Neutrophil apoptosis: impact of granulocyte macrophage colony stimulating factor on cell survival and viability in chronic kidney disease and hemodialysis patients

Inflammation: the driver of poor outcomes among children with severe acute malnutrition?

Severe acute malnutrition (SAM) is the most life-threatening form of undernutrition and underlies at least 10% of all deaths among children younger than 5 years in low-income countries. SAM is a complex, multisystem disease, with physiological perturbations observed in conjunction with the loss of lean mass, including structural and functional changes in many organ systems. Despite the high mortality burden, predominantly due to infections, the underlying pathogenic pathways remain poorly understood. Intestinal and systemic inflammation is heightened in children with SAM. Chronic inflammation and its consequent immunomodulation may explain the increased morbidity and mortality from infections in children with SAM, both during hospitalization and in the longer term after discharge. Recognition of the role of inflammation in SAM is critical in considering new therapeutic targets in this disease, which has not seen a transformational approach to treatment for several decades. This review highlights the central role of inflammation in the wide-ranging pathophysiology of SAM, as well as identifying potential interventions that have biological plausibility based on evidence from other inflammatory syndromes.

The outer membrane protein Tp92 of Treponema pallidum delays human neutrophil apoptosis via the ERK, PI3K/Akt, and NF-κB pathways

Syphilis is a persistent sexually transmitted disease caused by infiltration of the elusive pathogen Treponema pallidum. Despite the prevalence of human polymorphonuclear neutrophils (hPMNs) within cutaneous lesions, which are characteristic of incipient syphilis, their role in T. pallidum infection remains unclear. Tp92 is the only T. pallidum helical outer membrane protein that exhibits structural features similar to those of outer membrane proteins in other gram-negative bacteria. However, the functional mechanism of this protein in immune cells remains unclear. Neutrophils are short-lived cells that undergo innate apoptosis in response to external stimuli that typically influence this process. In this study, we determined that Tp92 impedes the activation of procaspase-3 via the ERK MAPK, PI3K/Akt, and NF-κB signaling pathways, consequently suppressing caspase-3 activity within hPMNs, and thereby preventing hPMNs apoptosis. Furthermore, Tp92 could also modulate hPMNs apoptosis by enhancing the expression of the anti-apoptotic protein Mcl-1, stimulating IL-8 secretion, and preserving the mitochondrial membrane potential. These findings provide valuable insights into the molecular mechanisms underlying T. pallidum infection and suggest potential therapeutic targets for syphilis treatment.

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Myeloid leukocytes' diverse effects on cardiovascular and systemic inflammation in chronic kidney disease

Chronic kidney disease's prevalence rises globally. Whereas dialysis treatment replaces the kidney's filtering function and prolongs life, dreaded consequences in remote organs develop inevitably over time. Even milder reductions in kidney function not requiring replacement therapy associate with bacterial infections, cardiovascular and heart valve disease, which markedly limit prognosis in these patients. The array of complications is diverse and engages a wide gamut of cellular and molecular mechanisms. The innate immune system is profoundly and systemically altered in chronic kidney disease and, as a unifying element, partakes in many of the disease's complications. As such, a derailed immune system fuels cardiovascular disease progression but also elevates the propensity for serious bacterial infections. Recent data further point towards a role in developing calcific aortic valve stenosis. Here, we delineate the current state of knowledge on how chronic kidney disease affects innate immunity in cardiovascular organs and on a systemic level. We review the role of circulating myeloid cells, monocytes and neutrophils, resident macrophages, dendritic cells, ligands, and cellular pathways that are activated or suppressed when renal function is chronically impaired. Finally, we discuss myeloid cells' varying responses to uremia from a systems immunology perspective.

Replacing centrifugation with mixing in urine analysis enriches protein pool in the urine samples

Urine is the basic diagnostic material, easy to collect, not requiring invasive approach. During standard procedure the urine samples are centrifuged and the supernatant analysed physically, biochemically, and microscopically. The centrifugation step removes proteins including those forming aggregates especially in the state of illness and after transplantation. Here, we analysed the effect of urine centrifuging on specific protein content in urine samples obtained from cardiovascular patients (CVD) and after kidney or liver transplantation. We tested homogeneous whole urine samples, standardly centrifuge one, and the pellet after centrifuging. Protein content was examined using Western blot analysis and mass spectrometry (MS) of samples from CVD patients or the one after transplantation. The average of 21% proteins from non-centrifuged samples were found in the pellet removed after standard centrifugation. MS analysis confirmed that diagnostically important proteins were located there in. In 90% of cases whole urine samples contained more proteins than standard supernatant, among them e.g. proteins involved in immunological response like immunoglobulins and complement compounds secreted by leucocytes. Replacing centrifuging with intensive mixing of urine samples provides a method of enriching the samples with proteins removed during standard procedure, thus increasing possibility of finding new biomarkers for diseases undiagnosable with classic urine analysis.

Oxidative stress, immunological and cellular hypoxia biomarkers in hepatitis C treatment-naïve and cirrhotic patients

INTRODUCTION

Hepatitis C virus (HCV) is the main cause of chronic liver disease, with calamitous complications. Its highest rate is recorded in Egypt. This study investigated whether oxidative stress, immunological chaos and cellular hypoxia are implicated in the pathophysiology of the disease.

MATERIAL AND METHODS

This cross-sectional study aimed to evaluate the changes in blood oxidative stress, cellular hypoxia/angiogenesis and cellular immunological biomarkers in hospital-diagnosed treatment-naïve HCV-infected Upper Egyptian chronic liver disease patients vs. healthy controls (n = 40). The consecutively included patients comprised 120 with normal serum enzymes (HCV-NE) and 130 with high serum enzymes (HCV-HE), along with 120 cirrhotic patients.

RESULTS

Oxidative stress biomarkers - malondialdehyde (MDA), total peroxides and oxidative stress index (OSI) - were significantly lower in controls vs. each of the patient groups. Cirrhotic patients presented the highest levels. However, total antioxidants (TAO) showed non-significant differences among the four groups. The cellular hypoxia/angiogenesis biomarkers - lactate, vascular endothelial cell growth factor (VEGF) and its soluble receptor 1 (sVEGFR1) - vs. controls were massively increased in patient groups. VEGF was lowest while sVEGFR1 was highest among cirrhotic patients. Immunological biomarkers, - granulocyte/monocyte-colony stimulating factor (GM-CSF) and total immunoglobulin G (IgG) - were massively increased in patient groups vs. controls. GM-CSF was lowest in HCV-HE and IgG was highest in cirrhotic patients. sVEGFR1 correlated with the progression towards cirrhosis.

CONCLUSIONS

Oxidative stress is implicated in the progress of HCV infection with marked induction of cellular hypoxia and dysfunctional angiogenesis, and a futile immunological reaction. sVEGFR1 level correlated with progression towards HCV-induced liver fibrosis.

Apocynin prevents GM-CSF-induced-ERK1/2 activation and -neutrophil survival independently of its inhibitory effect on the phagocyte NADPH oxidase NOX2

Neutrophils are key cells in innate immunity and inflammation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to enhance many neutrophil functions such as reactive oxygen species (ROS) production, degranulation and cell survival via the activation of the ERK1/2 pathway. ERK1/2 pathway activation is redox sensitive and could be modulated by ROS. In order to investigate whether NADPH oxidase NOX2-derived ROS could contribute to GM-CSF-induced ERK1/2 phosphorylation, we tested the effect of two selective NOX2 inhibitors, diphenylene iodonium (DPI) and apocynin. Results showed that, while both DPI and apocynin strongly inhibited neutrophil ROS production, only apocynin, but not DPI, inhibited GM-CSF-induced ERK1/2 phosphorylation, suggesting that ROS are not involved in this process. Apocynin did not affect GM-CSF-induced p38MAPKinase phosphorylation, another redox sensitive kinase. Interestingly, apocynin inhibited GM-CSF-induced MEK1/2 and AKT phosphorylation without affecting fMLF-induced phosphorylation of these proteins. GM-CSF is known to inhibit neutrophils apoptosis and to promote cell survival via the AKT-ERK1/2 pathway. In this regard, we found that apocynin also inhibited GM-CSF-induced anti-apoptotic effect in neutrophils. These results suggest that NADPH oxidase NOX2-derived ROS are not involved in GM-CSF-induced ERK1/2 phosphorylation and that apocynin inhibits GM-CSF-induced ERK1/2 phosphorylation pathway independently of its inhibitory action on NADPH oxidase NOX2. Thus, apocynin can exert an anti-inflammatory effect not only by limiting neutrophil ROS production but also by decreasing neutrophil survival at inflammatory site.

Neutrophil Elastase Inhibitors and Chronic Kidney Disease

End-stage renal disease (ESRD), the last stage of chronic kidney disease (CKD), is characterized by chronic inflammation and oxidative stress. Neutrophils are the front line cells that mediate an inflammatory response against microorganisms as they can migrate, produce reactive oxygen species (ROS), secrete neutrophil serine proteases (NSPs), and release neutrophil extracellular traps (NETs). Serine proteases inhibitors regulate the activity of serine proteases and reduce neutrophil accumulation at inflammatory sites. This review intends to relate the role of neutrophil elastase in CKD and the effects of neutrophil elastase inhibitors in predicting or preventing inflammation.

The role of granulocyte macrophage colony stimulating factor in hospitalized children with Mycoplasma pneumoniae pneumonia

BACKGROUND

Inappropriate inflammatory response in children with M. pneumoniae infection might be associated with disease severity. The role of Granulocyte macrophage colony stimulating factor (GM-CSF) in hospitalized children with Mycoplasma pneumoniae pneumonia (MPP) has not been fully discussed.

METHODS

Clinical and laboratory data of a total 40 children with MPP were collected. GM-CSF and myeloperoxidase (MPO) were detected by ELISAs. Meanwhile, normal human bronchial epithelium was infected by M. pneumoniae and neutrophils were stimulated by GM-CSF to explore GM-CSF and MPO release in supernatant, respectively.

RESULTS

Compared to control group, a significant increased percentage of neutrophils and decreased percentage of macrophages in bronchoalveolar lavage fluid of children with MPP was observed (P < 0.05). Children with MPP had significantly higher levels of GM-CSF (P = 0.0047) and MPO (P = 0.0002) in BALF compared to the controls. Level of GM-CSF in BALF was associated with duration of fever (r = 0.42, P = 0.007) and strongly correlated with level of MPO (r = 0.075, P = 0.0005). Levels of GM-CSF and MPO significantly decreased (both P < 0.05) after treatment. In vitro, M. pneumoniae induced GM-CSF expression in a time-dependent manner during a 72-h period (P < 0.05) and MPO secretion significantly increased by recombinant human GM-CSF stimulation at 24h (P < 0.05).

CONCLUSION

GM-CSF could be induced by M. pneumoniae infection in vivo and vitro. Childen with high level GM-CSF had longer duration of fever. GM-CSF probably plays a vital role in neutrophil inflammation in M. pneumoniae infection.

Neutrophil-Derived Interleukin 16 in Premetastatic Lungs Promotes Breast Tumor Cell Seeding

The premetastatic niche in distant organs prior to metastatic cell arrival emerged as an important step in the metastatic cascade. However, molecular mechanisms underlying this process are still poorly understood. In particular, whether neutrophil recruitment at a premetastatic stage promotes or inhibits metastatic cell seeding has to be clarified. We aimed at unraveling how neutrophil infiltration in lung parenchyma induced by the distant primary tumor influences the establishment of lung metastasis. Elevated neutrophil counts and IL-16 levels were found in premetastatic lungs in a syngenic mouse model using 4T1 tumor cells. 4T1 cell-derived soluble factors stimulated IL-16 secretion by neutrophils. The functional contribution of IL-16 is supported by metastasis burden reduction in lungs observed on instillation of an IL-16 neutralizing antibody. Moreover, IL-16 promotes in vitro 4T1 cell adhesiveness, invasiveness, and migration. In conclusion, at a premetastatic stage, neutrophil-derived IL-16 favors tumor cell engraftment in lung parenchyma.

The role of polymorphonuclear neutrophils during HIV-1 infection

It is well-recognized that human immunodeficiency virus type-1 (HIV-1) mainly targets CD4⁺ T cells and macrophages. Nonetheless, during the past three decades, a huge number of studies have reported that HIV-1 can directly or indirectly target other cellular components of the immune system including CD8⁺ T cells, B cells, dendritic cells, natural killer cells, and polymorphonuclear neutrophils (PMNs), among others. PMNs are the most abundant leukocytes in the human circulation, and are known to play principal roles in the elimination of invading pathogens, regulating different immune responses, healing of injured tissues, and maintaining mucosal homeostasis. Until recently, little was known about the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression. This is because early studies focused on neutropenia and recurrent microbial infections, particularly, during advanced disease. However, recent studies have extended the investigation area to cover new aspects of the interactions between HIV-1 and PMNs. This review aims to summarize these advances and address the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression to better understand the pathophysiology of HIV-1 infection.

Fibroblast growth factor 23, iron and inflammation - are they related in early stages of chronic kidney disease?

INTRODUCTION

Fibroblast growth factor 23 (FGF-23) levels are elevated in impaired renal function. Inflammation and iron are potential regulators of FGF-23. The aim of the study was to evaluate the association between FGF-23 concentration, novel iron status biomarkers and inflammatory parameters among patients with early stages of chronic kidney disease (CKD).

MATERIAL AND METHODS

The study population included 84 patients with CKD in the early stage. Serum hemoglobin, fibrinogen, creatinine, iron, transferrin saturation and ferritin levels were measured using standard laboratory methods. Commercially available kits were used to measure: intact FGF-23, hepcidin, soluble transferrin receptor (sTfR), interleukin 6 (IL-6) and high-sensitivity C-reactive protein (hsCRP).

RESULTS

In patients with CKD no differences in FGF-23 concentration according to iron status were observed. Lower iron concentration was associated with higher concentrations of hsCRP, IL-6 and fibrinogen. In univariate and multivariate analysis FGF-23 correlated with fibrinogen (r = -0.23, p < 0.05) and eGFR (r = -0.36, p < 0.05).

CONCLUSIONS

FGF-23 is affected by kidney function and fibrinogen but not iron status parameters in the early stages of CKD. Our data are paving the way for further studies on the role of FGF-23 in iron metabolism, especially in early stages of CKD.

Induction of mitochondrial apoptotic pathway by raloxifene and estrogen in human endometrial stromal ThESC cell line

INTRODUCTION

Endometrial hyperplasia is a condition that occurs as a result of hormonal imbalance between estrogen and progesterone. Morphological disturbance of endometrial cells occurs consequently leading towards endometrial cancer. In therapy of endometrial hyperplasia SERMs are used to supress effects of locally high estrogen level in uterus. There is strong evidence suggesting that estrogen could be involved in cell death - apoptosis. There are no experimental data demstrating the direct apoptotic effect of both raloxifene and estrogen on the ThESC cell line. The aim of our study wa sto investigate both cytotoxic and apototic mechanism of raloxifene and estrogen - induced death in the ThESC cell line.

MATERIAL AND METHODS

In order to determine their cytotoxic and apoptotic effects, various doses of raloxifene and estrogen were applied to the ThESC cell line for 24 h. After the treatment MTT assay, FACS analysis and immunofluoroscence method were conducted.

RESULTS

The results of this study for the first time demonstrated the cytotoxic and apoptotic effects of raloxifene and estrogen on human endometrial stromal cell line suggesting the involvement of the inner, mitochondrial apoptotic pathway.

CONCLUSIONS

Our results demonstrated apoptotic effects of investigated drugs in the ThESC cell line through increasing the Bax/Bcl-2 ratio and activation of caspase 3.

The influence of hypoxic physical activity on cfDNA as a new marker of vascular inflammation

The phenomenon of circulating cell-free DNA (cfDNA) is important for many biomedical disciplines including the field of exercise biochemistry and physiology. It is likely that cfDNA is released into the plasma by apoptosis of endothelial cells and circulating endothelial progenitor cells (EPCs), and/or by NETosis of immune cells induced by strenuous exercise. Increases of cfDNA are described to be a potential hallmark for the overtraining syndrome, and might be related to aseptic vascular inflammation in athletes. Yet, the relevance of systemic inflammation and cfDNA with endothelial dysfunction in athletes still remains unclear. In this review article, we provide a current overview of exercise-induced cfDNA release to the circulation with special emphasis on its relationship with apoptosis and NETosis and the effect of hypoxic physical activity on vascular inflammation in athletes.