Unconventional posttranslational modification in innate immunity.

Pattern recognition receptors (PRRs) play a crucial role in innate immunity, and a complex network tightly controls their signaling cascades to maintain immune homeostasis. Within the modification network, posttranslational modifications (PTMs) are at the core of signaling cascades. Conventional PTMs, which include phosphorylation and ubiquitination, have been extensively studied. The regulatory role of unconventional PTMs, involving unanchored ubiquitination, ISGylation, SUMOylation, NEDDylation, methylation, acetylation, palmitoylation, glycosylation, and myristylation, in the modulation of innate immune signaling pathways has been increasingly investigated. This comprehensive review delves into the emerging field of unconventional PTMs and highlights their pivotal role in innate immunity.

Protein Kinase STK24 Promotes Tumor Immune Evasion via the AKT-PD-L1 Axis.

Immunotherapy targeting PD-L1 is still ineffective for a wide variety of tumors with high unpredictability. Deploying combined immunotherapy with alternative targeting is practical to overcome this therapeutic resistance. Here, the deficiency of serine-threonine kinase STK24 is observed in tumor cells causing substantial attenuation of tumor growth in murine syngeneic models, a process relying on cytotoxic CD8+ T and NK cells. Mechanistically, STK24 in tumor cells associates with and directly phosphorylates AKT at Thr21, which promotes AKT activation and subsequent PD-L1 induction. Deletion or inhibition of STK24, by contrast, blocks IFN-γ-mediated PD-L1 expression. Various murine models indicate that in vivo silencing of STK24 can significantly enhance the efficacy of the anti-PD-1 blockade strategy. Elevated STK24 levels are observed in patient specimens in multiple tumor types and inversely correlated with intratumoral infiltration of cytotoxic CD8+ T cells and with patient survival. The study collectively identifies STK24 as a critical modulator of antitumor immunity, which engages in AKT and PD-L1/PD-1 signaling and is a promising target for combined immunotherapy.

Age-related trends in the incidence of metastatic colorectal cancer from 2010 to 2019 in the USA.

Aim: To evaluate temporal changes in metastatic colorectal cancer (mCRC), incidence, and use of chemotherapy treatment by age group using real-world data (RWD) from the USA. Methods: A retrospective, observational study describing temporal trends in mCRC incidence and FOLFOXIRI treatment by age group using a nationwide database of commercially and Medicare Advantage-insured patients from 2010 to 2019. Results: Incidence of mCRC increased by 22.1 and 14.9% in the 18-49 and 50-64 years cohorts, respectively, and decreased by 21.6% in the ≥65 years cohort. Overall, younger patients were more likely to receive FOLFOXIRI treatment versus older patients. Conclusion: The shifting age distribution of mCRC should be considered when recommending screening and treatment. Further research is needed to inform age-specific treatment guidelines.

What is this article about? This article reports the results of a study that used a US database of commercially and Medicare Advantage-insured adults to evaluate how the number of adults with metastatic colorectal cancer (mCRC) in three age groups (18­49 years, 50­64 years and 65 years and over) changed from 2010 to 2019. The study also looked at the use of an aggressive chemotherapy treatment, known as 5-fluorouracil, oxaliplatin, leucovorin calcium and irinotecan (FOLFOXIRI), by age group. What were the results? Overall, 23,970 adults with mCRC were included in the study. From 2010 to 2019, the number of adults with mCRC increased by 22.1% among those aged 18­49 years, increased by 14.9% among those aged 50­64 years, and decreased by 21.6% among those aged 65 years and over. There were some differences between age groups; a higher percentage of younger patients (18­49 years) were Hispanic or Asian, and from the South compared with the older age groups. In comparison, those aged 65 years and over were more likely to be from the West and Northeast of the USA. The study also found that a higher proportion of those aged 18­49 years received FOLFOXIRI (8.4%) compared with adults aged 50­64 years (4.4%) and 65 years and over (1.9%). What do the results of the study mean? Healthcare providers should be aware that early-onset mCRC is becoming more common and consider this when recommending screening and treatment.

FXYD3 enhances IL-17A signaling to promote psoriasis by competitively binding TRAF3 in keratinocytes.

Psoriasis is a common chronic inflammatory skin disease characterized by inflammatory cell infiltration and epidermal hyperplasia. However, the regulatory complexity of cytokine and cellular networks still needs to be investigated. Here, we show that the expression of FXYD3, a member of the FXYD domain-containing regulators of Na+/K+ ATPases family, is significantly increased in the lesional skin of psoriasis patients and mice with imiquimod (IMQ)-induced psoriasis. IL-17A, a cytokine important for the development of psoriatic lesions, contributes to FXYD3 expression in human primary keratinocytes. FXYD3 deletion in keratinocytes attenuated the psoriasis-like phenotype and inflammation in an IMQ-induced psoriasis model. Importantly, FXYD3 promotes the formation of the IL-17R-ACT1 complex by competing with IL-17R for binding to TRAF3 and then enhances IL-17A signaling in keratinocytes. This promotes the activation of the NF-κB and MAPK signaling pathways and leads to the expression of proinflammatory factors. Our results clarify the mechanism by which FXYD3 serves as a mediator of IL-17A signaling in keratinocytes to form a positive regulatory loop to promote psoriasis exacerbation. Targeting FXYD3 may serve as a potential therapeutic approach in the treatment of psoriasis.

Metabolic control of CD47 expression through LAT2-mediated amino acid uptake promotes tumor immune evasion.

Chemotherapy elicits tumor immune evasion with poorly characterized mechanisms. Here, we demonstrate that chemotherapy markedly enhances the expression levels of CD47 in osteosarcoma tissues, which are positively associated with patient mortality. We reveal that macrophages in response to chemotherapy secrete interleukin-18, which in turn upregulates expression of L-amino acid transporter 2 (LAT2) in tumor cells for substantially enhanced uptakes of leucine and glutamine, two potent stimulators of mTORC1. The increased levels of leucine and enhanced glutaminolysis activate mTORC1 and subsequent c-Myc-mediated transcription of CD47. Depletion of LAT2 or treatment of tumor cells with a LAT inhibitor downregulates CD47 with enhanced macrophage infiltration and phagocytosis of tumor cells, and sensitizes osteosarcoma to doxorubicin treatment in mice. These findings unveil a mutual regulation between macrophage and tumor cells that plays a critical role in tumor immune evasion and underscore the potential to intervene with the LAT2-mediated amino acid uptake for improving cancer therapies.

E3 ubiquitin ligase NEDD4L negatively regulates inflammation by promoting ubiquitination of MEKK2.

Aberrant activation of inflammation signaling triggered by tumor necrosis factor α (TNF-α), interleukin-1 (IL-1), and interleukin-17 (IL-17) is associated with immunopathology. Here, we identify neural precursor cells expressed developmentally down-regulated gene 4-like (NEDD4L), a HECT type E3 ligase, as a common negative regulator of signaling induced by TNF-α, IL-1, and IL-17. NEDD4L modulates the degradation of mitogen-activated protein kinase kinase kinase 2 (MEKK2) via constitutively and directly binding to MEKK2 and promotes its poly-ubiquitination. In interleukin-17 receptor (IL-17R) signaling, Nedd4l knockdown or deficiency enhances IL-17-induced p38 and NF-κB activation and the production of proinflammatory cytokines and chemokines in a MEKK2-dependent manner. We further show that IL-17-induced MEKK2 Ser520 phosphorylation is required not only for downstream p38 and NF-κB activation but also for NEDD4L-mediated MEKK2 degradation and the subsequent shutdown of IL-17R signaling. Importantly, Nedd4l-deficient mice show increased susceptibility to IL-17-induced inflammation and aggravated symptoms of experimental autoimmune encephalomyelitis (EAE) in IL-17R signaling-dependent manner. These data suggest that NEDD4L acts as an inhibitor of IL-17R signaling, which ameliorates the pathogenesis of IL-17-mediated autoimmune diseases.

SARS-CoV-2 Host Receptor ACE2 Protein Expression Atlas in Human Gastrointestinal Tract.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects host cells through interactions with its receptor, Angiotensin-converting enzyme 2 (ACE2), causing severe acute respiratory syndrome and death in a considerable proportion of people. Patients infected with SARS-CoV-2 experience digestive symptoms. However, the precise protein expression atlas of ACE2 in the gastrointestinal tract remains unclear. In this study, we aimed to explore the ACE2 protein expression pattern and the underlying function of ACE2 in the gastrointestinal tract, including the colon, stomach, liver, and pancreas. METHODS: We measured the protein expression of ACE2 in the gastrointestinal tract using immunohistochemical (IHC) staining with an ACE2-specific antibody of paraffin-embedded colon, stomach, liver, and pancreatic tissues. The correlation between the protein expression of ACE2 and the prognosis of patients with gastrointestinal cancers was analyzed by the log-rank (Mantel-Cox) test. The influence of ACE2 on colon, stomach, liver, and pancreatic tumor cell line proliferation was tested using a Cell Counting Kit 8 (CCK-8) assay. RESULTS: ACE2 presented heterogeneous expression patterns in the gastrointestinal tract, and it showed a punctate distribution in hepatic cells. Compared to that in parallel adjacent non-tumor tissues, the protein expression of ACE2 was significantly increased in colon cancer, stomach cancer, and pancreatic cancer tissues but dramatically decreased in liver cancer tissues. However, the expression level of the ACE2 protein was not correlated with the survival of patients with gastrointestinal cancers. Consistently, ACE2 did not affect the proliferation of gastrointestinal cancer cells in vitro. CONCLUSION: The ACE2 protein is widely expressed in the gastrointestinal tract, and its expression is significantly altered in gastrointestinal tumor tissues. ACE2 is not an independent prognostic marker of gastrointestinal cancers.

E3 ubiquitin ligase NEDD4L negatively regulates keratinocyte hyperplasia by promoting GP130 degradation.

Psoriasis is mainly characterized by abnormal hyperplasia of keratinocytes and immune cells infiltrating into the dermis and epidermis. Neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) is a highly conserved HECT type E3 ligase that plays an important role in regulating physiological and pathological processes. Here, we identify NEDD4L as a negative regulator of psoriasis. Nedd4l significantly inhibits imiquimod (IMQ)-induced skin hyperplasia, and this effect is attributed to the inhibitory effect of NEDD4L on IL-6/GP130 signaling in keratinocytes. Mechanistically, NEDD4L directly interacts with GP130 and mediates its Lys-27-linked ubiquitination and proteasomal degradation. Moreover, the expression of NEDD4L is downregulated in the epidermis from IMQ-treated mice and psoriasis patients and negatively correlates with the protein levels of GP130 and p-STAT3 in clinical samples. Collectively, we uncover an inhibitory role of NEDD4L in the pathogenesis of psoriasis and suggest a new therapeutic strategy for the treatment of psoriasis.

IRF3 prevents colorectal tumorigenesis via inhibiting the nuclear translocation of ß-catenin.

Occurrence of Colorectal cancer (CRC) is relevant with gut microbiota. However, role of IRF3, a key signaling mediator in innate immune sensing, has been barely investigated in CRC. Here, we unexpectedly found that the IRF3 deficient mice are hyper-susceptible to the development of intestinal tumor in AOM/DSS and Apcmin/+ models. Genetic ablation of IRF3 profoundly promotes the proliferation of intestinal epithelial cells via aberrantly activating Wnt signaling. Mechanically, IRF3 in resting state robustly associates with the active ß-catenin in the cytoplasm, thus preventing its nuclear translocation and cell proliferation, which can be relieved upon microbe-induced activation of IRF3. In accordance, the survival of CRC is clinically correlated with the expression level of IRF3. Therefore, our study identifies IRF3 as a negative regulator of the Wnt/ß-catenin pathway and a potential prognosis marker for Wnt-related tumorigenesis, and describes an intriguing link between gut microbiota and CRC via the IRF3-ß-catenin axis.

MEF2C/miR-133a-3p.1 circuit-stabilized AQP1 expression maintains endothelial water homeostasis.

Aquaporin 1 (AQP1) plays an important role in endothelial functions and is regulated by MEF2C. However, how AQP1 level is stabilized to maintain endothelial water homeostasis is still not clear. Here, we show that AQP1 expression is significantly upregulated by MEF2C transcriptionally and inhibited by miR-133a-3p.1 post-transcriptionally. Meanwhile, MEF2C activates the expression of miR-133a1. Simultaneous overexpression of MEF2C and miR-133a-3p.1 suppresses the aptitude of changes in AQP1 expression caused by either MEF2C or miR-133a-3p.1. Accordingly, the changes in migration and tube formation of human umbilical vein endothelial cells (HUVECs) caused by MEF2C or miR133a-3p.1 are blunted by coexpression of both of them. These data demonstrate that the homeostasis and physiological function of AQP1 in endothelial health are maintained by the MEF2C and miR-133a-3p.1 regulatory circuit.

Raf kinase inhibitor protein negatively regulates FcεRI-mediated mast cell activation and allergic response.

The signaling cascades triggered by the cross-linkage of immunoglobulin E (IgE) with its high-affinity receptor (FcεRI) on mast cells contribute to multiple allergic disorders, such as asthma, rhinitis, and atopic dermatitis. Restraint of intracellular signals for mast cell activation is essential to restore homeostasis. In this study, we found that Raf kinase inhibitor protein (RKIP) negatively regulated mast cell activation. RKIP-deficient mast cells showed greater IgE-FcεRI-mediated activation than wild-type mast cells. Consistently, RKIP deficiency in mast cells rendered mice more sensitive to IgE-FcεRI-mediated allergic responses and ovalbumin-induced airway inflammation. Mechanistically, RKIP interacts with the p85 subunit of PI3K, prevents it from binding to GRB2-associated binding protein 2 (Gab2), and eventually inhibits the activation of the PI3K/Akt/NF-κB complex and its downstream signaling. Furthermore, the expression of RKIP was significantly down-regulated in the peripheral blood of asthma patients and in the IgE-FcεRI-stimulated mast cells. Collectively, our findings not only suggest that RKIP plays an important role in controlling mast cell-mediated allergic responses but also provide insight into therapeutic targets for mast cell-related allergic diseases.

Downregulated NDR1 protein kinase inhibits innate immune response by initiating an miR146a-STAT1 feedback loop.

Interferon (IFN)-stimulated genes (ISGs) play crucial roles in the antiviral immune response; however, IFNs also induce negative regulators that attenuate the antiviral response. Here, we show that both viral and bacterial invasion downregulate Nuclear Dbf2-related kinase 1 (NDR1) expression via the type I IFN signaling pathway. NDR1 promotes the virus-induced production of type I IFN, proinflammatory cytokines and ISGs in a kinase-independent manner. NDR1 deficiency also renders mice more susceptible to viral and bacterial infections. Mechanistically, NDR1 enhances STAT1 translation by directly binding to the intergenic region of miR146a, thereby inhibiting miR146a expression and liberating STAT1 from miR146a-mediated translational inhibition. Furthermore, STAT1 binds to the miR146a promoter, thus decreasing its expression. Together, our results suggest that NDR1 promotion of STAT1 translation is an important event for IFN-dependent antiviral immune response, and suggest that NDR1 has an important role in controlling viral infections.

Protein Kinase Serine/Threonine Kinase 24 Positively Regulates Interleukin 17-Induced Inflammation by Promoting IKK Complex Activation.

Interleukin 17 (IL-17) is a key inflammatory cytokine that plays a critical role in tissue inflammation and autoimmune diseases. However, its signaling remains poorly understood. In this study, we identified serine/threonine kinase 24 (Stk24) as a positive modulator of IL-17-mediated signaling and inflammation. Stk24 deficiency or knockdown markedly inhibited IL-17-induced phosphorylation of NF-κB and impaired IL-17-induced chemokines and cytokines expression. Stk24 overexpression greatly enhanced IL-17-induced NF-κB activation and expression of chemokines and cytokines in a kinase activity-independent manner. The IL-17-induced inflammatory response was significantly reduced in Stk24-deficient mice. In addition, the severity of experimental autoimmune encephalomyelitis was markedly reduced in mice with a deficiency of Stk24 in non-hematopoietic cells. We further demonstrated that Stk24 directly interacts with TAK1 and IKKß and promotes the formation of TAK1/IKK complexes, leading to enhanced IKKß/NF-κB activation and downstream cytokines and chemokines induction. Collectively, our findings suggest that Stk24 plays an important role in controlling IL-17-triggered inflammation and autoimmune diseases and provides new insight into the therapeutic targets of IL-17-mediated inflammatory disease.

RKIP mediates autoimmune inflammation by positively regulating IL-17R signaling.

Th17 cells contribute to the development of autoimmune diseases by secreting interleukin-17 (IL-17), which activates its receptor (IL-17R) that is expressed on epithelial cells, macrophages, microglia, and resident neuroectodermal cells. However, the mechanisms through which IL-17R-mediated signaling contributes to the development of autoimmune disease have not been completely elucidated. Here, we demonstrate that Raf-1 kinase inhibitor protein (RKIP) deficiency in mice ameliorates the symptoms of experimental autoimmune encephalomyelitis (EAE). Adoptive T-cell-transfer experiments demonstrate that RKIP plays a predominant role in Th17-mediated, but not in Th1-mediated immune responses. RKIP deficiency has no effect on Th17-cell differentiation ex vivo, nor does it affect Th17-cell differentiation in EAE mice. However, RKIP significantly promotes IL-17R-induced proinflammatory cytokine and chemokine production. Mechanistically, RKIP directly interacts with IL-17RA and Act1 to promote the formation of an IL-17R-Act1 complex, resulting in enhanced MAPK- and P65-mediated NF-κB activation and downstream cytokine production. Together, these findings indicate that RKIP functions as an essential modulator of the IL-17R-Act1 axis in IL-17R signaling, which promotes IL-17-induced inflammation and autoimmune neuroinflammation.

Evaluation of hospitalization costs and associated factors among maternity stays involving low-risk and moderate- to high-risk childbirths in the United States.

OBJECTIVES: This study aimed to assess the costs of childbirth and to identify factors associated with such hospital costs for low- and moderate/high-risk childbirth groups. METHODS: All hospitalizations for childbirth between 2010-2014 in the Premier Perspective Hospital Database were identified. Risk category for each birth was defined by the age of the subject and/or presence of specific maternal comorbidities and obstetric risk factors. Hospital childbirth costs were determined and stratified by risk groups. Factors associated with costs for each risk group were evaluated by multiple regression. RESULTS: Among 2,367,195 hospitalizations for childbirth, vaginal birth was the most common delivery method (n = 1,596,757; 68%). Among women characterized as moderate/high-risk, 42% (n = 642,495) had C-sections, while 11% (n = 90,211) of women categorized as low-risk had C-sections. The proportion of women with serious maternal morbidity among moderate/high-risk vs. low-risk women was 2% (n = 29,496) vs. 0.3% (n = 2749), respectively. The mean costs for moderate/high-risk vs. low-risk hospitalizations were $6145 (median = $5760) and $5397 (median = $5001), respectively (p < 0.0001). Factors significantly associated with costs for moderate/high-risk hospitalizations included delivery type (C-section vs. vaginal birth), LOS, urban/rural hospital status, geographic regions, calendar year of hospitalization, teaching status, payer types and serious maternal morbidity. Similar factors were found to impact costs among low-risk hospitalizations. CONCLUSIONS: Characteristics such as delivery type, LOS, geographical region, teaching status, serious maternal morbidity and hospital urban/rural status were shown to impact hospital costs of childbirth. Screening and prevention strategies of factors that negatively impact costs may aid in reducing the hospitalization costs associated with childbirths.

Discrepancies between leg-to-leg bioelectrical Impedance analysis and computerized tomography in abdominal visceral fat measurement.

The aim of this study was to evaluate leg-to-leg bioelectrical impedance analysis (LBIA) using a four-contact electrode system for measuring abdominal visceral fat area (VFA). The present study recruited 381 (240 male and 141 female) Chinese participants to compare VFA measurements estimated by a standing LBIA system (VFALBIA) with computerized tomography (CT) scanned at the L4-L5 vertebrae (VFACT). The total mean body mass index (BMI) was 24.7 ± 4.2 kg/m2. Correlation analysis, regression analysis, Bland-Altman plot, and paired sample t-tests were used to analyze the accuracy of the VFALBIA. For the total subjects, the regression line was VFALBIA = 0.698 VFACT + 29.521, (correlation coefficient (r) = 0.789, standard estimate of error (SEE) = 24.470 cm2, p < 0.001), Lin's correlation coefficient (CCC) was 0.785; and the limit of agreement (LOA; mean difference ±2 standard deviation) ranged from -43.950 to 67.951 cm2, LOA% (given as a percentage of mean value measured by the CT) was 48.2%. VFALBIA and VFACT showed significant difference (p < 0.001). Collectively, the current study indicates that LBIA has limited potential to accurately estimate visceral fat in a clinical setting.

Raf Kinase Inhibitor Protein Preferentially Promotes TLR3-Triggered Signaling and Inflammation.

Raf kinase inhibitor protein (RKIP) protects against host immunological responses in nematodes and Drosophila Whether RKIP functions in innate immune responses in mammals remains unknown. In this article, we report that RKIP preferentially regulates the TLR3-mediated immune response in macrophages. RKIP deficiency or silencing significantly decreases polyinosinic:polycytidylic acid [Poly(I:C)]-induced IFN-ß, IL-6, and TNF-α production without affecting the counterpart induced by LPS or CpG. Compared with their wild-type counterparts, RKIP-deficient mice produce less IFN-ß, IL-6, and TNF-α in serum and display decreased lethality upon peritoneal Poly(I:C) plus d-galactosamine injection. Mechanistically, RKIP interacts with TBK1 and promotes the Poly(I:C)-induced TANK-binding kinase 1/IRF3 activation. Simultaneously, RKIP enhances the Poly(I:C)-induced interaction between TGF-ß-activated kinase 1 and MAPK kinase 3 (MKK3), thus promoting MKK3/6 and p38 activation. We further demonstrated that Poly(I:C) treatment, but not LPS treatment, induces RKIP phosphorylation at S109. This action is required for RKIP to promote TANK-binding kinase 1 activation, as well as the interaction between TGF-ß-activated kinase 1 and MKK3, which lead to activation of the downstream IRF3 and p38, respectively. Therefore, RKIP acts as a positive-feedback regulator of the TLR3-induced inflammatory response and may be a potential therapeutic target for inflammatory disease.