Objective: To assess the feasibility of proton density fat fraction (PDFF) MRI for estimating hepatic fat fraction with magnetic resonance spectroscopy (MRS) and histology as references and to investigate intrahepatic fat distribution and variability. Methods: Between November 2014 and September 2015, 85 adults (48 males, 47 females) who underwent MRI-PDFF (n = 139), MRS-PDFF (n = 49) and liver biopsy (n = 29) were enrolled in this study. Data were compared using linear regression. MRI-PDFF and standard deviations (variability) and differences between maximum and minimum PDFF (PDFF range) for whole liver, the lobes, and segment levels were calculated for each subject. Results: Whole-liver MRI-PDFF showed good correlation with MRS-PDFF (r = 0.961) and histologic degree of hepatic steatosis (σ = 0.809). Hepatic fat fraction is different between lobes and segments. Mean PDFF and mean PDFF range of the right lobe were higher than for the left lobe, whereas variability in the right lobe was lower than in the left lobe. Conclusion: MRI-PDFF is an accurate non-invasive method for quantifying hepatic fat for various hepatic disorders, and may be preferable for measuring fat fraction in the right liver for more precise values in longitudinal monitoring, while avoiding FF measurement in the left liver. Advances in knowledge: MRI-PDFF provides a non-invasive and accurate quantification of hepatic steatosis in various hepatic disorders. It would be preferable to measure FF in the right liver than in the left liver.

Tuberculosis is a global health problem and at least one-third of the world’s population is infected with Mycobacterium tuberculosis (MTB). MTB is a successful pathogen that enhances its own intracellular survival by inhibiting inflammation and arresting phago-lysosomal fusion. We previously demonstrated that Toxoplasma gondii (T. gondii) dense granule antigen (GRA) 7 interacts with TNF receptor-associated factor 6 via Myeloid differentiation primary response gene 88, enabling innate immune responses in macrophages. To extend these studies, we found that GRA7 interacts with host proteins involved in antimicrobial host defense mechanisms as a therapeutic strategy for tuberculosis. Here, we show that protein kinase C (PKC)α-mediated phosphorylation of T. gondii GRA7-I (Ser52) regulates the interaction of GRA7 with PYD domain of apoptosis-associated speck-like protein containing a carboxy-terminal CARD, which is capable of oligomerization and inflammasome activation can lead to antimicrobial defense against MTB. Furthermore, GRA7-III interacted with the PX domain of phospholipase D1, facilitating its enzyme activity, phago-lysosomal maturation, and subsequent antimicrobial activity in a GRA7-III (Ser135) phosphorylation-dependent manner via PKCα. Taken together, these results underscore a previously unrecognized role of GRA7 in modulating antimicrobial host defense mechanism during mycobacterial infection. We previously demonstrated that Toxoplasma gondii (T. gondii) dense granule antigen (GRA) 7 interacts with TRAF6 via MyD88, enabling innate immune responses in macrophages and effective protection against T. gondii infection in vivo. However, its exact role and how it regulates host innate immune responses have not been fully explained. Herein, we show that PKCα-mediated phosphorylation of GRA7 is essential for the interaction between GRA7 and ASC or PLD1, which can promote antimicrobial defense against Mycobacterium tuberculosis (MTB). Notably, PKCα specifically phosphorylated Ser52 and Ser135 of GRA7 in vitro and in vivo, indicating that GRA7 is a substrate of PKCα. The N-terminal of GRA7 (GRA7-I) was sufficient for interaction with the PYD domain of ASC, which is capable of ASC oligomerization and inflammasome activation. Furthermore, GRA7-III interacted with the PX domain of PLD1, facilitating its enzyme activity, phago-lysosomal maturation, and subsequent antimicrobial activity in a GRA7 phosphorylation-dependent manner. Interestingly, phosphomimetic mutation in GRA7 overcame the need for PKCα. Collectively, these results provide novel insight into how GRA7 can promote ASC and PLD1 activation in a PKCα-dependent manner as an antimicrobial host defense mechanism.

Choi SJ, et al. J Korean Med Sci. 2021 Jun;36(28):e189. https://doi.org/10.3346/jkms.2021.36.e189

The tumor suppressor gene CD82/KAI1 is a member of the tetraspanin superfamily and organizes various membrane-based processes. Mycobacterium tuberculosis (MTB) persists in host macrophages by interfering with phagolysosome biogenesis and inflammatory responses, but the role of CD82 in controlling the intracellular survival of pathogenic mycobacteria within macrophages remains poorly understood. In this study, we demonstrated that the virulent MTB strain H37Rv (MTB Rv) induced CD82 promoter hypomethylation, resulting in CD82 expression. Targeting of the runt-related transcription factor 1 (RUNX1) by CD82 is essential for phagosome arrest via interacting with Rab5/22. This arrest is required for the intracellular growth of MTB in vitro and in vivo, but not for that of MTB H37Ra (MTB Ra) in macrophages. In addition, knockdown or knockout of CD82 or RUNX1 increased antibacterial host defense via phagolysosome biogenesis, inflammatory cytokine production, and subsequent antimicrobial activity both in vitro and in vivo. Notably, the levels of CD82 and RUNX1 in granulomas were elevated in tuberculosis (TB) patients, indicating that CD82 and RUNX1 have clinical significance in human TB. Our findings identify a previously unrecognized role of CD82 hypomethylation in the regulation of phagosome maturation, enhanced intracellular survival, and the innate host immune response to MTB. Thus, the CD82–RUNX1–Rab5/22 axis may be a previously unrecognized virulence mechanism of MTB pathogenesis.

Recent research has demonstrated that forkhead box O3a (FoxO3a) may function as an oncogenic transcription factor. We sought to validate the clinicopathologic significance of FoxO3a expression in hepatocellular carcinoma (HCC). Western blotting and immunohistochemistry were used to determine FoxO3a expression. In vitro cell proliferation and migration assays were performed in a HepG2 cell line. FoxO3a was overexpressed in 121 (64.71%) cases of HCC. FoxO3a overexpression was associated with aggressive phenotypes of HCC, such as histologic grade (P < .001), stage (P = .031), and small vessel invasion (P < .001). FoxO3a overexpression was also correlated with poor disease-free survival in both univariate and multivariate survival analyses (P = .001 and P = .018, respectively). Downregulation of FoxO3a in a HepG2 cell line inhibited cell proliferation and migration. These results suggest a role for FoxO3a in HCC progression and support the potential use as a prognostic biomarker.