Cognitive dysfunction in early experimental metabolic dysfunction-associated steatotic liver disease is associated with systemic inflammation and neuroinflammation.

Background & Aims: Cognitive dysfunction is an increasingly recognised manifestation of metabolic dysfunction-associated steatotic liver disease (MASLD), but the mechanistic link remains unclear. The aim of this study was to investigate the hypothesis that experimental MASLD leads to cognitive dysfunction via systemic inflammation and neuroinflammation. Methods: Twenty male Sprague Dawley rats were randomised to a high-fat high-cholesterol (HFHC) diet to induce MASLD, or a standard diet (n = 10/group), for 16 weeks. Assessments included: MASLD severity (histology), neurobehaviour, inflammation (liver, plasma and cerebrospinal fluid), brain microglia and astrocyte activation, and synaptic density. Results: The HFHC diet induced MASLD with extensive steatosis and lobular inflammation without fibrosis. Several plasma cytokines were elevated (CXCL1, IL-6, IL-17, MIP-1α, MCP-1, IL-10; all p <0.05) and correlated with increases in hepatic chemokine gene expression. Cerebrospinal fluid concentrations of CXCL1 were elevated (p = 0.04). In the prefrontal brain cortex, we observed a 19% increase in microglial activation confirmed by Iba1 immunohistochemistry (p = 0.03) and 3H-PK11195 autoradiography (p <0.01). In parallel, synaptic density was reduced to 92%, assessed by 3H-UCB-J autoradiography (p <0.01). MASLD animals exhibited impaired memory to previously encountered objects in the novel object recognition test (p = 0.047) and showed depression-like behaviour evidenced by increased immobility time (p <0.01) and reduced swimming time (p = 0.03) in the forced swim test. Conclusions: Experimental non-fibrotic MASLD, as a model to reflect the early stage of human disease, results in cognitive impairment and depression-like behaviour. This is associated with an inflammatory phenotype not only in the liver but also in the plasma and brain, which together with diminished synaptic density, provides a pathophysiological link between liver disease and cognitive dysfunction in MASLD. Impact and implications: Cognitive dysfunction is an increasingly recognised comorbidity in patients with metabolic dysfunction-associated steatotic liver disease (MASLD), yet the underlying mechanisms remain unclear. This study provides evidence of impaired memory and depression-like symptoms in early experimental MASLD and indicates that hepatic inflammation may drive a systemic inflammatory response, resulting in neuroinflammation and reduced brain synaptic density. The evidence of impaired memory in MASLD and establishing its underlying pathophysiological link provides insights that could guide the development of potential new treatments for this increasingly common condition in people of working age. The study also emphasises the need to develop better tools for clinical cognitive testing, which will enable physicians to assess and manage brain dysfunction early in MASLD.

The impact of minimal invasive extracorporeal circulation on postoperative kidney function.

INTRODUCTION: Acute kidney injury following cardiac surgery is a frequent complication associated with increased mortality and morbidity. Minimal invasive extracorporeal circulation is suggested to preserve postoperative renal function. The aim of this study was to assess the impact of minimal invasive versus conventional extracorporeal circulation on early postoperative kidney function. METHODS: Randomized controlled trail including 60 patients undergoing elective stand-alone coronary artery bypass graft surgery and allocated in a 1:1 ratio to either minimal invasive (n = 30) or conventional extracorporeal circulation (n = 30). Postoperative kidney injury was assessed by elevation of plasma neutrophil gelatinase-associated lipocalin (NGAL), a sensitive tubular injury biomarker. In addition, we assessed changes in estimated glomerular filtration rate (eGFR), and the incidence of acute kidney injury according to the Acute Kidney Injury Network (AKIN) classification. RESULTS: We observed no differences between groups regarding increase of plasma NGAL (p = 0.31) or decline of eGFR (p = 0.82). In both groups, 6/30 patients developed acute kidney injury according to the AKIN classification, all regaining preoperative renal function within 30 days. CONCLUSION: Our findings challenge the superiority of minimal invasive compared to conventional extracorporeal circulation in terms of preservation of renal function following low-risk coronary surgery.

A Human Randomized Controlled Trial Comparing Metabolic Responses to Single and Repeated Hypoglycemia in Type 1 Diabetes.

AIMS: Hypoglycemia hinders optimal glycemic management in type 1 diabetes (T1D). Long diabetes duration and hypoglycemia impair hormonal counter-regulatory responses to hypoglycemia. Our study was designed to test whether (1) the metabolic responses and insulin sensitivity are impaired, and (2) whether they are affected by short-lived antecedent hypoglycemia in participants with T1D. MATERIALS AND METHODS: In a randomized, crossover, 2x2 factorial design, 9 male participants with T1D and 9 comparable control participants underwent 30 minutes of hypoglycemia (p-glucose < 2.9 mmol/L) followed by a euglycemic clamp on 2 separate interventions: with and without 30 minutes of hypoglycemia the day before the study day. RESULTS: During both interventions insulin sensitivity was consistently lower, while counter-regulatory hormones were reduced, with 75% lower glucagon and 50% lower epinephrine during hypoglycemia in participants with T1D, who also displayed 40% lower lactate and 5- to 10-fold increased ketone body concentrations following hypoglycemia, whereas palmitate and glucose turnover, forearm glucose uptake, and substrate oxidation did not differ between the groups. In participants with T1D, adipose tissue phosphatase and tensin homolog (PTEN) content, hormone-sensitive lipase (HSL) phosphorylation, and muscle glucose transporter type 4 (GLUT4) content were decreased compared with controls. And antecedent hypoglycemic episodes lasting 30 minutes did not affect counter-regulation or insulin sensitivity. CONCLUSIONS: Participants with T1D displayed insulin resistance and impaired hormonal counter-regulation during hypoglycemia, whereas glucose and fatty acid fluxes were intact and ketogenic responses were amplified. We observed subtle alterations of intracellular signaling and no effect of short-lived antecedent hypoglycemia on subsequent counter-regulation. This plausibly reflects the presence of insulin resistance and implies that T1D is a condition with defective hormonal but preserved metabolic responsiveness to short-lived hypoglycemia.

Low Interleukin-22 Binding Protein Is Associated With High Mortality in Alcoholic Hepatitis and Modulates Interleukin-22 Receptor Expression.

INTRODUCTION: In alcoholic hepatitis (AH), high interleukin (IL)-22 production is associated with disease improvement, purportedly through enhanced infection resistance and liver regeneration. IL-22 binding protein (BP) binds and antagonizes IL-22 bioactivity, but data on IL-22BP in liver disease suggest a complex interplay. Despite the scarcity of human data, IL-22 is in clinical trial as treatment of AH. We, therefore, in patients with AH, described the IL-22 system focusing on IL-22BP and associations with disease course, and mechanistically pursued the human associations in vitro. METHODS: We prospectively studied 41 consecutive patients with AH at diagnosis, days 7 and 90, and followed them for up to 1 year. We measured IL-22 pathway proteins in liver biopsies and blood and investigated IL-22BP effects on IL-22 in hepatocyte cultures. RESULTS: IL-22BP was produced in the gut and was identifiable in the patients with AH' livers. Plasma IL-22BP was only 50% of controls and the IL-22/IL-22BP ratio thus elevated. Consistently, IL-22-inducible genes were upregulated in AH livers at diagnosis. Low plasma IL-22BP was closely associated with high 1-year mortality. In vitro, IL-22 stimulation reduced IL-22 receptor (R) expression, but coincubation with IL-22BP sustained IL-22R expression. In the AH livers, IL-22R mRNA expression was similar to healthy livers, although IL-22R liver protein was higher at diagnosis. DISCUSSION: Plasma IL-22BP was associated with an adverse disease course, possibly because its low level reduces IL-22R expression so that IL-22 bioactivity was reduced. This suggests the IL-BP interplay to be central in AH pathogenesis, and in future treatment trials (see Visual abstract, Supplementary Digital Content 5, http://links.lww.com/CTG/A338).

Tyrosine Kinase Inhibitor-Induced Hypertension: Role of Hypertension as a Biomarker in Cancer Treatment.

Cancer treatment is an area of continuous improvement. Therapy is becoming more targeted and the use of anti-angiogenic agents in multiple cancers, specifically tyrosine kinase inhibitors (TKIs), has demonstrated prolonged survival outcomes compared with previous drugs. Therefore, they have become a well-established part of the treatment. Despite good results, there is a broad range of moderate to severe adverse effects associated with treatment. Hypertension (HTN) is one of the most frequent adverse effects and has been associated with favourable outcomes (in terms of cancer treatment) of TKI treatment. High blood pressure is considered a class effect of TKI treatment, although the mechanisms have not been fully described. Three current hypotheses of TKI-associated HTN are highlighted in this narrative review. These include nitric oxide decrease, a change in endothelin-1 levels and capillary rarefaction. Several studies have investigated HTN as a potential biomarker of TKI efficacy. HTN is easy to measure and adding this factor to prognostic models has been shown to improve specificity. HTN may become a potential biomarker in clinical practice involving treating advanced cancers. However, data are currently limited by the number of studies and knowledge of the mechanism of action.

Effects of Prednisolone on Serum and Tissue Fluid IGF-I Receptor Activation and Post-Receptor Signaling in Humans.

Context: Short-term glucocorticoid exposure increases serum insulinlike growth factor I (IGF-I) concentrations but antagonizes IGF-I tissue signaling. The underlying mechanisms remain unknown. Objective: To identify at which levels glucocorticoid inhibits IGF-I signaling. Design and Methods: Nineteen healthy males received prednisolone (37.5 mg/d) and placebo for 5 days in a randomized, double-blinded, placebo-controlled crossover study. Serum was collected on days 1, 3, and 5, and abdominal skin suction blister fluid (SBF; ~interstitial fluid) was taken on day 5 (n = 9) together with muscle biopsy specimens (n = 19). The ability of serum and SBF to activate the IGF-I receptor (IGF-IR) (bioactive IGF) and its downstream signaling proteins was assessed using IGF-IR-transfected cells. Results: Prednisolone increased IGF-I concentrations and bioactive IGF in serum (P ≤ 0.001) but not in SBF, which, compared with serum, contained less bioactive IGF (~28%) after prednisolone (P < 0.05). This observation was unexplained by SBF concentrations of IGFs and IGF-binding proteins (IGFBPs) 1 to 4. However, following prednisolone treatment, SBF contained less IGFBP-4 fragments (P < 0.05) generated by pregnancy-associated plasma protein A (PAPP-A). Concomitantly, prednisolone increased SBF levels of stanniocalcin 2 (STC2) (P = 0.02) compared with serum. STC2 blocks PAPP-A from cleaving IGFBP-4. Finally, prednisolone suppressed post-IGF-IR signaling pathways at the level of insulin receptor substrate 1 (P < 0.05) but did not change skeletal muscle IGF-IR, IGF-I, or STC2 messenger RNA. Conclusion: Prednisolone increased IGF-I concentrations and IGF bioactivity in serum but not in tissue fluid. The latter may relate to a STC2-mediated inhibition of PAPP-A in tissue fluids. Furthermore, prednisolone induced post-IGF-IR resistance. Thus, glucocorticoid may exert distinct, compartment-specific effects on IGF action.

Neutrophil gelatinase-associated lipocalin as a risk marker in cardiovascular disease.

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising diagnostic biomarker of early acute kidney injury. Increasing evidence suggests that NGAL may also be involved in inflammatory processes in cardiovascular disease. NGAL modulates the enzymatic activity of matrix metalloproteinase-9 (MMP-9), which is an important mediator of plaque instability in atherosclerosis. The complex formation between NGAL and MMP-9 therefore suggests that NGAL might play a role in progression of atherothrombotic disease. This review summarises current data on NGAL in atherosclerosis, acute myocardial infarction, and heart failure.

Long-Term Ethanol Exposure Decreases the Endotoxin-Induced Hepatic Acute Phase Response in Rats.

BACKGROUND: Long-term excessive alcohol intake predisposes to infectious diseases. The hepatic acute-phase response is a component of the innate immune system and is part of the first line of defense against invading pathogens, which may be compromised by alcohol. We aimed to investigate whether an induced acute-phase response is impaired in long-term ethanol (EtOH)-fed rats. METHODS: For 6 weeks, rats were either fed a Lieber-DeCarli EtOH-containing (36% as calories) liquid diet ad libitum or calorically pair-fed. Then, the rats were injected intraperitoneally with a low dose of lipopolysaccharide (LPS) (0.5 mg/kg) to induce an acute-phase response. Two hours after LPS, we measured the plasma concentrations of an array of inflammatory cytokines. Twenty-four hours after LPS, we measured the hepatic mRNA expression and serum concentrations of prominent rat acute-phase proteins. RESULTS: EtOH-fed rats showed either no liver histopathological changes or varying degrees of steatosis. EtOH feeding decreased the spontaneous liver mRNA expression of the prevailing acute-phase protein alpha-2-macroglobulin (α2M) by 30% (p < 0.01). LPS immediately increased plasma tumor necrosis factor-alpha and interleukin-6 more than 100-fold in both feeding groups (p < 0.001, all) and approximately twice as much in the EtOH-fed rats (p < 0.05 and p = 0.08, respectively). LPS also induced a variable but marked amplification of (α2M), haptoglobin, alpha-1-acid glycoprotein, and lipocalin-2 liver mRNA expression levels and serum concentrations in both feeding groups (p ≤ 0.01 to 0.001). However, the LPS-induced increases in serum (α2M) and haptoglobin were less pronounced in the EtOH-fed rats, averaging approximately 60% of the concentrations in the pair-fed rats (p < 0.01 and p < 0.001, respectively). CONCLUSIONS: Long-term EtOH exposure in rats reduces the spontaneous hepatic mRNA expression of (α2M) and markedly impairs the hepatic acute-phase response to endotoxin, despite higher pro-inflammatory cytokine release. The same phenomenon may contribute to the increased susceptibility to infections observed in humans with long-term excessive alcohol intake.

PAPP-A, IGFBP-4 and IGF-II are secreted by human adipose tissue cultures in a depot-specific manner.

OBJECTIVE: Adipose tissue secretes pregnancy-associated plasma protein-A (PAPP-A), which may increase local IGF action through cleavage of IGF-binding protein-4 (IGFBP-4). We tested whether this mechanism was operational in human visceral and subcutaneous adipose tissue (i.e. VAT and SAT). DESIGN: Explants of VAT and SAT from 26 obese subjects (hereof 17 women, BMI 39.5 (37.2; 42.8) kg/m2 (median (25%; 75% confidence interval) and SAT from eight lean, age-matched women (BMI 23.6 (22.4; 24.9) kg/m2) were incubated with or without GH (100 µg/L) and the media were harvested. METHODS: Media were assessed for concentrations of PAPP-A, intact and PAPP-A-cleaved IGFBP-4, IGF-I and IGF-II, and IGF-I receptor (IGF-IR) activation by bioassay. RESULTS: In obese subjects, VAT media contained higher concentrations than SAT of PAPP-A (4.4-fold) and both PAPP-A-generated IGFBP-4 fragments (C-terminal: 3.3-fold, N-terminal: 1.5-fold) (all P < 0.0005). Intact IGFBP-4 levels were similar in SAT and VAT. VAT media contained elevated IGF-II (1.4-fold; P < 0.005), but similar IGF-I concentrations compared with SAT. Still, VAT media contained a 1.8-fold increased ability to stimulate the IGF-IR (P < 0.005). IGF-I protein concentration and IGF-IR activation increased more in VAT media than SAT media following GH stimulation (both P < 0.05). At baseline, SAT media protein levels from lean and obese women were similar, with the exception of PAPP-A being 1.8-fold elevated in VAT media (P < 0.05). GH induced a similar increase in IGF-I media levels in SAT from obese and lean women. CONCLUSION: Human adipose tissue cultures secrete enzymatically active PAPP-A, IGFBP-4 and IGF-II in a depot-specific manner, suggesting differential regulation of IGF activity. Further, IGF-II appears to be more prominent than IGF-I. Finally, VAT appears more GH responsive than SAT.

Growth Hormone and Insulin Signaling in Acromegaly: Impact of Surgery Versus Somatostatin Analog Treatment.

CONTEXT: Somatostatin analogs (SAs) used in acromegaly to suppress GH secretion and tumor growth also suppress insulin secretion and may impact GH signaling. OBJECTIVE: To compare GH and insulin signaling after iv GH exposure in acromegalic patients controlled by surgery (n = 9) or SA (n = 9). DESIGN: Each patient was studied for 3 hours after an overnight fast (t = -60 to 120 minutes). GH was administered at t = 0 minutes; muscle and fat biopsies were obtained at t = 0 minutes and at t = 30 minutes (muscle) and t = 120 minutes (fat). Interstitial fluid was obtained from skin suction blisters (t = 0 minutes). MAIN OUTCOME MEASURES: GH and insulin signalling in muscle and fat. GH and IGF-1 in serum and interstitial fluid; insulin and free fatty acids in serum. RESULTS: The groups were comparable as regards GH and IGF-1. The SA group exhibited higher free fatty acid and glucose levels; basal suppressor of cytokine signaling protein 1 (SOCS1) mRNA in fat was increased in the SA group and correlated positively with SA dose (r2 = 0.54; P = .04). GH-induced GH signalling (pSTAT5b) in muscle occurred in both groups together with increased expression of SOCS and CISH genes. GH-induced pAKTthr308 was observed in SA patients. In both groups, mRNA expression of phosphatase and tensin homolog, a suppressor of insulin signaling, increased in fat after GH. CONCLUSION: 1) Signatures of GH and insulin signaling differ as a function of acromegaly treatment modality. 2) Extra-pituitary effects of SA may account for this. 3) The clinical implications remain to be investigated.

The impact of microgravity-based proteomics research.

Proteomics is performed in microgravity research in order to determine protein alterations occurring qualitatively and quantitatively, when single cells or whole organisms are exposed to real or simulated microgravity. To this purpose, antibody-dependent (Western blotting, flow cytometry, Luminex(®) technology) and antibody-independent (mass spectrometry, gene array) techniques are applied. The anticipated findings will help to understand microgravity-specific behavior, which has been observed in bacteria, as well as in plant, animal and human cells. To date, the analyses revealed that cell cultures are more sensitive to microgravity than cells embedded in organisms and that proteins changing under microgravity are highly interactive. Furthermore, one has to distinguish between primary gravity-induced and subsequent interaction-dependent changes of proteins, as well as between direct microgravity-related effects and indirect stress responses. Progress in this field will impact on tissue engineering and medicine and will uncover possibilities of counteracting alterations of protein expression at lowered gravity.

Effects of raloxifene and estrogen on bioactive IGF1 in GH-deficient women.

CONTEXT: GH action is attenuated by estrogens and selective estrogen receptor modulators (SERMs) administered orally. During GH therapy in hypopituitary women, co-treatment with raloxifene, a SERM, induced a smaller gain in lean body mass (LBM) compared with estrogen, despite an equal reduction in IGF1. As a higher IGF-binding protein-3 (IGFBP3) level was observed with raloxifene co-treatment, we hypothesize that an increase in IGFBP3 reduced IGF1 bioactivity causing the attenuated anabolic effect. OBJECTIVE: To assess the effects of 17ß-estradiol (E2) and raloxifene on bioactive IGF1. DESIGN: In study 1, 12 GH-deficient (GHD) women were randomized to raloxifene 120 mg/day or E2 4 mg/day for 1 month. In study 2, 16 GHD women were randomized to 1 month GH treatment alone (0.5 mg/day) and in combination with raloxifene (60 mg/day) or E2 (2 mg/day). We measured bioactive IGF1, immunoreactive IGF1 and IGF2, and IGFBP3 immunoreactivity and fragmentation. RESULTS: Raloxifene and estrogen suppressed (P<0.05) total IGF1 equally in GHD and GH-replaced hypopituitary women. In GHD patients, neither raloxifene nor estrogen affected bioactive IGF1. GH significantly increased IGF1 bioactivity, an effect attenuated by co-treatment with raloxifene (Δ -23 ± 7%, P<0.01) and estrogen (Δ -26 ± 3%, P=0.06). Total IGF1 correlated (r(2)=0.54, P<0.001) with bioactive IGF1, which represented 3.1 ± 0.2% of the total IGF1, irrespective of the treatments. Total IGF2 was unchanged by raloxifene and estrogen treatment. IGFBP3 was significantly higher during raloxifene administration, whereas no differences in IGFBP3 fragmentation were observed. CONCLUSION: Raloxifene effect on bioactive IGF1 is similar to that of estrogen despite higher IGFBP3 levels during raloxifene administration. We conclude that the observed different effects on LBM between raloxifene and estrogen treatments cannot be explained by differences in IGF1 bioactivity.