted in Ptpn6^spin mice, the expression of these target genes is reduced, leading to the reduced pathology in neutrophilic dermatoses.

Advances in Understanding Human Genetic Variations That Influence Innate Immunity to Fungi

Fungi are ubiquitous. Yet, despite our frequent exposure to commensal fungi of the normal mammalian microbiota and environmental fungi, serious, systemic fungal infections are rare in the general population. Few, if any, fungi are obligate pathogens that rely on infection of mammalian hosts to complete their lifecycle; however, many fungal species are able to cause disease under select conditions. The distinction between fungal saprophyte, commensal, and pathogen is artificial and heavily determined by the ability of an individual host's immune system to limit infection. Dramatic examples of commensal fungi acting as opportunistic pathogens are seen in hosts that are immune compromised due to congenital or acquired immune deficiency. Genetic variants that lead to immunological susceptibility to fungi have long been sought and recognized. Decreased myeloperoxidase activity in neutrophils was first reported as a mechanism for susceptibility to Candida infection in 1969. The ability to detect genetic variants and mutations that lead to rare or subtle susceptibilities has improved with techniques such as single nucleotide polymorphism (SNP) microarrays, whole exome sequencing (WES), and whole genome sequencing (WGS). Still, these approaches have been limited by logistical considerations and cost, and they have been applied primarily to Mendelian impairments in anti-fungal responses. For example, loss-of-function mutations in CARD9 were discovered by studying an extended family with a history of fungal infection. While discovery of such mutations furthers the understanding of human antifungal immunity, major Mendelian susceptibility loci are unlikely to explain genetic disparities in the rate or severity of fungal infection on the population level. Recent work using unbiased techniques has revealed, for example, polygenic mechanisms contributing to candidiasis. Understanding the genetic underpinnings of susceptibility to fungal infections will be a powerful tool in the age of personalized medicine. Future application of this knowledge may enable targeted health interventions for susceptible individuals, and guide clinical decision making based on a patient's individual susceptibility profile.

Invasive Saprochaete capitata Infection in a Patient with Autosomal Recessive CARD9 Deficiency and a Review of the Literature

PURPOSE

Autosomal recessive (AR) CARD9 deficiency is an inherited immune disorder which results in impaired innate immunity against various fungi. Superficial and invasive fungal infections, mainly caused by Candida or Trichophyton species, are the hallmark of CARD9 deficiency. Together with the increasing number of CARD9-deficient patients reported, different pathogenic fungal species have been described such as Phialophora, Exophiala, Corynespora, Aureobasidium, and Ochroconis. Saprochaete capitata is an opportunistic infectious agent in immunocompromised patients and is a common cause of invasive fungal disease in patients with hematological malignancies. In this study, we investigated the causative genetic defect in a patient with S. capitata fungal infection which disseminated to lymph nodes and common bile duct.

METHODS

The identification of the isolated yeast strain was made by direct microscopic examination and confirmed by internal transcribed spacer (ITS) sequencing. We applied whole exome sequencing to search for the disease-causing mutation. Sanger sequencing was used to validate the mutation in the patient and his parents.

RESULTS

S. capitata was isolated from the biopsy specimen as the causative microorganism responsible for the invasive fungal disease in the patient. Whole exome sequencing revealed a homozygous c.883C > T, (p.Q295*) mutation in CARD9, confirmed by Sanger sequencing.

CONCLUSIONS

This is the first report of invasive Saprochaete infection associated with autosomal recessive (AR) CARD9 deficiency in the literature and thereby further extends the spectrum of fungal diseases seen in these patients.

Myeloid-derived suppressor cells-new and exciting players in lung cancer

Lung cancer (LC) is the leading cause of cancer-related death worldwide due to its late diagnosis and poor outcomes. As has been found for other types of tumors, there is increasing evidence that myeloid-derived suppressor cells (MDSCs) play important roles in the promotion and progression of LC. Here, we briefly introduce the definition of MDSCs and their immunosuppressive functions. We next specifically discuss the multiple roles of MDSCs in the lung tumor microenvironment, including those in tumor growth and progression mediated by inhibiting antitumor immunity, and the associations of MDSCs with a poor prognosis and increased resistance to chemotherapy and immunotherapy. Finally, we also discuss preclinical and clinical treatment strategies targeting MDSCs, which may have the potential to enhance the efficacy of immunotherapy.

Myeloid-derived suppressor cells-new and exciting players in lung cancer

Lung cancer (LC) is the leading cause of cancer-related death worldwide due to its late diagnosis and poor outcomes. As has been found for other types of tumors, there is increasing evidence that myeloid-derived suppressor cells (MDSCs) play important roles in the promotion and progression of LC. Here, we briefly introduce the definition of MDSCs and their immunosuppressive functions. We next specifically discuss the multiple roles of MDSCs in the lung tumor microenvironment, including those in tumor growth and progression mediated by inhibiting antitumor immunity, and the associations of MDSCs with a poor prognosis and increased resistance to chemotherapy and immunotherapy. Finally, we also discuss preclinical and clinical treatment strategies targeting MDSCs, which may have the potential to enhance the efficacy of immunotherapy.

Beneficial Effects of Anti-Oxidative Herbal Medicines in Diabetic Patients Infected with COVID-19: A Hypothesis

During the pandemic of Coronavirus Disease 2019 (COVID-19), it is critical to introduce potential medical treatments. Anti-oxidative herbal medicines with evidence-based beneficial impacts in the treatment of diabetes mellitus can be suggested as an adjuvant therapy to its conventional treatments in patients infected with COVID-19.

Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling

Receptors of innate immune cells function synergistically to detect pathogens and elicit appropriate immune responses. Many receptor pairs also appear "colocalized" on the membranes of phagosomes, the intracellular compartments for pathogen ingestion. However, the nature of the seemingly receptor colocalization and the role it plays in immune regulation are unclear, due to the inaccessibility of intracellular phagocytic receptors. Here, we report a geometric manipulation technique to directly probe the role of phagocytic receptor "colocalization" in innate immune regulation. Using particles with spatially patterned ligands as phagocytic targets, we can decouple the receptor pair, Dectin-1 and Toll-like receptor (TLR)2, to opposite sides on a single phagosome or bring them into nanoscale proximity without changing the overall membrane composition. We show that Dectin-1 enhances immune responses triggered predominantly by TLR2 when their centroid-to-centroid proximity is <500 nm, but this signaling synergy diminishes upon receptor segregation beyond this threshold distance. Our results demonstrate that nanoscale proximity, not necessarily colocalization, between Dectin-1 and TLR2 is required for their synergistic regulation of macrophage immune responses. This study elucidates the relationship between the spatial organization of phagocytic receptors and innate immune responses. It showcases a technique that allows spatial manipulation of receptors and their signal cross-talk on phagosomes inside living cells.

The multifaceted role of CARD9 in inflammatory bowel disease

Inflammatory bowel disease (IBD) involves a dysregulated immune response to the gut microbiota. Emerging evidence has demonstrated that dysfunctions in caspase recruitment domain‐containing protein 9 (CARD9) may contribute to the pathogenesis of IBD. Interestingly, an allelic series of Card9 variants have both a common predisposing and rare protective function in IBD patients. In this review, we provide mechanistic insights into the role of the CARD9 adaptor molecule in intestinal inflammation and determine a potential CARD9‐targeting therapeutic approach against IBD.

A 7-Year-Old Child With Headaches and Prolonged Fever Associated With Oral and Nail Lesions

A 7-year-old child of Turkish origin presented with headache and vomiting in the context of prolonged fever of unknown source. At examination, oral candidiasis and chronic onychomycosis were noted. A Candida meningoencephalitis was diagnosed and intravenous Amphotericin B liposomal was given during 6 months relayed by oral Fluconazole after regression of CNS lesions was observed on MRI. A complete immune evaluation was performed, and genetic analysis detected homozygous CARD9 mutation. CARD9 deficiency have been associated with invasive candidiasis in otherwise healthy patients. Culture of the cerebrospinal fluid grew for multisensitive Candida albicans. Brain magnetic resonance (MRI) showed the presence of focal lesions in the left caudate nucleus and in the right cerebellar hemisphere. Medullar MRI showed diffuse meningeal nodular lesions. Treatment with intravenous amphotericin B liposomal was given during 6 months relayed by oral fluconazole after regression of CNS lesions was observed on MRI. A complete immune evaluation was performed and genetic analysis detected a homozygous CARD9 mutation. CARD9 deficiency have been associated with invasive candidiasis in otherwise healthy patients.

CARD9 inhibits mitochondria-dependent apoptosis of cardiomyocytes under oxidative stress via interacting with Apaf-1

Cardiomyocyte apoptosis is known to contribute to myocardial ischemia/reperfusion (I/R) injury. Caspase recruitment domain-containing protein 9 (CARD9) play a role in cardiac fibrosis and dysfunction. However, the role of CARD9 in apoptosis of cardiomyocytes in myocardial I/R injury and its underlying mechanisms are still unclear. In this study, CARD9 expression was found to increase in H9c2 cells in response to hydrogen peroxide. Loss of CARD9 significantly increased caspase-3 activation and cardiomyocyte death following oxidative stress in vitro. Conversely, CARD9 overexpression decreased apoptosis as evidenced by a reduction in caspase-3 activation and the apoptotic rate. The caspase recruitment domain (CARD) of CARD9 was necessary for the protective effect of CARD9 against oxidative stress in cardiomyocytes. CARD9 suppressed the activation of caspase-9 by interacting with Apaf-1 via its CARD domain in H9c2 cells exposed to H₂O₂. Ablation of caspase-9 activity by z-lehd-fmk effectively prevented the detrimental effect of CARD9 deficiency on cardiomyocytes. Wild-type (WT) and CARD9^-/- mice were subjected to 30 min of left ascending coronary (LAD) ischemia and 12 h of reperfusion. TdT-mediated dUTP nick end labeling (TUNEL) staining analysis showed that CARD9^-/- mice exhibited a significantly higher number of apoptotic-positive cells after myocardial I/R injury than the WT mice. These results suggest that CARD9 protects cardiomyocytes from apoptosis by interacting with Apaf-1 and interfering with apoptosome formation following myocardial I/R injury in vivo and in vitro.

The Role of Adaptor Protein CARD9 in Colitis-Associated Cancer

The adaptor protein CARD9 plays an important role in anti-fungal immunity responses, linking detection of fungi by surface receptors to activation of the transcription factor nuclear factor κB (NF-κB). Recent studies indicate that CARD9 also plays different but vital roles during the development of colitis-associated colorectal cancer (CAC). This review summarizes the current understanding of CARD9 functions in CAC, and we discuss its potentially carcinogenic mechanisms.

The adaptive immune role of metallothioneins in the pathogenesis of diabetic cardiomyopathy: good or bad

Diabetes is a metabolic disorder characterized by hyperglycemia, resulting in low-grade systemic inflammation. Diabetic cardiomyopathy (DCM) is a common complication among diabetic patients, and the mechanism underlying its induction of cardiac remodeling and dysfunction remains unclear. Numerous experimental and clinical studies have suggested that adaptive immunity, especially T lymphocyte-mediated immunity, plays a potentially important role in the pathogenesis of diabetes and DCM. Metallothioneins (MTs), cysteine-rich, metal-binding proteins, have antioxidant properties. Some potential mechanisms underlying the cardioprotective effects of MTs include the role of MTs in calcium regulation, zinc homeostasis, insulin sensitization, and antioxidant activity. Moreover, metal homeostasis, especially MT-regulated zinc homeostasis, is essential for immune function. This review discusses aberrant immune regulation in diabetic heart disease with respect to endothelial insulin resistance and the effects of hyperglycemia and hyperlipidemia on tissues and the different effects of intracellular and extracellular MTs on adaptive immunity. This review shows that intracellular MTs are involved in naïve T-cell activation and reduce regulatory T-cell (Treg) polarization, whereas extracellular MTs promote proliferation and survival in naïve T cells and Treg polarization but inhibit their activation, thus revealing potential therapeutic strategies targeting the regulation of immune cell function by MTs.

Card9 as a critical regulator of tumor development

Caspase recruitment domain-containing protein 9 (Card9) is a myeloid cell-specific signaling protein that plays a critical role in NF-κB and MAPK activation. This leads to initiation of the inflammatory cytokine cascade, and elicits the host immune response against microbial invasion, especially in fungal infection. Current research indicates that Card9 plays an important role in tumor progression. Here, we review the data from preclinical and clinical studies of Card9 and suggest the potential for Card9-targeted interventions in the prevention or treatment of certain tumors.

The Evolving Role of TRAFs in Mediating Inflammatory Responses

TRAFs [tumor necrosis factor (TNF) receptor associated factors] are a family of signaling molecules that function downstream of multiple receptor signaling pathways and play a pivotal role in the biology of innate, and adaptive immune cells. Following receptor ligation, TRAFs generally function as adapter proteins to mediate the activation of intracellular signaling cascades. With the exception of TRAF1 that lacks a Ring domain, TRAFs have an E3 ubiquitin ligase activity which also contributes to their ability to activate downstream signaling pathways. TRAF-mediated signaling pathways culminate in the activation of several transcription factors, including nuclear factor-κB (NF-κB), mitogen-activated protein kinases (MAPKs; e.g., ERK-1 and ERK-2, JNK, and p38), and interferon-regulatory factors (IRF; e.g., IRF3 and IRF7). The biological role of TRAFs is largely due to their ability to positively or negatively regulate canonical and non-canonical NF-κB signaling. While TRAF-mediated signaling regulates various immune cell functions, this review is focused on the recent advances in our knowledge regarding the molecular mechanisms through which TRAF proteins regulate, positively and negatively, inflammatory signaling pathways, including Toll-IL-1 receptors, RIG-I like receptors, and Nod-like receptors. The review also offers a perspective on the unanswered questions that need to be addressed to fully understand how TRAFs regulate inflammation.