Interferon regulatory factor 5 and nuclear factor kappa‐B exhibit cooperating but also divergent roles in the regulation of pro‐inflammatory cytokines important for the development of TH 1 and TH 17 responses

Effect of nonsteroidal anti-inflammatory drugs on pelvic floor muscle regeneration in a preclinical birth injury rat model

BACKGROUND

Pelvic floor muscle injury is a common consequence of vaginal childbirth. Nonsteroidal anti-inflammatory drugs are widely used postpartum analgesics. Multiple studies have reported negative effects of these drugs on limb muscle regeneration, but their impact on pelvic floor muscle recovery following birth injury has not been explored.

OBJECTIVE

Using a validated rat model, we assessed the effects of nonsteroidal anti-inflammatory drug on acute and longer-term pelvic floor muscle recovery following simulated birth injury.

STUDY DESIGN

Three-month old Sprague Dawley rats were randomly assigned to the following groups: (1) controls, (2) simulated birth injury, (3) simulated birth injury+nonsteroidal anti-inflammatory drug, or (4) nonsteroidal anti-inflammatory drug. Simulated birth injury was induced using a well-established vaginal balloon distension protocol. Ibuprofen was administered in drinking water (0.2 mg/mL), which was consumed by the animals ad libitum. Animals were euthanized at 1, 3, 5, 7, 10, and 28 days after birth injury/ibuprofen administration. The pubocaudalis portion of the rat levator ani, which, like the human pubococcygeus, undergoes greater parturition-associated strains, was harvested (N=3-9/time point/group). The cross-sectional areas of regenerating (embryonic myosin heavy chain+) and mature myofibers were assessed at the acute and 28-day time points, respectively. The intramuscular collagen content was assessed at the 28-day time point. Myogenesis was evaluated using anti-Pax7 and anti-myogenin antibodies to identify activated and differentiated muscle stem cells, respectively. The overall immune infiltrate was assessed using anti-CD45 antibody. Expression of genes coding for pro- and anti-inflammatory cytokines was assessed by quantitative reverse transcriptase polymerase chain reaction at 3, 5, and 10 days after injury.

RESULTS

The pubocaudalis fiber size was significantly smaller in the simulated birth injury+nonsteroidal anti-inflammatory drug compared with the simulated birth injury group at 28 days after injury (P<.0001). The median size of embryonic myosin heavy chain+ fibers was also significantly reduced, with the fiber area distribution enriched with smaller fibers in the simulated birth injury+nonsteroidal anti-inflammatory drug group relative to the simulated birth injury group at 3 days after injury (P<.0001), suggesting a delay in the onset of regeneration in the presence of nonsteroidal anti-inflammatory drugs. By 10 days after injury, the median embryonic myosin heavy chain+ fiber size in the simulated birth injury group decreased from 7 days after injury (P<.0001) with a tight cross-sectional area distribution, indicating nearing completion of this state of regeneration. However, in the simulated birth injury+nonsteroidal anti-inflammatory drug group, the size of embryonic myosin heavy chain+ fibers continued to increase (P<.0001) with expansion of the cross-sectional area distribution, signifying a delay in regeneration in these animals. Nonsteroidal anti-inflammatory drugs decreased the muscle stem cell pool at 7 days after injury (P<.0001) and delayed muscle stem cell differentiation, as indicated by persistently elevated number of myogenin+ cells 7 days after injury (P<.05). In contrast, a proportion of myogenin+ cells returned to baseline by 5 days after injury in the simulated birth injury group. The analysis of expression of genes coding for pro- and anti-inflammatory cytokines demonstrated only transient elevation of Tgfb1 in the simulated birth injury+nonsteroidal anti-inflammatory drug group at 5 but not at 10 days after injury. Consistently with previous studies, nonsteroidal anti-inflammatory drug administration following simulated birth injury resulted in increased deposition of intramuscular collagen relative to uninjured animals. There were no significant differences in any outcomes of interest between the nonsteroidal anti-inflammatory drug group and the unperturbed controls.

CONCLUSION

Nonsteroidal anti-inflammatory drugs negatively impacted pelvic floor muscle regeneration in a preclinical simulated birth injury model. This appears to be driven by the negative impact of these drugs on pelvic muscle stem cell function, resulting in delayed temporal progression of pelvic floor muscle regeneration following birth injury. These findings provide impetus to investigate the impact of postpartum nonsteroidal anti-inflammatory drug administration on muscle regeneration in women at high risk for pelvic floor muscle injury.

Lyn-mediated glycolysis enhancement of microglia contributes to neuropathic pain through facilitating IRF5 nuclear translocation in spinal dorsal horn

The pro-inflammatory phenotype of microglia usually induces neuroinflammatory reactions in neuropathic pain. Glycometabolism shift to glycolysis can promote the pro-inflammatory phenotype transition of microglia. The omics data analysis suggest a critical role for Lyn dysregulation in neuropathic pain. The present study aimed at exploring the mechanism of Lyn-mediated glycolysis enhancement of microglia in neuropathic pain. Neuropathic pain model was established by chronic constriction injury (CCI), then pain thresholds and Lyn expression were measured. Lyn inhibitor Bafetinib and siRNA-lyn knockdown were administrated intrathecally to evaluate the effects of Lyn on pain thresholds, glycolysis and interferon regulatory factor 5 (IRF5) nuclear translocation of microglia in vivo and in vitro. ChIP was carried out to observe the binding of transcription factors SP1, PU.1 to glycolytic gene promoters by IRF5 knockdown. Finally, the relationship between glycolysis and pro-inflammatory phenotype transition of microglia was evaluated. CCI led to the upregulation of Lyn expression and glycolysis enhancement in microglia of spinal dorsal horn. Bafetinib or siRNA-lyn knockdown intrathecally alleviated pain hyperalgesia, suppressed glycolysis enhancement and inhibited nuclear translocation of IRF5 in CCI mice. Also, IRF5 promoted the binding of transcription factors SP1, PU.1 to glycolytic gene promoters, and then the enhanced glycolysis facilitated the proliferation and pro-inflammatory phenotype transition of microglia and contributed to neuropathic pain. Lyn-mediated glycolysis enhancement of microglia contributes to neuropathic pain through facilitating IRF5 nuclear translocation in spinal dorsal horn.

Antiviral innate immunity is diminished in the upper respiratory tract of severe COVID-19 patients

Understanding early innate immune responses to coronavirus disease 2019 (COVID-19) is crucial to developing targeted therapies to mitigate disease severity. Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection elicits interferon expression leading to transcription of IFN-stimulated genes (ISGs) to control viral replication and spread. SARS-CoV-2 infection also elicits NF-κB signaling which regulates inflammatory cytokine expression contributing to viral control and likely disease severity. Few studies have simultaneously characterized these two components of innate immunity to COVID-19. We designed a study to characterize the expression of interferon alpha-2 (IFNA2) and interferon beta-1 (IFNB1), both type-1 interferons (IFN-1), interferon-gamma (IFNG), a type-2 interferon (IFN-2), ISGs, and NF-κB response genes in the upper respiratory tract (URT) of patients with mild (outpatient) versus severe (hospitalized) COVID-19. Further, we characterized the weekly dynamics of these responses in the upper and lower respiratory tracts (LRTs) and blood of severe patients to evaluate for compartmental differences. We observed significantly increased ISG and NF-κB responses in the URT of mild compared with severe patients early during illness. This pattern was associated with increased IFNA2 and IFNG expression in the URT of mild patients, a trend toward increased IFNB1-expression and significantly increased STING/IRF3/cGAS expression in the URT of severe patients. Our by-week across-compartment analysis in severe patients revealed significantly higher ISG responses in the blood compared with the URT and LRT of these patients during the first week of illness, despite significantly lower expression of IFNA2, IFNB1, and IFNG in blood. NF-κB responses, however, were significantly elevated in the LRT compared with the URT and blood of severe patients during peak illness (week 2). Our data support that severe COVID-19 is associated with impaired interferon signaling in the URT during early illness and robust pro-inflammatory responses in the LRT during peak illness.

Reprogramming Metabolism of Macrophages as a Target for Kidney Dysfunction Treatment in Autoimmune Diseases

Chronic kidney disease (CKD), as one of the main complications of many autoimmune diseases, is difficult to cure, which places a huge burden on patients’ health and the economy and poses a great threat to human health. At present, the mainstream view is that autoimmune diseases are a series of diseases and complications caused by immune cell dysfunction leading to the attack of an organism’s tissues by its immune cells. The kidney is the organ most seriously affected by autoimmune diseases as it has a very close relationship with immune cells. With the development of an in-depth understanding of cell metabolism in recent years, an increasing number of scientists have discovered the metabolic changes in immune cells in the process of disease development, and we have a clearer understanding of the characteristics of the metabolic changes in immune cells. This suggests that the regulation of immune cell metabolism provides a new direction for the treatment and prevention of kidney damage caused by autoimmune diseases. Macrophages are important immune cells and are a double-edged sword in the repair process of kidney injury. Although they can repair damaged kidney tissue, over-repair will also lead to the loss of renal structural reconstruction function. In this review, from the perspective of metabolism, the metabolic characteristics of macrophages in the process of renal injury induced by autoimmune diseases are described, and the metabolites that can regulate the function of macrophages are summarized. We believe that treating macrophage metabolism as a target can provide new ideas for the treatment of the renal injury caused by autoimmune diseases.

SARS-Coronavirus 2, A Metabolic Reprogrammer: A Review in the Context of the Possible Therapeutic Strategies

Novel coronavirus, SARS-CoV-2 is advancing at a staggering pace to devastate the health care system and foster the concerns over public health. In contrast to the past outbreaks, coronaviruses aren't clinging themselves as a strict respiratory virus. Rather, becoming a multifaceted virus, it affects multiple organs by interrupting a number of metabolic pathways leading to significant rates of morbidity and mortality. Following infection they rigorously reprogram multiple metabolic pathways of glucose, lipid, protein, nucleic acid and their metabolites to extract adequate energy and carbon skeletons required for their existence and further molecular constructions inside a host cell. Although the mechanism of these alterations are yet to be known, the impact of these reprogramming is reflected in the hyper inflammatory responses, so called cytokine storm and the hindrance of host immune defence system. The metabolic reprogramming during SARS-CoV-2 infection needs to be considered while devising therapeutic strategies to combat the disease and its further complication. The inhibitors of cholesterol and phospholipids synthesis and cell membrane lipid raft of the host cell can, to a great extent, control the viral load and further infection. Depletion of energy source by inhibiting the activation of glycolytic and hexoseamine biosynthetic pathway can also augment the antiviral therapy. The cross talk between these pathways also necessitates the inhibition of amino acid catabolism and tryptophan metabolism. A combinatorial strategy which can address the cross talks between the metabolic pathways might be more effective than a single approach and the infection stage and timing of therapy will also influence the effectiveness of the antiviral approach. We herein focus on the different metabolic alterations during the course of virus infection that help to exploit the cellular machinery and devise a therapeutic strategy which promotes resistance to viral infection and can augment body's antivirulence mechanisms. This review may cast the light into the possibilities of targeting altered metabolic pathways to defend virus infection in a new perspective.

Promotion Effect of EGCG on the Raised Expression of IL-23 through the Signaling of STAT3-BATF2-c-JUN/ATF2

Tea polyphenol of epigallocatechin-3-gallate (EGCG) has been verified to possess multiple biological activities. Interleukin-23 (IL-23) is a heterodimeric cytokine consisting of two subunits of IL-23p19 and IL-12p40, with the functionality in regulating the production of cytokines under physiological or pathological conditions. By serendipity, the raised expression of IL-23 was observed after treating cells with EGCG, whereas the detailed mechanism remains poorly understood. This study was proposed to investigate the signaling related to EGCG-induced IL-23. The raised expression of IL-23 was confirmed primarily by intraperitoneally injecting with different concentrations of EGCG (0, 20, 50, 80 mg/kg) into BALB/c mice, and the raised expression was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Results from enzyme-linked immunosorbent assay (ELISA) revealed the increase of IL-23 in serum from 116.09 to 153.90 pg/mL after treating with EGCG. The same results were also observed in RAW264.7 and peritoneal macrophages after treating with EGCG (0, 1, 5, 10, 25 μM) with the increased tendency of IL-23 in cultural medium (7.98 to 25.38 pg/mL for RAW264.7; 3.64 to 260.93 pg/mL for peritoneal macrophages). After preliminary exploration of the signaling related to the increased IL-23, the classical signaling pathways and key transcription factors, such as nuclear factor kappa-B (NF-κB), mitogen-activated protein kinase (MAPK) signaling pathways, and interferon regulatory factor 5 (IRF5), were demonstrated with no relevant contribution. A further study revealed the involvement of the key transcription factor of BATF2, which could antagonistically modulate the transcription and translation of IL-23. The signaling of STAT3-BATF2-c-JUN/ATF2-IL-23 has been further verified in RAW264.7 macrophages using the STAT3 inhibitor of AG490 and the activator of Colivelin TFA. The results indicated that EGCG inhibits the phosphorylation of STAT3 to facilitate the decreased level of BATF2, which contributed to the increased level of IL-23 by the enhancing heterodimerization of c-JUN and ATF2.

Transcriptome Analysis Reveals Key Genes and Pathways Associated with Mummify Piglets

China is the country with the largest pork consumption in the world. However, the incidence of high mummify piglets (3-5%) is one of the important factors that cause the slow improvement of pig reproductive capacity, and the genetic mechanism is still unclear. This study aimed to identify candidate genes related to high mummify piglets. RNA-seq technology was used to comparative transcriptome profiling of blood from high piglets mummified and healthy sow at different stages of pregnancy (35d, 56d, 77d and 98d). A total of 137 to 420 DEGs were detected in each stage. Seven differentially expressed genes were significantly differentially expressed at various stages. IL-9R, TLR8, ABLIM3, FSH-α, ASCC1, PRKCZ, and GCK may play an important role in course of mummify piglets. The differential genes we identified between the groups were mainly enriched in immune and inflammation regulation, and others were mainly enriched in reproduction. Considering the function of candidate genes, IL-9R and TLR8 were suggested as the most promising candidate genes involved in mummify piglet traits. We speculate that during pregnancy, it may be the combined effects of the above-mentioned inflammation, immune response, and reproduction-related signal pathways that affect the occurrence of mummifying piglets, and further affect pig reproduction.

Successful Direct Acting Antiviral Therapy in Chronic Hepatitis C Normalizes IFNγ and IL2 Production in T Cells Together with TLR8 Expression and Functionality in Peripheral Blood Mononuclear Cells

Chronic hepatitis C infection (HCV) activates a systemic cell-mediated immune response characterized by the production of IFNγ and an innate immune response addressed by the activation of TLR signaling. We aimed to investigate whether HCV eradication by direct acting antivirals (DAA) leads to a recovery in cell-mediated immune response and TLR expression and functionality. Blood samples were obtained in HCV infected patients before DAA treatment and at week +48 after the end of treatment. Results were compared to healthy controls. Cell surface expression of TLR8 was assessed on peripheral blood mononuclear cells (PBMCs) by flow cytometry. Freshly isolated PBMCs were cultured with specific TLR8 agonists and intracellular production of cytokines was determined by flow-cytometry after ex vivo TLR8 activation with ssRNA 40. Production of IFNγ, IL2 and IL17 was assessed by flow cytometry in T cells after polyclonal activation. Included were 50 HCV-infected patients and 15 controls. TLR8 expression in PBMCs was significantly increased before treatment and recovered normal levels at week +48. Production of IL1b, IL6 and TNFα dependent on the activation of TLR8 in PBMCs was also increased in patients before DAA treatment, with a significant reduction at week +48. Combined expression of IFNγ and IL2 in CD4+ T cells in HCV-infected patients was significantly increased compared to controls and recovered normal levels at week +48. DAA-mediated clearance of HCV is associated with a decreased expression and activation of TLR8 in PBMCs until healthy control levels which is accompanied by a reduction in the Th1 response.

Involvement of Interleukin-1 Receptor-Associated Kinase 4 and Interferon Regulatory Factor 5 in the Immunopathogenesis of SARS-CoV-2 Infection: Implications for the Treatment of COVID-19

Interleukin-1 receptor-associated kinase 4 (IRAK4) and interferon regulatory factor 5 (IRF5) lie sequentially on a signaling pathway activated by ligands of the IL-1 receptor and/or multiple TLRs located either on plasma or endosomal membranes. Activated IRF5, in conjunction with other synergistic transcription factors, notably NF-κB, is crucially required for the production of proinflammatory cytokines in the innate immune response to microbial infection. The IRAK4-IRF5 axis could therefore have a major role in the induction of the signature cytokines and chemokines of the hyperinflammatory state associated with severe morbidity and mortality in COVID-19. Here a case is made for considering IRAK4 or IRF5 inhibitors as potential therapies for the "cytokine storm" of COVID-19.

Role of interferon regulatory factor-mediated signaling in psoriasis

Psoriasis is a chronic inflammatory disease that involves both the innate and adaptive immune systems. Type I interferons (IFNs), the production of which is partially regulated by toll-like receptors (TLRs), play an important role in the pathogenesis of psoriasis, especially psoriasis caused by skin trauma, known as the Koebner phenomenon. IFN regulatory factors (IRFs) function in both innate and adaptive immune responses, and their effect is associated with the regulation of type I IFNs. In this review, we focus on recent advances in understanding the expression of TLRs, IRFs, and type I IFNs in psoriasis. We also highlight the interplay among TLRs, IRFs, and type I IFNs.

Implication of VDR Rs7975232 and FCGR2A Rs1801274 Gene Polymorphisms in the Risk and the Prognosis of autoimmune Thyroid Diseases in the Tunisian Population

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are autoimmune thyroid diseases (AITD) that cause hypothyroidism and hyperthyroidism, respectively. The vitamin D receptor (VDR) and the Fey receptor IIA (FcγRIIA), are implicated in the etiology of AITD. This study was conducted to examine the implication of VDR rs7975232 and FCGR2A rs 1801274 variations in the susceptibility and the prognosis of AITD in the Tunisian population. The rs7975232 and rs1801274 (R131H) polymorphisms were analyzed in 162 controls and 162 AITD patients (106 HT and 56 GD) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and amplification of refractory mutation system-PCR (ARMS-PCR), respectively. No significant difference was demonstrated for the rs7975232 between patients and controls. However, a significant association was shown between the rs1801274 polymorphism and AITD or HT in the dominant (p = 0.03 or p = 0.01), codominant (p = 0.019 or p = 0.026) and allelic (p = 0.011 or p = 0.012) models. The rs7975232 was associated with the absence or the presence of anti-thyroglobulin antibody, with the age of AITD and GD patients during the first diagnosis (p = 0.01 and p = 0.009, respectively) and with a high T4 level at the beginning of HT disease. However, the FCGR2A gene polymorphism was associated with a low T4 level at the beginning of GD disease. In conclusion, this study indicates that only the FCGR2A variation could be related to AITD and HT susceptibility and that VDR and FCGR2A gene variations constitute factors to prognosticate the severity of AITD, HT and GD.

Exacerbated Imiquimod-Induced Psoriasis-Like Skin Inflammation in IRF5-Deficient Mice

Interferon regulatory factors (IRFs) play diverse roles in the regulation of the innate and adaptive immune responses in various diseases. In psoriasis, IRF2 is known to be involved in pathogenesis, while studies on other IRFs are limited. In this study, we investigated the role of IRF5 in psoriasis using imiquimod-induced psoriasis-like dermatitis. Although IRF5 is known to play a critical role in the induction of proinflammatory cytokines by immune cells, such as dendritic cells (DCs), macrophages, and monocytes, IRF5 deficiency unexpectedly exacerbated psoriasiform skin inflammation. The interferon-α and tumor necrosis factor-α mRNA expression levels were decreased, while levels of Th17 cytokines including IL-17, IL-22, and IL-23 were increased in IRF5-deficient mice. Furthermore, IL-23 expression in DCs from IRF5-deficient mice was upregulated both in steady state and after toll-like receptor 7/8 agonist stimulation. Importantly, the expression of IRF4, which is also important for the IL-23 production in DCs, was augmented in DCs from IRF5-deficient mice. Taken together, our results suggest that IRF5 deficiency induces the upregulation of IRF4 in DCs followed by augmented IL-23 production, resulting in the amplification of Th17 responses and the exacerbation of imiquimod-induced psoriasis-like skin inflammation. The regulation of IRF4 or IRF5 expression may be a novel therapeutic approach to psoriasis.

A novel combination of intramuscular vaccine adjuvants, nanoemulsion and CpG produces an effective immune response against influenza A virus

BACKGROUND

Vaccination is the most effective approach to prevent infection with highly pathogenic avian influenza (HPAI). Adjuvants are often used to induce effective immune responses and overcome the immunological weakness of recombinant HPAI antigens. Given the logistical challenges of immunization to HPAI during pandemic situations, vaccines administered via the intramuscular (I.M.) route would be of value.

METHODS

A new formulation of nanoemulsion adjuvant (NE02) suitable for I.M. vaccination was developed. This NE02 was evaluated alone and in combination with CpG to develop H5 immune responses in mouse and ferret models. Measures of recombinant H5 (rH5) specific immunity evaluated included serum IgG and IgG subclasses, bronchoalveolar lavage fluid IgA, and cytokines. The activation of NF-kB was also analyzed. The efficacy of the vaccine was assessed by performing hemagglutination inhibition (HAI), virus neutralization (VN) assays, and viral challenges in ferrets.

RESULTS

I.M. vaccination with rH5-NE02 significantly increased rH5-specific IgG and protected ferrets in the viral challenge model providing complete protection and sterile immunity in all animals tested. Combining NE02 and CpG produced accelerated antibody responses and this was accompanied by an elevation of IFN-γ and IL-17 responses and the downregulation of IL-5. The combination also caused a synergistic effect on NF-kB activation. In immunized ferrets after viral challenge, the rH5-NE02 + CpG vaccine via I.M. achieved at least 75% and 88% seroconversion of HAI and VN antibody responses, respectively, and improved body temperature stabilization and weight loss over NE02 alone.

CONCLUSIONS

The I.M. injection of NE02 adjuvanted rH5 elicits strong and broad immune responses against H5 antigens and effectively protects animals from lethal H5 challenge. Combining this adjuvant with CpG enhanced immune responses and provided improvements in outcomes to viral challenge in ferrets. The results suggest that combinations of adjuvants may be useful to enhance H5 immune responses and improve protection against influenza infection.

RNA Sensing of Mycobacterium tuberculosis and Its Impact on TB Vaccination Strategies

Tuberculosis (TB) is still an important global threat and although the causing organism has been discovered long ago, effective prevention strategies are lacking. Mycobacterium tuberculosis (MTB) is a unique pathogen with a complex host interaction. Understanding the immune responses upon infection with MTB is crucial for the development of new vaccination strategies and therapeutic targets for TB. Recently, it has been proposed that sensing bacterial nucleic acid in antigen-presenting cells via intracellular pattern recognition receptors (PRRs) is a central mechanism for initiating an effective host immune response. Here, we summarize key findings of the impact of mycobacterial RNA sensing for innate and adaptive host immunity after MTB infection, with emphasis on endosomal toll-like receptors (TLRs) and cytosolic sensors such as NLRP3 and RLRs, modulating T-cell differentiation through IL-12, IL-21, and type I interferons. Ultimately, these immunological pathways may impact immune memory and TB vaccine efficacy. The novel findings described here may change our current understanding of the host response to MTB and potentially impact clinical research, as well as future vaccination design. In this review, the current state of the art is summarized, and an outlook is given on how progress can be made.

Black carp IRF5 interacts with TBK1 to trigger cell death following viral infection

Interferon regulated factor 5 (IRF5) is a key regulator of inflammatory responses in human and mammals; however, its role in teleost remains largely unknown. In this study, IRF5 homologue of black carp (Mylopharyngodon piceus) has been cloned and characterized, which possesses conservation in structure and sequence to its mammalian counterparts. Black carp IRF5 (bcIRF5) was characterized as a predominantly cytosolic protein by immunofluorescent staining and showed little IFN promoter-inducing ability in reporter assay. The direct association between bcIRF5 and black carp TBK1 (bcTBK1) were identified through co-immunoprecipitation assay, and co-expressed bcIRF5 in EPC cells suppressed bcTBK1-mediated IFN promoter transcription in reporter assay. Surprisingly, the titer of grass carp reovirus (GCRV) in the media of EPC cells co-expressing bcIRF5 and bcTBK1 was obviously lower than that of EPC cells expressing bcTBK1 alone. It was interesting that expression of bcIRF5 and/or bcTBK1 in EPC cells showed little effect on cell growth; however, the survival ratio of EPC cells co-expressing bcTBK1 and bcIRF5 post GCRV infection was much lower than that of EPC cells expressing bcIRF5 or bcTBK1 alone. These results indicate that bcIRF5 negatively regulates bcTBK1-mediated IFN signaling in healthy cells; however, it correlates with bcTBK1 and triggers cell death to inhibit the virus replication during the innate immune activation.

Irf5 deficiency in myeloid cells prevents necrotizing enterocolitis by inhibiting M1 macrophage polarization

Necrotizing enterocolitis (NEC) is a life-threatening inflammatory disease in newborns, but the mechanisms remain unclear. Interferon regulatory factor 5 (IRF5) is a master regulator of macrophage function and is essential for proinflammatory M1 macrophage polarization. Our previous data indicated that M1 macrophages promote NEC injury. Here, we investigated whether IRF5 is involved in the pathogenesis of NEC. First, we found that IRF5 was upregulated in infiltrated macrophages in human neonates with NEC compared to controls. We further confirmed IRF5 upregulation in macrophages in experimental murine NEC and that the infiltrated macrophages were predominantly polarized into the M1 but not the M2 phenotype. Myeloid-specific deficiency of Irf5, which was associated with reduced M1 macrophage polarization and systematic inflammation, dramatically prevented experimental NEC. Moreover, we found that the ablation of Irf5 in myeloid cells markedly suppressed intestinal epithelial cell apoptosis and further prevented intestinal barrier dysfunction in experimental NEC. Bioinformatic and chromatin immunoprecipitation analysis further showed that IRF5 binds to the promoters of the M1 macrophage-associated genes Ccl4, Ccl5, Tnf, and Il12b. Overall, our study provides evidence that IRF5 participates in the pathogenesis of NEC, while the deletion of Irf5 in myeloid cells prevents NEC via inhibiting M1 macrophage polarization.

NFκB and Kidney Injury

The global burden of chronic kidney disease will increase during the next century. As NFκB, first described more than 30 years ago, plays a major role in immune and non-immune-mediated diseases and in inflammatory and metabolic disorders, this review article summarizes current knowledge on the role of NFκB in in vivo kidney injury and describes the new and so far not completely understood crosstalk between canonical and non-canonical NFκB pathways in T-lymphocyte activation in renal disease.