Lipocalin-2 ameliorates granulocyte functionality

The role of bone in energy metabolism: A focus on osteocalcin

Understanding the mechanisms involved in whole body glucose regulation is key for the discovery of new treatments for type 2 diabetes (T2D). Historically, glucose regulation was largely focused on responses to insulin and glucagon. Impacts of incretin-based therapies, and importance of muscle mass, are also highly relevant. Recently, bone was recognized as an endocrine organ, with several bone proteins, known as osteokines, implicated in glucose metabolism through their effects on the liver, skeletal muscle, and adipose tissue. Research efforts mostly focused on osteocalcin (OC) as a leading example. This review will provide an overview on this role of bone by discussing bone turnover markers (BTMs), the receptor activator of nuclear factor kB ligand (RANKL), osteoprotegerin (OPG), sclerostin (SCL) and lipocalin 2 (LCN2), with a focus on OC. Since 2007, some, but not all, research using mostly OC genetically modified animal models suggested undercarboxylated (uc) OC acts as a hormone involved in energy metabolism. Most data generated from in vivo, ex vivo and in vitro models, indicate that exogenous ucOC administration improves whole-body and skeletal muscle glucose metabolism. Although data in humans are generally supportive, findings are often discordant likely due to methodological differences and observational nature of that research. Overall, evidence supports the concept that bone-derived factors are involved in energy metabolism, some having beneficial effects (ucOC, OPG) others negative (RANKL, SCL), with the role of some (LCN2, other BTMs) remaining unclear. Whether the effect of osteokines on glucose regulation is clinically significant and of therapeutic value for people with insulin resistance and T2D remains to be confirmed.

Potential of using an engineered indole lactic acid producing Escherichia coli Nissle 1917 in a murine model of colitis

The gut microbiome is a significant factor in the pathophysiology of ulcerative colitis (UC), prompting investigations into the use of probiotic therapies to counter gastrointestinal inflammation. However, while much attention has been given to the therapeutic potential of microbes at the species and strain level, the discovery and application of their metabolic products may offer more precise and controlled solutions in battling disease. In this work, we examined the therapeutic potential of indole lactic acid (ILA) to alleviate inflammation in a murine model of colitis. A previously constructed ILA-producing Escherichia coli Nissle 1917 strain (EcN aldh) and its isogenic non-ILA producing counterpart (EcN) were studied in a murine model of Dextran Sodium Sulfate (DSS) induced colitis. The colitic animals suffered from severe colitic symptoms, with no differentiation between the groups in body weight loss and disease activity index. However, three days after cessation of DSS treatment the EcN aldh-treated mice showed signs of reduced intestinal inflammation, as manifested by lower concentrations of fecal lipocalin-2. Additionally, expression analysis of the inflamed tissue revealed distinct effects of the EcN aldh strain on proteins associated with intestinal health, such as TFF3, occludin and IL-1β expression. These results show no impact of EcN or EcN aldh on acute DSS-induced colitis, but suggest that in particular EcN aldh may assist recovery from intestinal inflammation.

Angiotensin-II type 2 receptor-mediated renoprotection is independent of receptor Mas in obese Zucker rats fed high-sodium diet

The consumption of a high-sodium diet (HSD) is injurious and known to elevate blood pressure (BP), especially in obesity. Acute infusion studies depict a functional interdependency between angiotensin-II type 2 receptor (AT2R) and receptor Mas (MasR). Hence, we hypothesize that the subacute blockade of MasR should reverse AT2R-mediated renoprotection in obese Zucker rats (OZRs). Male OZRs were fed an HSD (for 14 days) and treated with the AT2R agonist C21 (100 ng/min) without or with a MasR antagonist A779 (1,000 ng/min). The indices of oxidative stress, proteinuria, kidney injury, and BP were measured before and after, along with the terminal measurements of an array of inflammatory and kidney injury markers. The HSD significantly decreased the estimated glomerular filtration rate and urinary osmolality and increased thirst, diuresis, natriuresis, kaliuresis, plasma creatinine, urinary excretion of H2O2, proteinuria, renal expression and urinary excretion of kidney injury markers (NGAL and KIM-1), and BP indexes. The HSD feeding showed early changes in the renal expression of CRP, ICAM-1, and galectin-1. The C21 treatment prevented these pathological changes. The MasR antagonist A779 attenuated C21-mediated effects on the urinary excretion and renal expression of NGAL and oxidative stress in the absence of inflammation and BP changes. Overall, we conclude that the subacute functional interactions between AT2R and MasR are weak or transient and that the beneficial effects of AT2R activation are independent of the MasR blockade in the kidney of male obese rats fed an HSD.

Sex-specific associations of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in patients with drug-naïve schizophrenia

This present study aimed to investigate the sex-specific association of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in drug-naïve schizophrenia patients for the first time. A total of 204 participants in this study, including 137 drug-naïve schizophrenia (DNS) patients and 67 healthy controls (HCs). All participants completed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB), and were collected fasting venous blood for NGAL measurement. DNS patients also complete the Positive and Negative Syndrome Scale (PANSS). Partial correlation analysis and multiple linear regression were used to explore sex-specific associations between NGAL and cognition. All dimensions of MCCB scores were significantly lower in both male and female DNS patients than HCs. Sex differences were significant in cognitive performance in both DNS patients and HCs. Female DNS patients experienced poorer working memory and reason& problem solving than male patients. Female HCs performed a better attention/vigilance and visual learning, a poorer reason& problem solving than male HCs. In patients with DNS, NGAL levels were negatively associated with positive subscale of PANSS and positively associated with working memory and visual learning only in female. However, there was no significant correlation between NGAL levels and all cognitive tests in both male and female HCs. Regression model showed that higher level of NGAL was an independent protective factor for cognitive performance in female patients with DNS, whereas there was no such role in male patients. Our findings suggest sex specificity between NGAL levels and cognitive performance in DNS patients.

Dexamethasone targets actin cytoskeleton signaling and inflammatory mediators to reverse sulfur mustard-induced toxicity in rabbit corneas

PURPOSE

Sulfur mustard (SM), a bi-functional alkylating agent, was used during World War I and the Iran-Iraq war. SM toxicity is ten times higher in eyes than in other tissues. Cornea is exceptionally susceptible to SM-injuries due to its anterior positioning and mucous-aqueous interphase. Ocular SM exposure induces blepharitis, photosensitivity, dry eye, epithelial defects, limbal ischemia and stem cell deficiency, and mustard gas keratopathy leading to temporary or permanent vision impairments. We demonstrated that dexamethasone (Dex) is a potent therapeutic intervention against SM-induced corneal injuries; however, its mechanism of action is not well known. Investigations employing proteomic profiling (LC-MS/MS) to understand molecular mechanisms behind SM-induced corneal injury and Dex efficacy were performed in the rabbit cornea exposed to SM and then received Dex treatment. PEAKS studio was used to extract, search, and summarize peptide identity. Ingenuity Pathway Analysis was used for pathway identification. Validation was performed using immunofluorescence. One-Way ANOVA (FDR < 0.05; p < 0.005) and Student's t-test (p < 0.05) were utilized for analyzing proteomics and IF data, respectively. Proteomic analysis revealed that SM-exposure upregulated tissue repair pathways, particularly actin cytoskeleton signaling and inflammation. Prominently dysregulated proteins included lipocalin2, coronin1A, actin-related protein2, actin-related protein2/3 complex subunit2, actin-related protein2/3 complex subunit4, cell division cycle42, ezrin, bradykinin/kininogen1, moesin, and profilin. Upregulated actin cytoskeleton signaling increases F-actin formation, dysregulating cell shape and motility. Dex reversed SM-induced increases in the aforementioned proteins levels to near control expression profiles. Dex aids corneal wound healing and improves corneal integrity via actin cytoskeletal signaling and anti-inflammatory effects following SM-induced injuries.

Understanding How Minerals Contribute to Optimal Immune Function

Sufficient mineral supply is vital not only for the innate immune system but also for the components of the adaptive immune defense, which encompass defense mechanisms against pathogens and the delicate balance of pro- and anti-inflammatory regulation in the long term. Generally, a well-balanced diet is capable of providing the necessary minerals to support the immune system. Nevertheless, specific vulnerable populations should be cautious about obtaining adequate amounts of minerals such as magnesium, zinc, copper, iron, and selenium. Inadequate levels of these minerals can temporarily impair immune competence and disrupt the long-term regulation of systemic inflammation. Therefore, comprehending the mechanisms and sources of these minerals is crucial. In exceptional circumstances, mineral deficiencies may necessitate supplementation; however, excessive intake of supplements can have adverse effects on the immune system and should be avoided. Consequently, any supplementation should be approved by medical professionals and administered in recommended doses. This review emphasizes the crucial significance of minerals in promoting optimal functioning of the immune system. It investigates the indispensable minerals required for immune system function and the regulation of inflammation. Moreover, it delves into the significance of maintaining an optimized intake of minerals from a nutritional standpoint.

Alcohol reshapes a liver premetastatic niche for cancer by extra- and intrahepatic crosstalk-mediated immune evasion

Cancer metastatic organotropism is still a mystery. The liver is known to be susceptible to cancer metastasis and alcoholic injury. However, it is unclear whether and how alcohol facilitates liver metastasis and how to intervene. Here, we show that alcohol preferentially promotes liver metastasis in colon-cancer-bearing mice and post-surgery pancreatic cancer patients. The mechanism is that alcohol triggers an extra- and intrahepatic crosstalk to reshape an immunosuppressive liver microenvironment. In detail, alcohol upregulates extrahepatic IL-6 and hepatocellular IL-6 receptor expression, resulting in hepatocyte STAT3 signaling activation and downstream lipocalin-2 (Lcn2) upregulation. Furthermore, LCN2 promotes T cell-exhaustion neutrophil recruitment and cancer cell epithelial plasticity. In contrast, knocking out hepatocellular Stat3 or systemic Il6 in alcohol-treated mice preserves the liver microenvironment and suppresses liver metastasis. This mechanism is reflected in hepatocellular carcinoma patients, in that alcohol-associated signaling elevation in noncancerous liver tissue indicates adverse prognosis. Accordingly, we discover a novel application for BBI608, a small molecular STAT3 inhibitor that can prevent liver metastasis. BBI608 pretreatment protects the liver and suppresses alcohol-triggered premetastatic niche formation. In conclusion, under extra- and intrahepatic crosstalk, the alcoholic injured liver forms a favorable niche for cancer cell metastasis, while BBI608 is a promising anti-metastatic agent targeting such microenvironments.

Different Kinetics of Serum ADAMTS13, GDF-15, and Neutrophil Gelatinase-Associated Lipocalin in the Early Phase of Aneurysmal Subarachnoid Hemorrhage

Growth differentiation factor 15 (GDF-15), neutrophil gelatinase-associated lipocalin (NGAL), and ADAMTS13 have previously been implicated in the pathophysiological processes of SAH. In the present study, we aim to examine their role in the early period of SAH and their relationship to primary and secondary outcomes. Serum samples were collected at five time periods after SAH (at 24 h (D1), at 72 h (D3), at 120 h (D5), at 168 h (D7) and at 216 h (D9), post-admission) and) were measured by using MILLIPLEX Map Human Cardiovascular Disease (CVD) Magnetic Bead Panel 2. We included 150 patients with SAH and 30 healthy controls. GDF-15 levels at D1 to D9 were significantly associated with a 3-month unfavorable outcome. Based on the ROC analysis, in patients with a good clinical grade at admission (WFNS I-III), the GDF-15 value measured at time point D3 predicted a 3-month unfavorable outcome (cut-off value: 3.97 ng/mL, AUC:0.833, 95%CI: 0.728-0.938, sensitivity:73.7%, specificity:82.6%, p < 0.001). Univariate binary logistic regression analysis showed that serum NGAL levels at D1-D5 and ADAMTS13 levels at D7-D9 were associated with MVS following SAH. GDF-15 is an early indicator of a poor 3-month functional outcome even in patients with mild clinical conditions at admission.

The regulation of TRPA1 expression and function by Th1 and Th2-type inflammation in human A549 lung epithelial cells

BACKGROUND

Transient Receptor Potential Ankyrin 1 (TRPA1) is a cation channel that mediates pain, itch, cough, and neurogenic inflammation in response to pungent compounds such as acrolein in cigarette smoke. TRPA1 is also activated by endogenous factors and promotes inflammation in asthma models. We have recently shown that TRPA1 is upregulated by inflammatory cytokines in A549 human lung epithelial cells. Here, we explored the effects of Th1 and Th2-type inflammation on TRPA1.

METHODS AND RESULTS

TRPA1 expression and function was studied in A549 human lung epithelial cells. To induce inflammation, the cells were exposed to a combination of cytokines TNF-α and IL-1β; and to model Th1 or Th2-type responses, IFN-γ or IL-4/IL-13 was added, respectively. TRPA1 expression (measured by RT-PCR and Western blot) and function (assessed by Fluo-3AM intracellular calcium measurement) was enhanced under the influence of TNF-α + IL-1β. IFN-γ further enhanced TRPA1 expression and function, whereas IL-4 and IL-13 suppressed them. The effects of IFN-γ and IL-4 on TRPA1 expression were reversed by the Janus kinase (JAK) inhibitors baricitinib and tofacitinib, and those of IL-4 also by the STAT6 inhibitor AS1517499. The glucocorticoid dexamethasone downregulated TRPA1 expression, whereas the PDE4 inhibitor rolipram had no effect. Under all conditions, TRPA1 blockade was found to reduce the production of LCN2 and CXCL6.

CONCLUSIONS

TRPA1 expression and function in lung epithelial cells was upregulated under inflammatory conditions. IFN-γ further increased TRPA1 expression while IL-4 and IL-13 suppressed that in a JAK-STAT6 dependent manner which is novel. TRPA1 also modulated the expression of genes relevant to innate immunity and lung disease. We propose that the paradigm of Th1 and Th2 inflammation is a major determinant of TRPA1 expression and function, which should be considered when targeting TRPA1 for pharmacotherapy in inflammatory (lung) disease.

Ferritinophagy-mediated iron competition in RUTIs: Tug-of-war between UPEC and host

Uropathogenic Escherichia coli (UPEC) is the main pathogen of recurrent urinary tract infections (RUTIs). Urinary tract infection is a complicated interaction between UPEC and the host. During infection, UPEC can evade the host's immune response and retain in bladder epithelial cells, which requires adequate nutritional support. Iron is the first necessary trace element in life and a key nutritional factor, making it an important part of the competition between UPEC and the host. On the one hand, UPEC grabs iron to satisfy its reproduction, on the other hand, the host relies on iron to build nutritional immunity defenses against UPEC. Ferritinophagy is a selective autophagy of ferritin mediated by nuclear receptor coactivator 4, which is not only a way for the host to regulate iron metabolism to maintain iron homeostasis, but also a key point of competition between the host and UPEC. Although recent studies have confirmed the role of ferritinophagy in the progression of many diseases, the mechanism of potential interactions between ferritinophagy in UPEC and the host is poorly understood. In this paper, we reviewed the potential mechanisms of ferritinophagy-mediated iron competition in the UPEC-host interactions. This competitive relationship, like a tug-of-war, is a confrontation between the capability of UPEC to capture iron and the host's nutritional immunity defense, which could be the trigger for RUTIs. Therefore, understanding ferritinophagy-mediated iron competition may provide new strategies for exploring effective antibiotic alternative therapies to prevent and treat RUTIs.

Protective Role for Smooth Muscle Cell Hepcidin in Abdominal Aortic Aneurysm

BACKGROUND

Hepcidin is a liver-derived hormone that controls systemic iron homeostasis, by inhibiting the iron exporter ferroportin in the gut and spleen, respective sites of iron absorption and recycling. Hepcidin is also expressed ectopically in the context of cardiovascular disease. However, the precise role of ectopic hepcidin in underlying pathophysiology is unknown. In patients with abdominal aortic aneurysm (AAA), hepcidin is markedly induced in smooth muscle cells (SMCs) of the aneurysm wall and inversely correlated with the expression of LCN2 (lipocalin-2), a protein implicated in AAA pathology. In addition, plasma hepcidin levels were inversely correlated with aneurysm growth, suggesting hepcidin has a potential disease-modifying role.

METHODS

To probe the role of SMC-derived hepcidin in the setting of AAA, we applied AngII (Angiotensin-II)-induced AAA model to mice harbouring an inducible, SMC-specific deletion of hepcidin. To determine whether SMC-derived hepcidin acted cell-autonomously, we also used mice harboring an inducible SMC-specific knock-in of hepcidin-resistant ferroportinC326Y. The involvement of LCN2 was established using a LCN2-neutralizing antibody.

RESULTS

Mice with SMC-specific deletion of hepcidin or knock-in of hepcidin-resistant ferroportinC326Y had a heightened AAA phenotype compared with controls. In both models, SMCs exhibited raised ferroportin expression and reduced iron retention, accompanied by failure to suppress LCN2, impaired autophagy in SMCs, and greater aortic neutrophil infiltration. Pretreatment with LCN2-neutralizing antibody restored autophagy, reduced neutrophil infiltration, and prevented the heightened AAA phenotype. Finally, plasma hepcidin levels were consistently lower in mice with SMC-specific deletion of hepcidin than in controls, indicating that SMC-derived hepcidin contributes to the circulating pool in AAA.

CONCLUSIONS

Hepcidin elevation in SMCs plays a protective role in the setting of AAA. These findings are the first demonstration of a protective rather than deleterious role for hepcidin in cardiovascular disease. They highlight the need to further explore the prognostic and therapeutic value of hepcidin outside disorders of iron homeostasis.

A Brief Overview of Neutrophils in Neurological Diseases

Neutrophils are the most abundant leukocyte in circulation and are the first line of defense after an infection or injury. Neutrophils have a broad spectrum of functions, including phagocytosis of microorganisms, the release of pro-inflammatory cytokines and chemokines, oxidative burst, and the formation of neutrophil extracellular traps. Traditionally, neutrophils were thought to be most important for acute inflammatory responses, with a short half-life and a more static response to infections and injury. However, this view has changed in recent years showing neutrophil heterogeneity and dynamics, indicating a much more regulated and flexible response. Here we will discuss the role of neutrophils in aging and neurological disorders; specifically, we focus on recent data indicating the impact of neutrophils in chronic inflammatory processes and their contribution to neurological diseases. Lastly, we aim to conclude that reactive neutrophils directly contribute to increased vascular inflammation and age-related diseases.

Lipocalin-2 as a biomarker for diabetic nephropathy

Diabetes is a major global public health issue. The prevalence of type 1 diabetes is comparatively static, as hereditary and genetic causes are involved, while type 2 diabetes (T2D) prevalence is increasing day by day. T2D is associated with chronic complications, including diabetic neuropathy (DN), nephropathy, retinopathy, and other complications like diabetic foot. DN is the main complication of both types of diabetes. DN can be diagnosed by routine laboratory tests, microalbuminuria > 300 mg/24 h, and a gradual decrease in glomerular filtration rate. As the appearance of microalbuminuria is a late manifestation, an early marker for renal damage is needed. Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL), is a small protein purified from neutrophil granules and a good marker for kidney disease. NGAL is a transporter protein responsible for many physiological processes, such as inflammation, generation of the immune response, and metabolic homeostasis. NGAL has been reported to depict the early changes in renal damage when urine microalbumin is still undetecable. Therefore, elucidating the role of NGAL in detecting DN and understanding its mechanism can help establish it as a potential early marker for DN.

Role of lipocalin 2 in stroke

Stroke is the second leading cause of death worldwide; however, the treatment choices available to neurologists are limited in clinical practice. Lipocalin 2 (LCN2) is a secreted protein, belonging to the lipocalin superfamily, with multiple biological functions in mediating innate immune response, inflammatory response, iron-homeostasis, cell migration and differentiation, energy metabolism, and other processes in the body. LCN2 is expressed at low levels in the brain under normal physiological conditions, but its expression is significantly up-regulated in multiple acute stimulations and chronic pathologies. An up-regulation of LCN2 has been found in the blood/cerebrospinal fluid of patients with ischemic/hemorrhagic stroke, and could serve as a potential biomarker for the prediction of the severity of acute stroke. LCN2 activates reactive astrocytes and microglia, promotes neutrophil infiltration, amplifies post-stroke inflammation, promotes blood-brain barrier disruption, white matter injury, and neuronal death. Moreover, LCN2 is involved in brain injury induced by thrombin and erythrocyte lysates, as well as microvascular thrombosis after hemorrhage. In this paper, we review the role of LCN2 in the pathological processes of ischemic stroke; intracerebral hemorrhage; subarachnoid hemorrhage; and stroke-related brain diseases, such as vascular dementia and post-stroke depression, and their underlying mechanisms. We hope that this review will help elucidate the value of LCN2 as a therapeutic target in stroke.

Overexpression of lipocalin 2 in PBX1-deficient decidual NK cells promotes inflammation at the maternal-fetal interface

PROBLEM

Impairment of PBX1 expression in decidual natural killer (dNK) cells is associated with the pathogenesis of unexplained recurrent spontaneous abortion, which results in fetal growth restriction (FGR) by affecting the secretion of downstream growth factors. However, whether other mechanisms limit embryo growth in decidua containing PBX1-deficient natural killer (NK) cells is unknown.

METHOD OF STUDY

Pbx1^f/f ; Ncr1^Cre mice were employed to explore the underlying mechanisms by which PBX1^- NK cells affect embryonic development. To simulate the clinical testing of pregnant women, Doppler ultrasound imaging was used to detect embryo implantation and development. Differentially expressed genes (DEGs) in PBX1^- NK cells that may affect normal pregnancy were screened using RNA-sequencing and real-time PCR. Immune cell changes caused by DEGs were detected by flow cytometry. Finally, the mechanism of FGR was explored by injecting the protein LCN2, corresponding to the selected DEG, into mice.

RESULTS

We verified the embryonic dysplasia in pregnant Pbx1^f/f ; Ncr1^Cre mice by Doppler ultrasound imaging and found that LCN2 was upregulated in dNK cells. We also observed higher infiltration of neutrophils and macrophages in the decidua of Pbx1^f/f ; Ncr1^Cre mice. Finally, we found an increase in the number and activation of neutrophils at the maternal-fetal interface after injecting LCN2 into pregnant mice and observed that these mice showed signs of FGR.

CONCLUSION

Excessive LCN2 secreted by PBX1^- dNK cells at the maternal-fetal interface recruit neutrophils and causes an inflammatory response, which is related to FGR.

Transthyretin Is Commonly Upregulated in the Hippocampus of Two Stress-Induced Depression Mouse Models

Chronic stress can affect gene expression in the hippocampus, which alters neural and cerebrovascular functions, thereby contributing to the development of mental disorders such as depression. Although several differentially expressed genes in the depressed brain have been reported, gene expression changes in the stressed brain remain underexplored. Therefore, this study examines hippocampal gene expression in two mouse models of depression induced by forced swim stress (FSS) and repeated social defeat stress (R-SDS). Transthyretin (Ttr) was commonly upregulated in the hippocampus of both mouse models, as determined by microarray, RT-qPCR, and Western blot analyses. Evaluation of the effects of overexpressed Ttr in the hippocampus using adeno-associated virus-mediated gene transfer revealed that TTR overexpression induced depression-like behavior and upregulation of Lcn2 and several proinflammatory genes (Icam1 and Vcam1) in the hippocampus. Upregulation of these inflammation-related genes was confirmed in the hippocampus obtained from mice vulnerable to R-SDS. These results suggest that chronic stress upregulates Ttr expression in the hippocampus and that Ttr upregulation may be involved in the induction of depression-like behavior.

The link between bone-derived factors osteocalcin, fibroblast growth factor 23, sclerostin, lipocalin 2 and tumor bone metastasis

The skeleton is the third most common site of metastatic disease, which causes serious bone complications and short-term prognosis in cancer patients. Prostate and breast cancers are responsible for the majority of bone metastasis, resulting in osteolytic or osteoblastic lesions. The crosstalk between bone cells and their interactions with tumor cells are important in the development of lesions. Recently, both preclinical and clinical studies documented the clinical relevance of bone-derived factors, including osteocalcin (OC) and its undercarboxylated form (ucOC), fibroblast growth factor 23 (FGF23), sclerostin (SCL), and lipocalin 2 (LCN2) as prognostic tumor biomarkers and potential therapeutic targets in bone metastasis. Both OC and ucOC could be useful targets for the prevention of bone metastasis in breast cancer. Moreover, elevated OC level may be a metastatic marker of prostate cancer. FGF23 is particularly important for those forms of cancer that primarily affect bone and/or are characterized by bone metastasis. In other tumor entities, increased FGF23 level is enigmatic. SCL plays a significant role in the pathogenesis of both osteolytic and osteoblastic lesions, as its levels are high in metastatic breast and prostate cancers. Elevated expression levels of LCN2 have been found in aggressive subtypes of cancer. However, its role in anti-metastasis varies significantly between different cancer types. Anyway, all aforementioned bone-derived factors can be used as promising tumor biomarkers. As metastatic bone disease is generally not curable, targeting bone factors represents a new trend in the prevention of bone metastasis and patient care.

Croix CM, Sinha D. Increased LCN2 (lipocalin 2) in the RPE decreases autophagy and activates inflammasome-ferroptosis processes in a mouse model of dry AMD

In dry age-related macular degeneration (AMD), LCN2 (lipocalin 2) is upregulated. Whereas LCN2 has been implicated in AMD pathogenesis, the mechanism remains unknown. Here, we report that in retinal pigmented epithelial (RPE) cells, LCN2 regulates macroautophagy/autophagy, in addition to maintaining iron homeostasis. LCN2 binds to ATG4B to form an LCN2-ATG4B-LC3-II complex, thereby regulating ATG4B activity and LC3-II lipidation. Thus, increased LCN2 reduced autophagy flux. Moreover, RPE cells from cryba1 KO, as well as sting1 KO and Sting1Gt mutant mice (models with abnormal iron chelation), showed decreased autophagy flux and increased LCN2, indicative of CGAS- and STING1-mediated inflammasome activation. Live cell imaging of RPE cells with elevated LCN2 also showed a correlation between inflammasome activation and increased fluorescence intensity of the Liperfluo dye, indicative of oxidative stress-induced ferroptosis. Interestingly, both in human AMD patients and in mouse models with a dry AMD-like phenotype (cryba1 cKO and KO), the LCN2 homodimer variant is increased significantly compared to the monomer. Sub-retinal injection of the LCN2 homodimer secreted by RPE cells into NOD-SCID mice leads to retinal degeneration. In addition, we generated an LCN2 monoclonal antibody that neutralizes both the monomer and homodimer variants and rescued autophagy and ferroptosis activities in cryba1 cKO mice. Furthermore, the antibody rescued retinal function in cryba1 cKO mice as assessed by electroretinography. Here, we identify a molecular pathway whereby increased LCN2 elicits pathophysiology in the RPE, cells known to drive dry AMD pathology, thus providing a possible therapeutic strategy for a disease with no current treatment options.Abbreviations: ACTB: actin, beta; Ad-GFP: adenovirus-green fluorescent protein; Ad-LCN2: adenovirus-lipocalin 2; Ad-LCN2-GFP: adenovirus-LCN2-green fluorescent protein; LCN2AKT2: AKT serine/threonine kinase 2; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ARPE19: adult retinal pigment epithelial cell line-19; Asp278: aspartate 278; ATG4B: autophagy related 4B cysteine peptidase; ATG4C: autophagy related 4C cysteine peptidase; ATG7: autophagy related 7; ATG9B: autophagy related 9B; BLOC-1: biogenesis of lysosomal organelles complex 1; BLOC1S1: biogenesis of lysosomal organelles complex 1 subunit 1; C57BL/6J: C57 black 6J; CGAS: cyclic GMP-AMP synthase; ChQ: chloroquine; cKO: conditional knockout; Cys74: cysteine 74; Dab2: DAB adaptor protein 2; Def: deferoxamine; DHE: dihydroethidium; DMSO: dimethyl sulfoxide; ERG: electroretinography; FAC: ferric ammonium citrate; Fe2+: ferrous; FTH1: ferritin heavy chain 1; GPX: glutathione peroxidase; GST: glutathione S-transferase; H2O2: hydrogen peroxide; His280: histidine 280; IFNL/IFNλ: interferon lambda; IL1B/IL-1β: interleukin 1 beta; IS: Inner segment; ITGB1/integrin β1: integrin subunit beta 1; KO: knockout; LC3-GST: microtubule associated protein 1 light chain 3-GST; C-terminal fusion; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; LCN2: lipocalin 2; mAb: monoclonal antibody; MDA: malondialdehyde; MMP9: matrix metallopeptidase 9; NLRP3: NLR family pyrin domain containing 3; NOD-SCID: nonobese diabetic-severe combined immunodeficiency; OS: outer segment; PBS: phosphate-buffered saline; PMEL/PMEL17: premelanosome protein; RFP: red fluorescent protein; rLCN2: recombinant LCN2; ROS: reactive oxygen species; RPE SM: retinal pigmented epithelium spent medium; RPE: retinal pigment epithelium; RSL3: RAS-selective lethal; scRNAseq: single-cell ribonucleic acid sequencing; SD-OCT: spectral domain optical coherence tomography; shRNA: small hairpin ribonucleic acid; SM: spent medium; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; STAT1: signal transducer and activator of transcription 1; STING1: stimulator of interferon response cGAMP interactor 1; TYR: tyrosinase; VCL: vinculin; WT: wild type.

Extracellular Vesicles' Role in the Pathophysiology and as Biomarkers in Cystic Fibrosis and COPD

In keeping with the extraordinary interest and advancement of extracellular vesicles (EVs) in pathogenesis and diagnosis fields, we herein present an update to the knowledge about their role in cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). Although CF and COPD stem from a different origin, one genetic and the other acquired, they share a similar pathophysiology, being the CF transmembrane conductance regulator (CFTR) protein implied in both disorders. Various subsets of EVs, comprised mainly of microvesicles (MVs) and exosomes (EXOs), are secreted by various cell types that are either resident or attracted in the airways during the onset and progression of CF and COPD lung disease, representing a vehicle for metabolites, proteins and RNAs (especially microRNAs), that in turn lead to events as such neutrophil influx, the overwhelming of proteases (elastase, metalloproteases), oxidative stress, myofibroblast activation and collagen deposition. Eventually, all of these pathomechanisms lead to chronic inflammation, mucus overproduction, remodeling of the airways, and fibrosis, thus operating a complex interplay among cells and tissues. The detection of MVs and EXOs in blood and biological fluids coming from the airways (bronchoalveolar lavage fluid and sputum) allows the consideration of EVs and their cargoes as promising biomarkers for CF and COPD, although clinical expectations have yet to be fulfilled.

Combination of IL-17A/F and TNF-α uniquely alters the bronchial epithelial cell proteome to enhance proteins that augment neutrophil migration

Background

The heterodimer interleukin (IL)-17A/F is elevated in the lungs in chronic respiratory disease such as severe asthma, along with the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). Although IL-17A/F and TNF-α are known to functionally cooperate to exacerbate airway inflammation, proteins altered by their interaction in the lungs are not fully elucidated.

Results

We used Slow Off-rate Modified Aptamer-based proteomic array to identify proteins that are uniquely and/or synergistically enhanced by concurrent stimulation with IL-17A/F and TNF-α in human bronchial epithelial cells (HBEC). The abundance of 38 proteins was significantly enhanced by the combination of IL-17A/F and TNF-α, compared to either cytokine alone. Four out of seven proteins that were increased > 2-fold were those that promote neutrophil migration; host defence peptides (HDP; Lipocalin-2 (LCN-2) and Elafin) and chemokines (IL-8, GROα). We independently confirmed the synergistic increase of these four proteins by western blots and ELISA. We also functionally confirmed that factors secreted by HBEC stimulated with the combination of IL-17A/F and TNF-α uniquely enhances neutrophil migration. We further showed that PI3K and PKC pathways selectively control IL-17A/F + TNF-α-mediated synergistic production of HDPs LCN-2 and Elafin, but not chemokines IL-8 and GROα. Using a murine model of airway inflammation, we demonstrated enhancement of IL-17A/F, TNF-α, LCN-2 and neutrophil chemokine KC in the lungs, thus corroborating our findings in-vivo.

Conclusion

This study identifies proteins and signaling mediated by concurrent IL-17A/F and TNF-α exposure in the lungs, relevant to respiratory diseases characterized by chronic inflammation, especially neutrophilic airway inflammation such as severe asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-022-00323-w.

NLRP3 activation in neutrophils induces lethal autoinflammation, liver inflammation, and fibrosis

Sterile inflammation is a central element in liver diseases. The immune response following injurious stimuli involves hepatic infiltration of neutrophils and monocytes. Neutrophils are major effectors of liver inflammation, rapidly recruited to sites of inflammation, and can augment the recruitment of other leukocytes. The NLRP3 inflammasome has been increasingly implicated in severe liver inflammation, fibrosis, and cell death. In this study, the role of NLRP3 activation in neutrophils during liver inflammation and fibrosis was investigated. Mouse models with neutrophil-specific expression of mutant NLRP3 were developed. Mutant mice develop severe liver inflammation and lethal autoinflammation phenocopying mice with a systemic expression of mutant NLRP3. NLRP3 activation in neutrophils leads to a pro-inflammatory cytokine and chemokine profile in the liver, infiltration by neutrophils and macrophages, and an increase in cell death. Furthermore, mutant mice develop liver fibrosis associated with increased expression of pro-fibrogenic genes. Taken together, the present work demonstrates how neutrophils, driven by the NLRP3 inflammasome, coordinate other inflammatory myeloid cells in the liver, and propagate the inflammatory response in the context of inflammation-driven fibrosis.

The role of lipocalin 2 in brain injury and recovery after ischemic and hemorrhagic stroke

Ischemic and hemorrhagic stroke (including intracerebral hemorrhage, intraventricular hemorrhage, and subarachnoid hemorrhage) is the dominating cause of disability and death worldwide. Neuroinflammation, blood–brain barrier (BBB) disruption, neuronal death are the main pathological progress, which eventually causes brain injury. Increasing evidence indicated that lipocalin 2 (LCN2), a 25k-Da acute phase protein from the lipocalin superfamily, significantly increased immediately after the stroke and played a vital role in these events. Meanwhile, there exists a close relationship between LCN2 levels and the worse clinical outcome of patients with stroke. Further research revealed that LCN2 elimination is associated with reduced immune infiltrates, infarct volume, brain edema, BBB leakage, neuronal death, and neurological deficits. However, some studies revealed that LCN2 might also act as a beneficial factor in ischemic stroke. Nevertheless, the specific mechanism of LCN2 and its primary receptors (24p3R and megalin) involving in brain injury remains unclear. Therefore, it is necessary to investigate the mechanism of LCN2 induced brain damage after stroke. This review focuses on the role of LCN2 and its receptors in brain injury and aiming to find out possible therapeutic targets to reduce brain damage following stroke.

Identification of Neutrophil-Related Factor LCN2 for Predicting Severity of Patients With Influenza A Virus and SARS-CoV-2 Infection

Background

Influenza and COVID-19 are respiratory infectious diseases that are characterized by high contagiousness and high mutation and pose a serious threat to global health. After Influenza A virus (IAV) and SARS-CoV-2 infection, severe cases may develop into acute lung injury. Immune factors act as an important role during infection and inflammation. However, the molecular immune mechanisms still remain unclear. We aimed to explore immune-related host factors and core biomarker for severe infection, to provide a new therapeutic target of host factor in patients.

Methods

Gene expression profiles were obtained from Gene Expression Omnibus and the Seurat R package was used for data process of single-cell transcriptome. Differentially expressed gene analysis and cell cluster were used to explore core host genes and source cells of genes. We performed Gene Ontology enrichment, Kyoto Encyclopedia of Genes and Genomes analysis, and gene set enrichment analysis to explore potential biological functions of genes. Gene set variation analysis was used to evaluate the important gene set variation score for different samples. We conduct Enzyme-linked immunosorbent assay (ELISA) to test plasma concentrations of Lipocalin 2 (LCN2).

Results

Multiple virus-related, cytokine-related, and chemokine-related pathways involved in process of IAV infection and inflammatory response mainly derive from macrophages and neutrophils. LCN2 mainly in neutrophils was significantly upregulated after either IAV or SARS-CoV-2 infection and positively correlated with disease severity. The plasma LCN2 of influenza patients were elevated significantly compared with healthy controls by ELISA and positively correlated with disease severity of influenza patients. Further bioinformatics analysis revealed that LCN2 involved in functions of neutrophils, including neutrophil degranulation, neutrophil activation involved in immune response, and neutrophil extracellular trap formation.

Conclusion

The neutrophil-related LCN2 could be a promising biomarker for predicting severity of patients with IAV and SARS-CoV-2 infection and may as a new treatment target in severe patients.

Gingival crevicular fluid lipocalin-2 and semaphorin3A in stage III periodontitis: Non-surgical periodontal treatment effects

BACKGROUND AND OBJECTIVE

Identification of biomarkers to assess individual risk and monitor periodontal health status is important. Research on lipocalin-2 (LCN2) and semaphorin3A (Sema3A) is lacking. This study aimed to evaluate gingival crevicular fluid (GCF) LCN2, Sema3A, and tumor necrosis factor-α (TNF-α) levels in periodontally healthy (H), gingivitis (G), and periodontitis (P) patients, and their changes following non-surgical periodontal therapy.

METHODS

Sixty systemically healthy and non-smoker participants, diagnosed as periodontally healthy, gingivitis, and stage III grade C periodontitis, were recruited (n = 20/group). Clinical periodontal parameters were recorded and GCF samples were obtained at baseline from all groups; for group P, these were repeated one and three months following non-surgical periodontal treatment. GCF LCN2, Sema3A, and TNF-α levels were evaluated with enzyme-linked immunosorbent assay.

RESULTS

GCF LCN2, Sema3A, and TNF-α total amounts were significantly higher in disease groups than group H (p < .001). Between P and G groups, only TNF-α levels were significantly different (p < .001). Non-surgical periodontal therapy resulted in significant improvement of all clinical parameters and significant decreases of GCF LCN2 and TNF-α levels, at both time points, compared with baseline (p < .001). Sema3A levels remained unchanged following treatment (p > .05). LCN2 and TNF-α levels were significantly positively correlated with clinical parameters. LCN2 (AUC [area under the curve] = 0.94) and TNF-α (AUC = 0.98) levels were similarly accurate in differentiating between periodontal disease (whether G or P) and healthy controls.

CONCLUSIONS

LCN2 and TNF-α levels in GCF are correlated with clinical parameters and could prove useful as non-invasive screening tools for periodontitis.

Critical changes in hypothalamic gene networks in response to pancreatic cancer as found by single-cell RNA sequencing

OBJECTIVE

Cancer cachexia is a devastating chronic condition characterized by involuntary weight loss, muscle wasting, abnormal fat metabolism, anorexia, and fatigue. However, the molecular mechanisms underlying this syndrome remain poorly understood. In particular, the hypothalamus may play a central role in cachexia, given that it has direct access to peripheral signals because of its anatomical location and attenuated blood-brain barrier. Furthermore, this region has a critical role in regulating appetite and metabolism.

METHODS

To provide a detailed analysis of the hypothalamic response to cachexia, we performed single-cell RNA-seq combined with RNA-seq of the medial basal hypothalamus (MBH) in a mouse model for pancreatic cancer.

RESULTS

We found many cell type-specific changes, such as inflamed endothelial cells, stressed oligodendrocyes and both inflammatory and moderating microglia. Lcn2, a newly discovered hunger suppressing hormone, was the highest induced gene. Interestingly, cerebral treatment with LCN2 not only induced many of the observed molecular changes in cachexia but also affected gene expression in food-intake decreasing POMC neurons. In addition, we found that many of the cachexia-induced molecular changes found in the hypothalamus mimic those at the primary tumor site.

CONCLUSION

Our data reveal that multiple cell types in the MBH are affected by tumor-derived factors or host factors that are induced by tumor growth, leading to a marked change in the microenvironment of neurons critical for behavioral, metabolic, and neuroendocrine outputs dysregulated during cachexia. The mechanistic insights provided in this study explain many of the clinical features of cachexia and will be useful for future therapeutic development.

Commonly expressed key transcriptomic profiles of sepsis in the human circulation and brain via integrated analysis

BACKGROUND

Sepsis is the leading cause of death in intensive care units and is characterized by multiple organ failure, including dysfuction of the immune system and brain. This study aims to determine the differential effect of sepsis on specific circulating immune cell subsets compared with brain transcriptome and identify the genes co-expressed by them, so as to identify key genes and regulatory factors involved in the pathogenesis of sepsis induced brain injury and identify novel therapeutic targets.

METHODS

The GSE133822 and GSE135838 datasets were obtained from the Gene Expression Omnibus (GEO) database and utilized for bioinformatics analyses. Functional enrichment analysis was used to identify commonly expressed genes that were differentially expressed between sepsis patients and non-sepsis patients with critical illness; protein-protein interaction (PPI) networks were also generated. Then, key transcriptomic biomarkers were further validated in an external dataset from the GEO. We also investigated the expression of key mRNAs in peripheral blood mononuclear cells (PBMCs) from sepsis patients by quantitative PCR (qPCR) and an in-vitro model stimulated by lipopolysaccharide (LPS) was generated in brain cell lines.

RESULTS

The transcriptomic profiles of brain tissue were relatively similar as those of specific immune cells. In addition, our validation showed that these key genes were up regulated both in PBMCs in sepsis patients and LPS-treated brain cells.

CONCLUSION

Brain injury in sepsis was correlated with circulating immune responses, and the expression of DEFA3, MMP8, MMP9 and LCN2 might be potential diagnostic biomarkers as well as therapeutic target in septic brain dysfunction.

Utility of Adipokines and IL-10 in Association with Anthropometry in Prediction of Insulin Resistance in Obese Children

AIM

This is a case-controlled study, with two hundred children enrolled. They were divided into an obese group of 100 children who had BMI ≥ 95th percentile according to CDC criteria and a group of 100 children with normal weight. All enrolled children were subjected to detailed medical history and clinical examination, in addition to measuring fasting blood sugar, fasting serum insulin, HOMA-IR calculation, lipid profile analysis, total serum cholesterol, low- and high-density lipoproteins (LDL and HDL), and serum triglyceride (TG). Two adipokines (lipocalin-2 and adipsin) serum levels plus IL-10 serum level were assessed.

RESULTS

Higher Z score of weight, MI, and waist/height ratio and high serum cholesterol, LDL, TG, and low HDL were observed in obese children. Higher levels of serum lipocalin-2 and adipsin and lower IL-10 blood level were observed in the obese group in comparison with the normal weight children. Higher insulin resistance index was observed in the obese group, with positive correlation of HOMA-IR with the anthropometric measurements and lipocalin serum level, while negative correlation was observed between IL-10 and fasting insulin in obese children.

CONCLUSION

Simple measurement of general and central adiposity markers and serum lipocalin-2 can predict insulin resistance in obese children while serum adipsin and IL-10 had no association with insulin resistance.

Depletion of Lipocalin 2 (LCN2) in Mice Leads to Dysbiosis and Persistent Colonization with Segmented Filamentous Bacteria

Lipocalin 2 (LCN2) mediates key roles in innate immune responses. It has affinity for many lipophilic ligands and binds various siderophores, thereby limiting bacterial growth by iron sequestration. Furthermore, LCN2 protects against obesity and metabolic syndrome by interfering with the composition of gut microbiota. Consequently, complete or hepatocyte-specific ablation of the Lcn2 gene is associated with higher susceptibility to bacterial infections. In the present study, we comparatively profiled microbiota in fecal samples of wild type and Lcn2 null mice and show, in contrast to previous reports, that the quantity of DNA in feces of Lcn2 null mice is significantly lower than that in wild type mice (p < 0.001). By using the hypervariable V4 region of the 16S rDNA gene and Next-Generation Sequencing methods, we found a statistically significant change in 16 taxonomic units in Lcn2^-/- mice, including eight gender-specific deviations. In particular, members of Clostridium, Escherichia, Helicobacter, Lactococcus, Prevotellaceae_UCG-001 and Staphylococcus appeared to expand in the intestinal tract of knockout mice. Interestingly, the proportion of Escherichia (200-fold) and Staphylococcus (10-fold) as well as the abundance of intestinal bacteria encoding the LCN2-sensitive siderphore enterobactin (entA) was significantly increased in male Lcn2 null mice (743-fold, p < 0.001). This was accompanied by significant higher immune cell infiltration in the ileum as demonstrated by increased immunoreactivity against the pan-leukocyte protein CD45, the lymphocyte transcription factor MUM-1/IRF4, and the macrophage antigen CD68/Macrosialin. In addition, we found a higher expression of mucosal mast cell proteases indicating a higher number of those innate immune cells. Finally, the ileum of Lcn2 null mice displayed a high abundance of segmented filamentous bacteria, which are intimately associated with the mucosal cell layer, provoking epithelial antimicrobial responses and affecting T-helper cell polarization.

Chronic mineral oil administration increases hepatic inflammation in wild type mice compared to lipocalin 2 null mice

Lipocalin 2 (LCN2), an acute-phase protein produced during acute liver injury, plays an important role in the innate immune response against bacterial infection via iron scavenging. LCN2 further influences neutrophil development and physiology leading to increased inflammatory responses. We investigated the roles of LCN2 in chronic inflammation and fibrosis, using repeated carbon tetrachloride (CCl4) in mineral-oil injection. Surprisingly, mice treated with the mineral oil vehicle alone showed liver inflammation, evidenced by neutrophil and monocyte-macrophage infiltration. Fluorescence-activated cell sorting (FACS) of isolated liver leukocytes showed significantly high CD45+ leukocyte concentrations in CCl4 mice, but no difference of Ly6G+ neutrophils between mineral oil and CCl4 application. Liver CD11b+ F4/80+ cells counted higher in CCl4 mice, but the proportions of Gr1high, an indicator of inflammation, were significantly higher in mineral oil groups. Liver myeloperoxidase (MPO), expressed in neutrophils and monocytes, showed higher levels in wild type mice compared to Lcn2-/- in both mineral-oil and CCl4 treated groups. Hepatic and serum LCN2 levels were remarkably higher in the mineral oil-injected wild type group compared to the CCl4. Wild type animals receiving mineral oil showed significantly higher inflammatory cytokine- and chemokine mRNA levels compared to Lcn2-/- mice, with no differences in the CCl4 treated groups. RNA sequencing (RNA-Seq) confirmed significant downregulation of gene sets involved in myeloid cell activation and immune responses in Lcn2 null mice receiving chronic mineral oil versus wild-type. We observed significant upregulation of gene sets and proteins involved in cell cycle DNA replication, with downregulation of collagen-containing extracellular matrix genes in Lcn2-/- mice receiving CCl4, compared to the wild type. Consequently, the wild type mice developed slightly more liver fibrosis compared to Lcn2-/- mice, evidenced by higher levels of collagen type I in the CCl4 groups and no liver fibrosis in mineral oil-treated mice. Our findings indicate that serum and hepatic LCN2 levels correlate with hepatic inflammation rather than fibrosis.

Neutrophil Gelatinase-Associated Lipocalin From Macrophages Plays a Critical Role in Renal Fibrosis Via the CCL5 (Chemokine Ligand 5)-Th2 Cells-IL4 (Interleukin 4) Pathway

NGAL (neutrophil gelatinase-associated lipocalin; or lipocalin 2, Lcn2) is a novel mineralocorticoid target in the cardiovascular system. We showed that Lcn2 gene invalidation protects against proteinuria and renal injury upon mineralocorticoid excess and we hypothesized that NGAL produced from macrophages promotes the expression of chemoattractant molecules involved these renal lesions. The role of NGAL was analyzed using myeloid-specific (MΦ KO NGAL) Lcn2 knockout mice challenged with uni-nephrectomy, aldosterone, and salt (NAS) for 6 weeks. The role of the CCL5 (chemokine ligand 5) and IL4 (interleukin 4) in kidney fibrosis was studied by administration of the CCL5 receptor antagonist maraviroc or by injections of an anti-IL4 neutralizing antibody. In CTL mice, NAS increased the renal expression of extracellular matrix proteins, such as collagen I, αSMA, and fibronectin associated with interstitial fibrosis which were blunted in MΦ KO NGAL mice. The expression of CCL5 was blunted in sorted macrophages from MΦ KO NGAL mice challenged by NAS and in macrophages obtained from KO NGAL mice and challenged ex vivo with aldosterone and salt. The pharmacological blockade of the CCL5 receptor reduced renal fibrosis and the CD4⁺ Th cell infiltration induced by NAS. Neutralization of IL4 in NAS mice blunted kidney fibrosis and the overexpression of profibrotic proteins, such as collagen I, αSMA, and fibronectin. In conclusion, NGAL produced by macrophages plays a critical role in renal fibrosis and modulates the CCL5/IL4 pathway in mice exposed to mineralocorticoid excess.

Markers for the involvement of endothelial cells and the coagulation system in chronic urticaria: A systematic review

Chronic urticaria (CU) is a chronic inflammatory mast cell-driven disorder. Endothelial cells (ECs) contribute importantly to key features of CU. Several markers of EC (dys)function in CU have been reported, but have not yet been systematically reviewed. In this study, we systematically reviewed and categorized all published markers of EC functions in CU through a comprehensive search in Pubmed, The Cochrane Library, Web of Science, and SCOPUS using the following Mesh terms: CU AND pathogenesis AND (vasculopathy OR microangiopathy OR ECs OR marker). In total, 79 articles were selected and the identified biomarkers were categorized according to EC (dys)function in CU. The most frequent and consistently reported upregulated biomarkers in CU skin were adhesion molecules, TF, and P-selectin. The most frequently reported upregulated and reliable biomarkers in sera of CU patients were F1+2 for coagulation cascade involvement, D-dimers for fibrinolysis, and MMP-9 for vascular permeability. Emerging biomarkers described in the selected articles were endostatin, heat shock proteins, cleaved high molecular weight kininogen, and adipokines. This systematic review contributes to the pool of growing evidence for vascular involvement in CU where EC dysfunction is present in different aspects of cell survival, maintenance of vascular structure, and coagulation/fibrinolysis balance.

Physiologic and molecular characterization of a novel murine model of metastatic head and neck cancer cachexia

BACKGROUND

Cancer cachexia is a metabolic disorder characterized by the progressive loss of fat and lean mass that results in significant wasting, ultimately leading to reduced quality of life and increased mortality. Effective therapies for cachexia are lacking, potentially owing to the mismatch in clinically relevant models of cachexia. Specifically, cachexia observed in a clinical setting is commonly associated with advanced or late-stage cancers that are metastatic, yet pre-clinical metastatic models of cachexia are limited. Furthermore, the prevalence of cachexia in head and neck cancer patients is high, yet few pre-clinical models of head and neck cancer cachexia exist. In addition to these shortcomings, cachexia is also heterogeneous among any given cancer, whereas patients with similar disease burden may experience significantly different degrees of cachexia symptoms. In order to address these issues, we characterize a metastatic model of human papilloma virus (HPV) positive head and neck squamous cell carcinoma that recapitulates the cardinal clinical and molecular features of cancer cachexia.

METHODS

Male and female C57BL/6 mice were implanted subcutaneously with oropharyngeal squamous cell carcinoma cells stably transformed with HPV16 E6 and E7 together with hRas and luciferase (mEERL) that metastasizes to the lungs (MLM). We then robustly characterize the physiologic, behavioural, and molecular signatures during tumour development in two MLM subclones.

RESULTS

Mice injected with MLM tumour cells rapidly developed primary tumours and eventual metastatic lesions to the lungs. MLM3, but not MLM5, engrafted mice progressively lost fat and lean mass during tumour development despite the absence of anorexia (P < 0.05). Behaviourally, MLM3-implanted mice displayed decreased locomotor behaviours and impaired nest building (P < 0.05). Muscle catabolism programmes associated with cachexia, including E3 ubiquitin ligase and autophagy up-regulation, along with progressive adipose wasting and accompanying browning gene signatures, were observed. Tumour progression also corresponded with hypothalamic and peripheral organ inflammation, as well as an elevation in neutrophil-to-lymphocyte ratio (P < 0.05). Finally, we characterize the fat and lean mass sparing effects of voluntary wheel running on MLM3 cachexia (P < 0.05).

CONCLUSIONS

This syngeneic MLM3 allograft model of metastatic cancer cachexia is reliable, consistent, and readily recapitulates key clinical and molecular features and heterogeneity of cancer cachexia. Because few metastatic models of cachexia exist-even though cachexia often accompanies metastatic progression-we believe this model more accurately captures cancer cachexia observed in a clinical setting and thus is well suited for future mechanistic studies and pre-clinical therapy development for this crippling metabolic disorder.

CSF lipocalin-2 increases early in subarachnoid hemorrhage are associated with neuroinflammation and unfavorable outcome

Lipocalin-2 mediates neuro-inflammation and iron homeostasis in vascular injuries of the central nervous system (CNS) and is upregulated in extra-CNS systemic inflammation. We postulate that cerebrospinal fluid (CSF) and blood lipocalin-2 levels are associated with markers of inflammation and functional outcome in subarachnoid hemorrhage (SAH). We prospectively enrolled 67 SAH subjects, serially measured CSF and plasma lipocalin-2, matrix metallopeptidase 9 (MMP-9), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) on post-SAH days 1-5 and assessed outcome by modified Rankin Scale (mRS) every 3 months. Unfavorable outcome is defined as mRS > 2. Twenty non-SAH patients undergoing lumbar drain trial were enrolled as controls. Lipocalin-2 was detectable in the CSF and significantly higher in SAH compared to controls (p < 0.0001). Higher CSF LCN2 throughout post-SAH days 1-5 was associated with unfavorable outcome at 3 (p = 0.0031) and 6 months (p = 0.014). Specifically, higher CSF lipocalin-2 on post-SAH days 3 (p = 0.036) and 5 (p = 0.016) were associated with unfavorable 3-month outcome. CSF lipocalin-2 levels positively correlated with CSF IL-6, TNF-α and MMP-9 levels. Higher plasma lipocalin-2 levels over time were associated with worse 6-month outcome. Additional studies are required to understand the role of lipocalin-2 in SAH and to validate CSF lipocalin-2 as a potential biomarker for SAH outcome.

Neutrophil Gelatinase-Associated Lipocalin Contributes to Increased Risk of Cardiovascular Death After Acute Coronary Syndrome

Background

Neutrophil gelatinase-associated lipocalin (NGAL) has been suggested to reflect early renal dysfunction. We investigated the predictive significance of serum NGAL in predicting cardiovascular (CV) death in an old-age population with coronary heart disease (CHD).

Methods

In total, 633 CHD patients with a stable clinical condition were enrolled. The measurements of serum NGAL and other laboratory indices were performed within 24 hours after admission. Adjusted analysis was used to assess relationships between serum NGAL and CV death during the 10-year follow-up period.

Results

Multivariate logistic regression analysis demonstrated that elevated NGAL levels were related to a higher prevalence of CV disease history [quartile 4, 2.41 (1.60–4.59), P-trend <0.001]. The Kaplan–Meier curve indicated that patients with high NGAL levels tended to have a higher rate of CV death than patients with low NGAL levels. A multivariate Cox model suggested that increased levels of NGAL were independently linked with elevated risk of CV death (HR=2.62, 95% CI 1.51–4.96, P<0.001) during the 10-year follow-up period, after adjusting for related confounding factors using sensitivity analysis. Furthermore, the receiver operating characteristics (ROC) curve demonstrated that serum NGAL (AUC=0.917, 95% CI 0.895–0.940, P<0.001) had an ideal predictive value in predicting CV death.

Conclusion

Serum levels of NGAL were elevated in patients with CHD and may be a new parameter that could independently predict CV death in these patients, which may strengthen its potential application in clinical practice.

Inhibition of Neutrophil Secretion Upon Adhesion as a Basis for the Anti-Inflammatory Effect of the Tricyclic Antidepressant Imipramine

Recent studies demonstrate the involvement of inflammatory processes in the development of depression and the anti-inflammatory effects of antidepressants. Infiltration and adhesion of neutrophils to nerve tissues and their aggressive secretion are considered as possible causes of inflammatory processes in depression. We studied the effect of the antidepressant imipramine on the adhesion and accompanied secretion of neutrophils under control conditions and in the presence of lipopolysaccharides (LPS). As a model of integrin-dependent neutrophil infiltration into tissues, we used integrin-dependent adhesion of neutrophils to the fibronectin-coated substrate. Imipramine inhibited neutrophil adhesion and concomitant secretion of proteins, including matrix metalloproteinase 9 (MMP-9) and neutrophil gelatinase-associated lipocalin (NGAL), which modify the extracellular matrix and basement membranes required for cell migration. Imipramine also significantly and selectively blocked the release of the free amino acid hydroxylysine, a product of lysyl hydroxylase, an enzyme that affects the organization of the extracellular matrix by modifying collagen lysine residues. In contrast, imipramine enhanced the release of ROS by neutrophils during adhesion to fibronectin and stimulated apoptosis. The anti-inflammatory effect of imipramine may be associated with the suppression of neutrophil infiltration and their adhesion to nerve tissues by inhibiting the secretion of neutrophils, which provides these processes.

In-Depth Analysis of the Hidradenitis Suppurativa Serum Proteome Identifies Distinct Inflammatory Subtypes

Hidradenitis suppurativa is a chronic inflammatory dermatosis with presentations ranging from painful nodules and abscesses to draining tunnels. Using an unbiased proteomics approach, we assessed cardiovascular-, cardiometabolic-, and inflammation-related biomarkers in the serum of patients with moderate-to-severe hidradenitis suppurativa. The serum of patients with hidradenitis suppurativa clustered separately from that of healthy controls and had an upregulation of neutrophil-related markers (Cathepsin D, IL-17A, CXCL1). Patients with histologically diagnosed dermal tunnels had higher serum lipocalin-2 levels compared with those without tunnels. Consistent with this, patients with tunnels had a more neutrophilic-rich serum signature, marked by Cathepsin D, IL-17A, and IL-17D alterations. There was a significant serum‒skin correlation between proteins in the serum and the corresponding mRNA expression in skin biopsies, with healthy-appearing perilesional skin demonstrating a significant correlation with neutrophil-related proteins in the serum. CSF3 mRNA levels in lesional skin significantly correlated with neutrophil-related proteins in the serum, suggesting that CFS3 in the skin may be a driver of neutrophilic inflammation. Clinical significantly correlated with the levels of lipocalin-2 and IL-17A in the serum. Using an unbiased, large-scale proteomic approach, we demonstrate that hidradenitis suppurativa is a systemic neutrophilic dermatosis, with a specific molecular signature associated with the presence of dermal tunnels.

Regulation of the Nfkbiz Gene and Its Protein Product IkBζ in Animal Models of Sepsis and Endotoxic Shock

Sepsis is a life-threatening condition that arises from a poorly regulated inflammatory response to pathogenic organisms. Current treatments are limited to antibiotics, fluid resuscitation, and other supportive therapies. New targets for monitoring disease progression and therapeutic interventions are therefore critically needed. We previously reported that lipocalin-2 (Lcn2), a bacteriostatic mediator with potent proapoptotic activities, was robustly induced in sepsis. Other studies showed that Lcn2 was a predictor of mortality in septic patients. However, how Lcn2 is regulated during sepsis is poorly understood. We evaluated how IkBζ, an inducer of Lcn2, was regulated in sepsis using both the cecal ligation and puncture (CLP) and endotoxemia (lipopolysaccharide [LPS]) animal models. We show that Nfkbiz, the gene encoding IkBζ, was rapidly stimulated but, unlike Lcn2, whose expression persists during sepsis, mRNA levels of Nfkbiz decline to near basal levels several hours after its induction. In contrast, we observed that IkBζ expression remained highly elevated in septic animals following CLP but not LPS, indicating the occurrence of a CLP-specific mechanism that extends IkBζ half-life. By using an inhibitor of IkBζ, we determined that the expression of Lcn2 was largely controlled by IkBζ. Altogether, these data indicate that the high IkBζ expression in tissues likely contributes to the elevated expression of Lcn2 in sepsis. Since IkBζ is also capable of promoting or repressing other inflammatory genes, it might exert a central role in sepsis.

Interaction between matrix metalloproteinase-9 (MMP-9) and neutrophil gelatinase-associated lipocalin (NGAL): A recent evolutionary event in primates

Matrix metalloproteases are known to represent an early step in the evolution of the immune system. Similarly, neutrophil gelatinase-associated lipocalin is known to be a key effector in immune response. MMP-9 interacts with NGAL, but their interaction mechanisms remain unclear. Functional interaction between proteins is ensured by coevolution. Protein coevolution was inferred by calculating the linear correlation coefficients between inter-protein distance matrices using MirrorTree. Among examined mammal species, we found a robust signal of MMP-9/NGAL coevolution exclusively within Primates (R = 0.96, p < 1e-06). Owing to the high conservation of these proteins among Mammals, we chose to utilize a recent version of Blocks in Sequences (BIS2) algorithm implemented in BIS2Analyzer webserver. Coevolution clusters between the two proteins were identified in MMP-9 fibronectin and hemopexin domains. Our results suggest that MMP-9/NGAL interaction is a recent evolutionary acquisition in Primates. Furthermore, MMP-9 hemopexin domain would represent a promising target for drug design against these molecules.

Antifibrotic effect of novel neutrophil gelatinase-associated lipocalin inhibitors in cardiac and renal disease models

Neutrophil gelatinase-associated lipocalin (NGAL) is involved in cardiovascular and renal diseases. Gene inactivation of NGAL blunts the pathophysiological consequences of cardiovascular and renal damage. We aimed to design chemical NGAL inhibitors and investigate its effects in experimental models of myocardial infarction (MI) and chronic kidney disease induced by 5/6 nephrectomy (CKD) on respectively 8–12 weeks old C57Bl6/j and FVB/N male mice. Among the 32 NGAL inhibitors tested, GPZ614741 and GPZ058225 fully blocked NGAL-induced inflammatory and profibrotic markers in human cardiac fibroblasts and primary mouse kidney fibroblasts. The administration of GPZ614741 (100 mg/kg/day) for three months, was able to improve cardiac function in MI mice and reduced myocardial fibrosis and inflammation. The administration of GPZ614741 (100 mg/kg/day) for two months resulting to no renal function improvement but prevented the increase in blood pressure, renal tubulointerstitial fibrosis and profibrotic marker expression in CKD mice. In conclusion, we have identified new compounds with potent inhibitory activity on NGAL-profibrotic and pro-inflammatory effects. GPZ614741 prevented interstitial fibrosis and dysfunction associated with MI, as well as tubulointerstitial fibrosis in a CKD model. These inhibitors could be used for other diseases that involve NGAL, such as cancer or metabolic diseases, creating new therapeutic options.

Iron in immune cell function and host defense

The control over iron availability is crucial under homeostatic conditions and even more in the case of an infection. This results from diverse properties of iron: first, iron is an important trace element for the host as well as for the pathogen for various cellular and metabolic processes, second, free iron catalyzes Fenton reaction and is therefore producing reactive oxygen species as a part of the host defense machinery, third, iron exhibits important effects on immune cell function and differentiation and fourth almost every immune activation in turn impacts on iron metabolism and spatio-temporal iron distribution. The central importance of iron in the host and microbe interplay and thus for the course of infections led to diverse strategies to restrict iron for invading pathogens. In this review, we focus on how iron restriction to the pathogen is a powerful innate immune defense mechanism of the host called "nutritional immunity". Important proteins in the iron-host-pathogen interplay will be discussed as well as the influence of iron on the efficacy of innate and adaptive immunity. Recently described processes like ferritinophagy and ferroptosis are further covered in respect to their impact on inflammation and infection control and how they impact on our understanding of the interaction of host and pathogen.

The impact of blood-processing time on the proteome of human peripheral blood mononuclear cells

Human peripheral blood mononuclear cells (PBMC) are key to several diagnostics assays and basic science research. Blood pre-analytical variations that occur before obtaining the PBMC fraction can significantly impact the assays results, including viability, composition, integrity, and gene expression changes of immune cells. With this as motivation, we performed a quantitative shotgun proteomics analysis using Isobaric Tag for Relative and Absolute Quantitation (iTRAQ 8plex) labeling to compare PBMC obtained from 24 h-stored blood at room temperature versus freshly isolated. We identified a total of 3195 proteins, of which 245 were differentially abundant (101 upregulated and 144 downregulated). Our results revealed enriched pathways of downregulated proteins related to exocytosis, localization, vesicle-mediated transport, cell activation, and secretion. In contrast, pathways related to exocytosis, neutrophil degranulation and activation, granulocyte activation, leukocyte degranulation, and myeloid leukocyte activation involved in immune response were enriched in upregulated proteins, which may indicate probable granulocyte contamination and activation due to blood storage time and temperature. Examples of upregulated proteins in the 24 h-PBMC samples are CAMP, S100A8, LTA4H, RASAL3, and S100A6, which are involved in an adaptive immune system and antimicrobial activity, proinflammatory mediation, aminopeptidase activities, and naïve T cells survival. Moreover, examples of downregulated proteins are NDUFA5, TAGLN2, H3C1, TUBA8, and CCT2 that are related to the cytoskeleton, cell junction, mitochondrial respiratory chain. In conclusion, the delay in blood-processing time directly impacts the proteomic profile of human PBMC, possibly through granulocyte contamination and activation.

Impact of bacterial infections on erythropoiesis

INTRODUCTION

The importance of iron is highlighted by the many complex metabolic pathways in which it is involved. A sufficient supply is essential for the effective production of 200 billion erythrocytes daily, a process called erythropoiesis.

AREAS COVERED

During infection, the human body can withhold iron from pathogens, mechanism termed nutritional immunity. The subsequent disturbances in iron homeostasis not only impact on immune function and infection control, but also negatively affect erythropoiesis. The complex interplay between iron, immunity, erythropoiesis and infection control on the molecular and clinical level are highlighted in this review. Diagnostic algorithms for correct interpretation and diagnosis of the iron status in the setting of infection are presented. Therapeutic concepts are discussed regarding effects on anemia correction, but also toward their role on the course of infection.

EXPERT OPINION

In the setting of infection, anemia is often neglected and its impact on the course of diseases is incompletely understood. Clinical expertise can be improved in correct diagnosing of anemia and disturbances of iron homeostasis. Systemic studies are needed to evaluate the impact of specific therapeutic interventions on anemia correction on the course of infection, but also on patients' cardiovascular performance and quality of life.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

Adipokines as Biomarkers of Atopic Dermatitis in Adults

Atopic dermatitis (AD) is characterized by chronic, relapsing, pruritic skin inflammation and does not have a well-understood pathogenesis. In this study, we addressed the contribution of adipokines to AD eczema based on the assessment of blood levels of adiponectin, resistin, leptin, lipocalin-2, and vaspin in adult non-obese patients suffering from chronic extrinsic childhood-onset AD. We investigated 49 AD patients with a median age of 37 years. The control group consisted of 30 age-matched healthy subjects. Adipokines were assessed in the serum by ELISA assays and the severity of AD with the SCORing Atopic Dermatitis (SCORAD) index. We found that adiponectin and resistin decreased and leptin appreciably increased in AD patients when compared to those in healthy subjects. Further, the levels of adiponectin and resistin were inversely related to the intensity of eczema. In conclusion, apart from the formerly investigated role of leptin in AD, this study points to adiponectin and resistin as the potential candidate adipokine biomarkers involved in shaping eczema intensity and severity, which may help predict disease exacerbations and enable the development of effective targeted therapeutic interventions.

Lipocalin-2 deficiency may predispose to the progression of spontaneous age-related adiposity in mice

Lipocalin-2 (Lcn2) is an innate immune protein elevated by several orders of magnitude in various inflammatory conditions including aging and obesity. Recent studies have shown that Lcn2 is secreted by adipocytes in response to inflammation and is categorized as a new adipokine cross-linking innate immunity and metabolic disorders including obesity. However, the involvement of Lcn2 and its function during the progression of obesity is largely unknown. Recently, browning of white adipose tissue (WAT) has gained attention as a therapeutic strategy to combat obesity. Herein, we have shown that treatment of mature 3T3-L1 adipocytes with recombinant Lcn2 (rec-Lcn2) resulted in the up-regulation of thermogenic and beige/brown markers (UCP1, PRDM16, ZIC-1 and TBX1) and increased mitochondrial activity. Additionally, global Lcn2 genetic knockout (Lcn2KO) mice exhibited accelerated weight gain and visceral fat deposition with age, when compared to wild type (WT) mice. Taken together, both in vitro and in vivo studies suggest that Lcn2 is a naturally occurring adipokine, and may serve as an anti-obesity agent by upregulating the thermogenic markers resulting in the browning of WAT. Therefore, Lcn2 and its downstream signaling pathways could be a potential therapeutic target for obesity.

The Dual Role of Reactive Oxygen Species-Generating Nicotinamide Adenine Dinucleotide Phosphate Oxidases in Gastrointestinal Inflammation and Therapeutic Perspectives

Significance: Despite their intrinsic cytotoxic properties, mounting evidence indicates that reactive oxygen species (ROS) physiologically produced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) of epithelial cells (NOX1, dual oxidase [DUOX]2) and phagocytes (NOX2) are critical for innate immune response and homeostasis of the intestinal mucosa. However, dysregulated ROS production could be a driving factor in inflammatory bowel diseases (IBDs). Recent Advances: In addition to NOX2, recent studies have demonstrated that NOX1- and DUOX2-derived ROS can regulate intestinal innate immune defense and homeostasis by impacting many processes, including bacterial virulence, expression of bacteriostatic proteins, epithelial renewal and restitution, and microbiota composition. Moreover, the antibacterial role of DUOX2 is a function conserved in evolution as it has been described in invertebrates, and lower and higher vertebrates. In humans, variants of the NOX2, NOX1, and DUOX2 genes, which are associated with impaired ROS production, have been identified in very early onset IBD, but overexpression of NOX/DUOX, especially DUOX2, has also been described in IBD, suggesting that loss-of-function or excessive activity of the ROS-generating enzymes could contribute to disease progression. Critical Issues: Therapeutic perspectives aiming at targeting NOX/DUOX in IBD should take into account the two sides of NOX/DUOX-derived ROS in intestinal inflammation. Hence, NOX/DUOX inhibitors or ROS inducers should be considered as a function of the disease context. Future Directions: A thorough understanding of the physiological and pathological regulation of NOX/DUOX in the gastrointestinal tract is an absolute pre-requisite for the development of therapeutic strategies that can modulate ROS levels in space and time.

Dendritic cells are crucial for cardiovascular remodeling and modulate neutrophil gelatinase-associated lipocalin expression upon mineralocorticoid receptor activation

BACKGROUND

Adaptive immunity is crucial in cardiovascular and renal inflammation/fibrosis upon hyperactivation of mineralocorticoid receptor. We have previously demonstrated that dendritic cells can respond to mineralocorticoid receptor activation, and the neutrophil gelatinase-associated lipocalin (NGAL) in dendritic cells is highly increased during aldosterone (Aldo)/mineralocorticoid receptor-dependent cardiovascular damage. However, the interrelationship among dendritic cells, target organs inflammation/fibrosis induced by mineralocorticoid receptor, and NGAL-dependence remains unknown.

OBJECTIVE

We studied the role of dendritic cells in mineralocorticoid receptor-dependent tissue remodeling and whether NGAL can modulate the inflammatory response of dendritic cells after mineralocorticoid receptor activation.

METHODS

Cardiovascular and renal remodeling induced by Aldo and high-salt diet [nephrectomy-Aldo-salt (NAS) model] were analyzed in CD11c.DOG mice, a model which allows dendritic cells ablation by using diphtheria toxin. In addition, in-vitro studies in NGAL-knock out dendritic cells were performed to determine the immunomodulatory role of NGAL upon Aldo treatment.

RESULTS

The ablation of dendritic cells prevented the development of cardiac hypertrophy, perivascular fibrosis, and the overexpression of NGAL, brain natriuretic peptide, and two profibrotic factors induced by NAS: collagen 1A1 and connective tissue growth factor. We determined that dendritic cells were not required to prevent renal hypertrophy/fibrosis induced by NAS. Between different immune cells analyzed, we observed that NGAL abundance was higher in antigen-presenting cells, while in-vitro studies showed that mineralocorticoid receptor stimulation in dendritic cells favored NGAL and IL-23 expression (p19 and p40 subunits), which are involved in the development of fibrosis and the Th17-driven response, respectively.

CONCLUSION

NGAL produced by dendritic cells may play a pivotal role in the activation of adaptive immunity that leads to cardiovascular fibrosis during mineralocorticoids excess.

Roles of bone-derived hormones in type 2 diabetes and cardiovascular pathophysiology

Background

Emerging evidence demonstrates that bone is an endocrine organ capable of influencing multiple physiological and pathological processes through the secretion of hormones. Recent research suggests complex crosstalk between the bone and other metabolic and cardiovascular tissues. It was uncovered that three of these bone-derived hormones—osteocalcin, lipocalin 2, and sclerostin—are involved in the endocrine regulations of cardiometabolic health and play vital roles in the pathophysiological process of developing cardiometabolic syndromes such as type 2 diabetes and cardiovascular disease. Chronic low-grade inflammation is one of the hallmarks of cardiometabolic diseases and a major contributor to disease progression. Novel evidence also implicates important roles of bone-derived hormones in the regulation of chronic inflammation.

Scope of review

In this review, we provide a detailed overview of the physiological and pathological roles of osteocalcin, lipocalin 2, and sclerostin in cardiometabolic health regulation and disease development, with a focus on the modulation of chronic inflammation.

Major conclusions

Evidence supports that osteocalcin has a protective role in cardiometabolic health, and an increase of lipocalin 2 contributes to the development of cardiometabolic diseases partly via pro-inflammatory effects. The roles of sclerostin appear to be complicated: It exerts pro-adiposity and pro-insulin resistance effects in type 2 diabetes and has an anti-calcification effect during cardiovascular disease. A better understanding of the actions of these bone-derived hormones in the pathophysiology of cardiometabolic diseases will provide crucial insights to help further research develop new therapeutic strategies to treat these diseases.

Lipocalin-2 expression and function in pancreatic diseases

Lipocalin-2 (LCN2) is a secreted molecule, expressed in various cell types, that is involved in the progression of numerous diseases and disorders. The biological functions and expression levels of LCN2 in diseases including pancreatic cancer, pancreatitis (acute and chronic), and diabetes mellitus, suggest the potential role of LCN2 as a biomarker and/or therapeutic target. However, findings on the role of LCN2 in pancreatic diseases have been contradictory. In pancreatic cancer and pancreatitis, LCN2 has been identified as a potential biomarker; increased expression levels in various biological specimens correlate with the presence of the disease and may be able to differentiate cancer and chronic pancreatitis from healthy subjects. LCN2 is also known to be an adipokine; it is upregulated in obesity and is a common co-factor in the development of pancreatic diseases. Emerging research suggests LCN2 is elevated in type 2 diabetes mellitus, but the exact role of LCN2 in this disease is not clear. In this review, we summarize research on LCN2 as it relates to pancreatic diseases, highlighting the discrepancies in the literature. By explaining and clarifying the role of LCN2 in these disorders, we aim to promote research in developing novel diagnostic and treatment strategies to reduce the burden of pancreatic diseases.