CXCL10 induces the recruitment of monocyte-derived macrophages into kidney, which aggravate puromycin aminonucleoside nephrosis

Psychosocial stress and associations with inflammation in mid-gestation maternal, fetal, and placental tissue

BACKGROUND

Inflammation has been implicated as an intermediary between psychosocial stress and adverse birth outcomes. However, prior work has mostly relied on maternal inflammation as a proxy for fetal inflammation mid-gestation or measured fetal inflammation in cord blood and placenta obtained at delivery. No studies have examined psychosocial stress in relation to fetal inflammation mid-gestation.

METHODS

Twenty cytokines were measured in matched maternal blood, cord blood, and placenta obtained mid-gestation from a socio-demographically diverse group of pregnant participants undergoing elective second-trimester pregnancy terminations (N = 106). Corticotropin-releasing hormone, a proposed biomarker of gestational length, was measured in maternal blood. Perceived stress, and exposure to stressful life events, job strain, and social support were measured via questionnaires. We used linear regression to estimate associations between individual stressors and inflammatory biomarkers in each biomatrix and principal component analysis to assess groups of inflammatory biomarkers.

RESULTS

We observed many matrix-specific associations between psychosocial stressors and inflammatory biomarkers. For example, low versus high social support was associated with significantly decreased levels of maternal blood CCL3 (β=-0.53; 95 % confidence interval [CI]=-0.98,-0.07), CCL4 (β=-0.26; 95 % CI=-0.47,-0.04), IL8 (β=-0.79; 95 % CI=-1.47,-0.11), CXCL9 (β=-0.47; 95 % CI=-0.89,-0.06), IFNγ (β=-2.28; 95 % CI=-3.60,-0.96), IL4 (β=-1.07; 95 % CI=-1.88,-0.26); and cord blood IFNγ (β=-0.83; 95 % CI=-1.52,-0.14). Social support was not associated with placental inflammation.

CONCLUSIONS

During mid-pregnancy, psychosocial stress─ particularly low social support─ was associated with maternal blood levels of select cytokines, suggesting a potential pathway linking social stress and inflammation. Our results indicate that the placenta may buffer these inflammatory effects on the fetus.

Microglial type I interferon signaling mediates chronic stress-induced synapse loss and social behavior deficits

Inflammation and synapse loss have been associated with deficits in social behavior and are involved in pathophysiology of many neuropsychiatric disorders. Synapse loss, characterized by reduction in dendritic spines can significantly disrupt synaptic connectivity and neural circuitry underlying social behavior. Chronic stress is known to induce loss of spines and dendrites in the prefrontal cortex (PFC), a brain region implicated in social behavior. However, the underlying mechanisms are not well understood. In the present study, we investigated the role of type I Interferon (IFN-I) signaling in chronic unpredictable stress (CUS)-induced synapse loss and behavior deficits in mice. We found increased expression of type I IFN receptor (IFNAR) in microglia following CUS. Conditional knockout of microglial IFNAR in adult mice rescued CUS-induced social behavior deficits and synapse loss. Bulk RNA sequencing data show that microglial IFNAR deletion attenuated CUS-mediated changes in the expression of genes such as Keratin 20 (Krt20), Claudin-5 (Cldn5) and Nuclear Receptor Subfamily 4 Group A Member 1 (Nr4a1) in the PFC. Cldn5 and Nr4a1 are known for their roles in synaptic plasticity. Krt20 is an intermediate filament protein responsible for the structural integrity of epithelial cells. The reduction in Krt20 following CUS presents a novel insight into the potential contribution of cytokeratin in stress-induced alterations in neuroplasticity. Overall, these results suggest that microglial IFNAR plays a critical role in regulating synaptic plasticity and social behavior deficits associated with chronic stress conditions.

Semaphorin 5A promotes Th17 differentiation via PI3K-Akt-mTOR in systemic lupus erythematosus

BACKGROUND

Previously, we reported that serum Semaphorin 5 A (Sema5A) levels were increased in systemic lupus erythematosus (SLE) patients compared with healthy controls (HC), and elevated Sema5A correlated with disease activity and lupus nephritis in SLE patients. In this study, we aimed to further understand the role of Sema5A in promoting Th17 cells differentiation in SLE.

METHODS

Sema5A, interferon gamma (IFN-γ), interleukin 4 (IL-4), interleukin 17 A (IL-17 A) and interleukin 10 (IL-10) were measured by Enzyme Linked Immunosorbent Assay (ELISA). RNA and protein were isolated from peripheral blood mononuclear cells (PBMCs) in SLE patients and HC. Expression of PlexinA1 and PlexinB3 were measured by quantitative RT-PCR (qRT-PCR) and Western Blot. Th cell subsets were detected by flow cytometry. Treatment with recombinant human Sema5A (rhSema5A) and small interfering RNA (siRNA) were employed to examine the in vitro effect of Sema5A in CD4+T cell differentiation in SLE patients.

RESULTS

IL-17 A elevated in SLE patients and positively correlated with Sema5A. PlexinA1 was upregulated and mainly expressed in CD4+ T cells of SLE; Sema5A treatment induced the differentiation of Th17 cells, while did not affect the Th1 and Th2 skewing. These effects were associated with an upregulation of the transcription factor RORγt by Th17 cells, but not T-bet or GATA3 in Th1 and Th2 cells, respectively. Knock down PlexinA1 regulates IL-17 A production by CD4+T cells. Functional assays showed that Sema5A-PlexinA1 axis promoted Th17 cells differentiation via PI3K/Akt/mTOR signaling.

CONCLUSIONS

These findings demonstrated that Sema5A-PlexinA1 axis acts as a key mediator on Th17 differentiation, suggesting that Sema5A might be a novel therapeutic target in SLE.

Reshaping tumor microenvironment by regulating local cytokines expression with a portable smart blue-light controlled device

Cytokines have attracted sustained attention due to their multi-functional cellular response in immunotherapy. However, their application was limited to their short half-time, narrow therapeutic window, and undesired side effects. To address this issue, we developed a portable smart blue-light controlled (PSLC) device based on optogenetic technology. By combining this PSLC device with blue-light controlled gene modules, we successfully achieved the targeted regulation of cytokine expression within the tumor microenvironment. To alter the tumor microenvironment of solid tumors, pro-inflammatory cytokines were selected as blue-light controlled molecules. The results show that blue-light effectively regulates the expression of pro-inflammatory cytokines both in vitro and in vivo. This strategy leads to enhanced and activated tumor-infiltrating immune cells, which facilitated to overcome the immunosuppressive microenvironment, resulting in significant tumor shrinkage in tumor-bearing mice. Hence, our study offers a unique strategy for cytokine therapy and a convenient device for animal studies in optogenetic immunotherapy.

Immunoregulatory mechanisms between epithelial clear cells and mononuclear phagocytes in the epididymis

INTRODUCTION

One of the most intriguing aspects of male reproductive physiology is the ability of the epididymis to prevent the mounting of immune responses against the onslaught of foreign antigens carried by spermatozoa while initiating very efficient immune responses versus stressors. Epithelial clear cells are strategically positioned to work in a concerted manner with region-specific heterogeneous subsets of mononuclear phagocytes to survey the epididymal barrier and regulate the balance between inflammation and immune tolerance in the post-testicular environment.

OBJECTIVE

This review aims to describe how clear cells communicate with mononuclear phagocytes to contribute to the unique immune environment in which sperm mature and are stored in the epididymis.

MATERIALS/METHODS

A comprehensive systematic review was performed. PubMed was searched for articles specific to clear cells, mononuclear phagocytes, and epididymis. Articles that did not specifically address the target material were excluded.

RESULTS

In this review, we discuss the unexpected roles of clear cells, including the transfer of new proteins to spermatozoa via extracellular vesicles and nanotubes as they transit along the epididymal tubule; and we summarize the immune phenotype, morphology, and antigen capturing, processing, and presenting abilities of mononuclear phagocytes. Moreover, we present the current knowledge of immunoregulatory mechanisms by which clear cells and mononuclear phagocytes may contribute to the immune-privileged environment optimal for sperm maturation and storage.

DISCUSSION AND CONCLUSION

Notably, we provide an in-depth characterization of clear cell-mononuclear phagocyte communication networks in the steady-state epididymis and in the presence of injury. This review highlights crucial concepts of mucosal immunology and cellcell interactions, all of which are critical but understudied facets of human male reproductive health.

Immune urinary biomarkers predict infant cardiac surgery-associated acute kidney injury

BACKGROUND

Acute kidney injury (AKI) occurs frequently after infant cardiac surgery and is associated with poor outcomes, including mortality and prolonged length of stay. AKI mechanisms are poorly understood, limiting therapeutic targets. Emerging data implicates dysregulated immune activation in post-cardiac surgery AKI development. We sought to identify immune-mediated AKI biomarkers after infant cardiopulmonary bypass (CPB)-assisted cardiac surgery.

METHODS

A single-center prospective study of 126 infants less than 1 year old undergoing CPB-assisted surgery enrolled between 10/2017 and 6/2019. Urine samples were collected before CPB and at 6, 24, 48, and 72 h after surgery. Immune-mediated biomarkers were measured using commercial ELISA and Luminex™ multiplex kits. Based on subject age, neonatal KDIGO (< 1 month) or KDIGO criteria defined AKI. The Kruskal-Wallis rank test determined the relationship between urinary biomarker measurements and AKI.

RESULTS

A total of 35 infants (27%) developed AKI. AKI subjects were younger, underwent more complex surgery, and had longer CPB time. Subjects with AKI vs. those without AKI had higher median urinary chemokine 10 (C-X-C motif) ligand levels at 24, 48, and 72 h, respectively: 14.3 pg/ml vs. 5.3 pg/ml, 3.4 pg/ml vs. 0.8 pg/ml, and 1.15 pg/ml vs. 0.22 pg/ml (p < 0.05) post-CPB. At 6 h post-CPB, median vascular cell adhesion protein 1 (VCAM) levels (pg/mL) were higher among AKI subjects (491 pg/ml vs. 0 pg/ml, p = 0.04).

CONCLUSIONS

Urinary CXCL10 and VCAM are promising pro-inflammatory biomarkers for early AKI detection and may indicate eventual AKI therapeutic targets. A higher resolution version of the Graphical abstract is available as Supplementary information.

Obesity-related Plasma CXCL10 Drives CX3CR1-dependent Monocytic Secretion of Macrophage Migration Inhibitory Factor

Obesity is characterized by excessive body fat accumulation and comorbidities such as diabetes mellitus, cardiovascular disease, and obstructive sleep apnea syndrome (OSAS). Both obesity and OSAS are associated with immune disturbance, alterations of systemic inflammatory mediators, and immune cell recruitment to metabolic tissues. Chemokine CXCL10 is an important regulator of proinflammatory immune responses and is significantly increased in patients with severe obesity. This research project aims to investigate the impact of CXCL10 on human monocytes in patients with obesity. We studied the distribution of the CD14/CD16 monocyte subsets as well as their CX3CR1 expression patterns in whole-blood measurements from 92 patients with obesity and/or OSAS with regard to plasma CXCL10 values and individual clinical parameters. Furthermore, cytokine secretion by THP-1 monocytes in response to CXCL10 was analyzed. Data revealed significantly elevated plasma CXCL10 in patients with obesity with an additive effect of OSAS. CXCL10 was found to drive monocytic secretion of macrophage migration inhibitory factor via receptor protein CX3CR1, which significantly correlated with the individual body mass index. Our data show, for the first time, to our knowledge, that CX3CR1 is involved in alternative CXCL10 signaling in human monocytes in obesity-related inflammation. Obesity is a multifactorial disease, and further investigations regarding the complex interplay between obesity-related inflammatory mediators and systemic immune balances will help to better understand and improve the individual situation of our patients.

Importance of PLD2 in an IL-23 driven psoriasiform dermatitis model and potential link to human psoriasis

Phospholipase D2 (PLD2), a major isoform of the PLD family, has been reported to regulate inflammatory responses. Thus far, the relevance of PLD2 in psoriasis, an inflammatory skin disease, has not been explored. In the current study, we examined PLD2 expression in the skin of psoriasis patients and the role of PLD2 in an interleukin (IL)-23-induced mouse model of psoriasiform dermatitis. Both in situ hybridization and bulk RNA sequencing showed PLD2 gene expression is significantly higher in lesional relative to non-lesional skin of psoriasis patients or the skin of healthy subjects. PLD2 expression is also enriched in residual lesions from patients on biologic therapies. Murine in vivo studies showed that PLD2 deficiency significantly reduced psoriasiform inflammation in IL-23-injected ears, as reflected by decreases in ear thickness, expression of defensin beta 4A and the S100 calcium binding protein A7A, macrophage infiltrate, and expression of CXCL10 and IL-6. However, the expression of type 17 cytokines, IL-17A and IL-17F, were not reduced. Dual knockout of PLD1 and PLD2 offered little additional protection compared to PLD2 knockout alone in the IL-23 model. In addition, pharmacological inhibition with a pan-PLD1/PLD2 inhibitor also suppressed IL-23-induced psoriasiform dermatitis. Bone-marrow-derived macrophages from wild type (WT) and PLD2 knockout (KO) mice exhibited little difference in viability and sensitivity to lipopolysaccharide and/or interferon gamma, or resiquimod (R848). PLD2 deficiency did not alter the differentiation and function of Th17 cells in an ex vivo study with splenocytes isolated from WT and PLD2 KO mice. Overall, these data suggest that PLD2 may play a role in the pathophysiology of psoriasis. Reducing macrophage infiltrate and cytokine/chemokine production might contribute to an anti-inflammatory effect observed in PLD2 knockout mice. Further studies are required to better understand the mechanisms by which PLD2 contributes to skin lesions in psoriasis patients and psoriasiform dermatitis models.

Assessing the effects of aging on the renal endothelial cell landscape using single-cell RNA sequencing

Endothelial cells (ECs) with senescence-associated secretory phenotypes (SASP) have been identified as a key mechanism of aging that contributes to various age-related kidney diseases. In this study, we used single-cell RNA sequencing (scRNA-seq) to create a transcriptome atlas of murine renal ECs and identify transcriptomic changes that occur during aging. We identified seven different subtypes of renal ECs, with glomerular ECs and angiogenic ECs being the most affected by senescence. We confirmed our scRNA-seq findings by using double immunostaining for an EC marker (CD31) and markers of specialized EC phenotypes. Our analysis of the dynamics of capillary lineage development revealed a chronic state of inflammation and compromised glomerular function as prominent aging features. Additionally, we observed an elevated pro-inflammatory and pro-coagulant microenvironment in aged glomerular ECs, which may contribute to age-related glomerulosclerosis and renal fibrosis. Through intercellular communication analysis, we also identified changes in signaling involved in immune regulation that may contribute to a hostile microenvironment for renal homeostasis and function. Overall, our findings provide new insights into the mechanisms of aging in the renal endothelium and may pave the way for the discovery of diagnostic biomarkers and therapeutic interventions against age-related kidney diseases.

Interrelation of T cell cytokines and autoantibodies in systemic lupus erythematosus: A cross-sectional study

T-helper cytokines interferon gamma (IFNɣ), interleukin 17 (IL-17) and IL-10 impact systemic lupus erythematosus (SLE) directly and indirectly via modulation of autoAb production. We determined the separate and combined effects on clinical manifestations of SLE (N = 62). IFNɣ, IL-17 but not IL-10 were significantly elevated in patients with SLE. IFNɣ positively correlated with anti-DNA and anti-SSA. IL-17 positively correlated with anti-SSA and was significantly higher in patients with discoid rash and class V LN. IL-10 did not correlate with circulating autoantibodies but was significantly elevated in patients with LN. Patients with LN had elevated plasma levels of anti-DNA and anti-Sm/ribonuclear protein (RNP). Anti-Sm/RNP levels were decreased in patients with acute mucocutaneous manifestations, including photosensitivity and/or malar rash. The study provides critical insights into pathological mechanisms of LN, which could help guide future diagnoses and therapies.

STING inhibitor ameliorates LPS-induced ALI by preventing vascular endothelial cells-mediated immune cells chemotaxis and adhesion

Acute lung injury (ALI) is a common and devastating clinical disorder featured by excessive inflammatory responses. Stimulator of interferon genes (STING) is an indispensable molecule for regulating inflammation and immune response in multiple diseases, but the role of STING in the ALI pathogenesis is not well elucidated. In this study, we explored the molecular mechanisms of STING in regulating lipopolysaccharide (LPS)-induced lung injury. Mice were pretreated with a STING inhibitor C-176 (15, 30 mg/kg, i.p.) before LPS inhalation to induce ALI. We showed that LPS inhalation significantly increased STING expression in the lung tissues, whereas C-176 pretreatment dose-dependently suppressed the expression of STING, decreased the production of inflammatory cytokines including TNF-α, IL-6, IL-12, and IL-1β, and restrained the expression of chemokines and adhesion molecule vascular cell adhesion protein-1 (VCAM-1) in the lung tissues. Consistently, in vitro experiments conducted in TNF-α-stimulated HMEC-1cells (common and classic vascular endothelial cells) revealed that human STING inhibitor H-151 or STING siRNA downregulated the expression levels of adhesion molecule and chemokines in HMEC-1cells, accompanied by decreased adhesive ability and chemotaxis of immunocytes upon TNF-α stimulation. We further revealed that STING inhibitor H-151 or STING knockdown significantly decreased the phosphorylation of transcription factor STAT1, which subsequently influenced its binding to chemokine CCL2 and adhesive molecule VCAM-1 gene promoter. Collectively, STING inhibitor can alleviate LPS-induced ALI in mice by preventing vascular endothelial cells-mediated immune cell chemotaxis and adhesion, suggesting that STING may be a promising therapeutic target for the treatment of ALI.

Single-cell analysis identifies the interaction of altered renal tubules with basophils orchestrating kidney fibrosis

Inflammation is an important component of fibrosis but immune processes that orchestrate kidney fibrosis are not well understood. Here we apply single-cell sequencing to a mouse model of kidney fibrosis. We identify a subset of kidney tubule cells with a profibrotic-inflammatory phenotype characterized by the expression of cytokines and chemokines associated with immune cell recruitment. Receptor-ligand interaction analysis and experimental validation indicate that CXCL1 secreted by profibrotic tubules recruits CXCR2+ basophils. In mice, these basophils are an important source of interleukin-6 and recruitment of the TH17 subset of helper T cells. Genetic deletion or antibody-based depletion of basophils results in reduced renal fibrosis. Human kidney single-cell, bulk gene expression and immunostaining validate a function for basophils in patients with kidney fibrosis. Collectively, these studies identify basophils as contributors to the development of renal fibrosis and suggest that targeting these cells might be a useful clinical strategy to manage chronic kidney disease.

Machine learning predicts cancer subtypes and progression from blood immune signatures

Clinical adoption of immune checkpoint inhibitors in cancer management has highlighted the interconnection between carcinogenesis and the immune system. Immune cells are integral to the tumour microenvironment and can influence the outcome of therapies. Better understanding of an individual's immune landscape may play an important role in treatment personalisation. Peripheral blood is a readily accessible source of information to study an individual's immune landscape compared to more complex and invasive tumour bioipsies, and may hold immense diagnostic and prognostic potential. Identifying the critical components of these immune signatures in peripheral blood presents an attractive alternative to tumour biopsy-based immune phenotyping strategies. We used two syngeneic solid tumour models, a 4T1 breast cancer model and a CT26 colorectal cancer model, in a longitudinal study of the peripheral blood immune landscape. Our strategy combined two highly accessible approaches, blood leukocyte immune phenotyping and plasma soluble immune factor characterisation, to identify distinguishing immune signatures of the CT26 and 4T1 tumour models using machine learning. Myeloid cells, specifically neutrophils and PD-L1-expressing myeloid cells, were found to correlate with tumour size in both the models. Elevated levels of G-CSF, IL-6 and CXCL13, and B cell counts were associated with 4T1 growth, whereas CCL17, CXCL10, total myeloid cells, CCL2, IL-10, CXCL1, and Ly6Cintermediate monocytes were associated with CT26 tumour development. Peripheral blood appears to be an accessible means to interrogate tumour-dependent changes to the host immune landscape, and to identify blood immune phenotypes for future treatment stratification.

Chronic kidney disease mediates cardiac dysfunction associated with increased resident cardiac macrophages

BACKGROUND

The leading cause of death in end-stage kidney disease is related to cardiovascular disease. Macrophages are known to be involved in both chronic kidney disease (CKD) and heart failure, however their role in the development of cardiorenal syndrome is less clear. We thus sought to investigate the role of macrophages in uremic cardiac disease.

METHODS

We assessed cardiac response in two experimental models of CKD and tested macrophage and chemokine implication in monocytopenic CCR2-/- and anti-CXCL10 treated mice. We quantified CXCL10 in human CKD plasma and tested the response of human iPSC-derived cardiomyocytes and primary cardiac fibroblasts to serum from CKD donors.

RESULTS

We found that reduced kidney function resulted in the expansion of cardiac macrophages, in particular through local proliferation of resident populations. Influx of circulating monocytes contributed to this increase. We identified CXCL10 as a crucial factor for cardiac macrophage expansion in uremic disease. In humans, we found increased plasma CXCL10 concentrations in advanced CKD, and identified the production of CXCL10 in cardiomyocytes and cardiac fibroblasts.

CONCLUSIONS

This study provides new insight into the role of the innate immune system in uremic cardiomyopathy.

Transcutaneous auricular vagus nerve stimulation (taVNS) for the treatment of pediatric nephrotic syndrome: a pilot study

BACKGROUND

Children with frequently relapsing nephrotic syndrome (FRNS) and steroid resistant nephrotic syndrome (SRNS) are exposed to immunosuppressant medications with adverse side effects and variable efficacy. Transcutaneous auricular vagus nerve stimulation (taVNS) modulates the immune system via the inflammatory reflex and has become a therapy of interest for treating immune-mediated illnesses.

METHODS

An open-label, pilot study of tavNS for five minutes daily for 26 weeks via a TENS 7000 unit was conducted.

RESULTS

Three FRNS participants and 4 SRNS participants had a mean age of 9.5±4.2 years (range 4 to 17). Those with FRNS remained relapse-free during the study period; two participants continued treatment and remained in remission for 15 and 21 months, respectively. Three SRNS participants experienced a reduction in first morning UPC (mean of 42%, range 25-76%). Although UPC decreased (13.7%) in one SRNS participant with congenital nephrotic syndrome, UPC remained in nephrotic range. All but one participant (non-compliant with treatment) experienced a reduction in TNF (7.33pg/mL vs. 5.46pg/mL, p=0.03). No adverse events or side effects were reported.

CONCLUSIONS

taVNS was associated with clinical remission in FRNS and moderately reduced proteinuria in non-congenital SRNS. Further study of taVNS as a treatment for nephrotic syndrome in children is warranted. ClinicalTrials.gov Identifier: NCT04169776, Registered November 20, 2019, https://clinicaltrials.gov/ct2/show/NCT04169776 .

Spinal Cord Injury Increases Pro-inflammatory Cytokine Expression in Kidney at Acute and Sub-chronic Stages

Accumulating evidence supports that spinal cord injury (SCI) produces robust inflammatory plasticity. We previously showed that the pro-inflammatory cytokine tumor necrosis factor (TNF)α is increased in the spinal cord after SCI. SCI also induces a systemic inflammatory response that can impact peripheral organ functions. The kidney plays an important role in maintaining cardiovascular health. However, SCI-induced inflammatory response in the kidney and the subsequent effect on renal function have not been well characterized. This study investigated the impact of high and low thoracic (T) SCI on C-fos, TNFα, interleukin (IL)-1β, and IL-6 expression in the kidney at acute and sub-chronic timepoints. Adult C57BL/6 mice received a moderate contusion SCI or sham procedures at T4 or T10. Uninjured mice served as naïve controls. mRNA levels of the proinflammatory cytokines IL-1β, IL-6, TNFα, and C-fos, and TNFα and C-fos protein expression were assessed in the kidney and spinal cord 1 day and 14 days post-injury. The mRNA levels of all targets were robustly increased in the kidney and spinal cord, 1 day after both injuries. Whereas IL-6 and TNFα remained elevated in the spinal cord at 14 days after SCI, C-fos, IL-6, and TNFα levels were sustained in the kidney only after T10 SCI. TNFα protein was significantly upregulated in the kidney 1 day after both T4 and T10 SCI. Overall, these results clearly demonstrate that SCI induces robust systemic inflammation that extends to the kidney. Hence, the presence of renal inflammation can substantially impact renal pathophysiology and function after SCI.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

Preconditioning Human Adipose-Derived Stromal Cells on Decellularized Adipose Tissue Scaffolds Within a Perfusion Bioreactor Modulates Cell Phenotype and Promotes a Pro-regenerative Host Response

Cell-based therapies involving the delivery of adipose-derived stromal cells (ASCs) on decellularized adipose tissue (DAT) scaffolds are a promising approach for soft tissue augmentation and reconstruction. Our lab has recently shown that culturing human ASCs on DAT scaffolds within a perfusion bioreactor prior to implantation can enhance their capacity to stimulate in vivo adipose tissue regeneration. Building from this previous work, the current study investigated the effects of bioreactor preconditioning on the ASC phenotype and secretory profile in vitro, as well as host cell recruitment following implantation in an athymic nude mouse model. Immunohistochemical analyses indicated that culturing within the bioreactor increased the percentage of ASCs co-expressing inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1), as well as tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10), within the peripheral regions of the DAT relative to statically cultured controls. In addition, bioreactor culture altered the expression levels of a range of immunomodulatory factors in the ASC-seeded DAT. In vivo testing revealed that culturing the ASCs on the DAT within the perfusion bioreactor prior to implantation enhanced the infiltration of host CD31⁺ endothelial cells and CD26⁺ cells into the DAT implants, but did not alter CD45⁺F4/80⁺CD68⁺ macrophage recruitment. However, a higher fraction of the CD45⁺ cell population expressed the pro-regenerative macrophage marker CD163 in the bioreactor group, which may have contributed to enhanced remodeling of the scaffolds into host-derived adipose tissue. Overall, the findings support that bioreactor preconditioning can augment the capacity of human ASCs to stimulate regeneration through paracrine-mediated mechanisms.

CXCL10 Signaling Contributes to the Pathogenesis of Arthritogenic Alphaviruses

Emerging and re-emerging arthritogenic alphaviruses, such as Chikungunya virus (CHIKV) and O'nyong nyong virus, cause acute and chronic crippling arthralgia associated with inflammatory immune responses. Approximately 50% of CHIKV-infected patients suffer from rheumatic manifestations that last 6 months to years. However, the physiological functions of individual immune signaling pathways in the pathogenesis of alphaviral arthritis remain poorly understood. Here, we report that a deficiency in CXCL10, which is a chemoattractant for monocytes/macrophages/T cells, led to the same viremia as wild-type animals, but fewer immune infiltrates and lower viral loads in footpads at the peak of arthritic disease (6-8 days post infection). Macrophages constituted the largest immune cell population in footpads following infection, and were significantly reduced in Cxcl10^-/- mice. The viral RNA loads in neutrophils and macrophages were reduced in Cxcl10^-/- compared to wild-type mice. In summary, our results demonstrate that CXCL10 signaling promotes the pathogenesis of alphaviral disease and suggest that CXCL10 may be a therapeutic target for mitigating alphaviral arthritis.

Rapamycin and dexamethasone during pregnancy prevent tuberous sclerosis complex-associated cystic kidney disease

Chronic kidney disease is the main cause of mortality in patients with tuberous sclerosis complex (TSC) disease. The mechanisms underlying TSC cystic kidney disease remain unclear, with no available interventions to prevent cyst formation. Using targeted deletion of TSC1 in nephron progenitor cells, we showed that cysts in TSC1-null embryonic kidneys originate from injured proximal tubular cells with high mTOR complex 1 activity. Injection of rapamycin to pregnant mice inhibited the mTOR pathway and tubular cell proliferation in kidneys of TSC1-null offspring. Rapamycin also prevented renal cystogenesis and prolonged the life span of TSC newborns. Gene expression analysis of proximal tubule cells identified sets of genes and pathways that were modified secondary to TSC1 deletion and rescued by rapamycin administration during nephrogenesis. Inflammation with mononuclear infiltration was observed in the cystic areas of TSC1-null kidneys. Dexamethasone administration during pregnancy decreased cyst formation by not only inhibiting the inflammatory response, but also interfering with the mTORC1 pathway. These results reveal mechanisms of cystogenesis in TSC disease and suggest interventions before birth to ameliorate cystic disease in offspring.

Acute Kidney Injury in Children after Hematopoietic Cell Transplantation Is Associated with Elevated Urine CXCL10 and CXCL9

Acute kidney injury (AKI) is nearly universally associated with worse outcomes, especially among children after hematopoietic stem cell transplant (HCT). Our objective was to examine urinary immune biomarkers of AKI after HCT to provide insights into novel mechanisms of kidney injury in this population. Studying patients undergoing allogeneic HCT provides a unique opportunity to examine immune markers of AKI because the risk of AKI is high and the immune system newly develops after transplant. Children (>2 years old) and young adults undergoing their first allogeneic HCT and enrolled in a prospective, observational cohort study at 2 large children's hospitals had urine collected pre-HCT and monthly for the first 4 months after HCT. Urine samples at each monthly time point were assayed for 8 immune-related biomarkers. AKI was defined as a 1.5-fold increase in the monthly serum creatinine value, which was recorded ±1 day from when the research urine sample was obtained, as compared with the pre-HCT baseline. Generalized estimating equation regression analysis evaluated the association between the monthly repeated measures (urinary biomarkers and AKI). A total of 176 patients were included from 2 pediatric centers. Thirty-six patients from 1 center were analyzed as a discovery cohort and the remaining 140 patients from the second center were analyzed as a validation cohort. AKI rates were 18% to 35% depending on the monthly time point after HCT. Urine CXCL10 and CXCL9 concentrations were significantly higher among children who developed AKI compared with children who did not (P < .01) in both cohorts. In order to gain a better understanding of the cellular source for these biomarkers in the urine, we also analyzed in vitro expression of CXCL10 and CXCL9 in kidney cell lines after stimulation with interferon-γ and interferon-α. HEK293-epithelial kidney cells demonstrated interferon-induced expression of CXCL10 and CXCL9, suggesting a potential mechanism driving the key finding. CXCL10 and CXCL9 are associated with AKI after HCT and are therefore promising biomarkers to guide improved diagnostic and treatment strategies for AKI in this high-risk population.

Role of Chemokine (C-X-C Motif) Ligand 10 (CXCL10) in Renal Diseases

Chemokine C-X-C ligand 10 (CXCL10), also known as interferon-γ-inducible protein 10 (IP-10), exerts biological function mainly through binding to its specific receptor, CXCR3. Studies have shown that renal resident mesangial cells, renal tubular epithelial cells, podocytes, endothelial cells, and infiltrating inflammatory cells express CXCL10 and CXCR3 under inflammatory conditions. In the last few years, strong experimental and clinical evidence has indicated that CXCL10 is involved in the development of renal diseases through the chemoattraction of inflammatory cells and facilitation of cell growth and angiostatic effects. In addition, CXCL10 has been shown to be a significant biomarker of disease severity, and it can be used as a prognostic indicator for a variety of renal diseases, such as renal allograft dysfunction and lupus nephritis. In this review, we summarize the structures and biological functions of CXCL10 and CXCR3, focusing on the important role of CXCL10 in the pathogenesis of kidney disease, and provide a theoretical basis for CXCL10 as a potential biomarker and therapeutic target in human kidney disease.

Novel role of proton-secreting epithelial cells in sperm maturation and mucosal immunity

Epithelial cells are immune sensors and mediators that constitute the first line of defense against infections. Using the epididymis, a model for studying tubular organs, we uncovered a novel and unexpected role for professional proton-secreting 'clear cells' in sperm maturation and immune defense. The epididymal epithelium participates in the maturation of spermatozoa via the establishment of an acidic milieu and transfer of proteins to sperm cells, a poorly characterized process. We show that proton-secreting clear cells express mRNA transcripts and proteins that are acquired by maturing sperm, and that they establish close interactions with luminal spermatozoa via newly described 'nanotubes'. Mechanistic studies show that injection of bacterial antigens in vivo induces chemokine expression in clear cells, followed by macrophage recruitment into the organ. Injection of an inflammatory intermediate mediator (IFN-γ) increased Cxcl10 expression in clear cells, revealing their participation as sensors and mediators of inflammation. The functional diversity adopted by clear cells might represent a generalized phenomenon by which similar epithelial cells decode signals, communicate with neighbors and mediate mucosal immunity, depending on their precise location within an organ.

Cyclophosphamide Enhances Cancer Antibody Immunotherapy in the Resistant Bone Marrow Niche by Modulating Macrophage FcγR Expression

Therapy-resistant microenvironments represent a major barrier toward effective elimination of disseminated cancer. Many hematologic and solid tumors are resistant to therapeutic antibodies in the bone marrow (BM), but not in the periphery (e.g., spleen). We previously showed that cyclophosphamide (CTX) sensitizes the BM niche to antibody therapeutics. Here, we show that (i) BM resistance was induced not only by the tumor but also by the intrinsic BM microenvironment; (ii) CTX treatment overcame both intrinsic and extrinsic resistance mechanisms by augmenting macrophage activation and phagocytosis, including significant upregulation of activating Fcγ receptors (FcγRIII and FcγRIV) and downregulation of the inhibitory receptor, FcγRIIB; and (iii) CTX synergized with cetuximab (anti-EGFR) and trastuzumab (anti-Her2) in eliminating metastatic breast cancer in the BM of humanized mice. These findings provide insights into the mechanisms by which CTX synergizes with antibody therapeutics in resistant niche-specific organs and its applicability in treating BM-resident tumors.

IFN-mediated negative feedback supports bacteria class-specific macrophage inflammatory responses

Despite existing evidence for tuning of innate immunity to different classes of bacteria, the molecular mechanisms used by macrophages to tailor inflammatory responses to specific pathogens remain incompletely defined. By stimulating mouse macrophages with a titration matrix of TLR ligand pairs, we identified distinct stimulus requirements for activating and inhibitory events that evoked diverse cytokine production dynamics. These regulatory events were linked to patterns of inflammatory responses that distinguished between Gram-positive and Gram-negative bacteria, both in vitro and after in vivo lung infection. Stimulation beyond a TLR4 threshold and Gram-negative bacteria-induced responses were characterized by a rapid type I IFN-dependent decline in inflammatory cytokine production, independent of IL-10, whereas inflammatory responses to Gram-positive species were more sustained due to the absence of this IFN-dependent regulation. Thus, disparate triggering of a cytokine negative feedback loop promotes tuning of macrophage responses in a bacteria class-specific manner and provides context-dependent regulation of inflammation dynamics.

Promiscuous Chemokine Antagonist (BKT130) Suppresses Laser-Induced Choroidal Neovascularization by Inhibition of Monocyte Recruitment

Background

Age-related macular degeneration (AMD), the most common cause of blindness in the developed world, usually affects individuals older than 60 years of age. The majority of visual loss in this disease is attributable to the development of choroidal neovascularization (CNV). Mononuclear phagocytes, including monocytes and their tissue descendants, macrophages, have long been implicated in the pathogenesis of neovascular AMD (nvAMD). Current therapies for nvAMD are based on targeting vascular endothelial growth factor (VEGF). This study is aimed at assessing if perturbation of chemokine signaling and mononuclear cell recruitment may serve as novel complementary therapeutic targets for nvAMD.

Methods

A promiscuous chemokine antagonist (BKT130), aflibercept treatment, or combined BKT130+aflibercept treatment was tested in an in vivo laser-induced model of choroidal neovascularization (LI-CNV) and in an ex vivo choroidal sprouting assay (CSA). Quantification of CD11b+ cell in the CNV area was performed, and mRNA levels of genes implicated in CNV growth were measured in the retina and RPE-choroid.

Results

BKT130 reduced the CNV area and recruitment of CD11b+ cells by 30-35%. No effect of BKT130 on macrophages' proangiogenic phenotype was demonstrated ex vivo, but a lower VEGFA and CCR2 expression was found in the RPE-choroid and a lower expression of TNFα and NOS1 was found in both RPE-choroid and retinal tissues in the LI-CNV model under treatment with BKT130.

Conclusions

Targeting monocyte recruitment via perturbation of chemokine signaling can reduce the size of experimental CNV and should be evaluated as a potential novel therapeutic modality for nvAMD.

NF-κB RelA Is Required for Hepatoprotection during Pneumonia and Sepsis

Pneumonia and sepsis are distinct but integrally linked public health concerns. The hepatic acute-phase response (APR), which is largely dependent on transcription factors NF-κB RelA and STAT3, is a hallmark of these pathologies and other injurious conditions. Inactivation of the APR can promote liver injury, a frequently observed organ dysfunction during sepsis. However, whether or how the acute-phase changes promote liver tissue resilience during infections is unclear. To determine the hepatoprotective role of the hepatic APR, we utilized mice bearing hepatocyte-specific deletions of either RelA or STAT3. Mice were challenged intratracheally (i.t.), intravenously (i.v.), or intraperitoneally (i.p.) with Escherichia coli, Klebsiella pneumoniae, Streptococcus pneumoniae, lipopolysaccharide (LPS), or alpha-galactosylceramide (αGalCer) to induce pneumonia, sepsis, or NKT cell activation. Liver injury was observed in RelA-null (hepRelAΔ/Δ) mice but not STAT3-null (hepSTAT3Δ/Δ) mice during pneumonia. The absence of RelA resulted in hepatotoxicity across several models of pneumonia, sepsis, and NKT cell activation. Injury was associated with increased levels of activated caspase-3 and -8 and substantial alteration of the hepatic transcriptome. Hepatotoxicity in the absence of RelA could be reversed by neutralization of tumor necrosis factor alpha (TNF-α). These results indicate the requirement of RelA-dependent inducible hepatoprotection during pneumonia and sepsis. Further, the results demonstrate that RelA-dependent gene programs are critical for maintaining liver homeostasis against TNF-α-driven immunotoxicity.

Group 1 innate lymphoid cells are involved in the progression of experimental anti-glomerular basement membrane glomerulonephritis and are regulated by peroxisome proliferator-activated receptor α

Innate lymphoid cells play an important role in the early effector cytokine-mediated response. In Wistar Kyoto rats, CD8⁺ non-T lymphocytes (CD8⁺Lym) infiltrate into glomeruli during the development of anti-glomerular basement membrane (anti-GBM) glomerulonephritis. Here, we examined the profiles and roles of CD8⁺Lym in anti-GBM glomerulonephritis. The regulation of CD8⁺Lym by peroxisome proliferator-activated receptor (PPAR)-α in anti-GBM glomerulonephritis was also evaluated. Glomerular infiltrating CD8⁺Lym were lineage-negative cells that showed markedly high expression of IFN-γ and T-bet mRNAs but not Eomes, indicating these cells are group 1 innate lymphoid cells. In anti-GBM glomerulonephritis, the glomerular mRNAs of innate lymphoid cell-related cytokines (IFN-γ and TNF-α) and chemokines (CXCL9, CXCL10, and CXCL11) are significantly increased. Treatment with a PPARα agonist ameliorated renal injury, with reduced expression of these mRNAs. In vitro, enhanced IFN-γ production from innate lymphoid cells upon IL-12 and IL-18 stimulation was reduced by the PPARα agonist. Moreover, CXCL9 mRNA in glomerular endothelial cells and CXCL9, CXCL10, and CXCL11 mRNAs in podocytes and macrophages were upregulated by IFN-γ, whereas the PPARα agonist downregulated their expression. We also detected the infiltration of innate lymphoid cells into glomeruli in human anti-GBM glomerulonephritis. Thus, innate lymphoid cells are involved in the progression of anti-GBM glomerulonephritis and regulated directly or indirectly by PPARα. Our findings suggest that innate lymphoid cells could serve as novel therapeutic targets for anti-GBM glomerulonephritis.

Hydrogel scaffold with substrate elasticity mimicking physiological-niche promotes proliferation of functional keratinocytes

High numbers of autologous human primary keratinocytes (HPKs) are required for patients with burns, wounds and for gene therapy of skin disorders. Although freshly isolated HPKs exhibit a robust regenerative capacity, traditional methodology fails to provide a sufficient number of cells. Here we demonstrated a well characterized, non-cytotoxic and inert hydrogel as a substrate that mimics skin elasticity, which can accelerate proliferation and generate higher numbers of HPKs compared to existing tissue culture plastic (TCP) dishes. More importantly, this novel method was independent of feeder layer or any exogenous pharmaceutical drug. The HPKs from the hydrogel-substrate were functional as demonstrated by wound-healing assay, and the expression of IFN-γ-responsive genes (CXCL10, HLADR). Importantly, gene delivery efficiency by a lentiviral based delivery system was significantly higher in HPKs cultured on hydrogels compared with TCP. In conclusion, our study provides the first evidence that cell-material mechanical interaction is enough to provide a rapid expansion of functional keratinocytes that might be used as autologous grafts for skin disorders.

High numbers of autologous human primary keratinocytes (HPKs) are required for patients with burns, wounds and for gene therapy of skin disorders.

Higher plane of nutrition pre-weaning enhances Holstein calf mammary gland development through alterations in the parenchyma and fat pad transcriptome

Background

To reduce costs of rearing replacement heifers, researchers have focused on decreasing age at breeding and first calving. To increase returns upon initiation of lactation the focus has been on increasing mammary development prior to onset of first lactation. Enhanced plane of nutrition pre-weaning may benefit the entire replacement heifer operation by promoting mammary gland development and greater future production.

Methods

Twelve Holstein heifer calves (< 1 week old) were reared on 1 of 2 dietary treatments (n = 6/group) for 8 weeks: a control group fed a restricted milk replacer at 0.45 kg/d (R, 20% crude protein, 20% fat), or an accelerated group fed an enhanced milk replacer at 1.13 kg/d (EH, 28% crude protein, 25% fat). At weaning (8 weeks), calves were euthanized and sub-samples of mammary parenchyma (PAR) and mammary fat pad (MFP) were harvested upon removal from the body. Total RNA from both tissues was extracted and sequenced using the Illumina HiSeq2500 platform. The Dynamic Impact Approach (DIA) and Ingenuity Pathway Analysis (IPA) were used for pathway analysis and functions, gene networks, and cross-talk analyses of the two tissues.

Results

When comparing EH vs R 1561 genes (895 upregulated, 666 downregulated) and 970 genes (506 upregulated, 464 downregulated) were differentially expressed in PAR and MFP, respectively. DIA and IPA results highlight a greater proliferation and differentiation activity in both PAR and MFP, supported by an increased metabolic activity. When calves were fed EH, the PAR displayed transcriptional signs of greater overall organ development, with higher ductal growth and branching, together with a supportive blood vessel and nerve network. These activities were mediated by intracellular cascades, such as AKT, SHH, MAPK, and Wnt, probably activated by hormones, growth factors, and endogenous molecules. The analysis also revealed strong communication between MFP and PAR.

Conclusion

The transcriptomics and bioinformatics approach highlighted key mechanisms that mediate the mammary gland response to a higher plane of nutrition in the pre-weaning period.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5303-8) contains supplementary material, which is available to authorized users.

DDX3 Participates in Translational Control of Inflammation Induced by Infections and Injuries

Recent studies have suggested that DDX3 functions in antiviral innate immunity, but the underlying mechanism remains elusive. We previously identified target mRNAs whose translation is controlled by DDX3. Pathway enrichment analysis of these targets indicated that DDX3 is involved in various infections and inflammation. Using immunoblotting, we confirmed that PACT, STAT1, GNB2, Rac1, TAK1, and p38 mitogen-activated protein kinase (MAPK) proteins are downregulated by DDX3 knockdown in human monocytic THP-1 cells and epithelial HeLa cells. Polysome profiling revealed that DDX3 knockdown reduces the translational efficiency of target mRNAs. We further demonstrated DDX3-mediated translational control of target mRNAs by luciferase reporter assays. To examine the effects of DDX3 knockdown on macrophage migration and phagocytosis, we performed in vitro cell migration assay and flow cytometry analysis of the uptake of green fluorescent protein-expressing Escherichia coli in THP-1 cells. The DDX3 knockdown cells exhibited impaired macrophage migration and phagocytosis. Moreover, we used a human cytokine antibody array to identify the cytokines affected by DDX3 knockdown. Several chemokines were decreased considerably in DDX3 knockdown THP-1 cells after lipopolysaccharide or poly(I·C) stimulation. Lastly, we demonstrated that DDX3 is crucial for the recruitment of phagocytes to the site of inflammation in transgenic zebrafish.

Targeting of the Nasal Mucosa by Japanese Encephalitis Virus for Non-Vector-Borne Transmission

JEV, a main cause of severe viral encephalitis in humans, has a complex ecology composed of a mosquito-waterbird cycle and a cycle involving pigs, which amplifies virus transmission to mosquitoes, leading to increased human cases. JEV can be transmitted between pigs by contact in the absence of arthropod vectors. Moreover, virus or viral RNA is found in oronasal secretions and the nasal epithelium. Using nasal mucosa tissue explants and three-dimensional porcine nasal epithelial cells cultures and macrophages as ex vivo and in vitro models, we determined that the nasal epithelium could be a route of entry as well as exit for the virus. Infection of nasal epithelial cells resulted in apical and basolateral virus shedding and release of monocyte recruiting chemokines and therefore infection and replication in macrophages, which is favored by epithelial-cell-derived cytokines. The results are relevant to understand the mechanism of non-vector-borne direct transmission of JEV.

The mosquito-borne Japanese encephalitis virus (JEV) causes severe central nervous system diseases and cycles between Culex mosquitoes and different vertebrates. For JEV and some other flaviviruses, oronasal transmission is described, but the mode of infection is unknown. Using nasal mucosal tissue explants and primary porcine nasal epithelial cells (NEC) at the air-liquid interface (ALI) and macrophages as ex vivo and in vitro models, we determined that the nasal epithelium could represent the route of entry and exit for JEV in pigs. Porcine NEC at the ALI exposed to with JEV resulted in apical and basolateral virus shedding and release of monocyte recruiting chemokines, indicating infection and replication in macrophages. Moreover, macrophages stimulated by alarmins, including interleukin-25, interleukin-33, and thymic stromal lymphopoietin, were more permissive to the JEV infection. Altogether, our data are important to understand the mechanism of non-vector-borne direct transmission of Japanese encephalitis virus in pigs.

IMPORTANCE JEV, a main cause of severe viral encephalitis in humans, has a complex ecology composed of a mosquito-waterbird cycle and a cycle involving pigs, which amplifies virus transmission to mosquitoes, leading to increased human cases. JEV can be transmitted between pigs by contact in the absence of arthropod vectors. Moreover, virus or viral RNA is found in oronasal secretions and the nasal epithelium. Using nasal mucosa tissue explants and three-dimensional porcine nasal epithelial cells cultures and macrophages as ex vivo and in vitro models, we determined that the nasal epithelium could be a route of entry as well as exit for the virus. Infection of nasal epithelial cells resulted in apical and basolateral virus shedding and release of monocyte recruiting chemokines and therefore infection and replication in macrophages, which is favored by epithelial-cell-derived cytokines. The results are relevant to understand the mechanism of non-vector-borne direct transmission of JEV.

lncRNA NTT/PBOV1 Axis Promotes Monocyte Differentiation and Is Elevated in Rheumatoid Arthritis

Monocytes/macrophages are important in orchestrating inflammatory responses. However, knowledge of the long noncoding RNA (lncRNA) regulation of monocytic cell differentiation and diseases remains limited. We aimed to elucidate the role of the 17 kb lncRNA noncoding transcript in T cells (NTT) in monocyte functions. Knockdown and chromatin immunoprecipitation (ChIP) assays in THP-1 cells (human monocytic leukemia cell line) revealed that NTT is regulated by the monocyte key transcription factor C/EBPβ and that it binds to the promoter of nearby gene PBOV1 via hnRNP-U. Overexpression of PBOV1 in THP-1 cells resulted in cell cycle G1 arrest, differentiation into macrophages, a marked increase in IL-10 and CXCL10 mRNA levels, and upregulation of the costimulatory molecules. In contrast to the downregulated NTT observed in lipopolysaccharide (LPS)-treated THP-1 cells, the C/EBPβ/NTT/PBOV1 axis was found to be hyperactivated in peripheral blood mononuclear cells (PBMCs) of first-time diagnosed untreated early rheumatoid arthritis (RA) patients, and their gene expression levels decreased markedly after treatment. Higher initial C/EBPβ/NTT/PBOV1 expression levels were associated with a trend of higher disease activity DAS28 scores. In conclusion, our study suggests that the lncRNA NTT is a regulator of inflammation in monocytes, and its activation participates in monocyte/macrophage differentiation and the pathogenesis of RA.

P2Y6 Receptors Regulate CXCL10 Expression and Secretion in Mouse Intestinal Epithelial Cells

In this study, we investigated the role of extracellular nucleotides in chemokine (KC, MIP-2, MCP-1, and CXCL10) expression and secretion by murine primary intestinal epithelial cells (IECs) with a focus on P2Y₆ receptors. qRT-PCR experiments showed that P2Y₆ was the dominant nucleotide receptor expressed in mouse IEC. In addition, the P2Y₆ ligand UDP induced expression and secretion of CXCL10. For the other studies, we took advantage of mice deficient in P2Y₆ (P2ry6^-/-). Similar expression levels of P2Y₁, P2Y₂, P2X2, P2X4, and A_2A were detected in P2ry6^-/- and WT IEC. Agonists of TLR3 (poly(I:C)), TLR4 (LPS), P2Y₁, and P2Y₂ increased the expression and secretion of CXCL10 more prominently in P2ry6^-/- IEC than in WT IEC. CXCL10 expression and secretion induced by poly(I:C) in both P2ry6^-/- and WT IEC were inhibited by general P2 antagonists (suramin and Reactive-Blue-2), by apyrase, and by specific antagonists of P2Y₁, P2Y₂, P2Y₆ (only in WT), and P2X4. Neither adenosine nor an A_2A antagonist had an effect on CXCL10 expression and secretion. Macrophage chemotaxis was induced by the supernatant of poly(I:C)-treated IEC which was consistent with the level of CXCL10 secreted. Finally, the non-nucleotide agonist FGF2 induced MMP9 mRNA expression also at a higher level in P2ry6^-/- IEC than in WT IEC. In conclusion, extracellular nucleotides regulate CXCL10 expression and secretion by IEC. In the absence of P2Y₆, these effects are modulated by other P2 receptors also present on IEC. These data suggest that the presence of P2Y₆ regulates chemokine secretion and may also regulate IEC homeostasis.

Dual Roles of Graphene Oxide To Attenuate Inflammation and Elicit Timely Polarization of Macrophage Phenotypes for Cardiac Repair

Development of localized inflammatory environments by M1 macrophages in the cardiac infarction region exacerbates heart failure after myocardial infarction (MI). Therefore, the regulation of inflammation by M1 macrophages and their timely polarization toward regenerative M2 macrophages suggest an immunotherapy. Particularly, controlling cellular generation of reactive oxygen species (ROS), which cause M1 differentiation, and developing M2 macrophage phenotypes in macrophages propose a therapeutic approach. Previously, stem or dendritic cells were used in MI for their anti-inflammatory and cardioprotective potentials and showed inflammation modulation and M2 macrophage progression for cardiac repair. However, cell-based therapeutics are limited due to invasive cell isolation, time-consuming cell expansion, labor-intensive and costly ex vivo cell manipulation, and low grafting efficiency. Here, we report that graphene oxide (GO) can serve as an antioxidant and attenuate inflammation and inflammatory polarization of macrophages via reduction in intracellular ROS. In addition, GO functions as a carrier for interleukin-4 plasmid DNA (IL-4 pDNA) that propagates M2 macrophages. We synthesized a macrophage-targeting/polarizing GO complex (MGC) and demonstrated that MGC decreased ROS in immune-stimulated macrophages. Furthermore, DNA-functionalized MGC (MGC/IL-4 pDNA) polarized M1 to M2 macrophages and enhanced the secretion of cardiac repair-favorable cytokines. Accordingly, injection of MGC/IL-4 pDNA into mouse MI models attenuated inflammation, elicited early polarization toward M2 macrophages, mitigated fibrosis, and improved heart function. Taken together, the present study highlights a biological application of GO in timely modulation of the immune environment in MI for cardiac repair. Current therapy using off-the-shelf material GO may overcome the shortcomings of cell therapies for MI.

Sirt6 deficiency results in progression of glomerular injury in the kidney

Aging is associated with an increased incidence and prevalence of renal glomerular diseases. Sirtuin (Sirt) 6, a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, has been shown to protect against multiple age-associated phenotypes; however it is unknown whether Sirt6 has a direct pathophysiologic role in the kidney. In the present study, we demonstrate that Sirt6 is expressed in the kidney and aging Sirt6-deficient mice exhibit renal hypertrophy with glomerular enlargement. Sirt6 deletion induces podocyte injury, including decreases in slit diaphragm proteins, foot process effacement, and cellular loss, resulting in proteinuria. Knockdown of Sirt6 in cultured primary murine podocytes induces shape changes with loss of process formation and cell apoptosis. Moreover, Sirt6 deficiency results in progressive renal inflammation and fibrosis. Collectively, these data provide compelling evidence that Sirt6 is important for podocyte homeostasis and maintenance of glomerular function, and warrant further investigation into the role of Sirt6 in age-associated kidney dysfunction.

Reducing Inflammatory Cytokine Production from Renal Collecting Duct Cells by Inhibiting GATA2 Ameliorates Acute Kidney Injury

Acute kidney injury (AKI) is a leading cause of chronic kidney disease. Proximal tubules are considered to be the primary origin of pathogenic inflammatory cytokines in AKI. However, it remains unclear whether other cell types, including collecting duct (CD) cells, participate in inflammatory processes. The transcription factor GATA2 is specifically expressed in CD cells and maintains their cellular identity. To explore the pathophysiological function of GATA2 in AKI, we generated renal tubular cell-specific Gata2 deletion (G2CKO) mice and examined their susceptibility to ischemia reperfusion injury (IRI). Notably, G2CKO mice exhibited less severe kidney damage, with reduced granulomacrophagic infiltration upon IRI. Transcriptome analysis revealed that a series of inflammatory cytokine genes were downregulated in GATA2-deficient CD cells, suggesting that GATA2 induces inflammatory cytokine expression in diseased kidney CD cells. Through high-throughput chemical library screening, we identified a potent GATA inhibitor. The chemical reduces cytokine production in CD cells and protects the mouse kidney from IRI. These results revealed a novel pathological mechanism of renal IRI, namely, that CD cells produce inflammatory cytokines and promote IRI progression. In injured kidney CD cells, GATA2 exerts a proinflammatory function by upregulating inflammatory cytokine gene expression. GATA2 can therefore be considered a therapeutic target for AKI.

The Origins and Functions of Tissue-Resident Macrophages in Kidney Development

The adult kidney hosts tissue-resident macrophages that can cause, prevent, and/or repair renal damage. Most of these macrophages derive from embryonic progenitors that colonize the kidney during its development and proliferate in situ throughout adulthood. Although the precise origins of kidney macrophages remain controversial, recent studies have revealed that embryonic macrophage progenitors initially migrate from the yolk sac, and later from the fetal liver, into the developing kidney. Once in the kidney, tissue-specific transcriptional regulators specify macrophage progenitors into dedicated kidney macrophages. Studies suggest that kidney macrophages facilitate many processes during renal organogenesis, such as branching morphogenesis and the clearance of cellular debris; however, little is known about how the origins and specification of kidney macrophages dictate their function. Here, we review significant new findings about the origins, specification, and developmental functions of kidney macrophages.

A network-based method using a random walk with restart algorithm and screening tests to identify novel genes associated with Menière's disease

As a chronic illness derived from hair cells of the inner ear, Menière’s disease (MD) negatively influences the quality of life of individuals and leads to a number of symptoms, such as dizziness, temporary hearing loss, and tinnitus. The complete identification of novel genes related to MD would help elucidate its underlying pathological mechanisms and improve its diagnosis and treatment. In this study, a network-based method was developed to identify novel MD-related genes based on known MD-related genes. A human protein-protein interaction (PPI) network was constructed using the PPI information reported in the STRING database. A classic ranking algorithm, the random walk with restart (RWR) algorithm, was employed to search for novel genes using known genes as seed nodes. To make the identified genes more reliable, a series of screening tests, including a permutation test, an interaction test and an enrichment test, were designed to select essential genes from those obtained by the RWR algorithm. As a result, several inferred genes, such as CD4, NOTCH2 and IL6, were discovered. Finally, a detailed biological analysis was performed on fifteen of the important inferred genes, which indicated their strong associations with MD.

Stromal ETS2 Regulates Chemokine Production and Immune Cell Recruitment during Acinar-to-Ductal Metaplasia

Preclinical studies have suggested that the pancreatic tumor microenvironment both inhibits and promotes tumor development and growth. Here we establish the role of stromal fibroblasts during acinar-to-ductal metaplasia (ADM), an initiating event in pancreatic cancer formation. The transcription factor V-Ets avian erythroblastosis virus E26 oncogene homolog 2 (ETS2) was elevated in smooth muscle actin–positive fibroblasts in the stroma of pancreatic ductal adenocarcinoma (PDAC) patient tissue samples relative to normal pancreatic controls. LSL-Kras^G12D/+; LSL-Trp53^R172H/+; Pdx-1-Cre (KPC) mice showed that ETS2 expression initially increased in fibroblasts during ADM and remained elevated through progression to PDAC. Conditional ablation of Ets-2 in pancreatic fibroblasts in a Kras^G12D-driven mouse ADM model decreased the amount of ADM events. ADMs from fibroblast Ets-2–deleted animals had reduced epithelial cell proliferation and increased apoptosis. Surprisingly, fibroblast Ets-2 deletion significantly altered immune cell infiltration into the stroma, with an increased CD8+ T-cell population, and decreased presence of regulatory T cells (Tregs), myeloid-derived suppressor cells, and mature macrophages. The mechanism involved ETS2-dependent chemokine ligand production in fibroblasts. ETS2 directly bound to regulatory sequences for Ccl3, Ccl4, Cxcl4, Cxcl5, and Cxcl10, a group of chemokines that act as potent mediators of immune cell recruitment. These results suggest an unappreciated role for ETS2 in fibroblasts in establishing an immune-suppressive microenvironment in response to oncogenic Kras^G12D signaling during the initial stages of tumor development.

Divergent roles for Ly6C+CCR2+CX3CR1+ inflammatory monocytes during primary or secondary infection of the skin with the intra-phagosomal pathogen Leishmania major

Inflammatory monocytes can be manipulated by environmental cues to perform multiple functions. To define the role of monocytes during primary or secondary infection with an intra-phagosomal pathogen we employed Leishmania major-red fluorescent protein (RFP) parasites and multi-color flow cytometry to define and enumerate infected and uninfected inflammatory cells in the skin. During primary infection, infected monocytes had altered maturation and were the initial mononuclear host cell for parasite replication. In contrast, at a distal site of secondary infection in mice with a healed but persistent primary infection, this same population rapidly produced inducible nitric oxide synthase (iNOS) in an IFN-γ dependent manner and was critical for parasite killing. Maturation to a dendritic cell-like phenotype was not required for monocyte iNOS-production, and enhanced monocyte recruitment correlated with IFN-γ dependent cxcl10 expression. In contrast, neutrophils appeared to be a safe haven for parasites in both primary and secondary sites. Thus, inflammatory monocytes play divergent roles during primary versus secondary infection with an intra-phagosomal pathogen.

Many infectious diseases are initiated in the context of inflammation. This inflammatory response may be initiated by the pathogen itself or by damage to barrier sites associated with the infectious process. In the case of the vector-transmitted intra-phagosomal pathogen Leishmania, the parasite must contend with the robust inflammatory response initiated by the bite of an infected sand fly. Traditionally, rapid infection of macrophages in the skin and manipulation of these cells was seen as the mechanism by which the parasite avoided elimination by inflammatory cells. In the present study, we find that this is not the case following primary infection. After transient residence in neutrophils, Leishmania parasites transitioned into immature inflammatory monocytes, where they underwent proliferation and suppressed the maturation of these cells. In stark contrast, in a setting of pre-existing immunity, inoculation of parasites at a secondary site of infection resulted in parasite killing by monocytes in an IFN-γ dependent manner. Therefore, the role of monocytes is dependent upon the primary or secondary nature of the infection site into which they are recruited, emphasizing both the plasticity of this cell population and the central role these cells play during Leishmaniasis.

Multiple Myeloma Cells Express Key Immunoregulatory Cytokines and Modulate the Monocyte Migratory Response

Multiple myeloma (MM) is a plasma cell disorder that still remains incurable. The immune dysfunction of the host is a striking characteristic of MM, leading to tumor growth and reducing the survival rate of patients. Monocytes are precursors of conventional dendritic cells (DCs), a major player in the immunity mechanisms driving protective T cell responses against tumor. Herein, we report that human MM RPMI 8226 cell line shows a pronounced chemoattractant activity for monocytes and also expresses enhanced levels of the leukocyte chemotactic cytokines CXCL12, CCL5, MIP-1β, and CXCL10 in association with elevated levels of both key immunoregulatory interleukins such as IL-4 and IL-10. This cytokine profile was observed together with reduced expression of IFN-γ by MM RPMI 8226 cell line, a determinant interleukin involved in the acquisition of cellular-mediated protective responses against tumor cells. We further demonstrate that MM RPMI 8226 cell line expresses elevated levels of soluble form of the intercellular adhesion molecule-1 known to inhibit antitumoral T cell responses. This attractive modulation of immune responses by MM cells might provide a means to impair early antitumor responses during the establishment of cytokine-mediated immunosuppressive tumor niche.

Microglia-derived IL-1β promotes chemokine expression by Müller cells and RPE in focal retinal degeneration

Background

Chemokine signalling is required for the homing of leukocytes during retinal inflammation, and is associated with pathogenesis of diseases such as age-related macular degeneration (AMD). Here, we explore the role of interleukin-1β (IL-1β) in modulating AMD-associated chemokines Ccl2, Cxcl1, and Cxcl10 during photo-oxidative retinal damage, and the effect on both the accumulation of outer-retinal macrophages, and death of photoreceptors.

Methods

Inhibition of retinal IL-1β expression was performed using either siRNA or antibody neutralisation, which was intravitreally injected in SD rats prior to photo-oxidative damage. Changes in the expression and localisation of Il-1β, Ccl2, Cxcl1 and Cxcl10 genes were assessed using qPCR and in situ hybridisation, while the recruitment of retinal macrophages was detected using immunohistochemistry for IBA1. Levels of photoreceptor cell death were determined using TUNEL.

Results

Photo-oxidative damage elevated the expression of Il-1β and inflammasome-related genes, and IL-1β protein was detected in microglia infiltrating the outer retina. This was associated with increased expression of Ccl2, Cxcl1, and Cxcl10. Intravitreal IL-1β inhibitors suppressed chemokine expression following damage and reduced macrophage accumulation and photoreceptor death. Moreover, in Müller and RPE cell cultures, and in vivo, Ccl2, Cxcl1 and Cxcl10 were variously upregulated when stimulated with IL-1β, with increased macrophage accumulation detected in vivo.

Conclusions

IL-1β is produced by retinal microglia and macrophages and promotes chemokine expression by Müller cells and RPE in retinal degeneration. Targeting IL-1β may prove efficacious in broadly suppressing chemokine-mediated inflammation in retinal dystrophies such as AMD.

Targeting Tumor Cells with Anti-CD44 Antibody Triggers Macrophage-Mediated Immune Modulatory Effects in a Cancer Xenograft Model

CD44, a transmembrane receptor reported to be involved in various cellular functions, is overexpressed in several cancer types and supposed to be involved in the initiation, progression and prognosis of these cancers. Since the sequence of events following the blockage of the CD44-HA interaction has not yet been studied in detail, we profiled xenograft tumors by RNA Sequencing to elucidate the mode of action of the anti-CD44 antibody RG7356. Analysis of tumor and host gene-expression profiles led us to the hypothesis that treatment with RG7356 antibody leads to an activation of the immune system. Using cytokine measurements we further show that this activation involves the secretion of chemo-attractants necessary for the recruitment of immune cells (i.e. macrophages) to the tumor site. We finally provide evidence for antibody-dependent cellular phagocytosis (ADCP) of the malignant cells by macrophages.

Glomerular Epithelial Cells-Targeted Heme Oxygenase-1 Over Expression in the Rat: Attenuation of Proteinuria in Secondary But Not Primary Injury

BACKGROUND/AIMS

Induction of heme oxygenase 1 (HO-1) in glomerular epithelial cells (GEC) in response to injury is poor and this may be a disadvantage. We, therefore, explored whether HO-1 overexpression in GEC can reduce proteinuria induced by puromycin aminonucleoside (PAN) or in anti-glomerular basement membrane (GBM) antibody (Ab)-mediated glomerulonephritis (GN).

METHODS

HO-1 overexpression in GEC (GECHO-1) of Sprague-Dawley rats was achieved by targeting a FLAG-human (h) HO-1 using transposon-mediated transgenesis. Direct GEC injury was induced by a single injection of PAN. GN was induced by administration of an anti-rat GBM Ab and macrophage infiltration in glomeruli was assessed by immunohistochemistry and western blot analysis, which was also used to assess glomerular nephrin expression.

RESULTS

In GECHO-1 rats, FLAG-hHO-1 transprotein was co-immunolocalized with nephrin. Baseline glomerular HO-1 protein levels were higher in GECHO-1 compared to wild type (WT) rats. Administration of either PAN or anti-GBM Ab to WT rats increased glomerular HO-1 levels. Nephrin expression markedly decreased in glomeruli of WT or GECHO-1 rats treated with PAN. In anti-GBM Ab-treated WT rats, nephrin expression also decreased. In contrast, it was preserved in anti-GBM Ab-treated GECHO-1 rats. In these, macrophage infiltration in glomeruli and the ratio of urine albumin to urine creatinine (Ualb/Ucreat) were markedly reduced. There was no difference in Ualb/Ucreat between WT and GECHO-1 rats treated with PAN.

CONCLUSION

Depending on the type of injury, HO-1 overexpression in GEC may or may not reduce proteinuria. Reduced macrophage infiltration and preservation of nephrin expression are putative mechanisms underlying the protective effect of HO-1 overexpression following immune injury.

Cytokine and Chemokine Expression in Kidneys during Chronic Leptospirosis in Reservoir and Susceptible Animal Models

Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira. Humans can be infected after exposure to contaminated urine of reservoir animals, usually rodents, regarded as typical asymptomatic carriers of leptospires. In contrast, accidental hosts may present an acute form of leptospirosis with a range of clinical symptoms including the development of Acute Kidney Injury (AKI). Chronic Kidney Disease (CKD) is considered as a possible AKI-residual sequela but little is known about the renal pathophysiology consequent to leptospirosis infection. Herein, we studied the renal morphological alterations in relation with the regulation of inflammatory cytokines and chemokines, comparing two experimental models of chronic leptospirosis, the golden Syrian hamster that survived the infection, becoming carrier of virulent leptospires, and the OF1 mouse, a usual reservoir of the bacteria. Animals were monitored until 28 days after injection with a virulent L. borgpetersenii serogroup Ballum to assess chronic infection. Hamsters developed morphological alterations in the kidneys with tubulointerstitial nephritis and fibrosis. Grading of lesions revealed higher scores in hamsters compared to the slight alterations observed in the mouse kidneys, irrespective of the bacterial load. Interestingly, pro-fibrotic TGF-β was downregulated in mouse kidneys. Moreover, cytokines IL-1β and IL-10, and chemokines MIP-1α/CCL3 and IP-10/CXCL-10 were significantly upregulated in hamster kidneys compared to mice. These results suggest a possible maintenance of inflammatory processes in the hamster kidneys with the infiltration of inflammatory cells in response to bacterial carriage, resulting in alterations of renal tissues. In contrast, lower expression levels in mouse kidneys indicated a better regulation of the inflammatory response and possible resolution processes likely related to resistance mechanisms.

Mixed lineage kinase 3 mediates release of C-X-C motif ligand 10-bearing chemotactic extracellular vesicles from lipotoxic hepatocytes

Mixed lineage kinase 3 (MLK3) deficiency reduces macrophage-associated inflammation in a murine model of nonalcoholic steatohepatitis (NASH). However, the mechanistic links between MLK3 activation in hepatocytes and macrophage-driven inflammation in NASH are uncharted. Herein, we report that MLK3 mediates the release of (C-X-C motif) ligand 10 (CXCL10)-laden extracellular vesicles (EVs) from lipotoxic hepatocytes, which induce macrophage chemotaxis. Primary mouse hepatocytes (PMHs) and Huh7 cells were treated with palmitate or lysophosphatidylcholine (LPC). Released EVs were isolated by differential ultracentrifugation. LPC treatment of PMH or Huh7 cells induced release of EVs, which was prevented by either genetic or pharmacological inhibition of MLK3. Mass spectrometry identified the potent chemokine, CXCL10, in the EVs, which was markedly enriched in EVs isolated from LPC-treated hepatocytes versus untreated cells. Green fluorescent protein (GFP)-tagged CXCL10 was present in vesicular structures and colocalized with the red fluorescent protein (RFP)-tagged EV marker, CD63, after LPC treatment of cotransfected Huh-7 cells. Either genetic deletion or pharmacological inhibition of MLK3 prevented CXCL10 enrichment in EVs. Treatment of mouse bone-marrow-derived macrophages with lipotoxic hepatocyte-derived EVs induced macrophage chemotaxis, an effect blocked by incubation with CXCL10-neutralizing antisera. MLK3-deficient mice fed a NASH-inducing diet had reduced concentrations of total plasma EVs and CXCL10 containing EVs compared to wild-type mice.

CONCLUSIONS

During hepatocyte lipotoxicity, activated MLK3 induces the release of CXCL10-bearing vesicles from hepatocytes, which are chemotactic for macrophages.

Animal models of pediatric chronic kidney disease. Is adenine intake an appropriate model?

Pediatric chronic kidney disease (CKD) has peculiar features. In particular, growth impairment is a major clinical manifestation of CKD that debuts in pediatric age because it presents in a large proportion of infants and children with CKD and has a profound impact on the self-esteem and social integration of the stunted patients. Several factors associated with CKD may lead to growth retardation by interfering with the normal physiology of growth plate, the organ where longitudinal growth rate takes place. The study of growth plate is hardly possible in humans and justifies the use of animal models. Young rats made uremic by 5/6 nephrectomy have been widely used as a model to investigate growth retardation in CKD. This article examines the characteristics of this model and analyzes the utilization of CKD induced by high adenine diet as an alternative research protocol.

Protein domains of APOL1 and its risk variants

Increasing lines of evidence have demonstrated that the development of higher rates of non-diabetic glomerulosclerosis (GS) in African Americans can be attributed to two coding sequence variants (G1 and G2) in the Apolipoprotein L1 (APOL) gene. Recent studies indicate that the gene products of these APOL1 risk variants have augmented toxicity to kidney cells. However, the biological characteristics of APOL1 and its risk variants are not well elucidated. The APOL1 protein can be divided into several functional domains, including signal peptide (SP), pore forming domain (PFD), membrane address domain (MAD), and SRA-interacting domain. To investigate the relative contribution of each domain to cell injury, we constructed a serial expression vectors to delete or express each domain. These vectors were transfected into the human embryonic kidney cell line 293T, and then compared the cytotoxicity. In addition, we conducted studies in which APOL1 wild type (G0) was co-transfected in combination with G1 or G2 to see whether G0 could counteract the toxicity of the risk variants. The results showed that deleting the SP did not abolish the toxicity of APOL1, though deletion of 26 amino acid residues of the mature peptide at the N-terminal partially decreased the toxicity. Deleting PFD or MAD or SRA-interacting domain abolished toxicity, while, overexpressing each domain alone could not cause toxicity to the host cells. Deletion of the G2 sites while retaining G1 sites in the risk state resulted in persistent toxicity. Either deletion or exchanging the BH3 domain in the PFD led to complete loss of the toxicity in this experimental platform. Adding G0 to either G1 or G2 did not attenuate the toxicity of the either moiety. These results indicate that the integrity of the mature APOL1 protein is indispensable for its toxicity. Our study not only reveals the contribution of each domain of the APOL1 protein to cell injury, but also highlights some potential suggested targets for drug design to prevent or treat APOL1-associated nephropathy.