Restoring SRSF3 in Kupffer cells attenuates obesity-related insulin resistance.

BACKGROUND AND AIMS: In obesity, depletion of KCs expressing CRIg (complement receptor of the Ig superfamily) leads to microbial DNA accumulation, which subsequently triggers tissue inflammation and insulin resistance. However, the mechanism underlying obesity-mediated changes in KC complement immune functions is largely unknown. APPROACH AND RESULTS: Using KC-specific deactivated Cas9 transgenic mice treated with guide RNA, we assessed the effects of restoring CRIg or the serine/arginine-rich splicing factor 3 (SRSF3) abundance on KC functions and metabolic phenotypes in obese mice. The impacts of weight loss on KC responses were evaluated in a diet switch mouse model. The role of SRSF3 in regulating KC functions was also evaluated using KC-specific SRSF3 knockout mice. Here, we report that overexpression of CRIg in KCs of obese mice protects against bacterial DNA accumulation in metabolic tissues. Mechanistically, SRSF3 regulates CRIg expression, which is essential for maintaining the CRIg+ KC population. During obesity, SRSF3 expression decreases, but it is restored with weight loss through a diet switch, normalizing CRIg+ KCs. KC SRSF3 is also repressed in obese human livers. Lack of SRSF3 in KCs in lean and obese mice decreases their CRIg+ population, impairing metabolic parameters. During the diet switch, the benefits of weight loss are compromised due to SRSF3 deficiency. Conversely, SRSF3 overexpression in obese mice preserves CRIg+ KCs and improves metabolic responses. CONCLUSIONS: Restoring SRSF3 abundance in KCs offers a strategy against obesity-associated tissue inflammation and insulin resistance by preventing bacterial DNA accumulation.

Gut lumen-leaked microbial DNA causes myocardial inflammation and impairs cardiac contractility in ageing mouse heart.

Emerging evidence indicates the critical roles of microbiota in mediating host cardiac functions in ageing, however, the mechanisms underlying the communications between microbiota and cardiac cells during the ageing process have not been fully elucidated. Bacterial DNA was enriched in the cardiomyocytes of both ageing humans and mice. Antibiotic treatment remarkably reduced bacterial DNA abundance in ageing mice. Gut microbial DNA containing extracellular vesicles (mEVs) were readily leaked into the bloodstream and infiltrated into cardiomyocytes in ageing mice, causing cardiac microbial DNA enrichment. Vsig4+ macrophages efficiently block the spread of gut mEVs whereas Vsig4+ cell population was greatly decreased in ageing mice. Gut mEV treatment resulted in cardiac inflammation and a reduction in cardiac contractility in young Vsig4-/- mice. Microbial DNA depletion attenuated the pathogenic effects of gut mEVs. cGAS/STING signaling is critical for the effects of microbial DNA. Restoring Vsig4+ macrophage population in ageing WT mice reduced cardiac microbial DNA abundance and inflammation and improved heart contractility.

Loss-of-function mutations in the histone methyltransferase EZH2 promote chemotherapy resistance in AML.

Chemotherapy resistance is the main impediment in the treatment of acute myeloid leukaemia (AML). Despite rapid advances, the various mechanisms inducing resistance development remain to be defined in detail. Here we report that loss-of-function mutations (LOF) in the histone methyltransferase EZH2 have the potential to confer resistance against the chemotherapeutic agent cytarabine. We identify seven distinct EZH2 mutations leading to loss of H3K27 trimethylation via multiple mechanisms. Analysis of matched diagnosis and relapse samples reveal a heterogenous regulation of EZH2 and a loss of EZH2 in 50% of patients. We confirm that loss of EZH2 induces resistance against cytarabine in the cell lines HEK293T and K562 as well as in a patient-derived xenograft model. Proteomics and transcriptomics analysis reveal that resistance is conferred by upregulation of multiple direct and indirect EZH2 target genes that are involved in apoptosis evasion, augmentation of proliferation and alteration of transmembrane transporter function. Our data indicate that loss of EZH2 results in upregulation of its target genes, providing the cell with a selective growth advantage, which mediates chemotherapy resistance.

Loss of KDM6A confers drug resistance in acute myeloid leukemia.

Acute myeloid leukemia (AML) is an aggressive hematologic neoplasm resulting from the malignant transformation of myeloid progenitors. Despite intensive chemotherapy leading to initial treatment responses, relapse caused by intrinsic or acquired drug resistance represents a major challenge. Here, we report that histone 3 lysine 27 demethylase KDM6A (UTX) is targeted by inactivating mutations and mutation-independent regulation in relapsed AML. Analyses of matched diagnosis and relapse specimens from individuals with KDM6A mutations showed an outgrowth of the KDM6A mutated tumor population at relapse. KDM6A expression is heterogeneously regulated and relapse-specific loss of KDM6A was observed in 45.7% of CN-AML patients. KDM6A-null myeloid leukemia cells were more resistant to treatment with the chemotherapeutic agents cytarabine (AraC) and daunorubicin. Inducible re-expression of KDM6A in KDM6A-null cell lines suppressed proliferation and sensitized cells again to AraC treatment. RNA expression analysis and functional studies revealed that resistance to AraC was conferred by downregulation of the nucleoside membrane transporter ENT1 (SLC29A1) by reduced H3K27 acetylation at the ENT1 locus. Our results show that loss of KDM6A provides cells with a selective advantage during chemotherapy, which ultimately leads to the observed outgrowth of clones with KDM6A mutations or reduced KDM6A expression at relapse.

Adenoma size and postoperative IGF-1 levels predict surgical outcomes in acromegaly patients: results of the Swiss Pituitary Registry (SwissPit).

AIMS OF THE STUDY: Acromegaly due to a growth hormone-secreting pituitary adenoma is a rare disease with high morbidity if not treated adequately. Using data of the Swiss Pituitary Registry (SwissPit), we studied initial presentation and predictors for adverse clinical outcomes in acromegalic patients treated during the last 10 years in our institution. METHODS: We evaluated 21 patients from the SwissPit registry with a final diagnosis of acromegaly confirmed by laboratory results (insulin-like growth factor-1 [IGF-1] and growth hormone suppression tests) and magnetic resonance imaging. Our main endpoint was clinical cure defined as complete remission, remission with need for medical treatment and uncontrolled disease defined by non-normalisation of IGF-1 and growth hormone levels. RESULTS: The most prevalent clinical symptoms at presentation were acral enlargement (81%), headache (29%), macroglossia (29%) and visual field defects (19%). Arterial hypertension was present in 67%, carpal tunnel syndrome in 38% and diabetes in 24%. A total of 19 of the 21 patients underwent initial surgical treatment. Eight patients had complete remission and 13 patients had active disease, with 7 having remission with need for medical treatment and 6 uncontrolled disease. Larger initial adenoma size (odds ratio [OR] 12.0, 95% confidence interval [CI] 1.02-141.3; p = 0.048) and high post-operative IGF-1 levels (OR 4.5, 95% CI 1.1-19.2; p = 0.040) were predictors for non-full remission and uncontrolled disease, respectively. CONCLUSION: This small, observational registry study showed a relevant success rate of initial pituitary surgery in patients with confirmed acromegaly. Initial tumour size and postoperative IGF-1 levels help to risk stratify patients regarding expected outcomes. In the case of disease persistence, a multimodal approach using drug and radiotherapy is mandatory.

Sleep-wake disturbances 3 years after traumatic brain injury.

BACKGROUND: 6 months after traumatic brain injury (TBI), almost three out of four patients suffer from sleep-wake disturbances (SWD) such as post-traumatic hypersomnia (increased sleep need of ≥2 h compared with before injury), excessive daytime sleepiness (EDS), fatigue and insomnia. The long-term course of post-traumatic SWD, however, is unknown. OBJECTIVES: To assess the prevalence and characteristics of post-traumatic SWD 3 years after trauma. DESIGN: Prospective longitudinal clinical study in 51 consecutive TBI patients (43 males, eight females, mean age 40±16 years). MAIN OUTCOME MEASURES: EDS (as assessed by the Epworth sleepiness scale), fatigue (fatigue severity scale), post-traumatic hypersomnia (sleep length per 24 h), insomnia, depression and anxiety. RESULTS: Post-traumatic SWD were found in 34 patients (67%): post-traumatic hypersomnia in 14 (27%), EDS in six (12%), fatigue in 18 patients (35%) and insomnia in five patients (10%). SWD were not associated with severity or localisation of, or time interval since, TBI. Insomnia was linked to depressive symptoms. CONCLUSIONS: This prospective study shows that 3 years after TBI, two out of three patients suffer from residual SWD, particularly fatigue and post-traumatic hypersomnia. In 45% of TBI patients, SWD appear directly related to the trauma itself.