Expression of tumor necrosis factor receptors in normal kidney and rejecting renal transplants

Tumour necrosis factor-alpha at the intersection of renal epithelial and immune cell function

This review explores the roles of tumour necrosis factor-alpha (TNF) in kidney physiology and pathology. TNF, produced by renal epithelial cells, regulates glucose, electrolyte, water and urea transport by modulating key transporters such as sodium-glucose co-transporter-2 (SGLT2), sodium-potassium-chloride cotransporter 2 (NKCC2), sodium chloride cotransporter (NCC), epithelial sodium channel (ENaC), aquaporin-2 (AQP2) and urea transporters. Under non-inflammatory conditions, TNF functions as a regulatory 'brake' on water and solute transport, particularly by attenuating NKCC2 and AQP2 activity. Disruption of these actions, coupled with increased salt intake, shifts mice from being salt-resistant to salt-sensitive, thereby altering their blood pressure. In autoimmune diseases, chronic kidney disease (CKD), hypertension with renal inflammation, and sepsis, TNF drives immune responses and disease progression. Although mechanisms underlying tubular epithelial cell (TEC)-immune cell interactions remain unclear, emerging evidence indicates that the spatial organization of immune responses in the kidney is associated with distinct TEC signature phenotypes. Hypertonicity- and NFAT5 (i.e. nuclear factor of activated T cells 5)-driven TNF production in TECs and T lymphocytes may influence immune cell communication by affecting co-stimulatory molecule expression and ENaC activity on macrophages and dendritic cells. Although TNF is generally pathogenic in renal diseases, its inhibition does not always confer protection because its effects on endoplasmic reticulum stress, ion transport, vascular smooth muscle and immune cells are influenced by distinct cellular sources and signalling mechanisms through TNF receptors 1 and 2. Anti-TNF therapies are crucial for treating chronic inflammatory diseases and may also aid in preventing the progression of acute kidney injury to CKD. A more complete understanding of the role of TNF in immunophysiological responses may enable the development of more targeted therapeutic strategies.

Peficitinib halts acute kidney injury via JAK/STAT3 and growth factors immunomodulation

Acute Kidney Injury (AKI) is characterized by a sudden loss of kidney function and its management continues to be a challenge. In this study the effect of peficitinib, a Janus kinase inhibitor (JAKi), was studied in an aim to stop the progression of AKI at an early point of injury. Adult male mice were injected with aristolochic acid (AA) a single dose (10 mg/kg, i.p) to induce AKI. Peficitinib was injected in one of the two tested doses (5 or 10 mg/kg, i.p) 1 h after AA injection and was continued daily for seven days. Histopathological evaluation showed that peficitinib alleviated necrosis and hyaline cast formation induced by aristolochic acid. It decreased serum creatinine and the kidney injury molecule-1 (KIM-1) elevated by AA. Peficitinib also mitigated AA induced oxidative stress through regulating total antioxidant capacity (TAC) and reduced glutathione (GSH) level in renal tissue. Additionally, renal sections isolated from groups that received peficitinib revealed a decrease in vascular endothelial growth factor receptor 1 interstitial expression and transforming growth factor-beta 1 (TGF-β1) renal level. Peficitinib received groups showed a decrease in the active phosphorylated form of signal transducers and activators of transcription (STAT3). Moreover, peficitinib decreased renal protein levels and gene expression of the pro-inflammatory cytokines; interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and interferon gamma (IFN-γ). These findings suggest that peficitinib is helpful in halting AKI progression into chronic kidney disease through modulating JAK/STAT3 dependent inflammatory pathways and growth factors involved in normal glomerular function.

Role of baseline soluble tumor necrosis factor receptor 2 as a biomarker in primary podocytopathy: Implications for renal impairment and disease progression

BACKGROUND

Podocytopathies, including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and collapsing glomerulopathy (CG), are kidney diseases that damage glomerular podocytes, leading to heavy proteinuria and nephrotic syndrome (NS). Inflammation plays a critical role in the progression of chronic kidney disease (CKD), with recent studies linking inflammatory biomarkers to declining kidney function. Tumor necrosis factor-alpha (TNF-α), an essential inflammatory cytokine, interacts with its circulating receptors, TNFR1 and TNFR2. The TNF-α pathway has been implicated in the pathogenesis of FSGS and MCD. Increased circulating TNFR2 levels have been associated with worsening renal function in podocytopathies, suggesting that the TNF-α inflammatory pathway significantly contributes to disease progression.

METHODS

We conducted a study involving 53 patients with biopsy-proven MCD or FSGS and 53 healthy, age- and gender-matched controls. All patients were followed for 18 months. We analyzed serum and urine TNFR2 levels and gene expression at baseline and after three months. To assess the ability of TNFR2 to predict persistent decline in estimated glomerular filtration rate (eGFR < 30 mL/min/1.73m2), remission, and relapse, we employed Cox regression analysis. Additionally, we evaluated its prognostic utility for predicting progression to stage 4 CKD using ROC curve analysis.

RESULTS

Serum and urine TNFR2 levels were significantly elevated in patients compared to controls. Serum TNFR2 was a significant predictor in univariate Cox regression analysis for persistent eGFR decline (HR 1.017, 95% CI: 1.003 to 1.032, p = 0.018), remission (HR 0.995, 95% CI: 0.992 to 0.999, p = 0.006), and relapse (HR 1.005, 95% CI: 1.001 to 1.010, p = 0.029). The ROC curve analysis demonstrated that serum TNFR2 levels had a strong prognostic ability for predicting progression to stage 4 CKD, with an AUC of 0.848 (95% CI: 0.737-0.960), sensitivity of 81%, and specificity of 71%.

CONCLUSION

This study underscores the critical role of circulating TNFR2 in kidney injury among patients with primary podocytopathy. Elevated TNFR2 levels are significant predictors of persistent eGFR decline and disease relapse, highlighting their potential as biomarkers for disease progression and prognosis.

Noninvasive biomarkers for lupus nephritis

Lupus nephritis (LN) is one of the most severe clinical manifestations of systemic lupus erythematosus (SLE). Notably, the clinical manifestations of LN are not always consistent with the histopathological findings. Therefore, the diagnosis and activity monitoring of this disease are challenging and largely depend on invasive renal biopsy. Renal biopsy has side effects and is associated with the risk of bleeding and infection. There is a growing interest in the development of novel noninvasive biomarkers for LN. In this review, we summarize most of the LN biomarkers discovered so far by correlating current knowledge with future perspectives. These biomarkers fundamentally reflect the biological processes of kidney damage and repair during disease. Furthermore, this review highlights the role of urinary cell phenotype detection in the diagnosis, monitoring, and treatment of LN and summarizes the limitations and countermeasures of this test.

The role of TNF-α in osteoporosis, bone repair and inflammatory bone diseases: A review

Tumour necrosis factor alpha (TNF-α) is a pleiotropic cytokine synthesised primarily by mononuclear cells; it has a potent pro-inflammatory effect, playing a crucial role in metabolic, immune, and inflammatory diseases. This cytokine has been studied in various biological systems. In bone tissue, TNF-α plays an integral role in skeletal disorders such as osteoporosis, fracture repair and rheumatoid arthritis through its involvement in regulating the balance between osteoblasts and osteoclasts, mediating inflammatory responses, promoting angiogenesis and exacerbating synovial proliferation. The biological effect TNF-α exerts in this context is determined by a combination of the signalling pathway it activates, the type of receptor it binds, and the concentration and duration of exposure. This review summarises the participation and pathophysiological role of TNF-α in osteoporosis, bone damage repair, chronic immunoinflammatory bone disease and spinal cord injury, and discusses its main mechanisms.

Anti-inflammatory potential of aconitine produced by endophytic fungus Acremonium alternatum

Argemone mexicana belonging to family Papaveraceae is a traditional medicinal plant widely utilized by tribal people in India for treating various ailments like skin infections, wounds and inflammation. This plant is very rich in alkaloidal content, which has a great potential in the treatment of anti-inflammatory disorders. Therapeutically promising bioactive molecules are often produced by endophytic fungi associated with medicinal plants. In this investigation, endophytic fungi were isolated from various parts of A. mexicana and screened for alkaloidal content. Among these, one of the fungal isolate, Acremonium alternatum AMEF-5 producing maximum alkaloids showed significant anti-inflammatory activity. Fractionation of this crude fungal extract through column chromatography yielded eight fractions, which were further screened for anti-inflammatory activities. Fraction 3 exhibited significant anti-inflammatory activity by the inhibition of lipoxygenase enzyme (IC50 15.2 ± 0.09 µg/ml), scavenging of the nitric oxide radicals (IC50 11.38 ± 0.35 µg/ml), protein denaturation (IC50 14.93 ± 0.4 µg/ml), trypsin inhibition (IC50 12.06 ± 0.64 µg/ml) and HRBC stabilization (IC50 11.9 ± 0.22 µg/ml). The bioactive alkaloid in fraction 3 was identified as aconitine which was confirmed by UV, FTIR, HPLC, HRMS, 1H NMR, and 13C NMR analysis. This study demonstrates that endophytic fungi serve a potential source for sustainable production of therapeutically important alkaloids.

Tumor Necrosis Factor Receptor-2 Signals Clear-Cell Renal Carcinoma Proliferation via Phosphorylated 4E Binding Protein-1 and Mitochondrial Gene Translation

Clear-cell renal cell carcinoma (ccRCC), a tubular epithelial malignancy, secretes tumor necrosis factor (TNF), which signals ccRCC cells in an autocrine manner via two cell surface receptors, TNFR1 and TNFR2, to activate shared and distinct signaling pathways. Selective ligation of TNFR2 drives cell cycle entry of malignant cells via a signaling pathway involving epithelial tyrosine kinase, vascular endothelial cell growth factor receptor type 2, phosphatidylinositol-3-kinase, Akt, pSer727-Stat3, and mammalian target of rapamycin. In this study, phosphorylated 4E binding protein-1 (4EBP1) serine 65 (pSer65-4EBP1) was identified as a downstream target of this TNFR2 signaling pathway. pSer65-4EBP1 expression was significantly elevated relative to total 4EBP1 in ccRCC tissue compared with that in normal kidneys, with signal intensity increasing with malignant grade. Selective ligation of TNFR2 with the TNFR2-specific mutein increased pSer65-4EBP1 expression in organ cultures that co-localized with internalized TNFR2 in mitochondria and increased expression of mitochondrially encoded COX (cytochrome c oxidase subunit) Cox1, as well as nuclear-encoded Cox4/5b subunits. Pharmacologic inhibition of mammalian target of rapamycin reduced both TNFR2-specific mutein-mediated phosphorylation of 4EBP1 and cell cycle activation in tumor cells while increasing cell death. These results signify the importance of pSer65-4EBP1 in mediating TNFR2-driven cell-cycle entry in tumor cells in ccRCC and implicate a novel relationship between the TNFR2/pSer65-4EBP1/COX axis and mitochondrial function.

Proteomics coupled transcriptomics reveals Slc34a1 and Slc34a3 downregulation as potential features of nephrotoxin-induced acute kidney injury

Acute kidney injury (AKI) stands as a prevalent and economically burdensome condition worldwide, yet its complex molecular mechanisms remain incompletely understood. To address this gap, our study employs a multifaceted approach, combining mass spectrometry and RNA sequencing technologies, to elucidate the intricate molecular landscape underlying nephrotoxin-induced AKI in mice by cisplatin- and LPS-induced. By examining the protein and RNA expression profiles, we aimed to uncover novel insights into the pathogenesis of AKI and identify potential diagnostic and therapeutic targets. Our results demonstrate significant down-regulation of Slc34a1 and Slc34a3, shedding light on their crucial roles in AKI pathology and highlighting their promise as actionable targets for diagnosis and treatment. This comprehensive analysis not only enhances our understanding of AKI pathophysiology but also offers valuable avenues for the development of targeted interventions to mitigate its clinical impact. SIGNIFICANCE: Nephrotoxicity acute kidney injury (AKI) is a common clinical condition whose pathogenesis is the process by which some drugs, chemicals or other factors cause damage to the kidneys, resulting in impaired kidney function. Although it has been proved that different nephrotoxic substances can affect the kidney through different pathways, whether they have a commonality has not been registered. Here, we combined transcriptomics and proteomics to study the molecular mechanism of LPS and cisplatin-induced nephrotoxic acute kidney injury finding that the down-regulation of Slc34a1 and Slc34a3 may be a critical link in nephrotoxic acute kidney injury, which can be used as a marker for its early diagnosis.

Soluble Tumor Necrosis Factor Receptor 2: A Promising Predictive Biomarker for Renal Dysfunction in Membranous Glomerulonephritis

Background and objective Membranous glomerulonephritis (MGN) is a common cause of adult nephrotic syndrome. Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine that signals by attaching to TNF receptors. TNF-α plays a pivotal role in the development and progression of different forms of glomerulonephritis. Several research findings suggest that TNF-α receptors (TNFR1 and TNFR2) are predictors of estimated glomerular filtration rate (eGFR) decline. In light of this, this study aimed to explore the relationship between TNFR2 and eGFR, as well as the predictive role of TNFR2 in eGFR decline in MGN. Methods A total of 50 consecutive patients with a diagnosis of primary MGN based on renal biopsies and clinical workups were included in the study. TNFR2 levels in serum, urine, and gene expression were evaluated at baseline and after three months of follow-up by using enzyme-linked immunosorbent assay (ELISA) kits for TNFR2 (KTE60215, Abbkine, Wuhan, China). Cox regression was employed to determine the predictive significance of TNFR2 in persistent eGFR decline. Additionally, an ROC curve analysis was conducted to assess the prognostic value of TNFR2 in predicting persistent eGFR decline among MGN patients. Results We assessed the levels of inflammatory markers TNF-α and TNFR2, examined their correlation with eGFR and renal injury, and investigated their potential in predicting persistent eGFR. Patients with MGN exhibited elevated levels of TNFR2 in their serum, urine, and gene expression compared to healthy individuals. Additionally, there was a positive correlation between serum TNFR2 and TNF-α, urine protein-creatinine ratio (UPCR), uric acid, and total cholesterol. Conversely, there was a negative correlation with eGFR, serum albumin, and calcium. Serum TNFR2 showed statistical significance in a univariate Cox regression analysis (HR: 1.010, 95% CI: 1.00-1.01, p = 0.045) for predicting a persistent decline in eGFR. However, it did not show significance concerning relapse and remission. An ROC curve was created to assess TNFR2's prognostic potential as a biomarker, demonstrating an AUC of 0.683, with a sensitivity of 68% and specificity of 64%. Conclusions Based on our findings, TNFR2 is a predictive biomarker for eGFR decline in MGN, correlating with renal inflammation and predicting deterioration in renal function. TNFR2 emerges as a promising biomarker for early identification in patients at risk of renal function decline.

Study the mRNA level of IL-27/IL-27R pathway molecules in kidney transplant rejection

BACKGROUND

Renal transplantation stands as the sole remedy for individuals afflicted with end-stage renal diseases, and safeguarding them from transplant rejection represents a vital, life-preserving endeavor posttransplantation. In this context, the impact of cytokines, notably IL-27, assumes a critical role in managing immune responses aimed at countering rejection. Consequently, this investigation endeavors to explore the precise function of IL-27 and its associated cytokines in the context of kidney transplant rejection.

METHODS

The study involved the acquisition of blood samples from a cohort of participants, consisting of 61 individuals who had undergone kidney transplantation (comprising 32 nonrejected patients and 29 rejected patients), and 33 healthy controls. The expression levels of specific genes were examined using SYBR Green Real-time PCR. Additionally, the evaluation encompassed the estimation of the ROC curve, the assessment of the relationship between certain blood factors, and the construction of protein-protein interaction networks for the genes under investigation.

RESULTS

Significant statistical differences in gene expression levels were observed between the rejected group and healthy controls, encompassing all the genes examined, except for TLR3 and TLR4 genes. Moreover, the analysis of the Area Under the Curve (AUC) revealed that IL-27, IL-27R, TNF-α, and TLR4 exhibited greater significance in discriminating between the two patient groups. These findings highlight the potential importance of IL-27, IL-27R, TNF-α, and TLR4 as key factors for distinguishing between individuals in the rejected group and those in the healthy control group.

CONCLUSIONS

In the context of kidney rejections occurring within the specific timeframe of 2 weeks to 2 months post-transplantation, it is crucial to emphasize the significance of cytokines mRNA level, including IL-27, IL-27R, TNF-α, and TLR4, in elucidating and discerning the diverse immune system responses. The comprehensive examination of these cytokines' mRNA level assumes considerable importance in understanding the intricate mechanisms underlying kidney rejection processes during this critical period.

Acute kidney injury is an unfavorable prognostic factor in acute liver failure and is associated with tumor necrosis factor-alpha

Acute kidney injury (AKI) is a common complication of acute liver failure (ALF); but its pathogenesis is unknown. ALF was divided into 2 subgroups; ALF with hepatic coma, which corresponds to ALF in the US and Europe, and ALF without hepatic coma. AKI has been shown to worsen the prognosis of ALF patients with hepatic coma; however, its prognostic significance in ALF without hepatic coma remains unknown. A single-center retrospective study of 174 patients with ALF was performed. AKI was defined according to KDIGO criteria. AKI developed in 29 (66.0%) of 44 ALF patients with hepatic coma and 27 (38.5%) of 130 ALF patients without hepatic coma. Systemic inflammatory response syndrome (SIRS) was found to be significantly associated with AKI incidence in ALF patients (P < .001). Tumor necrosis factor-alpha (TNF-α) was found to be significantly associated with the presence and severity of AKI (P = .0039 and P = .0140, respectively). On multivariate analysis, TNF-α was an independent risk factor linked with AKI (P = .0103). Even in the absence of hepatic coma, the transplant-free survival rate of ALF was significantly associated with the presence and severity of AKI. Even when hepatic coma is absent, AKI complicated in ALF is strongly associated with TNF-α and worsens the transplant-free survival rate. Before the onset of hepatic coma, plasma exchange, or extracorporeal blood purification to remove inflammatory cytokines should be considered in ALF patients.

TNFR2 as a Potential Biomarker for Early Detection and Progression of CKD

The inflammatory pathway driven by TNF-α, through its receptors TNFR1 and TNFR2, is a common feature in the pathogenesis of chronic kidney disease (CKD), regardless of the initial disease cause. Evidence correlates the chronic inflammatory status with decreased renal function. Our aim was to evaluate the potential of TNF receptors as biomarkers for CKD diagnosis and staging, as well as their association with the progression of renal lesions, in rat models of early and moderate CKD. We analyzed the circulating levels of inflammatory molecules—tumor necrosis factor-alpha (TNF-α), tumor necrosis factor receptor 1 (TNFR1) and 2 (TNFR2) and tissue inhibitor of metalloproteinase-1 (TIMP-1)—and studied their associations with TNFR1 and TNFR2 renal expression, glomerular and tubulointerstitial lesions, and with biomarkers of renal (dys)function. An increase in all inflammatory markers was observed in moderate CKD, as compared to controls, but only circulating levels of both TNFR1 and TNFR2 were significantly increased in the early disease; TNFR2 serum levels were negatively correlated with eGFR. However, only TNFR2 renal expression increased with CKD severity and showed correlations with the score of mild and advanced tubular lesions. Our findings suggest that renal TNFR2 plays a role in CKD development, and has potential to be used as a biomarker for the early detection and progression of the disease. Still, the potential value of this biomarker in disease progression warrants further investigation.

Responses to Ang II (Angiotensin II), Salt Intake, and Lipopolysaccharide Reveal the Diverse Actions of TNF-α (Tumor Necrosis Factor-α) on Blood Pressure and Renal Function

TNF-α (tumor necrosis factor-alpha) is the best known as a proinflammatory cytokine; yet, this cytokine also has important immunomodulatory and regulatory functions. As the effects of TNF-α on immune system function were being revealed, the spectrum of its activities appeared in conflict with each other before investigators defined the settings and mechanisms by which TNF-α contributed to both host defense and chronic inflammation. These effects reflect self-protective mechanisms that may become harmful when dysregulated. The paradigm of physiological and pathophysiological effects of TNF-α has since been uncovered in the lung, colon, and kidney where its role has been identified in pulmonary edema, electrolyte reabsorption, and blood pressure regulation, respectively. Recent studies on the prohypertensive and inflammatory effects of TNF-α in the cardiovascular system juxtaposed to those related to NaCl and blood pressure homeostasis, the response of the kidney to lipopolysaccharide, and protection against bacterial infections are helping define the mechanisms by which TNF-α modulates distinct functions within the kidney. This review discusses how production of TNF-α by renal epithelial cells may contribute to regulatory mechanisms that not only govern electrolyte excretion and blood pressure homeostasis but also maintain the appropriate local hypersalinity environment needed for optimizing the innate immune response to bacterial infections in the kidney. It is possible that the wide range of effects mediated by TNF-α may be related to severity of disease, amount of inflammation and TNF-α levels, and the specific cell types that produce this cytokine, areas that remain to be investigated further.

Subclinical Acute Kidney Injury in COVID-19: Possible Mechanisms and Future Perspectives

Since the outbreak of COVID-19 disease, a bidirectional interaction between kidney disease and the progression of COVID-19 has been demonstrated. Kidney disease is an independent risk factor for mortality of patients with COVID-19 as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leading to the development of acute kidney injury (AKI) and chronic kidney disease (CKD) in patients with COVID-19. However, the detection of kidney damage in patients with COVID-19 may not occur until an advanced stage based on the current clinical blood and urinary examinations. Some studies have pointed out the development of subclinical acute kidney injury (subAKI) syndrome with COVID-19. This syndrome is characterized by significant tubule interstitial injury without changes in the estimated glomerular filtration rate. Despite the complexity of the mechanism(s) underlying the development of subAKI, the involvement of changes in the protein endocytosis machinery in proximal tubule (PT) epithelial cells (PTECs) has been proposed. This paper focuses on the data relating to subAKI and COVID-19 and the role of PTECs and their protein endocytosis machinery in its pathogenesis.

Anti-inflammatory compounds from the mangrove endophytic fungus Amorosia sp. SCSIO 41026

Three new chlorinated compounds, including two propenylphenol derivatives, chlorophenol A and B (1 and 2), and one benzofuran derivative, chlorophenol C (3), together with 16 known compounds, were isolated from the mangrove endophytic fungus Amorosia sp. SCSIO 41026. 7-Chloro-3,4-dihydro-6,8-dihydroxy-3-methylisocoumarine (4) and 2,4-dichloro-3-hydroxy-5-methoxy-toluene (5) were obtained as new natural products. Their structures were elucidated by physicochemical properties and extensive spectroscopic analysis. Compounds 1, 4, 7, 9, 13, 15, 16, and 19 possessed inhibitory effects against the excessive production of nitric oxide (NO) and pro-inflammatory cytokines in lipopolysaccharide (LPS)-challenged RAW264.7 macrophages without obvious cytotoxicity. Moreover, 5-chloro-6-hydroxymellein (13) further alleviated the pathological lung injury of LPS-administrated mice and protected RAW264.7 macrophages against LPS-induced inflammation through PI3K/AKT pathway in vivo. Our research laid the foundation for the application of compound 13 as a potential anti-inflammatory candidate.

TFNR2 in Ischemia-Reperfusion Injury, Rejection, and Tolerance in Transplantation

Tumor necrosis factor receptor 2 (TNFR2) has been shown to play a crucial role in CD4+ T regulatory cells (CD4+Tregs) expansion and suppressive function. Increasing evidence has also demonstrated its role in a variety of immune regulatory cell subtypes such as CD8+ T regulatory cells (CD8+ Tregs), B regulatory cells (Bregs), and myeloid-derived suppressor cells (MDSCs). In solid organ transplantation, regulatory immune cells have been associated with decreased ischemia-reperfusion injury (IRI), improved graft survival, and improved overall outcomes. However, despite TNFR2 being studied in the context of autoimmune diseases, cancer, and hematopoietic stem cell transplantation, there remains paucity of data in the context of solid organ transplantation and islet cell transplantation. Interestingly, TNFR2 signaling has found a clinical application in islet transplantation which could guide its wider use. This article reviews the current literature on TNFR2 expression in immune modulatory cells as well as IRI, cell, and solid organ transplantation. Our results highlighted the positive impact of TNFR2 signaling especially in kidney and islet transplantation. However, further investigation of TNFR2 in all types of solid organ transplantation are required as well as dedicated studies on its therapeutic use during induction therapy or treatment of rejection.

Decoy Receptor 3 Suppresses T-Cell Priming and Promotes Apoptosis of Effector T-Cells in Acute Cell-Mediated Rejection: The Role of Reverse Signaling

Background

Decoy receptor 3 (DcR3) belongs to the tumor necrosis factor (TNF) receptor superfamily and neutralizes TNF ligands, including FasL and TRAIL, to prevent T activation during T-cell priming. However, the cellular mechanisms underlying acute cell-mediated rejection (ACMR) remain unknown.

Methods

We generated DcR3 transgenic (Tg) mice and mice with high DcR3 expression (HDE) to study both in vivo and in vitro. FasR RNA knockdown in immortalized CD4⁺CD8⁺ T-cells was used to survey the role of DcR3 on FasR/Fas-associated protein with death domain (FADD)/caspase 8 pathway and its cross-link to TNF receptor-associated factor 1 (TNFR1)-associated death domain protein (TRADD) in suppressing TNFR1. TNF/TRADD knockout mice were used to show the importance of TNF adaptor protein.

Results

DcR3.Fc suppressed C57BL/6 female T-cell activation and transformation into CD4⁺CD69⁺, CD4⁺CD44⁺, and CD4⁺CD25⁺Foxp3⁺ when compared with isotype IgG1 and its co-treatment with FasL/TRAIL after exposing to bone marrow-derived dendritic cells (BMDCs) that carried alloantigen with male H-Y and minor antigenic determinant. Interleukin-17 and interferon-γ productions by BMDC-activated T-cells were lowered after co-treating with DcR3.Fc. DcR3.Fc induced effector T-cells (Teffs) and was susceptible to FasR-mediated apoptosis through the FADD/TRADD/caspase 8 pathway. After exposing to DcR3.Fc, TRADD was silenced, likely turning down the inflammatory response. The systemic effects of DcR3 Tg mice and HDE phenotype induced by the promoter of cytomegalovirus not only attenuated ACMR severity but also ameliorated the high serum creatinine and blood urea nitrogen levels even with high T-cell exposure frequencies. Besides this, DcR3 has minor biological effects on both MHC-matched and MHC-mismatched models.

Conclusions

High DcR3 doses protect renal tubular epithelial cells from acute T-cell attack during the T-cell priming stage via interfering with TNF ligand-mediated reverse signaling and possibly promoting Teff apoptosis through FasR upregulation. Our findings supported that the decoy receptor is involved in T-cell modulation in kidney transplant rejection.

Inflammatory biomarkers in staging of chronic kidney disease: elevated TNFR2 levels accompanies renal function decline

BACKGROUND

Inflammation is a common feature in the pathogenesis of chronic kidney disease (CKD), regardless of the disease cause. Our aim was to evaluate the potential of several inflammatory biomarkers in CKD diagnosis and staging.

METHODS

A total of 24 healthy controls and 92 pre-dialysis CKD patients with diverse etiologies, were enrolled in this study and grouped according to their CKD stage. We analysed the circulating levels of inflammatory molecules, C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), tumor necrosis factor receptor 2 (TNFR2), pentraxin 3 (PTX3) and leptin, as well as the hemogram. We studied their association with parameters of kidney function and kidney injury, to evaluate their potential as early markers of the disease and/or of its worsening, as well as their interplay.

RESULTS

Compared to controls, patients in CKD stages 1-2 presented significantly higher IL-6 and TNFR2 levels, and higher neutrophil-to-lymphocyte ratio. All inflammatory cytokines and acute-phase proteins showed a trend to increase up to stage 3, stabilizing or declining thereafter, save for TNFR2, which steadily increased from stage to stage. All inflammatory molecules, apart from PTX3, were negatively and significantly correlated with eGFR, with a remarkable value for TNFR2 (r = - 0.732, p < 0.001).

CONCLUSION

TNFR2 might be useful for an early detection of CKD, as well as for disease staging/worsening. Still, the potential value of this biomarker in disease progression warrants further investigation.

Co-Expression and Functional Interactions of Death Receptor 3 and E-Selectin in Clear Cell Renal Cell Carcinoma

Similar to the behavior of inflamed tubular epithelial cells, clear cell renal cell carcinoma (ccRCC) cells express death receptor 3 (DR3 or TNFSFR25) in situ, and expression increases with tumor grade. Surprisingly, E-selectin, which can be induced in endothelial cells by DR3 signaling, is also expressed by ccRCC cells and increases with tumor grade. In ccRCC organ cultures, addition of tumor necrosis factor-like 1A (TL1A or TNFSF15), the ligand for DR3, activates NF-κB and mitogen-activated protein kinases, induces both DR3 and E-selectin expression in an NF-κB-dependent manner, and promotes cell cycle entry. DR3 immunoprecipitated from ccRCC tissue contains sialyl Lewis X moieties (the ligand recognized by E-selectin), proximity ligation assays reveal DR3, and E-selectin interacts on ccRCC cells. Similar to that with the addition of TL1A, the addition of soluble E-selectin to ccRCC organ cultures activates NF-κB and mitogen-activated protein kinases in ccRCC cells and increases both DR3 and E-selectin expression and cell-cycle entry. In contrast, normal renal tubular epithelium, which poorly expresses DR3, is minimally responsive to either of these ligands. These data suggest a functional role for autocrine/paracrine DR3/E-selectin interactions in ccRCC and its progression, revealing a potential new target for therapeutic intervention.

The Signaling Pathway of TNF Receptors: Linking Animal Models of Renal Disease to Human CKD

Chronic kidney disease (CKD) has been recognized as a global public health problem. Despite the current advances in medicine, CKD-associated morbidity and mortality remain unacceptably high. Several studies have highlighted the contribution of inflammation and inflammatory mediators to the development and/or progression of CKD, such as tumor necrosis factor (TNF)-related biomarkers. The inflammation pathway driven by TNF-α, through TNF receptors 1 (TNFR1) and 2 (TNFR2), involves important mediators in the pathogenesis of CKD. Circulating levels of TNFRs were associated with changes in other biomarkers of kidney function and injury, and were described as predictors of disease progression, cardiovascular morbidity, and mortality in several cohorts of patients. Experimental studies describe the possible downstream signaling pathways induced upon TNFR activation and the resulting biological responses. This review will focus on the available data on TNFR1 and TNFR2, and illustrates their contributions to the pathophysiology of kidney diseases, their cellular and molecular roles, as well as their potential as CKD biomarkers. The emerging evidence shows that TNF receptors could act as biomarkers of renal damage and as mediators of the disease. Furthermore, it has been suggested that these biomarkers could significantly improve the discrimination of clinical CKD prognostic models.

Renal microvascular endothelial cell responses in sepsis-induced acute kidney injury

Microvascular endothelial cells in the kidney have been a neglected cell type in sepsis-induced acute kidney injury (sepsis-AKI) research; yet, they offer tremendous potential as pharmacological targets. As endothelial cells in distinct cortical microvascular segments are highly heterogeneous, this Review focuses on endothelial cells in their anatomical niche. In animal models of sepsis-AKI, reduced glomerular blood flow has been attributed to inhibition of endothelial nitric oxide synthase activation in arterioles and glomeruli, whereas decreased cortex peritubular capillary perfusion is associated with epithelial redox stress. Elevated systemic levels of vascular endothelial growth factor, reduced levels of circulating sphingosine 1-phosphate and loss of components of the glycocalyx from glomerular endothelial cells lead to increased microvascular permeability. Although coagulation disbalance occurs in all microvascular segments, the molecules involved differ between segments. Induction of the expression of adhesion molecules and leukocyte recruitment also occurs in a heterogeneous manner. Evidence of similar endothelial cell responses has been found in kidney and blood samples from patients with sepsis. Comprehensive studies are needed to investigate the relationships between segment-specific changes in the microvasculature and kidney function loss in sepsis-AKI. The application of omics technologies to kidney tissues from animals and patients will be key in identifying these relationships and in developing novel therapeutics for sepsis.

Etanercept-Induced Anti-Glomerular Basement Membrane Disease

Anti-glomerular basement membrane (anti-GBM) disease is a rare form of small-vessel vasculitis that typically causes rapidly progressive glomerulonephritis with or without alveolar haemorrhage. Previously, there has only been one reported case of tumour necrosis factor-α (TNF-α) antagonist-induced anti-GBM disease. Here, we describe the first reported case of etanercept-induced anti-GBM disease. A 55-year-old Caucasian man was referred to our tertiary specialist renal centre with a history of painless macroscopic haematuria. The patient has been receiving weekly etanercept injections over the past 12 months for psoriatic arthropathy. The serum immunology panel results highlighted a significantly raised anti-GBM titre (370.1 U). Etanercept was stopped, and the patient was empirically commenced on pulsed methylprednisolone, cyclophosphamide, and plasma exchange. A renal biopsy showed crescentic glomerulonephritis. Few days after admission, he tested positive for coronavirus disease 2019 (COVID-19), and a decision was made to withhold cyclophosphamide. There was further decline in renal function with hyperkalaemia for which he received 2 sessions of haemodialysis. He was restarted on cyclophosphamide upon discharge. The patient was switched to rituximab treatment afterwards as he developed leucopenia 2 weeks following the commencement of cyclophosphamide. The serum creatinine level continued to improve and remained dialysis-independent. In conclusion, with the increased use of etanercept and other TNF-α antagonists, the prescribing clinician must be aware of the rare but life-threatening drug-induced vasculitis. We recommend careful monitoring of renal indices with the use of this class of medications.

Effects of the SGLT2 inhibitor canagliflozin on plasma biomarkers TNFR-1, TNFR-2 and KIM-1 in the CANVAS trial

AIMS/HYPOTHESIS

Higher plasma concentrations of tumour necrosis factor receptor (TNFR)-1, TNFR-2 and kidney injury molecule-1 (KIM-1) have been found to be associated with higher risk of kidney failure in individuals with type 2 diabetes in previous studies. Whether drugs can reduce these biomarkers is not well established. We measured these biomarkers in samples of the CANVAS study and examined the effect of the sodium-glucose cotransporter 2 inhibitor canagliflozin on these biomarkers and assessed whether the early change in these biomarkers predict cardiovascular and kidney outcomes in individuals with type 2 diabetes in the CANagliflozin cardioVascular Assessment Study (CANVAS).

METHODS

Biomarkers were measured with immunoassays (proprietary multiplex assay performed by RenalytixAI, New York, NY, USA) at baseline and years 1, 3 and 6. Mixed-effects models for repeated measures assessed the effect of canagliflozin vs placebo on the biomarkers. Associations of baseline levels and the early change (baseline to year 1) for each biomarker with the kidney outcome were assessed using multivariable-adjusted Cox regression.

RESULTS

In total, 3523/4330 (81.4%) of the CANVAS participants had available samples at baseline. Each doubling in baseline TNFR-1, TNFR-2 and KIM-1 was associated with a higher risk of kidney outcomes, with corresponding HRs of 3.7 (95% CI 2.3, 6.1; p < 0.01), 2.7 (95% CI 2.0, 3.6; p < 0.01) and 1.5 (95% CI 1.2, 1.8; p < 0.01), respectively. Canagliflozin reduced the level of the plasma biomarkers with differences in TNFR-1, TNFR-2 and KIM-1 between canagliflozin and placebo during follow-up of 2.8% (95% CI 3.4%, 1.3%; p < 0.01), 1.9% (95% CI 3.5%, 0.2%; p = 0.03) and 26.7% (95% CI 30.7%, 22.7%; p < 0.01), respectively. Within the canagliflozin treatment group, each 10% reduction in TNFR-1 and TNFR-2 at year 1 was associated with a lower risk of the kidney outcome (HR 0.8 [95% CI 0.7, 1.0; p = 0.02] and 0.9 [95% CI 0.9, 1.0; p < 0.01] respectively), independent of other patient characteristics. The baseline and 1 year change in biomarkers did not associate with cardiovascular or heart failure outcomes.

CONCLUSIONS/INTERPRETATION

Canagliflozin decreased KIM-1 and modestly reduced TNFR-1 and TNFR-2 compared with placebo in individuals with type 2 diabetes in CANVAS. Early decreases in TNFR-1 and TNFR-2 during canagliflozin treatment were independently associated with a lower risk of kidney disease progression, suggesting that TNFR-1 and TNFR-2 have the potential to be pharmacodynamic markers of response to canagliflozin.

The Association of Aspartate Aminotransferase/Alanine Aminotransferase Ratio with Diabetic Nephropathy in Patients with Type 2 Diabetes

PURPOSE

To investigate the relationship between aspartate aminotransferase to alanine aminotransferase ratio (AST/ALT) and diabetic nephropathy (DN).

PATIENTS AND METHODS

A total of 402 patients with type 2 diabetes mellitus were divided into three groups, such as normoalbuminuria (n = 196), microalbuminuria (n = 131) and macroalbuminuria (n = 75) groups. Basic information and laboratory results were collected. Serum AST/ALT, tumor necrosis factor-α (TNF-α), interleukin (IL)-2, IL-4, IL-6, IL-10 and interferon- γ (INF- γ) were also measured. DN was defined as microalbuminuria or macroalbuminuria. The estimated glomerular filtration rate (eGFR) was calculated using the following formula: 186 × (serum creatinine)^-1.154× (age)^-0.203× (0.742 if female).

RESULTS

The AST/ALT in the macroalbuminuria group was higher than in the microalbuminuria and normoalbuminuria groups. The concentrations of tumor necrosis factor-α (TNF-α), IL-2, IL-4, IL-10 and INF-γ in the macroalbuminuria group were significantly higher than those in the two other groups. Multivariate logistical analysis showed that after adjusting confounding factors, TNF-α and high AST/ALT were independent risks for DN and macroalbuminuria. Furthermore, the AST/ALT had significantly positive correlation with TNF-α (r = 0.101, P = 0.048), IL-4 (r = 0.185, P = 0.005) and IL-6 (r = 0.274, P < 0.001) levels.

CONCLUSION

This study showed that high AST/ALT was an independent risk factor for the DN. Additionally, AST/ALT was positively correlated with inflammation cytokines, such as TNF-α, IL-4 and IL-6 levels.

Prostaglandin F2α receptor antagonist attenuates LPS-induced systemic inflammatory response in mice

Although it is known that prostaglandin (PG) F_2α level is elevated in the plasma of patients with sepsis, the roles of PGF_2α is still unknown. We aimed to clarify the roles of PGF_2α in the regulation of lipopolysaccharide (LPS)-induced systemic inflammation. At 24 hours after LPS administration, neutrophil infiltration in peritoneal cavity, the mRNA expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and macrophage inflammatory protein-2, and tissue damages in lung, liver, and kidney were all increased. Inhibition of FP receptors significantly decreased LPS-induced neutrophil infiltration and lowered the mRNA expression of the pro-inflammatory cytokines. At 6 hour after LPS administration, the level of anti-inflammatory cytokine, IL-10 in peritoneal lavage fluid was higher than that in naïve mice. Inhibition of FP receptors in these mice increased IL-10 level further. Stimulation of isolated peritoneal neutrophils by LPS increased the gene expression of IL-10, which was further increased by AL8810 treatment. Administration of an anti-IL-10 antibody antagonized the AL8810-decreased mRNA expression of pro-inflammatory cytokines and tissue damages. These results indicate that inhibition of FP receptors by AL8810 attenuated LPS-induced systemic inflammation in mice via enhanced IL-10 production.

Signaling through tumor necrosis receptor 2 induces stem cell marker in CD133+ regenerating tubular epithelial cells in acute cell-mediated rejection of human renal allografts

Tumor necrosis factor receptor 2 (TNFR2) is strongly upregulated on renal tubular epithelial cells by acute cell-mediated rejection (ACR. In human kidney organ culture, TNFR2 signaling both upregulates TNFR2 expression and promotes cell cycle entry of tubular epithelial cells. We find significantly more cells express CD133 mRNA and protein, a putative stem cell marker, in allograft biopsy samples with ACR compared to acute tubular injury without rejection or pretransplant "normal kidney" biopsy samples. Of CD133⁺ cells, ~85% are within injured tubules and ~15% are interstitial. Both populations express stem cell marker TRA-1-60 and TNFR2, but only tubular CD133⁺ cells express proximal tubular markers megalin and aquaporin-1. TNFR2⁺ CD133⁺ cells in tubules express proliferation marker phospho-histone H3^S10 (pH3^S10 ). Tubular epithelial cells in normal kidney organ cultures respond to TNFR2 signaling by expressing CD133 mRNA and protein, stem cell marker TRA-1-60, and pH3^S10 within 3 hours of treatment. This rapid response time suggests that CD133⁺ cells in regenerating tubules of kidneys undergoing ACR represent proliferating tubular epithelial cells with TNFR2-induced stem cell markers rather than expansion of resident stem cells. Infiltrating host mononuclear cells are a likely source of TNF as these changes are absent in acute tubular injury .

Renal expression of cytokines and chemokines in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. Inflammatory mediators have been implicated in the pathogenesis of DN, thus considered an inflammatory disease. However, further studies are required to assess the renal damage caused by the action of these molecules. Therefore, the objective of this study was to analyze the expression of cytokines and chemokines in renal biopsies from patients with DN and to correlate it with interstitial inflammation and decreased renal function.

METHODS

Forty-four native renal biopsies from patients with DN and 23 control cases were selected. In situ expression of eotaxin, MIP-1α (macrophage inflammatory protein-1α), IL-8 (interleukin-8), IL-4, IL-10, TNF-α (tumor necrosis factor-α), TNFR1 (tumor necrosis factor receptor-1), IL-1β, and IL-6 were evaluated by immunohistochemistry.

RESULTS

The DN group showed a significant increase in IL-6 (p < 0.0001), IL-1β (p < 0.0001), IL-4 (p < 0.0001) and eotaxin (p = 0.0012) expression, and a decrease in TNFR1 (p = 0.0107) and IL-8 (p = 0.0262) expression compared to the control group. However, there were no significant differences in IL-10 (p = 0.4951), TNF-α (p = 0.7534), and MIP-1α (p = 0.3816) expression among groups. Regarding interstitial inflammation, there was a significant increase in IL-6 in scores 0 and 1 compared to score 2 (p = 0.0035), in IL-10 in score 2 compared to score 0 (p = 0.0479), and in eotaxin in score 2 compared to scores 0 and 1 (p < 0.0001), whereas IL-8 (p = 0.0513) and MIP-1α (p = 0.1801) showed no significant differences. There was a tendency for negative correlation between eotaxin and estimated glomerular filtration rate (eGFR) (p = 0.0566).

CONCLUSIONS

Our results indicated an increased in situ production of cytokines and chemokines in DN, including IL-6, IL-1β, IL-4, and eotaxin. It was observed that, possibly, eotaxin may have an important role in the progression of interstitial inflammation in DN and in eGFR decrease of these patients.

Mesenchymal Stem Cells Anti-Inflammatory Activity in Rats: Proinflammatory Cytokines

Introduction

Many widespread intractable diseases are caused or supported by chronic inflammation. Such conditions include the 2nd type of diabetes mellitus, atherosclerosis, neurodegenerative diseases, chronic inflammatory diseases of the connective tissue - ankylosing spondylitis, rheumatoid arthritis, autoimmune myositis, etc. Therefore, the search for targeted treatment of these illnesses is extremely in high demand. Immunomodulatory activity of mesenchymal stem cells is one of their remarkable properties. Several biomarkers (cytokines and nonspecific proteins) are known to be associated with chronic inflammation.

Methods

Our study aimed to investigate the serum levels of tumor necrosis factor-alpha, interleukin 6 and C-reactive protein in carrageenan myositis in rats, because there is more and more evidence of the significance of these markers in the course and resolution of the diseases mentioned above. For the first time in our experiment, it was shown and evaluated using analysis of variance, how MSCs influence the indicators of proinflammatory cytokines on the model of carrageenan myositis. The levels of α-TNF, IL-6 and CRP in the plasma of rats were studied in groups with chronic carrageenan inflammation and chronic inflammation with local injection of MSCs into the affected area.

Results

Our study proved the effectiveness of MSCs by showing a significant decrease in the levels of inflammatory mediators in the plasma of the studied animals.

Discussion and Conclusions

Thus, the administration of MSCs is a promising tool in the pathogenic treatment of chronic inflammation and concomitant conditions.

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Increased circulating cytokine levels in African American women with obesity and elevated HbA1c

PURPOSE

Obesity has emerged as one of the biggest health crisis and is the leading cause of death and disabilities around the world. BMI trends suggest that majority of the increase in T2D is resulting from the increased prevalence of obesity. In fact, 85.2% of people with T2D are overweight or obese. The highest prevalence for obesity is seen in non-Hispanic, African American women (56.6%). T2D is classified as an inflammatory disease because of elevated, circulating pro-inflammatory cytokines and acute-phase inflammatory proteins. This study was designed to determine how high HbA1c and serum glucose correlate with circulatory cytokine levels in obese, African American women.

METHODS

We investigated cytokine/chemokine serum levels using a multiplex assay. Then we used Pairwise Pearson Correlation Test to determine the relationship between clinical metabolic parameters and cytokine/chemokine serum levels.

RESULTS

The results indicated that participants with elevated HbA1c exhibited an up regulation of IL-3, IL-4, IL-7, TNF-α, IFN-α2 and CX3CL1 serum levels compared to participants with normal HbA1c. These cytokines were also correlated with several clinical metabolic parameters.

CONCLUSIONS

The results suggest that IL-3, IL-4, IL-7, TNF-α, IFN-α2 and CX3CL1 serum levels may contribute to the development and onset of type 2 diabetes.

Tumor necrosis factor receptor-2 signaling pathways promote survival of cancer stem-like CD133+ cells in clear cell renal carcinoma

Clear cell renal cell carcinoma (ccRCC) contains cancer stem-like cells (CSCs) that express CD133 (ccRCC-CD133+). CSCs are rarely in cell cycle and, as nonproliferating cells, resist most chemotherapeutic agents. Previously, we reported that tumor necrosis factor receptor-2 (TNFR2) signaling promotes the cell cycle entry of ccRCC-CD133+CSCs, rendering them susceptible to cell-cycle-dependent chemotherapeutics. Here, we describe a TNFR2-activated signaling pathway in ccRCC-CD133+CSCs that is required for cell survival. Wild-type (wt)TNF or R2TNF but not R1TNF (TNF muteins that selectively bind to TNFR2 and TNFR1) induces phosphorylation of signal transducer and activator of transcription 3 (STAT3) on serine727 but not tyrosine705, resulting in pSTAT3Ser727 translocation to and colocalization with TNFR2 in mitochondria. R2TNF signaling activates a kinase cascade involving the phosphorylation of VEGFR2, PI-3K, Akt, and mTORC. Inhibition of any of the kinases or siRNA knockdown of TNFR2 or STAT3 promotes cell death associated with mitochondrial morphological changes, cytochrome c release, generation of reactive oxygen species, and TUNEL+cells expressing phosphorylated mixed lineage kinase-like (MLKL). Pretreatment with necrostatin-1 is more protective than z-VAD.fmk, suggesting that most death is necroptotic and TNFR2 signaling promotes cell survival by preventing mitochondrial-mediated necroptosis. These data suggest that a TNFR2 selective agonist may offer a potential therapeutic strategy for ccRCC.

Urinary metabolomic profiling for noninvasive diagnosis of acute T cell-mediated rejection after kidney transplantation

To improve early renal allograft function, it is important to develop a noninvasive diagnostic method for acute T cell-mediated rejection (TCMR). This study aims to explore potential noninvasive urinary biomarkers to screen for acute TCMR in kidney transplant recipients (KTRs) using untargeted metabolomic profiling. Urinary metabolites, collected from KTRs with stable graft function (STA) or acute TCMR episodes, were analyzed using liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analyses were performed to discriminate differences in urinary metabolites between the two groups. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of potential urinary biomarkers. Statistical analysis revealed the differences in urinary metabolites between the two groups and indicated several statistically significant metabolic features suitable for potential biomarkers. By comparing the retention times and mass fragmentation patterns of the chemicals in metabolite databases, samples, and standards, six of these features were clearly identified. ROC curve analysis showed the best performance of the training set (area under the curve value, 0.926; sensitivity, 90.0%; specificity, 84.6%) using a panel of five potential biomarkers: guanidoacetic acid, methylimidazoleacetic acid, dopamine, 4-guanidinobutyric acid, and L-tryptophan. The diagnostic accuracy of this model was 62.5% for an independent test dataset. LC-MS-based untargeted metabolomic profiling is a promising method to discriminate between acute TCMR and STA groups. Our model, based on a panel of five potential biomarkers, needs to be further validated in larger scale studies.

Preventive effect on endothelial surface layer damage of Fusu agent in LPS-induced acute lung injury in rats

Acute lung injury (ALI) is one of major causes of morbidity and mortality in intensive care. In pathophysiological events of ALI, endothelial surface layer (ESL) injury can result in capillary leakage as the initial event. The “Fusu agent”, a traditional Chinese medicine, can inhibit inflammatory factors, attenuate lung capillary leak as seen in our previous study. This study was aimed to explore the molecular mechanism of Fusu agent treatment with ALI. Consistent with previous studies, we found that Fusu agent has the protective effect on LPS-induced ALI model rats. Further investigation demonstrated that heparanase activation is necessary for the LPS-induced ALI model to aggravate ESL loss. Fusu agent can inhibit heparanase activation and heparan sulfate proteoglycans’ (HSPGs) degradation to mitigate the ESL injury. Furthermore, TNF-α and intercellular adhesion molecule-1 (ICAM-1) were significantly reduced upon Fusu agent pre-treatment to inhibit inflammatory cell influx and neutrophil adhesion in ALI. These findings shed light on the pharmacologic basis for the clinical application of traditional Chinese medicine in treating ALI.

Therapeutic approaches for the delivery of TNF-α siRNA

Immune-mediated diseases are emerging as a major healthcare concern in the present era. TNF-α, a proinflammatory cytokine, plays a major role in the manifestation of these diseases by mediating different pathways and inducing the expression of other cytokines. In last decades, monoclonal antibodies and extracellular portion of human TNF-α receptors are explored in this area; however, the risk of immunological response and undesired effects urge a need to develop more effective therapies to control TNF-α levels. siRNA therapeutic strategies are emerging for the treatment of myriad of diseases, but the delivery challenges associated with siRNA require the development of suitable delivery vectors. For delivery of TNF-α siRNA, both viral and nonviral vectors are explored. This review attempts to describe different delivery approaches for TNF-α siRNA with special focus on nonviral delivery vectors.

Burn injury mortality in patients with preexisting and new onset renal disease

INTRODUCTION

We sought to examine the impact of preexisting and new onset renal disease on burn injury mortality.

METHODS

Retrospective analysis of patients admitted to a regional burn center from 2002-2012 was performed. Variables analyzed included demographics, burn mechanism, inhalation injury status, and % TBSA. Poisson regression was performed to estimate risk of in-hospital burn mortality.

RESULTS

There were a total of 7640 patients over the study period. The adjusted 60-day risk of in-hospital mortality in patients with preexisting renal disease (PRD was 3 times higher compared to patients with no preexisting renal disease (IRR = 3.22, 95% CI = 1.26-8.25). The adjusted 60-day risk of mortality is 2 times higher for patients with new onset renal disease compared to those without (IRR = 2.11, 95% CI = 1.55-2.87).

CONCLUSION

Preexisting and new onset renal disease results in a significantly higher risk of mortality following burn injury compared to patients without renal disease. Prevention of new onset renal injury and careful management of patients with preexisting renal disease to prevent exacerbation should be pursued.

Pre-clinical study of a TNFR1-targeted 18F probe for PET imaging of breast cancer

Tumor necrosis factor receptor 1 (TNFR1) is overexpressed in several varieties of carcinoma, including breast cancer. WH701 (Ala-Thr-Ala-Gln-Ser-Ala-Tyr-Gly), which was identified by phage display, can specifically bind to TNFR1. In this study, we labeled WH701 with ¹⁸F and investigated its tumor diagnostic value. WH701 was synthesized by standard Fmoc-solid phase synthetic protocols and conjugated by NOTA-NHS. NOTA-WH701 was radiolabeled with ¹⁸F using NOTA-AlF chelation reaction. The tumor target properties were evaluated in vitro and in vivo using MCF-7 xenografts and inflammation models. [¹⁸F]AlF-NOTA-WH701 was labeled in 25 min with a decay-corrected yield of 38.1 ± 4.8% (n = 5) and a specific activity of 10.4-13.0 GBq/μmol. WH701 had relatively high affinity for MCF-7 cells in vitro and [¹⁸F]AlF-NOTA-WH701 displayed relatively high tumor uptake in vivo. The tumor to muscle ratio was 4.25 ± 0.56 at 30 min post-injection (p.i.); further, there was a significant difference between the tumor/muscle and inflammation/muscle (3.22 ± 0.56) ratio, which could differentiate the tumor and inflammation. The tumor uptake of [¹⁸F]AlF-NOTA-WH701 could be inhibited by 71.1% by unlabeled WH701 at 30 min p.i. We have developed a promising PET tracer [¹⁸F]AlF-NOTA-WH701 for the noninvasive detection of breast cancer in vivo.

High levels of circulating TNFR1 increase the risk of all-cause mortality and progression of renal disease in type 2 diabetic nephropathy

BACKGROUND

Several studies have demonstrated that levels of circulating inflammatory markers such as tumour necrosis factorα (TNFα), are associated with early progression of diabetic nephropathy (DN). The aim of this study was to investigate whether there is an association between circulating TNFα receptor and disease progression in patients with advanced type 2 DN and severe proteinuria.

METHODS

Between 2006 and 2011, we measured levels of circulating soluble TNFα receptor 1 (TNFR1) and soluble TNFα receptor 2 (TNFR2) at baseline and 4 and 12 months in 101 patients included in a multicenter randomized controlled trial to compare the effect of optimal doses of renin-angiotensin system blockers in monotherapy or in combination (dual blockade) to slow progression of established type 2 DN. The primary composite endpoint was a >50% increase in baseline serum creatinine, end-stage renal disease, or death.

RESULTS

The median follow-up was 32 months (IQR, 18-48), during which time 28 patients (22.7%) achieved the primary endpoint. The TNFR1 level, but not the TNFR2 level, was correlated with other inflammatory markers. Cox regression analysis showed that the highest TNFR1 levels (HR, 2.60; 95%CI, 1.11-86.34) and baseline proteinuria (HR 1.32; 95%CI 1.15-1.52) were associated with the primary endpoint. The mixed model analysis revealed that TNFR1 and the TNFR2 levels did not change after starting treatment with renin-angiotensin system blockers.

CONCLUSIONS

Our results show that the highest levels of TNFR1 are independently associated with progression of renal disease and death in type 2 DN. The renin angiotensin blockers have no effect on these inflammatory markers.

Effect of tonsillectomy with steroid pulse therapy on circulating tumor necrosis factor receptors 1 and 2 in IgA nephropathy

BACKGROUND

High circulating levels of soluble tumor necrosis factor receptors (TNFRs: TNFR1, TNFR2) predict renal function decline in a variety of kidney diseases. Tonsillectomy with steroid pulse (TSP) therapy has been reported as a remission induction therapy in IgA nephropathy (IgAN), mainly in Japan. However, little is known about whether TNFR levels change after TSP therapy in patients with IgAN.

METHODS

Two hundred twenty-three patients with IgAN were stratified according to the estimated glomerular filtration rate (eGFR): Group I (eGFR ≥ 60 mL/min/1.73 m², n = 172) and Group II (eGFR < 60 mL/min/1.73 m², n = 51). We measured serum TNFR levels with immunoassay in all patients at the time of renal biopsy, and also in patients whose samples just before the first (after tonsillectomy) (n = 34) and/or the third steroid pulse therapy (n = 77) were available.

RESULTS

The TNFR levels were significantly higher in Group II than in Group I. A significant negative correlation was observed between TNFR levels and eGFR at baseline (TNFRs: r > -0.50). In multivariate logistic regression analysis, both TNFRs were associated with renal function decline, independent of age and uric acid levels. Proteinuria and hematuria remarkably improved after TSP therapy, as expected. In comparison with baseline TNFR levels, the levels of TNFR2, but not TNFR1, decreased significantly just before the third steroid pulse therapy, although both levels did not change after tonsillectomy.

CONCLUSIONS

The TNFR2 level did not change after tonsillectomy alone but decreased significantly after steroid pulse therapy in patients with IgAN.

Serum soluble tumour necrosis factor receptor-2 (sTNFR2) as a biomarker of kidney tissue damage and long-term renal outcome in lupus nephritis

OBJECTIVES

We investigated the performance of soluble tumour necrosis factor receptor-2 (sTNFR2) as a biomarker of renal activity, damage, treatment response, and long-term outcome in lupus nephritis (LN).

METHOD

Serum sTNFR2 levels were assessed in 64 LN patients (52 proliferative, 12 membranous) before and after induction treatment, and in 314 non-lupus controls. In LN patients, renal biopsies were performed at baseline and post-treatment. Patients with ≥ 50% reduced proteinuria, normal or improved estimated glomerular filtration rate (eGFR) by ≥ 25%, and inactive urinary sediment were considered clinical responders (CRs). Patients with ≥ 50% improved renal activity index were considered histopathological responders (HRs). Long-term renal outcome was determined using the chronic kidney disease (CKD) stage after a median follow-up of 11.3 years.

RESULTS

sTNFR2 levels were elevated in LN patients versus controls both at baseline (p < 0.001) and post-treatment (p < 0.001), and decreased following treatment (p < 0.001). Baseline sTNFR2 correlated with Chronicity Index scores in both baseline (r = 0.34, p = 0.006) and post-treatment (r = 0.43, p < 0.001) biopsies. In membranous LN, baseline sTNFR2 levels were higher in CRs (p = 0.048) and HRs (p = 0.03) than in non-responders, and decreased only in CRs (p = 0.03). Both baseline (p = 0.02) and post-treatment (p = 0.03) sTNFR2 levels were associated with decreasing eGFR throughout long-term follow-up, and post-treatment levels were higher in patients with long-term follow-up CKD stage ≥ 3 versus 1-2 (p = 0.008).

CONCLUSIONS

Our data suggest serum sTNFR2 as a marker of kidney tissue damage and a predictor of long-term prognosis in LN, and merit further evaluation of sTNFR2 as a predictor of clinical and histopathological treatment outcomes in membranous LN.

A new form of amphotericin B - the complex with copper (II) ions - downregulates sTNFR1 shedding and changes the activity of genes involved in TNF-induced pathways: AmB-Cu2+ downregulates sTNFR1 shedding and changes the activity of genes involved in TNF-induced pathways

BACKGROUND

A new form of amphotericin B (AmB)- complex with copper (II) ions (AmB-Cu²⁺) - is less toxic to human renal cells. Cytokines, including Tumor Necrosis Factor (TNF), are responsible for nephrotoxicity observed in patients treated with AmB. Another problem during therapy is the occurrence of oxidized forms of AmB (AmB-ox) in patients' circulation. To elucidate the molecular mechanism responsible for the reduction of the toxicity of AmB-Cu²⁺, we evaluated the expression of genes encoding TNF and its receptors alongside encoding proteins involved in TNF-induced signalization.

METHODS

Renal cells (RPTECs) were treated with AmB, AmB-Cu²⁺ or AmB-ox. The expression of TNF and its receptors was evaluated by ELISA tests and real-time RT-qPCR. The expression of TNF-related genes was appointed using oligonucleotide microarrays.

RESULTS

Only sTNFR1 was detected, and its level was lower in AmB-Cu²⁺- and AmB-ox-treated cells. TNFR1 mRNA was downregulated in AmB-ox, while TNFR2 mRNA was upregulated in AmB and AmB-Cu²⁺. Several changes in the expression of TNF-related genes coincided with changes in the expression of TNF receptors.

CONCLUSIONS

The lower toxicity of AmB-Cu²⁺ could result from the changes in the expression of TNF receptors, which coincided with the changes in the expression of genes encoding proteins involved in TNF-induced pathways. This situation might subsequently result in a changes in intracellular signalization and influence the toxicity of tested forms of AmB on renal cells.

Tubular epithelial cells in renal clear cell carcinoma express high RIPK1/3 and show increased susceptibility to TNF receptor 1-induced necroptosis

We previously reported that renal clear cell carcinoma cells (RCC) express both tumor necrosis factor receptor (TNFR)-1 and -2, but that, in organ culture, a TNF mutein that only engages TNFR1, but not TNFR2, causes extensive cell death. Some RCC died by apoptosis based on detection of cleaved caspase 3 in a minority TUNEL-positive cells but the mechanism of death in the remaining cells was unexplained. Here, we underpin the mechanism of TNFR1-induced cell death in the majority of TUNEL-positive RCC cells, and show that they die by necroptosis. Malignant cells in high-grade tumors displayed threefold to four fold higher expression of both receptor-interacting protein kinase (RIPK)1 and RIPK3 compared with non-tumor kidney tubular epithelium and low-grade tumors, but expression of both enzymes was induced in lower grade tumors in organ culture in response to TNFR1 stimulation. Furthermore, TNFR1 activation induced significant MLKL(Ser358) and Drp1(Ser616) phosphorylation, physical interactions in RCC between RIPK1-RIPK3 and RIPK3-phospho-MLKL(Ser358), and coincidence of phospho-MLKL(ser358) and phospho-Drp1(Ser616) at mitochondria in TUNEL-positive RCC. A caspase inhibitor only partially reduced the extent of cell death following TNFR1 engagement in RCC cells, whereas three inhibitors, each targeting a different step in the necroptotic pathway, were much more protective. Combined inhibition of caspases and necroptosis provided additive protection, implying that different subsets of cells respond differently to TNF-α, the majority dying by necroptosis. We conclude that most high-grade RCC cells express increased amounts of RIPK1 and RIPK3 and are poised to undergo necroptosis in response to TNFR1 signaling.

Increased concentration of plasma TNFR1 and TNFR2 in paediatric lupus nephritis

BACKGROUND

Juvenile-onset systemic lupus erythematous (JSLE) is a debilitating condition that frequently involves the kidneys (lupus nephritis; LN). Tumour necrosis factor alpha (TNF-α), an important pro-inflammatory cytokine, is expressed locally in the kidney and correlates with LN disease activity. The aim of this study was to ascertain whether soluble receptors for TNF-α (sTNFR1/sTNFR2) are significantly increased in children with LN.

METHODS

Plasma samples were collected from JSLE patients at routine review. Concentrations of sTNFR1 and sTNFR2 were measured (median; interquartile range, IQR) using enzyme-linked immunosorbent assay (ELISA) in 25 JSLE patients (seven LN) and 20 healthy controls (HCs).

RESULTS

sTNFR2 concentration was significantly increased in JSLE (5149 pg/dl, 3413-8561) compared to HCs (3858 pg/dl, 2254-5165; p = 0.049). sTNFR1 concentration was significantly increased in active LN (n = 7, 1765 pg/dl, IQR 1133-4167) compared to inactive LN (n = 18, 1104 pg/dl, 886-1272; p = 0.018). There was a non-significant increase in sTNFR2 concentration in active LN (9829 pg/dl, 3298-21271) compared to inactive LN (4595 pg/dl, 3345-6993; p = 0.146). sTNFR1 concentration correlated moderately with sTNFR2 (r = 0.66, p < 0.001). sTNFR2 demonstrated strong positive correlations with ESR (r = 0.941, p < 0.01) and anti-dsDNA antibodies (r = 0.998, p = 0.041). Both receptors also positively correlated with creatinine (TNFR1 r = 0.81, p < 0.001; TNFR2 r = 0.50, p = 0.015) and urinary albumin creatinine ratio (TNFR1 r = 0.64, p < 0.01; TNFR2 r = 0.63, p < 0.01).

CONCLUSIONS

These data indicate that sTNFR1 and sTNFR2 concentrations are elevated in LN and may reflect renal activity. These results provide basis for further investigation into the pathological pathways underlying LN.

TNF causes changes in glomerular endothelial permeability and morphology through a Rho and myosin light chain kinase-dependent mechanism

A key function of the endothelium is to serve as a regulated barrier between tissue compartments. We have previously shown that tumor necrosis factor (TNF) plays a crucial role in lipopolysaccharide (LPS)‐induced acute kidney injury, in part by causing injury to the renal endothelium through its receptor TNFR1. Here, we report that TNF increased permeability to albumin in primary culture mouse renal endothelial cells, as well as human glomerular endothelial cells. This process occurred in association with changes in the actin cytoskeleton and was associated with gaps between previously confluent cells in culture and decreases in the tight junction protein occludin. This process was dependent on myosin light chain activation, as seen by its prevention with Rho‐associated kinase and myosin light chain kinase (MLCK) inhibitors. Surprisingly, permeability was not blocked by inhibition of apoptosis with caspase inhibitors. Additionally, we found that the renal glycocalyx, which plays an important role in barrier function, was also degraded by TNF in a Rho and MLCK dependent fashion. TNF treatment caused a decrease in the size of endothelial fenestrae, dependent on Rho and MLCK, although the relevance of this to changes in permeability is uncertain. In summary, TNF‐induced barrier dysfunction in renal endothelial cells is crucially dependent upon the Rho/MLCK signaling pathway.

IL-32θ gene expression in acute myeloid leukemia suppresses TNF-α production

The proinflammatory cytokine TNF-α is highly expressed in patients with acute myeloid leukemia (AML) and has been demonstrated to induce rapid proliferation of leukemic blasts. Thus suppressing the production of TNF-α is important because TNF-α can auto-regulate own expression through activation of NF-κB and p38 mitogen-activated protein kinase (MAPK). In this study, we focused on the inhibitory effect of IL-32θ on TNF-α production in acute myeloid leukemia. Approximately 38% of patients with AML express endogenous IL-32θ, which is not expressed in healthy individuals. Furthermore, plasma samples were classified into groups with or without IL-32θ; then, we measured proinflammatory cytokine TNF-α, IL-1β, and IL-6 levels. TNF-α production was not increased in patients with IL-32θ expression than that in the no-IL-32θ group. Using an IL-32θ stable expression system in leukemia cell lines, we found that IL-32θ attenuated phorbol 12-myristate 13-acetate (PMA)-induced TNF-α production. IL-32θ inhibited phosphorylation of p38 MAPK, inhibitor of κB (IκB), and nuclear factor κB (NF-κB), which are key positive regulators of TNF-α expression, and inhibited nuclear translocation of NF-κB. Moreover, the presence of IL-32θ attenuated TNF-α promoter activity and the binding of NF-κB with the TNF-α promoter. In addition, IL-32γ-induced TNF-α production has no correlation with inhibition of TNF-α via IL-32θ expression. Thus, IL-32θ may serve as a potent inhibitor of TNF-α in patients with AML.

BK virus infection activates the TNFα/TNF receptor system in Polyomavirus-associated nephropathy

Polyomavirus-associated nephropathy due to BK virus infection (BKVAN) is recognized as an important cause of significant kidney transplant dysfunction often leading to renal graft loss. The activation of innate immune defense mechanisms during BKVAN is still poorly understood and an altered regulation of inflammatory mediators by resident kidney cells upon viral infection can be expected to contribute to the onset and progression of disease. TNFα interacting with its receptors, TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2), is largely accepted to be involved in viral responses, exhibiting both proinflammatory and immunosuppressive effects. Our aim was to examine the expressions of TNFα and TNFR1 and 2 in human collecting duct epithelial cells (HCDC) after infection with BKV as well as to study the effect of TNFα and poly(I:C), a synthetic analog of viral RNA, on the expressions of TNF receptors and proinflammatory cytokines and chemokines in HCDC. Quantitative RT-PCR analyses showed a downregulation of TNFα and an upregulation of both TNFR1 and 2 upon exposure of HCDC to the BK virus. TNFα stimulation induced the expressions of IL-6, IL-8, RANTES, and TNFR2. Poly(I:C) upregulated the expressions of both TNFR1 and TNFR2, a response that could be effectively blocked by siRNA to TLR3 and RIG-I, two double-stranded (ds) RNA receptors of the innate immune system. Poly(I:C)-dependent expression of TNFR2 but not TNFR1 was enhanced by TNFα. Taken together, our results suggest an involvement of TNF/TNFR system in virus-associated nephropathy.

Expression of decoy receptor 3 in kidneys is associated with allograft survival after kidney transplant rejection

Decoy receptor 3 (DcR3) expression in kidneys has been shown to predict progression of chronic kidney disease. We prospectively investigated a cohort comprising 96 renal transplant recipients (RTRs) undergoing graft kidney biopsies. Computer-assisted quantitative immunohistochemical staining value of DcR3 in renal tubular epithelial cells (RTECs) was used to determine the predictive role of DcR3 in kidney disease progression. The primary end point was doubling of serum creatinine and/or graft failure. A multivariate Cox proportional hazards model was used to assess the risk of DcR3 expression in rejected kidney grafts toward the renal end point. In total, RTRs with kidney allograft rejection were evaluated and the median follow-up was 30.9 months. The greater expression of DcR3 immunoreactivity in RTECs was correlated with a higher rate of the histopathological concordance of acute T cell-mediated rejection. Compared with 65 non-progressors, 31 progressors had higher DcR3 expression (HDE) regardless of the traditional risk factors. Cox regression analysis showed HDE was significantly associated with the risk of renal end point with a hazard ratio of 3.19 (95% confidence interval, 1.40 to 7.27; P = 0.006) after adjusting for other variables. In repetitive biopsies, HDE in tissue showed rapid kidney disease progression due to persistent inflammation.

Circulating Tumor Necrosis Factor α Receptors Predict the Outcomes of Human IgA Nephropathy: A Prospective Cohort Study

The circulating tumor necrosis factor receptors (TNFRs) could predict the long-term renal outcome in diabetes, but the role of circulating TNFRs in other chronic kidney disease has not been reported. Here, we investigated the correlation between circulating TNFRs and renal histologic findings on kidney biopsy in IgA nephropathy (IgAN) and assessed the notion that the circulating TNFRs could predict the clinical outcome. 347 consecutive biopsy-proven IgAN patients between 2006 and 2012 were prospectively enrolled. Concentrations of circulating TNFRs were measured using serum samples stored at the time of biopsy. The primary clinical endpoint was the decline of estimated glomerular filtration rate (eGFR; ≥ 30% decline compared to baseline). Mean eGFR decreased and proteinuria worsened proportionally as circulating TNFR1 and TNFR2 increased (P < 0.001). Tubulointerstitial lesions such as interstitial fibrosis and tubular atrophy were significantly more severe as concentrations of circulating TNFRs increased, regardless of eGFR levels. The risks of reaching the primary endpoint were significantly higher in the highest quartile of TNFRs compared with other quartiles by the Cox proportional hazards model (TNFR1; hazard ratio 7.48, P < 0.001, TNFR2; hazard ratio 2.51, P = 0.021). In stratified analysis according to initial renal function classified by the eGFR levels of 60 mL/min/1.73 m², TNFR1 and TNFR2 were significant predictors of renal progression in both subgroups. In conclusion, circulating TNFRs reflect the histology and clinical severity of IgAN. Moreover, elevated concentrations of circulating TNFRs at baseline are early biomarkers for subsequent renal progression in IgAN patients.