Activation of nucleotide-binding oligomerization domain 2 by muramyl dipeptide negatively regulates Toll-like receptor 9-mediated colonic inflammation through the induction of deubiquitinating enzyme A expression

Mutations in nucleotide-binding oligomerization domain 2 (NOD2) are associated with Crohn's disease (CD). Although NOD2 activation contributes to the maintenance of intestinal homeostasis through the negative regulation of pro-inflammatory cytokine responses mediated by Toll-like receptors (TLRs), the effects of NOD2 activation on interferon (IFN)-α responses induced by TLR9 have been poorly defined. To explore the cross-talk between NOD2 and TLR9, human monocytes or dendritic cells (DCs) were stimulated with NOD2 and/or TLR9 ligands to measure IFN-α production. The severity of dextran sodium sulfate (DSS)-induced colitis was compared in mice treated with NOD2 and/or TLR9 ligands. Expression of IFN-α and IFN-stimulated genes (ISGs) was examined in the colonic mucosa of patients with inflammatory bowel disease (IBD). NOD2 activation reduced TLR9-induced IFN-α production by monocytes and DCs in a deubiquitinating enzyme A (DUBA)-dependent manner. Activation of DUBA induced by the co-stimulation of TLR9 and NOD2 inhibited Lys63-linked polyubiquitination of TRAF3 and suppressed TLR9-mediated IFN-α production. NOD2 activation in hematopoietic cells protected mice from TLR9-induced exacerbation of DSS-induced colitis by down-regulating IFN-α responses and up-regulating DUBA expression. Colonic mucosa of patients with active and remitted IBD phases was characterized by the enhanced and reduced expression of ISGs, respectively. Expression levels of IFN-α and IL-6 positively correlated in the active colonic mucosa of patients with ulcerative colitis and CD, whereas DUBA expression inversely correlated with that of IFN-α in patients with CD. Collectively, these data suggest that DUBA-dependent negative effect of NOD2 on TLR9-mediated IFN-α responses contributes to the maintenance of intestinal homeostasis.

Activation of NOD1 and NOD2 in the development of liver injury and cancer

Hepatocytes and liver-resident antigen-presenting cells are exposed to microbe-associated molecular patterns (MAMPs) and microbial metabolites, which reach the liver from the gut via the portal vein. MAMPs induce innate immune responses via the activation of pattern recognition receptors (PRRs), such as toll-like receptors (TLRs), nucleotide-binding oligomerization domain 1 (NOD1), and NOD2. Such proinflammatory cytokine responses mediated by PRRs likely contribute to the development of chronic liver diseases and hepatocellular carcinoma (HCC), as shown by the fact that activation of TLRs and subsequent production of IL-6 and TNF-α is required for the generation of chronic fibroinflammatory responses and hepatocarcinogenesis. Similar to TLRs, NOD1 and NOD2 recognize MAMPs derived from the intestinal bacteria. The association between the activation of NOD1/NOD2 and chronic liver diseases is poorly understood. Given that NOD1 and NOD2 can regulate proinflammatory cytokine responses mediated by TLRs both positively and negatively, it is likely that sensing of MAMPs by NOD1 and NOD2 affects the development of chronic liver diseases, including HCC. Indeed, recent studies have highlighted the importance of NOD1 and NOD2 activation in chronic liver disorders. Here, we summarize the roles of NOD1 and NOD2 in hepatocarcinogenesis and liver injury.

Activation of the aryl hydrocarbon receptor inhibits the development of experimental autoimmune pancreatitis through IL-22-mediated signaling pathways

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor expressed in hematopoietic and non-hematopoietic cells. Activation of the AhR by xenobiotics, microbial metabolites, and natural substances induces immunoregulatory responses. Autoimmune pancreatitis (AIP) is a chronic fibroinflammatory disorder of the pancreas driven by autoimmunity. Although AhR activation generally suppresses pathogenic autoimmune responses, the roles played by the AhR in AIP have been poorly defined. In this study, we examined how AhR activation affected the development of experimental AIP caused by the activation of plasmacytoid dendritic cells producing IFN-α and IL-33. Experimental AIP was induced in MRL/MpJ mice by repeated injections of polyinosinic-polycytidylic acid. Activation of the AhR by indole-3-pyruvic acid and indigo naturalis, which were supplemented in the diet, inhibited the development of experimental AIP, and these effects were independent of the activation of plasmacytoid dendritic cells producing IFN-α and IL-33. Interaction of indole-3-pyruvic acid and indigo naturalis with AhRs robustly augmented the production of IL-22 by pancreatic islet α cells. The blockade of IL-22 signaling pathways completely canceled the beneficial effects of AhR ligands on experimental AIP. Serum IL-22 concentrations were elevated in patients with type 1 AIP after the induction of remission with prednisolone. These data suggest that AhR activation suppresses chronic fibroinflammatory reactions that characterize AIP via IL-22 produced by pancreatic islet α cells.

Observational pilot study of switching from entecavir to tenofovir alafenamide in patients with chronic hepatitis B

This study evaluated the long-term efficacy and safety of the widely used drugs entecavir (ETV) and tenofovir alafenamide (TAF), as well as the incidence of HCC.A nonrandomized, prospective, observational analysis included 77 patients with chronic hepatitis B who were assigned to continue ETV or switch TAF. After 240 weeks, the mean changes in serum hepatitis B surface antigen (- 0.365 ± 0.069 log IU/mL vs. 0.301 ± 0.039 log IU/mL, p = 0.39) and hepatitis B core-related antigen (- 0.215 ± 0.092 log IU/mL vs. - 0.195 ± 0.056 log IU/mL) were not significantly different between the ETV and TAF groups. There were also no differences between the two groups in estimated glomerular filtration rate (- 5.407 ± 1.660 vs. - 2.666 ± 1.52, p = 0.240), urinary β2-microglobulin β/creatinine (ETV: 2.330 ± 0.374 at baseline and 2.335 ± 0.257 at 240 weeks; TAF: 2.720 ± 0.073 and 2.123 ± 0.310, p = 0.996 and 0.455, respectively) or urinary N-acetyl-β-D-glucosaminidase/creatinine (ETV: 0.040 ± 0.005 at baseline and 0.044 ± 0.004 at 240 weeks; TAF: 0.049 ± 0.005 and 0.053 ± 0.005, p = 0.642 and 0.684, respectively). Finally, no significant difference was found in the incidence of HCC between the ETV and TAF groups (log-rank test, p = 0.08). In conclusion, the long-term observation of this study demonstrated that ETV and TAF have comparable efficacy and safety.Clinical trial registration: UMIN000026465.

Microbe-associated molecular patterns derived from fungi and bacteria promote IgG4 antibody production in patients with type 1 autoimmune pancreatitis

Enhanced IgG4 antibody (Ab) response is a prominent feature of type 1 autoimmune pancreatitis (AIP). Innate immune responses associated with IgG4 Ab production are poorly defined. We have previously reported that peripheral blood mononuclear cells (PBMCs) isolated from patients with type 1 AIP produce large amounts of IgG4 Abs upon stimulation with bacterial cell wall components. In addition, we showed that activation of plasmacytoid dendritic cells producing interferon (IFN)-α, interleukin (IL)-33, and B cell-activating factor (BAFF) upon sensing intestinal bacteria mediates the development of experimental AIP. In this study, we attempted to clarify the role of innate immunity against fungi in inducing enhanced IgG4 Ab responses in type 1 AIP. PBMCs isolated from healthy controls and patients with type 1 AIP were stimulated with a broad range of bacterial and fungal cell wall components. The concentrations of IgG1, IgG4, and cytokines were measured using enzyme-linked immunosorbent assays. Cell wall components derived from bacteria and fungi induced IgG1 and IgG4 Ab production in patients with type 1 AIP. Various types of microbe-associated molecular pattern motifs enhanced IgG4 Ab production in patients with type 1 AIP compared with the limited motifs in healthy controls. The enhanced IgG1 and IgG4 Ab production that followed in response to bacterial and fungal cell wall components was parallel to that of IFN-α, IFN-γ, IL-10, IL-33, and BAFF. In conclusion, cell wall components derived from fungi as well as bacteria promote IgG4 Ab responses in patients with type 1 AIP.

A Case of Fibrolamellar Hepatocellular Carcinoma in Which Tumor Control Was Achieved by Re-Administering Atezolizumab and Bevacizumab

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FL-HCC) clinically occurs in young people aged 20-30 years, who often have a normal liver background. We propose a treatment for such cases in which a combination therapy of atezolizumab and bevacizumab is followed by sandwiching radiation therapy to release tumor antigens and then re-administering the combination therapy of atezolizumab and bevacizumab (ABC conversion therapy).

CASE

The patient is a 15-year-old girl. On April 18, 2022, she noticed skin yellowing and visited her local doctor. Computed tomography (CT) revealed a large mass in the right lobe of the liver and bile duct obstruction due to the tumor. She also had a nodule on her chest that appeared to be a metastatic tumor and was referred to Kinki University Hospital in April 2023. She was suspected to have FL-HCC based on contrast-enhanced ultrasound and CT scan results. There were findings suggestive of lung metastasis; however, she underwent a right hepatic lobectomy on May 17, 2023, considering the risk of liver failure and intra-abdominal bleeding due to the large liver tumor. A CT scan conducted on July 25, 2022, showing increased lung metastases, and she started atezolizumab/bevacizumab combination treatment on October 20, 2022. On March 15, 2023, multiple lung metastases and new intrahepatic lesions appeared, which was diagnosed as progressive disease (PD), and lenvatinib was discontinued. On November 17, 2023, radiation therapy (25 Gy/5 Fr) was administered to the lung and intrahepatic lesions to release tumor antigens, and on November 27, 2023, atezolizumab and bevacizumab combination treatment was resumed to control the tumor.

CONCLUSION

Combination therapy with atezolizumab, bevacizumab, and radiation therapy may be an option for the treatment of FL-HCC.

Development of Diffuse Large B Cell Lymphoma in a Patient with Systemic Lupus Erythematosus within Two Years after the Initiation of Anifrolumab and Mycophenolate Mofetil Treatment

Anifrolumab is a newly developed biological agent for patients with moderate-to-severe systemic lupus erythematosus (SLE). Anifrolumab neutralizes the signaling pathways mediated by type I interferons (IFNs), which are involved in viral clearance and anticancer immunity. Although susceptibility to viral infections has been reported in patients treated with anifrolumab, whether anifrolumab treatment increases the cancer risk in patients with SLE is unknown. We herin report a case of SLE that manifested as aggressive diffuse large B-cell lymphoma (DLBCL) after treatment with anifrolumab. The neutralization of type I IFNs by anifrolumab may promote the development of DLBCL owing to defective anticancer immunity.