Expression of mitochondrial membrane–linked SAB determines severity of sex-dependent acute liver injury

Abstract

Figure 3. SAB expression in male mice determines the susceptibility to APAP-induced liver injury in a JNK-dependent fashion. WT C57BL/6N male mice received Ad-lacZ or Ad-SAB. (A) Fourteen days later, SAB expression was analyzed by immunoblotting, and (B) APAP (150 mg/kg) was given i.p., and H&E staining was performed and serum ALT levels were determined after 24 hours. Original magnification, ×10. Scale bars: 100 μm. n = 3/group. ALT: *P < 0.05 versus Ad-lacZ-injected Sab iΔHep mice, by unpaired, 2-tailed Student's t test. Data are presented as the mean ± SD. (C) Sab fl/fl or Sab iΔHep mice received 0.05 5 × 10 9 to approximately 5 × 10 9 IU Ad-lacZ or Ad-SAB. Fourteen days later, SAB expression was determined by immunoblotting. Immunoblot is representative of 3 separate experiments. n = 3/group. *P < 0.05 versus Sab iΔHep + Ad-lacZ, by 1-way ANOVA with Bonferroni's correction. Data are presented as the mean ± SEM. (D) Mice received APAP (300 mg/kg, i.p.), and 24 hours later, liver sections were stained with H&E, and the necrotic area (percentage) was measured. Serum ALT (± SEM) (U/L) was measured. Scale bars: 100 μm. n = 3 mice/group. ALT: *P < 0.05, versus Ad-lacZ-injected Sab fl/fl mice; **P < 0.05, versus Ad-lacZ-injected Sab iΔHep mice, by unpaired, 2-tailed Student's t test. Data are presented as the mean ± SD. (E and F) Jnk1/2 fl/fl mice received AAV8-TBG-GFP (n = 3), AAV8-TBG-Cre (n = 5), or AAV8-TBG-Cre plus Ad-SAB (n = 3). Fourteen days later, JNK and SAB expression levels were determined by immunoblotting, or mice were treated with APAP to analyze liver injury and serum ALT levels. Scale bars: 100 μm. ALT: *P < 0.05, versus AAV8-TBG-GFP, by unpaired, 2-tailed Student's t test. Data are presented as the mean ± SD.

Acetaminophen-Induced Liver Injury Exposes Murine IL-22 as Sex-Related Gene Product

“…Of note, whereas the 6 h time point only displayed a tendency towards decreased liver damage in female mice, this difference became highly significant at 24 h after APAP administration ( Figure 1 c). This latter observation is in accordance with previously published data [ 30 , 31 ]. Because necroinflammation driven by liver damage is a prerequisite for induction of inflammatory cytokines in this model, APAP-treated mice without toxicity within 6 h (as defined by ALT levels) were excluded (3 × males, 4 × females; Figure 1 a, mice below the dashed line represent a cut-off at 100 units/L of serum ALT) from further analysis when comparing sex-related cytokine responses.…”

“…Specifically, as compared to their male counterparts, female mice displayed significantly enhanced IL-22 expression, which became apparent at local hepatic and systemic levels. Because female mice are far less sensitive to APAP-induced ALI, it is tempting to speculate that endogenous levels of IL-22 may contribute to this phenomenon, in addition to sex-dependent effects on levels of protective glutathione [ 30 ] or SH3 domain-binding protein-5 [ 31 ]. Although application of recombinant IL-22 is clearly protective [ 20 , 21 , 22 ], the role of endogenous IL-22 in APAP intoxication appears to be complex.…”

“…Because immune responses are affected by sex in a qualitative and quantitative manner [ 28 , 29 ], it is reasonable to assume that reparative inflammation, and thus the course of ALI, is similarly affected by this parameter. Interestingly, female mice display attenuated APAP toxicity [ 30 , 31 ]. Because the role of sexes in hepatic diseases is a pressing understudied topic, sex-dependent production of pro-regenerative IL-22 was analyzed herein in murine APAP-induced ALI and cell culture models of IL-22 expression.…”

Beyond the X Factor: Relevance of Sex Hormones in NAFLD Pathophysiology

“…NAFLD progression and liver degeneration can be sustained by the propagation of inflammation, which is different between males and females [ 251 , 363 , 364 ], possibly as a consequence of the inhibitory control exerted by estrogen signaling over JNK and NF-κB signaling pathways [ 365 , 366 , 367 , 368 ]. In OVX females, the lack of estrogens fosters NAFLD development and progression by boosting pro-inflammatory response (e.g., TNFα, IL-1β and IL-6), and decreasing antioxidant defense and anti-inflammatory response (e.g., IL-10, interleukin 10), all changes that can be rescued or, at least, limited by estrogen therapy [ 369 , 370 , 371 ].…”

Non-alcoholic Fatty Liver Disease as a Canonical Example of Metabolic Inflammatory-Based Liver Disease Showing a Sex-Specific Prevalence: Relevance of Estrogen Signaling

“…JNK is a member of mitogen activated protein kinases, which activation in fatty liver is associated with insulin resistance, activation of apoptosis and development of NASH ( 247 – 249 ). JNK pathway is differentially regulated between males and females during liver injury ( 250 , 251 ), likely through an estrogen- and ERα-mediated inhibition of lipotoxicity-induced hepatic mitochondrial oxidative stress and, in turn, of JNK signaling pathway, thus avoiding the over-regulation of pro-inflammatory and pro-apoptotic process ( 252 ).…”