S100A8/A9 (calprotectin) is critical for development of glomerulonephritis and promotes inflammatory leukocyte-renal cell interactions

S100A9: The Unusual Suspect Connecting Viral Infection and Inflammation

The study of S100A9 in viral infections has seen increased interest since the COVID-19 pandemic. S100A8/A9 levels were found to be correlated with the severity of COVID-19 disease, cytokine storm, and changes in myeloid cell subsets. These data led to the hypothesis that S100A8/A9 proteins might play an active role in COVID-19 pathogenesis. This review explores the structures and functions of S100A8/9 and the current knowledge on the involvement of S100A8/A9 and its constituents in viral infections. The potential roles of S100A9 in SARS-CoV-2 infections are also discussed.

Dietary supplementation with α-ionone alleviates chronic UVB exposure-induced skin photoaging in mice

Photoaging is widely regarded as the most significant contributor to skin aging damage. It is triggered by prolonged exposure to ultraviolet (UV) light and typically manifests as dryness and the formation of wrinkles. Nutritional intervention is a viable strategy for preventing and treating skin photoaging. In previous studies, we demonstrated that α-ionone had ameliorating effects on photoaging in both epidermal keratinocytes and dermal fibroblasts. Here, we investigated the potential anti-photoaging effects of dietary α-ionone using a UVB-irradiated male C57BL/6N mouse model. Our findings provided compelling evidence that dietary α-ionone alleviates wrinkle formation, skin dryness, and epidermal thickening in chronic UVB-exposed mice. α-Ionone accumulated in mouse skin after 14 weeks of dietary intake of α-ionone. α-Ionone increased collagen density and boosted the expression of collagen genes, while attenuating the UVB-induced increase of matrix metalloproteinase genes in the skin tissues. Furthermore, α-ionone suppressed the expression of senescence-associated secretory phenotypes and reduced the expression of the senescence marker p21 and DNA damage marker p53 in the skin of UVB-irradiated mice. Transcriptome sequencing results showed that α-ionone modifies gene expression profiles of skin. Multiple pathway enrichment analyses on both the differential genes and the entire genes revealed that α-ionone significantly affects multiple physiological processes and signaling pathways associated with skin health and diseases, of which the p53 signaling pathway may be the key signaling pathway. Taken together, our findings reveal that dietary α-ionone intervention holds promise in reducing the risks of skin photoaging, offering a potential strategy to address skin aging concerns.

Single cell spatial transcriptomic profiling of childhood-onset lupus nephritis reveals complex interactions between kidney stroma and infiltrating immune cells

Children with systemic lupus erythematosus (SLE) are at increased risk of developing kidney disease, termed childhood-onset lupus nephritis (cLN). Single cell transcriptomics of dissociated kidney tissue has advanced our understanding of LN pathogenesis, but loss of spatial resolution prevents interrogation of in situ cellular interactions. Using a technical advance in spatial transcriptomics, we generated a spatially resolved, single cell resolution atlas of kidney tissue (>400,000 cells) from eight cLN patients and two controls. Annotated cells were assigned to 35 reference cell types, including major kidney subsets and infiltrating immune cells. Analysis of spatial distribution demonstrated that individual immune lineages localize to specific regions in cLN kidneys, including myeloid cells trafficking to inflamed glomeruli and B cells clustering within tubulointerstitial immune hotspots. Notably, gene expression varied as a function of tissue location, demonstrating how incorporation of spatial data can provide new insights into the immunopathogenesis of SLE. Alterations in immune phenotypes were accompanied by parallel changes in gene expression by resident kidney stromal cells. However, there was little correlation between histologic scoring of cLN disease activity and glomerular cell transcriptional signatures at the level of individual glomeruli. Finally, we identified modules of spatially-correlated gene expression with predicted roles in induction of inflammation and the development of tubulointerstitial fibrosis. In summary, single cell spatial transcriptomics allows unprecedented insights into the molecular heterogeneity of cLN, paving the way towards more targeted and personalized treatment approaches.

Serum calprotectin and renal function decline in ANCA-associated vasculitides: a post hoc analysis of MAINRITSAN trial

OBJECTIVE

Serum calprotectin appears to be an interesting biomarker associated with renal vascular disease activity in antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). The aim of this study was to assess whether serum calprotectin levels can predict decline in renal function in AAV patients receiving maintenance therapy.

METHODS

Serum calprotectin levels were assessed at inclusion and month 6 in AAV patients, in complete remission after induction therapy, randomly assigned to rituximab or azathioprine. Renal function decline was defined as a 25% decrease in estimated glomerular filtration rate (eGFR) and a change in the eGFR category, or a decrease of 15 mL/min/1.73 m2. Relapse was defined as a Birmingham Vasculitis Activity Score >0 attributable to active vasculitis.

RESULTS

Seventy-six AAV were included. Serum calprotectin increased from baseline to month 6 in patients with renal function decline (7940 (-226.0, 28 691) ng/ml vs -4800 (-18 777, 3708) ng/ml; p<0.001). An increase of calprotectin level was associated with a higher risk of subsequent renal function decline even after adjustment (OR 6.50 (95% CI 1.7 to 24.9) p=0.006). A significantly higher risk of relapse was observed in proteinase 3- AAV patients with an increase of serum calprotectin levels (OR 5.6 (95% CI 1.0 to 31.2), p=0.03).

CONCLUSION

An increase in serum calprotectin by month 6 compared with inclusion during remission-maintenance therapy in AAV was associated with a higher risk of renal function decline in the following 12 months.

TRIAL REGISTRATION NUMBER

NCT00748644.

Blockage of S100A8/A9 ameliorates septic nephropathy in mice

Septic acute kidney injury (AKI) is the commonest cause of complication of sepsis in intensive care units, but its pathophysiology remains unclear. Calprotectin (S100A8/A9), which is a damage-associated molecular patterns (DAMPs) molecule, exerts a critical role in modulating leukocyte recruitment and inflammatory response during various diseases. However, role of S100A8/A9 in septic AKI is largely unknown. In this research, Septic AKI was triggered by cecal ligation and puncture (CLP) operation in wild-type mice, which treated with or without an S100A9 inhibitor, Paquinimod (Paq, 10 mg/kg) that prevents S100A8/A9 to bind to Toll-like receptor 4 (TLR4). Renal function, pathological changes, cell death, and oxidative stress were evaluated. Our research indicated that the mRNA and protein expression of S100A9 are time-dependently elevated in the kidney following CLP. Moreover, the administration of Paq for 24 h significantly improved CLP-induced renal dysfunction and pathological alterations compared with vehicle treatment in mice. These beneficial effects were associated with the inhibition of CLP-triggered renal tubular epithelial cell apoptosis, inflammation, superoxide production, and mitochondrial dynamic imbalance. What's more, we further confirmed the above findings by cell co-culture experiments. Our study demonstrates that S100A9 is a prominent protein to lead to septic AKI, and the selective inhibition of S100A9 could represent a new therapeutic approach which can treat septic AKI.

Plasma calprotectin is extremely high in patients with lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is a rare autosomal recessive disorder affecting the transport of cationic amino acids. Elevated plasma zinc concentrations have been described in patients with LPI. Calprotectin is a calcium- and zinc-binding protein, produced by polymorphonuclear leukocytes and monocytes. Both zinc and calprotectin have an important role in immune system. In this study, we describe plasma zinc and plasma calprotectin concentrations in Finnish LPI patients. Plasma calprotectin concentration was measured from 10 LPI patients using an enzyme-linked immunosorbent assay (ELISA) and it was remarkably high in all LPI patients (median: 622 338 μg/L) compared to that in healthy controls (608 μg/L). Plasma zinc concentration was measured by photometry and it was normal or only mildly elevated (median: 14.9 μmol/L). All the patients had decreased glomerular infiltration rate (median: 50 mL/min/1.73 m2). In conclusion, we observed extremely high plasma calprotectin concentration in patients with LPI. Mechanism of this phenomenon is unknown.

S-100 Proteins: Basics and Applications as Biomarkers in Animals with Special Focus on Calgranulins (S100A8, A9, and A12)

S100 proteins are a group of calcium-binding proteins which received this name because of their solubility in a 100% saturated solution of ammonium sulphate. They have a similar molecular mass of 10-12 KDa and share 25-65% similarity in their amino acid sequence. They are expressed in many tissues, and to date 25 different types of S100 proteins have been identified. This review aims to provide updated information about S100 proteins and their use as biomarkers in veterinary science, with special emphasis on the family of calgranulins that includes S100A8 (calgranulin A; myeloid-related protein 8, MRP8), S100A9 (calgranulin B; MRP14), and S100A12 (calgranulin C). The proteins SA100A8 and S100A9 can be linked, forming a heterodimer which is known as calprotectin. Calgranulins are related to the activation of inflammation and the immune system and increase in gastrointestinal diseases, inflammation and sepsis, immunomediated diseases, and obesity and endocrine disorders in different animal species. This review reflects the current knowledge about calgranulins in veterinary science, which should increase in the future to clarify their role in different diseases and potential as biomarkers and therapeutic targets, as well as the practical use of their measurement in non-invasive samples such as saliva or feces.

Inhibition of S100A8/A9 ameliorates renal interstitial fibrosis in diabetic nephropathy

BACKGROUND

Renal interstitial fibrosis (RIF) is one of the main features of diabetic nephropathy (DN), but the molecular mechanisms mediating RIF in DN has yet been fully understood. S100A8 and S100A9 are the proteins associated with immune and inflammation response. Here we reported the expression of S100A8 and S100A9 were significantly increased on tubular epithelial cells in diabetic kidneys through a proteomic analysis.

METHODS

We detected the expression of S100A8/A9 in diabetic kidneys by using immunoblotting, real-time PCR and immunostaining. RNA silencing and overexpression were performed by using S100A8/A9 expression/knockdown lentivirus to investigate the connection between S100A8/A9 and epithelial to mesenchymal transition (EMT) process. We also identify the expression of TLR4/NFκB pathway-related molecules in the case mentioned above. Afterwards a CO-IP assay was used to verify that compound AB38b ameliorates the EMT by interfering S100A8/A9 expression.

RESULTS

The expression of S100A8 and S100A9 were significantly increased on tubular epithelial cells in diabetic kidneys. S100A8/A9 knocking-down alleviate and over-expression promote the renal interstitial fibrosis of diabetic mice. Mechanically, high levels of S100A8/A9 expression in tubular epithelial cells during diabetic condition activated the TLR4/NF-κB signal pathway which promoted the EMT process and finally led to RIF progression. S100A8/A9 knockdown ameliorated RIF of diabetic mice. Further experiments revealed that compound AB38b inhibited the EMT progression of tubular epithelial cells induced by S100A8/A9 through interfering the expressions of S100A8/A9.

CONCLUSIONS

Our study suggest that abnormal expression of S100A8/A9 in the disease condition promotes EMT process and RIF through TLR4/NF-κB signal pathway. Using small molecular inhibitor AB38b to inhibit the abnormal expressions of S100A8/A9 might be a novel therapeutic strategy in treating DN.

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

The potential pathogenic roles of S100A8/A9 and S100A12 in patients with MPO-ANCA-positive vasculitis

Background

The significance of S100A8/A9 and S100A12 in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has not been clarified. This study was dedicated to exploring the potential pathogenic roles of S100A8/A9 and S100A12 in patients with myeloperoxidase (MPO)-ANCA-positive vasculitis.

Methods

Serum and urine concentrations of S100A8/A9 and S100A12 of forty-two AAV patients were evaluated. The influence of S100A8/A9 and S100A12 on the chemotaxis, the apoptosis, the release of IL-1β, the complement activation, the respiratory burst, as well as the neutrophil extracellular traps (NETs) formation of MPO-ANCA-activated neutrophils was investigated.

Results

The serum and urine S100A8/A9 and S100A12 of active MPO-AAV significantly increased (compared with inactive AAV and healthy controls, p < 0.001) and were correlated with the severity of the disease. In vitro study showed that S100A8/A9 and S100A12 activated the p38 MAPK/NF-κB p65 pathway, increased the chemotaxis index (CI) and the release of IL-1β, extended the life span, and enhanced the complement activation ability of MPO-ANCA-activated neutrophils. The Blockade of TLR4 and RAGE inhibited the effects of S100A8/A9 and S100A12. All above-mentioned effects of S100A8/A9 and S100A12 were ROS-independent because neither S100A8/A9 nor S100A12 enhanced the ROS formation and NETs formation of MPO-ANCA-activated neutrophils.

Conclusion

S100A8/A9 and S100A12 serve as markers for assessing the disease severity, and they may also play a role in MPO-AAV pathogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00513-4.

RAGE pathway activation and function in chronic kidney disease and COVID-19

The multi-ligand receptor for advanced glycation end-products (RAGE) and its ligands are contributing factors in autoimmunity, cancers, and infectious disease. RAGE activation is increased in chronic kidney disease (CKD) and coronavirus disease 2019 (COVID-19). CKD may increase the risk of COVID-19 severity and may also develop in the form of long COVID. RAGE is expressed in essentially all kidney cell types. Increased production of RAGE isoforms and RAGE ligands during CKD and COVID-19 promotes RAGE activity. The downstream effects include cellular dysfunction, tissue injury, fibrosis, and inflammation, which in turn contribute to a decline in kidney function, hypertension, thrombotic disorders, and cognitive impairment. In this review, we discuss the forms and mechanisms of RAGE and RAGE ligands in the kidney and COVID-19. Because various small molecules antagonize RAGE activity in animal models, targeting RAGE, its co-receptors, or its ligands may offer novel therapeutic approaches to slowing or halting progressive kidney disease, for which current therapies are often inadequate.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

Single Cell RNA Sequencing Identifies a Unique Inflammatory Macrophage Subset as a Druggable Target for Alleviating Acute Kidney Injury

Acute kidney injury (AKI) is a complex clinical disorder associated with poor outcomes. Targeted regulation of the degree of inflammation has been a potential strategy for AKI management. Macrophages are the main effector cells of kidney inflammation. However, macrophage heterogeneity in ischemia reperfusion injury induced AKI (IRI-AKI) remains unclear. Using single-cell RNA sequencing of the mononuclear phagocytic system in the murine IRI model, the authors demonstrate the complementary roles of kidney resident macrophages (KRMs) and monocyte-derived infiltrated macrophages (IMs) in modulating tissue inflammation and promoting tissue repair. A unique population of S100a9^hi Ly6c^hi IMs is identified as an early responder to AKI, mediating the initiation and amplification of kidney inflammation. Kidney infiltration of S100A8/A9⁺ macrophages and the relevance of renal S100A8/A9 to tissue injury is confirmed in human AKI. Targeting the S100a8/a9 signaling with small-molecule inhibitors exhibits renal protective effects represented by improved renal function and reduced mortality in bilateral IRI model, and decreased inflammatory response, ameliorated kidney injury, and improved long-term outcome with decreased renal fibrosis in the unilateral IRI model. The findings support S100A8/A9 blockade as a feasible and clinically relevant therapy potentially waiting for translation in human AKI.

Evaluation of Serum Calprotectin Levels in Patients with Inflammatory Bowel Disease

BACKGROUND

Fecal calprotectin has been proposed as a useful biomarker of disease activity in inflammatory bowel disease (IBD). However, the role of calprotectin in systemic circulation is not well established. Thus, this study aimed to quantify serum calprotectin levels to identify a potential inflammatory marker for IBD.

METHODS

Ninety-eight patients with ulcerative colitis (UC) and 105 patients with Crohn's disease (CD) were prospectively enrolled and clinically scored. Ninety-two healthy, age-matched subjects served as controls. Blood samples from UC and CD patients and controls were analyzed for serum calprotectin levels and routine laboratory parameters. Disease activity was assessed by partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum calprotectin levels were higher in CD and UC patients than in controls and were higher during active disease than during inactive disease in CD but not in UC. In UC, serum calprotectin levels were correlated with C-reactive protein (CRP) but not with other laboratory parameters or disease activity. In CD, serum calprotectin levels were positively correlated with disease activity, serum CRP, and platelet count. In UC and CD, serum calprotectin and CRP levels increased during the acute phase and decreased towards remission.

CONCLUSIONS

Serum calprotectin is an inflammatory marker in IBD but might be more effective in evaluating patients with CD than those with UC. Further studies are needed to confirm these findings and to better determine the specific uses of serum calprotectin in routine practice.

Does Artificial Intelligence Make Clinical Decision Better? A Review of Artificial Intelligence and Machine Learning in Acute Kidney Injury Prediction

Acute kidney injury (AKI) is a common complication of hospitalization that greatly and negatively affects the short-term and long-term outcomes of patients. Current guidelines use serum creatinine level and urine output rate for defining AKI and as the staging criteria of AKI. However, because they are not sensitive or specific markers of AKI, clinicians find it difficult to predict the occurrence of AKI and prescribe timely treatment. Advances in computing technology have led to the recent use of machine learning and artificial intelligence in AKI prediction, recent research reported that by using electronic health records (EHR) the AKI prediction via machine-learning models can reach AUROC over 0.80, in some studies even reach 0.93. Our review begins with the background and history of the definition of AKI, and the evolution of AKI risk factors and prediction models is also appraised. Then, we summarize the current evidence regarding the application of e-alert systems and machine-learning models in AKI prediction.

Acute skin exposure to ultraviolet light triggers neutrophil-mediated kidney inflammation

Photosensitivity to ultraviolet (UV) light affects up to ∼80% of lupus patients. Sunlight exposure can exacerbate local as well as systemic manifestations of lupus, including nephritis, by mechanisms that are poorly understood. Here, we report that acute skin exposure to UV light triggers a neutrophil-dependent injury response in the kidney characterized by upregulated expression of endothelial adhesion molecules as well as inflammatory and injury markers associated with transient proteinuria. We showed that UV light stimulates neutrophil migration not only to the skin but also to the kidney in an IL-17A-dependent manner. Using a photoactivatable lineage tracing approach, we observed that a subset of neutrophils found in the kidney had transited through UV light-exposed skin, suggesting reverse transmigration. Besides being required for the renal induction of genes encoding mediators of inflammation (vcam-1, s100A9, and Il-1b) and injury (lipocalin-2 and kim-1), neutrophils significantly contributed to the kidney type I interferon signature triggered by UV light. Together, these findings demonstrate that neutrophils mediate subclinical renal inflammation and injury following skin exposure to UV light. Of interest, patients with lupus have subpopulations of blood neutrophils and low-density granulocytes with similar phenotypes to reverse transmigrating neutrophils observed in the mice post-UV exposure, suggesting that these cells could have transmigrated from inflamed tissue, such as the skin.

The Role of Macrophages in Staphylococcus aureus Infection

Staphylococcus aureus is a member of the human commensal microflora that exists, apparently benignly, at multiple sites on the host. However, as an opportunist pathogen it can also cause a range of serious diseases. This requires an ability to circumvent the innate immune system to establish an infection. Professional phagocytes, primarily macrophages and neutrophils, are key innate immune cells which interact with S. aureus, acting as gatekeepers to contain and resolve infection. Recent studies have highlighted the important roles of macrophages during S. aureus infections, using a wide array of killing mechanisms. In defense, S. aureus has evolved multiple strategies to survive within, manipulate and escape from macrophages, allowing them to not only subvert but also exploit this key element of our immune system. Macrophage-S. aureus interactions are multifaceted and have direct roles in infection outcome. In depth understanding of these host-pathogen interactions may be useful for future therapeutic developments. This review examines macrophage interactions with S. aureus throughout all stages of infection, with special emphasis on mechanisms that determine infection outcome.

Effects of unsaturated fatty acids (Arachidonic/Oleic Acids) on stability and structural properties of Calprotectin using molecular docking and molecular dynamics simulation approach

Calprotectin is a heterodimeric protein complex with two subunits called S100A8/A9. The protein has an essential role in inflammation process and various human diseases. It has the ability to bind to unsaturated fatty acids including Arachidonic acid, Oleic acid and etc., which could be considered as a major carrier for fatty acids. In this study we aimed to appraise the thermodynamics and structural changes of Calprotectin in presence of Arachidonic acid/Oleic acid) using docking and molecular dynami simulation method. To create the best conformation of Calprotectin-Oleic acid/Arachidonic acid complexes, the docking process was performed. The complexes with the best binding energy were selected as the models for molecular dynamics simulation process. Furthermore, the structural and thermodynamics properties of the complexes were evaluated too. The Root Mean Square Deviation and Root Mean Square Fluctuation results showed that the binding of Arachidonic acid/Oleic acid to Calprotectin can cause the protein structural changes which was confirmed by Define Secondary Structure of Proteins results. Accordingly, the binding free energy results verified that binding of Oleic acid to Calprotectin leads to instability of S100A8/A9 subunits in the protein. Moreover, the electrostatic energy contribution of the complexes (Calprotectin-Oleic acid/Arachidonic acid) was remarkably higher than van der Waals energy. Thus, the outcome of this study confirm that Oleic acid has a stronger interaction with Calprotectin in comparison with Arachidonic acid. Our findings indicated that binding of unsaturated fatty acids to Calprotectin leads to structural changes of the S100A8/A9 subunits which could be beneficial to play a biological role in inflammation process.

S100A9 Increases IL-6 and RANKL Expressions through MAPKs and STAT3 Signaling Pathways in Osteocyte-Like Cells

Objective

Calprotectin is a heterocomplex of S100A8 and S100A9 and is mainly secreted from neutrophils, monocytes, and chondrocytes in inflammatory condition. Calprotectin binds to RAGE and TLR4 and induces the expression of proinflammatory chemokines and cytokines in various cells. Periodontitis is a chronic inflammatory disease that leads to gingival inflammation and alveolar bone resorption. Calprotectin levels in gingival crevicular fluid of periodontitis patients are higher than healthy patients. In the present study, the effects of S100A8 and S100A9 on the expressions of proinflammatory cytokines and bone metabolism-related factors in mouse osteocyte-like cells (MLO-Y4-A2) were investigated.

Design

MLO-Y4-A2 cells were treated with S100A8 and S100A9, and the expressions of RAGE, TLR4, RANKL, and several inflammatory cytokines were analyzed by PCR and Western blotting or ELISA methods. To investigate the intracellular signaling pathways, phosphorylation of MAPK and STAT3 was determined by Western blotting, and chemical specific inhibitors and siRNAs were used.

Results

Expressions of IL-6 and RANKL were increased by treatment with S100A9 but not S100A8. However, both S100A8 and S100A9 did not change expression of IL-1β, IL-8, and TNF-α. Although RAGE and TLR4 expressions were not upregulated by S100A9 treatment, transfection of siRNA for RAGE and TLR4 significantly decreased IL-6 and RANKL expressions. In addition, S100A9 activated p38, ERK, and STAT3 signaling pathways, and inhibitors for these factors significantly decreased S100A9-induced IL-6 and RANKL expressions.

Conclusions

These results indicated that S100A9 induces IL-6 and RANKL production via engagement with RAGE and TLR4 signalings in osteocytes and suggested that S100A9 may play important roles in the periodontal alveolar bone destruction.

Altered molecular signatures during kidney development after intrauterine growth restriction of different origins

Abstract

This study was performed to identify transcriptional alterations in male intrauterine growth restricted (IUGR) rats during and at the end of nephrogenesis in order to generate hypotheses which molecular mechanisms contribute to adverse kidney programming. IUGR was induced by low protein (LP) diet throughout pregnancy, bilateral uterine vessel ligation (LIG), or intrauterine stress (IUS) by sham operation. Offspring of unimpaired dams served as controls. Significant acute kidney damage was ruled out by negative results for proteins indicative of ER-stress, autophagy, apoptosis, or infiltration with macrophages. Renal gene expression was examined by transcriptome microarrays, demonstrating 53 (LP, n = 12; LIG, n = 32; IUS, n = 9) and 134 (LP, n = 10; LIG, n = 41; IUS, n = 83) differentially expressed transcripts on postnatal days (PND) 1 and 7, respectively. Reduced Pilra (all IUGR groups, PND 7), Nupr1 (LP and LIG, PND 7), and Kap (LIG, PND 1) as well as increased Ccl20, S100a8/a9 (LIG, PND 1), Ifna4, and Ltb4r2 (IUS, PND 7) indicated that inflammation-related molecular dysregulation could be a “common” feature after IUGR of different origins. Network analyses of transcripts and predicted upstream regulators hinted at proinflammatory adaptions mainly in LIG (arachidonic acid-binding, neutrophil aggregation, toll-like-receptor, NF-kappa B, and TNF signaling) and dysregulation of AMPK and PPAR signaling in LP pups. The latter may increase susceptibility towards obesity-associated kidney damage. Western blots of the most prominent predicted upstream regulators confirmed significant dysregulation of RICTOR in LP (PND 7) and LIG pups (PND 1), suggesting that mTOR-related processes could further modulate kidney programming in these groups of IUGR pups.

Key messages

Inflammation-related transcripts are dysregulated in neonatal IUGR rat kidneys.

Upstream analyses indicate renal metabolic dysregulation after low protein diet.

RICTOR is dysregulated after low protein diet and uterine vessel ligation.

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01875-1) contains supplementary material, which is available to authorized users.

S100 Calcium Binding Protein A9 Represses Angiogenic Activity and Aggravates Osteonecrosis of the Femoral Head

Ischemic damage aggravation of femoral head collapse is a prominent pathologic feature of osteonecrosis of the femoral head (ONFH). In this regard, S100 calcium binding protein A9 (S100A9) is known to deteriorate joint integrity, however, little is understood about which role S100A9 may play in ONFH. In this study, a proteomics analysis has revealed a decrease in the serum S100A9 level in patients with ONFH upon hyperbaric oxygen therapy. Serum S100A9 levels, along with serum vascular endothelial growth factor (VEGF), soluble vascular cell adhesion molecule-1 (sVCAM-1), interleukin-6 (IL-6), and tartrate-resistant acid phosphatase 5b levels were increased in patients with ONFH, whereas serum osteocalcin levels were decreased as compared to healthy controls. Serum S100A9 levels were increased with the Ficat and Arlet stages of ONFH and correlated with the patients with a history of being on glucocorticoid medication and alcohol consumption. Osteonecrotic tissue showed hypovasculature histopathology together with weak immunostaining for vessel marker CD31 and von Willrbrand factor (vWF) as compared to femoral head fracture specimens. Thrombosed vessels, fibrotic tissue, osteocytes, and inflammatory cells displayed strong S100A9 immunoreactivity in osteonecrotic lesion. In vitro, ONFH serum and S100A9 inhibited the tube formation of vessel endothelial cells and vessel outgrowth of rat aortic rings, whereas the antibody blockade of S100A9 improved angiogenic activities. Taken together, increased S100A9 levels are relevant to the development of ONFH. S100A9 appears to provoke avascular damage, ultimately accelerating femoral head deterioration through reducing angiogenesis. This study provides insight into the molecular mechanism underlying the development of ONFH. Here, analysis also highlights that serum S100A9 is a sensitive biochemical indicator of ONFH.

An integrative approach to cisplatin chronic toxicities in mice reveals importance of organic cation-transporter-dependent protein networks for renoprotection

Cisplatin (CDDP) is one of the most important chemotherapeutic drugs in modern oncology. However, its use is limited by severe toxicities, which impair life quality after cancer. Here, we investigated the role of organic cation transporters (OCT) in mediating toxicities associated with chronic (twice the week for 4 weeks) low-dose (4 mg/kg body weight) CDDP treatment (resembling therapeutic protocols in patients) of wild-type (WT) mice and mice with OCT genetic deletion (OCT1/2^-/-). Functional and molecular analysis showed that OCT1/2^-/- mice are partially protected from CDDP-induced nephrotoxicity and peripheral neurotoxicity, whereas ototoxicity was not detectable. Surprisingly, proteomic analysis of the kidneys demonstrated that genetic deletion of OCT1/2 itself was associated with significant changes in expression of proinflammatory and profibrotic proteins which are part of an OCT-associated protein network. This signature directly regulated by OCT consisted of three classes of proteins, viz., profibrotic proteins, proinflammatory proteins, and nutrient sensing molecules. Consistent with functional protection, CDDP-induced proteome changes were more severe in WT mice than in OCT1/2^-/- mice. Laser ablation-inductively coupled plasma-mass spectrometry analysis demonstrated that the presence of OCT was not associated with higher renal platinum concentrations. Taken together, these results redefine the role of OCT from passive membrane transporters to active modulators of cell signaling in the kidney.

Systemic calprotectin and chronic inflammatory rheumatic diseases

Calprotectin is a calcium binding protein produced by neutrophils and monocytes locally at the site of inflammation in order to trigger the innate immunity receptors. This unique characteristic makes it a good proxy for evaluation of local inflammation in chronic inflammatory rheumatic diseases. Complete data suggest, in inflammatory rheumatic diseases, a relevant role of calprotectin in the inflammatory process. The interest of serum or plasma calprotectin dosage has been studied intensively, in the current years, especially in rheumatoid arthritis, spondyloarthritis, juvenile idiopathic arthritis and ANCA associated vasculitis. Calprotectin seems to be a great candidate as biomarker to assess and monitor disease activity, to predict structural progression or response to the treatment. Calprotectin showed its ability to predict radiological progression in rheumatoid arthritis and ankylosing spondylitis. Serum calprotectin can predict the risk of relapse in ANCA associated vasculitis and the risk of inflammatory bowel disease in spondyloarthritis. Nevertheless, studies report controversial result requiring replication in other large cohort. The lack of assay standardization between studies is a problem to replicate and compare studies. In this review, we discuss on the interest of systemic calprotectin in chronic inflammatory rheumatic disease as a diagnostic, activity or prognostic biomarker.

Arterial Thrombosis Is Accompanied by Elevated Mitogen-Activated Protein Kinase (MAPK) and Cyclooxygenase-2 (COX-2) Expression via Toll-Like Receptor 4 (TLR-4) Activation by S100A8/A9

BACKGROUND The aim of this study was to determine the involvement of S100A8/A9 in the development of arterial thrombosis. MATERIAL AND METHODS A total of 303 patients were enrolled in this study, with 110 having acute coronary syndrome (ACS) and 110 having coronary heart disease (CHD), and 83 subjects served as healthy blood donors. The concentrations of Toll-like receptor 4 (TLR-4), cyclooxygenase-2 (COX-2), and S100A8/A9 protein were determined in the sera of the participants and in peripheral blood mononuclear cells (PBMCs) derived from a rat carotid artery thrombosis model and in human aortic endothelial cells (HAECs). The mitogen-activated protein kinase (MAPK) inhibitor SB203580 and the TLR-4 blocker CLI-095 were used to investigate the role of the TLR-4-MAPK-COX2 signaling axis in thrombosis. RESULTS The levels of COX-2, TLR-4, and S100A8/A9 in the sera of patients with ACS and CHD were significantly higher than in healthy controls (P<0.05). S100A8/A9 expression was significantly correlated with TLR-4 and COX-2 in the ACS group and with TLR-4 in the CHD group. In the rat carotid thrombosis model, the expressions of TLR-4, COX-2, and p-p38 MAPK significantly increased until 14 days after thrombosis induction, whereas S100A8/A9 expression increased until day 7, but then decreased. Administration of SB203580 to rats reduced COX-2 expression in PBMCs after thrombosis induction, and incubation of HAECs with CLI-095 reduced their p-p38 MAPK and COX-2 response to S100A8/A9 stimulation. CONCLUSIONS S100A8/A9 is upregulated after blood vessel injury and is enhanced in combination with TLR-4 COX-2 induction via p38 MAPK activation.

New insights into crosstalk in the kidney

PURPOSE OF REVIEW

The kidney is a highly complex organ and renal function depends on many factors, both extrinsic to the kidney and intrinsic. The kidney responds both to systemic hormonal and neuronal signals and to autocrine and paracrine factors produced within the renal tissue. Recently, there has been an increased emphasis on crosstalk in and between different compartments in the kidney.

RECENT FINDINGS

Crosstalk in the kidney between different cellular compartments has added new and important understanding of renal function and the development of kidney disease.

SUMMARY

Most of the literature cited concern glomerular crosstalk but also tubular and interstitial crosstalk are being reviewed. Mechanistic insight into the communication between the cells may help us find new targets for treating kidney disease.

Detection of calprotectin in inflammatory bowel disease: Fecal and serum levels and immunohistochemical localization

The aim of the present study was to quantify calprotectin levels using an enzyme-linked immunosorbent assay (ELISA) and a point-of-care test (POCT) in patients with inflammatory bowel disease. Overall, 113 patients with ulcerative colitis (UC; 51 men and 62 women) and 42 patients with Crohn's disease (CD; 29 men and 13 women), who were scheduled to undergo a colonoscopy, were prospectively enrolled and scored endoscopically and clinically. An additional 96 healthy, age-matched subjects served as the normal controls. Feces and blood samples from the patients with UC and CD, and the normal controls were analyzed. These patients had received adequate medical treatment. The tissue distribution of calprotectin was investigated using immunohistochemistry. The fecal calprotectin levels, as measured using an ELISA, were correlated with the endoscopic and clinical disease activities and laboratory parameters, including serum levels of hemoglobin (Hb), albumin and C-reactive protein, and erythrocyte sedimentation rate, particularly among the patients with UC. The fecal Hb level was close to that of the fecal calprotectin level (r=0.57; P<0.0001). The fecal calprotectin level measured using an ELISA was well-correlated with the fecal calprotectin level measured using the POCT (r=0.81; P<0.0001), but was not correlated with the serum calprotectin level (r=0.1013; P=0.47). An immunohistochemical investigation revealed that patients with both UC and CD had higher neutrophil and monocyte/macrophage calprotectin-positive cell expression levels, compared with those in the normal controls. Fecal calprotectin was considered a reliable marker for disease activity, and the assessment of fecal calprotectin via POCT showed potential as a rapid and simple measurement in clinical settings.

The NF-κB1 is a key regulator of acute but not chronic renal injury

The NF-κB family of transcription factors is important for many cellular functions, in particular initiation and propagation of inflammatory and immune responses. However, recent data has suggested that different subunits of the NF-κB family can suppress the inflammatory response. NF-κB1, from the locus nfκb1, can inhibit transcription, acting as a brake to the recognised pro-inflammatory activity of other NF-κB subunits. We tested the function of NF-κB1 in an acute (nephrotoxic serum (NTS) nephritis) and a chronic (unilateral ureteric obstruction (UUO)) model of renal injury using NF-κB1 (nfκb1^−/−) knockout mice. Deficiency in NF-κB1 increased the severity of glomerular injury in NTS-induced nephritis and was associated with greater proteinuria and persistent pro-inflammatory gene expression. Induction of disease in bone marrow chimeric mice demonstrated that the absence of NF-κB1 in either bone marrow or glomerular cells increased the severity of injury. Early after UUO (day 3) there was more severe histological injury in the nfκb1^−/− mice but by day 10, disease severity was equivalent in wild type and nfκb1^−/− mice. In conclusion, NF-κB1 modifies acute inflammatory renal injury but does not influence chronic fibrotic injury.

Serum Calprotectin Expression as a Diagnostic Marker for Sepsis in Postoperative Intensive Care Unit Patients

The research was performed to explore the diagnosis value of dynamic serum calprotectin (SC) expression for sepsis in postoperative intensive care unit patients. One hundred sixty-three patients who met the inclusion criteria served as the study group. All cases in the study group were further divided into the sepsis subgroup (51 cases) and the nonsepsis subgroup (112 cases). Fifty healthy volunteers served as the control group. The levels of SC and other laboratory indexes including complete blood counts, leukocytes, the immature-to-total-neutrophil ratio, procalcitonin (PCT), C-reactive protein, and blood lactate were detected, cytokines [interleukin (IL)-2, IL-6, and interferon-γ] released by neutrophils were also determined. The Acute Physiology and Chronic Health Evaluation II (APACHE II) score and the Sequential Organ Failure Assessment score were calculated. The factors related to prognosis were analyzed with multivariate logistic regression analysis. The diagnostic accuracies of ΔSC [the differences of SC levels between postoperative day (POD) 1 and POD 2, 3, 5, 7] and ΔPCT (the differences of PCT levels between POD 1 and POD 2, 3, 5, 7) on sepsis were compared with other markers for sepsis. The levels of SC and cytokines were markedly increased on POD 1, 2, 3, 5, and 7 in the study group compared with the control group (P < 0.05 or P < 0.01). The same results were found in the sepsis subgroup compared with the nonsepsis subgroup (P < 0.05 or P < 0.01). Significant positive correlations between SC and cytokines were confirmed in patients of the study group (P < 0.05 or P < 0.01). APACHE II scores and the levels of SC and PCT on POD 1 were the variables significantly associated with sepsis. The diagnostic accuracies of ΔSC_1-3 (sensitivity 87%, specificity 89%) and ΔPCT_1-3 (sensitivity 89%, specificity 90%) for sepsis were greater than other ΔSCs and ΔPCTs. It appears that the dynamic changes in SC are of the predictive values for septic patients after major surgeries.

The role of monocytes in ANCA-associated vasculitides

The anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV) are a heterogeneous group of diseases causing inflammation in small blood vessels and linked by the presence of circulating ANCA specific for proteinase 3 (PR3) or myeloperoxidase (MPO). These antigens are present both in the cytoplasmic granules and on the surface of neutrophils, and the effect of ANCA on neutrophil biology has been extensively studied. In contrast, less attention has been paid to the role of monocytes in AAV. These cells contain PR3 and MPO in lysosomes and can also express them at the cell surface. Monocytes respond to ANCA by producing pro-inflammatory and chemotactic cytokines, reactive-oxygen-species and by up-regulating CD14. Moreover, soluble and cell surface markers of monocyte activation are raised in AAV patients, suggesting an activated phenotype that may persist even during disease remission. The presence of monocyte-derived macrophages and giant cells within damaged renal and vascular tissue in AAV also attests to their role in pathogenesis. In particular, their presence in the tertiary lymphoid organ-like granulomas of AAV patients may generate an environment predisposed to maintaining autoimmunity. Here we discuss the evidence for a pathogenic role of monocytes in AAV, their role in granuloma formation and tissue damage, and their potential to both direct and maintain autoimmunity. ANCA-activation of monocytes may therefore provide an explanation for the relapsing-remitting course of disease and its links with infections. Monocytes may thus represent a promising target for the treatment of this group of life-threatening diseases.

Resolution of Inflammation: What Controls Its Onset?

An effective resolution program may be able to prevent the progression from non-resolving acute inflammation to persistent chronic inflammation. It has now become evident that coordinated resolution programs initiate shortly after inflammatory responses begin. In this context, several mechanisms provide the fine-tuning of inflammation and create a favorable environment for the resolution phase to take place and for homeostasis to return. In this review, we focus on the events required for an effective transition from the proinflammatory phase to the onset and establishment of resolution. We suggest that several mediators that promote the inflammatory phase of inflammation can simultaneously initiate a program for active resolution. Indeed, several events enact a decrease in the local chemokine concentration, a reduction which is essential to inhibit further infiltration of neutrophils into the tissue. Interestingly, although neutrophils are cells that characteristically participate in the active phase of inflammation, they also contribute to the onset of resolution. Further understanding of the molecular mechanisms that initiate resolution may be instrumental to develop pro-resolution strategies to treat complex chronic inflammatory diseases, in humans. The efforts to develop strategies based on resolution of inflammation have shaped a new area of pharmacology referred to as "resolution pharmacology."

Resolution of Inflammation: What Controls Its Onset?

An effective resolution program may be able to prevent the progression from non-resolving acute inflammation to persistent chronic inflammation. It has now become evident that coordinated resolution programs initiate shortly after inflammatory responses begin. In this context, several mechanisms provide the fine-tuning of inflammation and create a favorable environment for the resolution phase to take place and for homeostasis to return. In this review, we focus on the events required for an effective transition from the proinflammatory phase to the onset and establishment of resolution. We suggest that several mediators that promote the inflammatory phase of inflammation can simultaneously initiate a program for active resolution. Indeed, several events enact a decrease in the local chemokine concentration, a reduction which is essential to inhibit further infiltration of neutrophils into the tissue. Interestingly, although neutrophils are cells that characteristically participate in the active phase of inflammation, they also contribute to the onset of resolution. Further understanding of the molecular mechanisms that initiate resolution may be instrumental to develop pro-resolution strategies to treat complex chronic inflammatory diseases, in humans. The efforts to develop strategies based on resolution of inflammation have shaped a new area of pharmacology referred to as “resolution pharmacology.”