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Many patients with cancer suffer from anemia, depression, and an impaired quality of life (QoL). These patients often also show decreased plasma tryptophan levels and increased kynurenine concentrations in parallel with elevated concentrations of Th1 type immune activation marker neopterin. In the course of anti-tumor immune response, the pro-inflammatory cytokine interferon gamma (IFN-γ) induces both, the enzyme indoleamine 2,3-dioxygenase (IDO) to degrade tryptophan and the enzyme GTP-cyclohydrolase I to form neopterin. High neopterin concentrations as well as an increased kynurenine to tryptophan ratio (Kyn/Trp) in the blood of cancer patients are predictive for a worse outcome. Inflammation-mediated tryptophan catabolism along the kynurenine pathway is related to fatigue and anemia as well as to depression and a decreased QoL in patients with solid tumors. In fact, enhanced tryptophan breakdown might greatly contribute to the development of anemia, fatigue, and depression in cancer patients. IDO activation and stimulation of the kynurenine pathway exert immune regulatory mechanisms, which may impair anti-tumor immune responses. In addition, tumor cells can degrade tryptophan to weaken immune responses directed against them. High IDO expression in the tumor tissue is associated with a poor prognosis of patients. The efficiency of IDO-inhibitors to inhibit cancer progression is currently tested in combination with established chemotherapies and with immune checkpoint inhibitors. Inflammation-mediated tryptophan catabolism and its possible influence on the development and persistence of anemia, fatigue, and depression in cancer patients are discussed.

Damaged erythrocytes accumulate in various pathological conditions, such as hemolytic anemia, anemia of inflammation, and sickle cell disease. In mice challenged with damaged erythorcytes, a monocyte subset migrates to the liver (but not to the spleen), and this subset differentiates into a transient macrophage population that removes the damaged erythrocytes, thus preventing organ damage. Iron is an essential component of the erythrocyte protein hemoglobin and is crucial to oxygen transport in vertebrates. In the steady state, erythrocyte production is in equilibrium with erythrocyte removal 1 . In various pathophysiological conditions, however, erythrocyte life span is compromised severely, which threatens the organism with anemia and iron toxicity 2 , 3 . Here we identify an on-demand mechanism that clears erythrocytes and recycles iron. We show that monocytes that express high levels of lymphocyte antigen 6 complex, locus C1 (LY6C1, also known as Ly-6C) ingest stressed and senescent erythrocytes, accumulate in the liver via coordinated chemotactic cues, and differentiate into ferroportin 1 (FPN1, encoded by SLC40A1 )-expressing macrophages that can deliver iron to hepatocytes. Monocyte-derived FPN1 + Tim-4 neg macrophages are transient, reside alongside embryonically derived T cell immunoglobulin and mucin domain containing 4 (Timd4, also known as Tim-4) high Kupffer cells (KCs), and depend on the growth factor Csf1 and the transcription factor Nrf2 (encoded by Nfe2l2 ). The spleen, likewise, recruits iron-loaded Ly-6C high monocytes, but these do not differentiate into iron-recycling macrophages, owing to the suppressive action of Csf2. The accumulation of a transient macrophage population in the liver also occurs in mouse models of hemolytic anemia, anemia of inflammation, and sickle cell disease. Inhibition of monocyte recruitment to the liver during stressed erythrocyte delivery leads to kidney and liver damage. These observations identify the liver as the primary organ that supports rapid erythrocyte removal and iron recycling, and uncover a mechanism by which the body adapts to fluctuations in erythrocyte integrity.

Background Sepsis, a dysregulated host response following infection, is associated with massive immune activation and high mortality rates. There is still a need to define further risk factors and laboratory parameters predicting the clinical course. Iron metabolism is regulated by both, the body’s iron status and the immune response. Iron itself is required for erythropoiesis but also for many cellular and metabolic functions. Moreover, iron availability is a critical determinant in infections because it is an essential nutrient for most microbes but also impacts on immune function and intravascular oxidative stress. Herein, we used a prospective study design to investigate the putative impact of serum iron parameters on the outcome of sepsis. Methods Serum markers of iron metabolism were measured in a prospective cohort of 61 patients (37 males, 24 females) with sepsis defined by Sepsis-3 criteria in a medical intensive care unit (ICU) and compared between survivors and non-survivors. Regulation of iron parameters in patients stratified by focus of infection and co-medication as well as association of the markers with sepsis severity scores and survival were investigated with linear and logistic regression corrected for sex and age effects. Results Positive correlations of increased serum iron and ferritin concentrations upon ICU admission with the severity of organ failure (SOFA score) and with mortality were observed. Moreover, high TF-Sat, elevated ferritin and serum iron levels and low transferrin concentrations were associated with reduced survival. A logistic regression model consisting of SOFA and transferrin saturation (SOFA–TF-Sat) had the best predictive power for survival in septic ICU patients. Of note, administration of blood transfusions prior to ICU admission resulted in increased TF-Sat and reduced survival of septic patients. Conclusions Our study could show an important impact of serum iron parameters on the outcome of sepsis. Furthermore, we identified transferrin saturation as a stand-alone predictor of sepsis survival and as a parameter of iron metabolism which may in a combined model improve the prediction power of the SOFA score. Trial registration The study was carried out in accordance with the recommendations of the Declaration of Helsinki on biomedical research. The study was approved by the institutional ethics review board of the Medical University Innsbruck (study AN2013-0006 ).

Anemia is present in up to two-thirds of patients undergoing colorectal surgery mainly caused by iron deficiency and inflammation. As anemia is associated with increased risk of perioperative death, diagnosis and treatment of preoperative anemia according to etiology have been recommended. The aim of the present study was to assess if the association between anemia and survival in patients undergoing colorectal surgery was determined by the severity of anemia alone or also by anemia etiology. To determine the prevalence of anemia and etiology, preoperative hematological parameters, C-reactive protein, ferritin and transferrin saturation were retrospectively assessed and correlated with outcome in a cohort of patients undergoing colorectal surgery between 2005 and 2019 at the University Hospital of Innsbruck. Anemia was defined as hemoglobin <120 g/L in females and <130 g/L in males. The etiology of anemia was classified on the basis of serum iron parameters, as iron deficiency anemia, anemia of inflammation or other anemia etiologies. Preoperative anemia was present in 54% (1316/2458) of all patients. Anemia was associated with iron deficiency in 45% (134/299) and classified as anemia of inflammation in 32% (97/299) of patients with available serum iron parameters. The etiology of anemia was a strong and independent predictor of survival, where iron deficiency and anemia of inflammation were associated with better postoperative survival than other anemia etiologies. One year survival rates were 84.3%, 77.3% and 69.1% for patients with iron deficiency anemia, anemia of inflammation and other anemia types. Inflammation indicated by high C-reactive protein is a strong negative predictor of overall survival. Anemia has a high prevalence among patients undergoing colorectal surgery and rational treatment requires early assessment of serum iron parameters and C-reactive protein.

Although neglected in the past, the interest on Zika virus (ZIKV) raised dramatically in the last several years. The rapid spread of the virus in Latin America and the association of the infection with microcephaly in newborns or Guillain-Barré Syndrome in adults prompted the WHO to declare the ZIKV epidemic to be an international public health emergency in 2016. As the virus gained only limited attention in the past, investigations on interactions of ZIKV with human complement are limited. This prompted us to investigate the stability of the virus to human complement. At low serum concentrations (10%) which refers to complement concentrations found on mucosal surfaces, the virus was relatively stable at 37°C, while at high complement levels (50% serum concentration) ZIKV titers were dramatically reduced, although the virus remained infectious for about 4-5 min under these conditions. The classical pathway was identified as the main actor of complement activation driven by IgM antibodies. In addition, direct binding of C1q to both envelope and NS1 proteins was observed. Formation of the MAC on the viral surface and thus complement-mediated lysis and not opsonization seems to be essential for the reduction of viral titers.

Nuclear receptors regulate key functions of mononuclear phagocytes and are critical components of the innate immune system, acting as regulators of organ health and disease. In healthy mice, the loss of the nuclear orphan receptor NR2F6 alters tissue‐resident macrophage populations in the liver, lung, and spleen. In response to Salmonella Typhimurium infection, Nr2f6‐deficient mice exhibit improved clinical outcomes, characterized by reduced weight loss, bacterial loads in the spleen and liver, and decreased plasma pro‐inflammatory cytokines. Despite unchanged basal iron metabolism in the spleen and liver, iron regulatory proteins and the interleukin (IL)‐6‐hepcidin axis are altered in Nr2f6‐deficient mice during Salmonella infection, reducing hypoferremia. Transcriptomic analysis of splenic red pulp macrophages reveals significant alterations of phagocytosis‐related genes, including upregulation of signal‐regulatory protein alpha (Sirpa). In vitro, phagocytosis of red blood cells, regulated by the inhibitory CD47‐Sirpα axis, and Salmonella Typhimurium phagocytosis are significantly impaired in Nr2f6‐deficient splenic macrophages. Blocking Sirpα in vitro restores the phagocytic activity of Nr2f6‐deficient macrophages to wild‐type levels. In vivo, Salmonella Typhimurium loads are partially increased post‐infection in anti‐Sirpα treated Nr2f6‐deficient mice. These findings uncover a previously unrecognized role of NR2F6 in host‐pathogen interactions, positioning it as a potential therapeutic target for infectious diseases. Loss of nuclear receptor NR2F6 reduces tissue‐resident macrophage populations. Nr2f6‐deficient mice are protected from weight loss and bacterial load during infection with Salmonella Typhimurium. Pro‐inflammatory cytokines and iron levels are altered in infected Nr2f6‐deficient mice. Enhanced Sirpα levels reduce phagocytic uptake in Nr2f6‐deficient splenic macrophages. Blocking Sirpα partially adjusts phagocytic responses of Nr2f6‐deficient macrophages to wild‐type.

BackgroundAdult growth hormone (GH) deficiency is associated with fatty liver disease and shows several features of the metabolic syndrome. Vice versa obesity is characterized as a state of low GH function. Here, we aimed to define the role of hepatic GH signaling and its metabolic consequences in non-alcoholic fatty liver disease.MethodsIn humans, GHR and IGF-1 levels were determined in liver samples of 29 obese patients with non-alcoholic steatohepatitis (NASH) or simple steatosis. Cellular effects of GH on insulin signaling were investigated in GH receptor (GHR) knockdown HepG2 cells.ResultsHepatic IGF-1 expression levels reflecting GH action were significantly lower and fasting glucose concentrations higher in patients with NASH than in patients with simple steatosis. GHR knockdown in hepatocytes resulted in a scenario of high glucose output displayed by reduced glycogen content, increased gluconeogenesis and diminished insulin signaling.ConclusionsOur data suggest that GH signaling in the liver is diminished in patients with NASH and associated with deteriorated hepatic insulin sensitivity and metabolic activity. Reduced hepatic GH action might contribute to insulin resistance in obese patients with NASH.

Aims Iron is essential to maintain cellular energy metabolism in the myocardium. Impaired cellular iron availability negatively affects myocardial physiology and can aggravate heart failure (HF). Iron deficiency (ID) is frequently found in patients with acute and chronic HF (AHF, CHF) and associated with clinical outcome. The aim of this analysis was to assess the true ID prevalence in HF patients on the basis of different ID definitions. Methods We performed a retrospective analysis of 329 AHF and 613 CHF patients, recruited between 02/2021 and 05/2022 at the Innsbruck Medical University (47%/32% female, median age 81/64 years). ID was defined according to a general definition, gastroenterology and cardiology guidelines as ferritin <30 or <45 ng/mL or <100/ng/mL (absolute ID), ferritin 30–100 or 45–150 or 100–299 ng/mL plus TSAT <20% (combined ID), and ferritin >100 or >150 or ≥300 ng/mL plus TSAT <20% (functional ID). Results ID prevalence was significantly higher in AHF compared with CHF patients: general definition (74.8% vs. 32.6%, P < 0.001), gastroenterology guidelines (75.7% vs. 34.7%, P < 0.001), cardiology guidelines (79.9% vs. 47.3%, P < 0.001). We found distinctive differences in prevalence of ID types between the three definitions. Absolute ID prevalence was highest when applying cardiology compared with gastroenterology guidelines and general definition (AHF: 44.7% vs. 20.4% vs. 7.0%; CHF: 34.1% vs. 13.4% vs. 7.2%), while frequency of combined ID was almost equally distributed. Functional ID prevalence was highest when applying general definition compared with gastroenterology and cardiology guidelines (AHF: 34.7% vs. 23.4% vs. 11.6%; CHF: 13.1% vs. 9.0% vs. 3.4%). Out of 494 patients classified as having absolute or combined ID according to the cardiology guidelines, only 252 patients received the same classification while 107 and 135 patients were classified having no and functional ID when applying the general definition. Conclusions We show that ID prevalence is higher in AHF versus CHF patients in a continuous cohort of HF patients managed at the same institution over the same period of time. There were distinctive differences in detection of ID and the type of ID when applying several recommended definitions thus affecting sensitivity and specificity for absolute and functional ID detection. This may result in exclusion of patients, which may benefit from iron supplementation and inclusion of those who may not respond or even anticipate site effects. Our study calls for the urgent need of prospective trials for redefinition of ID and identification of biomarkers associated with therapeutic response to optimize patient outcomes.

Patients with cancer often suffer from fatigue and decreased quality of life which might be related to the breakdown of essential amino acid tryptophan. In 50 patients with lung cancer we examined fatigue and the deterioration of quality of life in patients using the Functional Assessment of Cancer Therapy Anemia (FACT-An) and -Fatigue (FACT-F) subscales of FACT-General and the Mental adjustment to Cancer (MAC) questionnaires. Results were compared with tryptophan breakdown as well as serum concentrations of immune activation markers. Scores of psychological tests correlated significantly with tryptophan breakdown and with circulatory markers of inflammation. However, immune activation and tryptophan breakdown were not related to MAC scores. Tryptophan breakdown relates with fatigue and impaired quality of life in patients with lung cancer, while declining tryptophan levels are not associated with patients'coping strategies.

[...]a chronic inflammatory state which is prevalent in countries with a high burden of infections negatively impacts on oral iron absorption due to inflammation driven increased formation of the iron regulatory hormone hepcidin which blocks the transfer of iron from enterocytes to the circulation. 7 The subsequent reduction in iron absorption results in higher concentrations of metal in the small and large intestines where it can aggravate inflammation via its catalytic activity towards the formation of tissue-toxic radicals. 8 Fourth, the results of Jaeggi et al are likewise also of importance for other diseases, specifically for inflammatory bowel disease where oral iron supplementation in animal models of IBD resulted in disease aggravation which may be linked to iron mediated emergence of pathogenic bacteria and subsequent infection 9 along with additional inflammation promoting effects of the metal.