Th17 cells contribute to pulmonary fibrosis and inflammation during chronic kidney disease progression after acute ischemia

A pathological joint-liver axis mediated by matrikine-activated CD4+ T cells

The knee joint has long been considered a closed system. The pathological effects of joint diseases on distant organs have not been investigated. Herein, our clinical data showed that post-traumatic joint damage, combined with joint bleeding (hemarthrosis), exhibits a worse liver function compared with healthy control. With mouse model, hemarthrosis induces both cartilage degeneration and remote liver damage. Next, we found that hemarthrosis induces the upregulation in ratio and differentiation towards Th17 cells of CD4+ T cells in peripheral blood and spleen. Deletion of CD4+ T cells reverses hemarthrosis-induced liver damage. Degeneration of cartilage matrix induced by hemarthrosis upregulates serological type II collagen (COL II), which activates CD4+ T cells. Systemic application of a COL II antibody blocks the activation. Furthermore, bulk RNAseq and single-cell qPCR analysis revealed that the cartilage Akt pathway is inhibited by blood treatment. Intra-articular application of Akt activator blocks the cartilage degeneration and thus protects against the liver impairment in mouse and pig models. Taken together, our study revealed a pathological joint-liver axis mediated by matrikine-activated CD4+ T cells, which refreshes the organ-crosstalk axis and provides a new treatment target for hemarthrosis-related disease. Intra-articular bleeding induces cartilage degradation through down-reulation of cartilage Akt pathway. During this process, the soluble COL II released from the damaged cartilage can activate peripheral CD4+ T cells, differention into Th17 cells and secretion of IL-17, which consequently induces liver impairment. Intra-articular application of sc79 (inhibitor of Akt pathway) can prevent the cartilage damage as well as its peripheral influences.

Th17 cells: A new target in kidney disease research

Type 17 T helper (Th17) cells, which are a subtype of CD4+ T helper cells, secrete pro-inflammatory cytokines such as IL-17A, IL-17F, IL-21, IL-22, and GM-CSF, which play crucial roles in immune defence and protection against fungal and extracellular pathogen invasion. However, dysfunction of Th17 cell immunity mediates inflammatory responses and exacerbates tissue damage. This pathological process initiated by Th17 cells is common in kidney diseases associated with renal injury, such as glomerulonephritis, lupus nephritis, IgA nephropathy, hypertensive nephropathy, diabetic kidney disease and acute kidney injury. Therefore, targeting Th17 cells to treat kidney diseases has been a hot topic in recent years. This article reviews the mechanisms of Th17 cell-mediated inflammation and autoimmune responses in kidney diseases and discusses the related clinical drugs that modulate Th17 cell fate in kidney disease treatment.

Gut microbiota dysbiosis in AKI to CKD transition

BACKGROUND AND AIM

The symptoms of acute kidney injury (AKI) include a sudden drop-in glomerular filtration rate (GFR), a rise in serum creatinine (sCr), blood urea nitrogen (BUN), and electrolytes, which leads to a rapid loss of kidney function. Chronic kidney disease progresses when AKI symptoms persist for over three months or 90 days. Numerous prevalent secondary risk factors, including diabetes, hypertension, obesity, and heart illness, are directly or indirectly linked to the development of AKI and the switch from AKI to CKD. Recently, the change of intestinal bacteria known as "gut dysbiosis" has been linked to distant organ dysfunction, including the heart, lungs, kidneys, and brain. Indirectly or directly, gut dysbiosis contributes to the progression of CKD and AKI. However, the effects of gut dysbiosis and the mechanism of action in the progression from AKI to CKD are unknown or need further investigation. The mechanism by which gut dysbiosis initiates AKI's progression to CKD should be explicitly concerned. The review primarily focuses on the action of gut dysbiosis in kidney disease, the effects of dysbiosis, the characterisation of dysbiosis and its pathogenic products, the various pathogenic routes and mechanism involved in expediting the transition from AKI to CKD.

CONCLUSION

We identified and briefly reviewed the impacts of dysbiosis in various situations such as hypoxia, mitochondrial induced reactive oxygen species (mtROS), aryl hydrocarbon receptor (AhR) activation and microbiota derived uremic toxemic substances profoundly to push AKI to CKD conditions.

Respiratory complications and sleep disorders in children with chronic kidney disease: A correlation often underestimated

Chronic Kidney Disease (CKD) is characterized by a progressive and irreversible loss of kidney function which gradually leads to end-stage kidney disease (ESKD). Virtually all the organs are damaged by the toxicity of uremic compounds. The lungs may be affected and the impaired pulmonary function may be the direct result of fluid retention and metabolic, endocrine and cardiovascular alterations, as well as systemic activation of the inflammation. An increased prevalence in sleep disorders (SD) is also reported in patients with CKD, leading to a further negative impact on overall health and quality of life. While these complex relationships are well documented in the adult population, these aspects remain relatively little investigated in children. The aim of this review is to provide a brief overview of the pathophysiology between lung and kidney and to summarize how CKD may affect respiratory function and sleep in children.

Toxicity profile of combined immune checkpoint inhibitors and thoracic radiotherapy in esophageal cancer: A meta-analysis and systematic review

Background

Therapies based on the combination of immune checkpoint inhibitors (ICIs) and thoracic radiotherapy (TRT) are transforming the treatment landscape of esophageal cancer. Nevertheless, the available data on adverse events (AEs) mainly stemmed from several prospective clinical trials and retrospective studies, in which, AE data are often handled and reported with less rigor than the primary beneficial outcomes of the study. Thus, we conducted a systematic review to investigate the toxicity spectrum of these novel regimens.

Method

We searched for all prospective clinical trials investigating the role of ICIs combined with TRT published between January 2010 and August 2022. Study articles and conference proceedings involving esophageal cancers and reporting the overall incidence or details of treatment-related AEs (trAEs) were synthesized to determine the toxicity profile of combination treatment. We compared trAEs between cancer type, programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors, and between sequential and concurrent administration of ICIs and TRT to identify potentially high-risk patients.

Results

We obtained toxicity data from 14 clinical trials involving 863 patients. The pooled overall incidence was 88.97% for any-grade trAEs and 18.48% for high-grade trAEs. The three most frequent non-hematologic any-grade trAEs were reactive cutaneous capillary endothelial proliferation (RCCEP, 63.80%), esophagitis (51.54%), and fatigue (33.63%). Meanwhile, RCCEP (15.69%) was the most common non-hematologic high-grade trAE, followed by nausea (4.91%) and anorexia (3.81%). The occurrence rates of any-grade and high-grade pneumonitis were 10.82% and 0.66%, respectively. In subgroup analysis, the toxicity profiles of PD-1 and PD-L1 inhibitors were mostly similar, except for any-grade pneumonitis (15.20% vs 4.88%, p=0.03) and high-grade leukopenia (6.25% vs 59.09%, p=0.00). In addition, concurrent treatment seemed to have a higher incidence of any-grade trAEs (95.20% vs 70.85%, p=0.03) compared with sequential treatment. ESCC seems to have higher incidence of any-grade hypothyroidism (22.55% vs 8.96%, p=0.049) compared to EAC.

Conclusion

Our study is the first systematic review to provide a toxicity profile of trAEs in esophageal cancer patients who received ICIs combined with TRT. Most AEs of this combination treatment are tolerable, although the incidence of any-grade trAEs was higher in the concurrent group. The difference in any-grade pneumonitis between PD-1 and PD-L1 inhibitor groups needs further validation in a large clinical trial.

Inflammation in kidney repair: Mechanism and therapeutic potential

The kidney has a remarkable ability of repair after acute kidney injury (AKI). However, when injury is severe or persistent, the repair is incomplete or maladaptive and may lead to chronic kidney disease (CKD). Maladaptive kidney repair involves multiple cell types and multifactorial processes, of which inflammation is a key component. In the process of inflammation, there is a bidirectional interplay between kidney parenchymal cells and the immune system. The extensive and complex crosstalk between renal tubular epithelial cells and interstitial cells, including immune cells, fibroblasts, and endothelial cells, governs the repair and recovery of the injured kidney. Further research in this field is imperative for the discovery of biomarkers and promising therapeutic targets for kidney repair. In this review, we summarize the latest progress in the immune response and inflammation during maladaptive kidney repair, analyzing the interaction between immune cells and intrinsic kidney cells, pointing out the potentialities of inflammation-related pathways as therapeutic targets, and discussing the challenges and future research prospects in this field.

Serum IL-17 levels are higher in critically ill patients with AKI and associated with worse outcomes

Background

Interleukin-17 (IL-17) antagonism in rats reduces the severity and progression of AKI. IL-17-producing circulating T helper-17 (TH17) cells is increased in critically ill patients with AKI indicating that this pathway is also activated in humans. We aim to compare serum IL-17A levels in critically ill patients with versus without AKI and to examine their relationship with mortality and major adverse kidney events (MAKE).

Methods

Multicenter, prospective study of ICU patients with AKI stage 2 or 3 and without AKI. Samples were collected at 24–48 h after AKI diagnosis or ICU admission (in those without AKI) [timepoint 1, T1] and 5–7 days later [timepoint 2, T2]. MAKE was defined as the composite of death, dependence on kidney replacement therapy or a reduction in eGFR of ≥ 30% from baseline up to 90 days following hospital discharge.

Results

A total of 299 patients were evaluated. Patients in the highest IL-17A tertile (versus lower tertiles) at T1 had higher acuity of illness and comorbidity scores. Patients with AKI had higher levels of IL-17A than those without AKI: T1 1918.6 fg/ml (692.0–5860.9) versus 623.1 fg/ml (331.7–1503.4), p < 0.001; T2 2167.7 fg/ml (839.9–4618.9) versus 1193.5 fg/ml (523.8–2198.7), p = 0.006. Every onefold higher serum IL-17A at T1 was independently associated with increased risk of hospital mortality (aOR 1.35, 95% CI: 1.06–1.73) and MAKE (aOR 1.26, 95% CI: 1.02–1.55). The highest tertile of IL-17A (vs. the lowest tertile) was also independently associated with higher risk of MAKE (aOR 3.03, 95% CI: 1.34–6.87). There was no effect modification of these associations by AKI status. IL-17A levels remained significantly elevated at T2 in patients that died or developed MAKE.

Conclusions

Serum IL-17A levels measured by the time of AKI diagnosis or ICU admission were differentially elevated in critically ill patients with AKI when compared to those without AKI and were independently associated with hospital mortality and MAKE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03976-4.

The CTRP3-AdipoR2 Axis Regulates the Development of Experimental Autoimmune Encephalomyelitis by Suppressing Th17 Cell Differentiation

C1q/TNF-related proteins (CTRP) including CTRP3 are a group of secreted proteins which have a complement C1q-like domain in common, and play versatile roles in lipid metabolism, inflammation, tumor metastasis and bone metabolism. Previously, we showed that the expression of C1qtnf3, encoding CTRP3, is highly augmented in joints of autoimmune arthritis models and CTRP3-deficiency exacerbates collagen-induced arthritis in mice. However, the mechanisms how CTRP3-deficiency exacerbates arthritis still remain to be elucidated. In this study, we showed that CTRP3 was highly expressed in Th17 cell, a key player for the development of autoimmune diseases, and Th17 cell differentiation was augmented in C1qtnf3^–/– mice. Th17 cell differentiation, but not Th1 cell differentiation, was suppressed by CTRP3 and this suppression was abolished by the treatment with a receptor antagonist against AdipoR2, but not AdipoR1, associated with suppression of Rorc and Stat3 expression. Furthermore, AdipoR1 and AdipoR2 agonist, AdipoRon suppressed Th17 cell differentiation via AdipoR2, but not AdipoR1. The development of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis was enhanced in C1qtnf3^–/– mice associated with increase of Th17 cell population. CTRP3 inhibited MOG-induced IL-17 production from T cells by affecting both T cells and dendritic cells. These results show that CTRP3 is an endogenous regulator of Th17 differentiation, suggesting that the CTRP3-AdipoR2 axis is a good target for the treatment of Th17 cell-mediated diseases.

Lymphocytes: Versatile Participants in Acute Kidney Injury and Progression to Chronic Kidney Disease

Background: Acute kidney injury (AKI) remains a major global public health concern due to its high morbidity and mortality. The progression from AKI to chronic kidney disease (CKD) makes it a scientific problem to be solved. However, it is with lack of effective treatments.

Summary: Both innate and adaptive immune systems participate in the inflammatory process during AKI, and excessive or dysregulated immune responses play a pathogenic role in renal fibrosis, which is an important hallmark of CKD. Studies on the pathogenesis of AKI and CKD have clarified that renal injury induces the production of various chemokines by renal parenchyma cells or resident immune cells, which recruits multiple-subtype lymphocytes in circulation. Some infiltrated lymphocytes exacerbate injury by proinflammatory cytokine production, cytotoxicity, and interaction with renal resident cells, which constructs the inflammatory environment and induces further injury, even death of renal parenchyma cells. Others promote tissue repair by producing protective cytokines. In this review, we outline the diversity of these lymphocytes and their mechanisms to regulate the whole pathogenic stages of AKI and CKD; discuss the chronological responses and the plasticity of lymphocytes related to AKI and CKD progression; and introduce the potential therapies targeting lymphocytes of AKI and CKD, including the interventions of chemokines, cytokines, and lymphocyte frequency regulation in vivo, adaptive transfer of ex-expanded lymphocytes, and the treatments of gut microbiota or metabolite regulations based on gut-kidney axis.

Key Message: In the process of AKI and CKD, T helper (Th) cells, innate, and innate-like lymphocytes exert mainly pathogenic roles, while double-negative T (DNT) cells and regulatory T cells (Tregs) are confirmed to be protective. Understanding the mechanisms by which lymphocytes mediate renal injury and renal fibrosis is necessary to promote the development of specific therapeutic strategies to protect from AKI and prevent the progression of CKD.

ZFP36 protects lungs from intestinal I/R-induced injury and fibrosis through the CREBBP/p53/p21/Bax pathway

Acute lung injury induced by ischemia-reperfusion (I/R)-associated pulmonary inflammation is associated with high rates of morbidity. Despite advances in the clinical management of lung disease, molecular therapeutic options for I/R-associated lung injury are limited. Zinc finger protein 36 (ZFP36) is an AU-rich element-binding protein that is known to suppress the inflammatory response. A ZFP36 binding site occurs in the 3' UTR of the cAMP-response element-binding protein (CREB) binding protein (CREBBP) gene, which is known to interact with apoptotic proteins to promote apoptosis. In this study, we investigate the involvement of ZFP36 and CREBBP on I/R-induced lung injury in vivo and in vitro. Intestinal ischemia/reperfusion (I/R) activates inflammatory responses, resulting in injury to different organs including the lung. Lung tissues from ZFP36-knockdown mice and mouse lung epithelial (MLE)-2 cells were subjected to either Intestinal I/R or hypoxia/reperfusion, respectively, and then analyzed by Western blotting, immunohistochemistry, and real-time PCR. Silico analyses, pull down and RIP assays were used to analyze the relationship between ZFP36 and CREBBP. ZFP36 deficiency upregulated CREBBP, enhanced I/R-induced lung injury, apoptosis, and inflammation, and increased I/R-induced lung fibrosis. In silico analyses indicated that ZFP36 was a strong negative regulator of CREBBP mRNA stability. Results of pull down and RIP assays confirmed that ZFP36 direct interacted with CREBBP mRNA. Our results indicated that ZFP36 can mediate the level of inflammation-associated lung damage following I/R via interactions with the CREBBP/p53/p21/Bax pathway. The downregulation of ZFP36 increased the level of fibrosis.

IFN-γ+ IL-17+ Th17 cells regulate fibrosis through secreting IL-21 in systemic scleroderma

This study aimed to explore the function of IFN‐γ⁺IL‐17⁺Th17 cells on fibrosis in systemic scleroderma (SSc). Blood and skin samples were collected from 20 SSc cases and 10 healthy individuals. The percentage of IFN‐γ⁺IL‐17⁺Th17 cells was detected using flow cytometry. The in vitro induction of IFN‐γ⁺IL‐17⁺Th17 cells was performed adopting PHA and rIL‐12. Gene expression was detected via quantitative real‐time polymerase chain reaction (qRT‐PCR), whereas western blot analysis was adopted for protein analysis. The distribution of IFN‐γ⁺IL‐17⁺Th17 cells was significantly increased in SSc cases and positively correlated with SSc stages (P = .031), disease duration (P = .016), activity (P = .025) and skin scores (P < .001). In vitro, IFN‐γ⁺IL‐17⁺Th17 cells could promote the expressions of α‐SMA and COL1A1, revealing increased fibroblasts’ proliferation and enhanced collagen‐secreting capacity. In addition, IL‐21 expression was significantly increased in co‐culture medium of IFN‐γ⁺IL‐17⁺Th17 cells and fibroblasts (P < .001). IL‐21 neutralizer treatment resulted in the down‐regulation of α‐SMA and COL1A1. IL‐21 was confirmed as an effector of IFN‐γ⁺IL‐17⁺Th17 cells in fibrosis process. The distribution of IFN‐γ⁺IL‐17⁺Th17 cells was significantly increased in SSc cases and positively correlated with disease activity. IFN‐γ⁺IL‐17⁺Th17 cells could promote fibroblast proliferation and enhance collagen‐secreting ability via producing IL‐21, thus contributing to fibrosis in SSc.

The Use of Immune Checkpoint Inhibitors in Oncology and the Occurrence of AKI: Where Do We Stand?

Immune checkpoint inhibitors (ICIs) are a novel class of immunotherapy drugs that have improved the treatment of a broad spectrum of cancers as metastatic melanoma, non-small lung cancer or renal cell carcinoma. These humanized monoclonal antibodies target inhibitory receptors (e.g. CTLA-4, PD-1, LAG-3, TIM-3) and ligands (PD-L1) expressed on T lymphocytes, antigen presenting cells and tumor cells and elicit an anti-tumor response by stimulating immune system. Nevertheless, the improved overall survival is complicated by the manifestation of Immune-related Adverse Effects (irAEs). During treatment with ICIs, the most common adverse kidney effect is represented by the development of acute kidney injury (AKI) with the acute tubulointerstitial nephritis as recurrent histological feature. The mechanisms involved in ICIs-induced AKI include the re-activation of effector T cells previously stimulated by nephrotoxic drugs (i.e. by antibiotics), the loss of tolerance versus self-renal antigens, the increased PD-L1 expression by tubular cells or the establishment of a pro-inflammatory milieu with the release of self-reactive antibodies. For renal transplant recipient treated with ICIs, the increased incidence of rejection is a serious concern. Therefore, the combination of ICIs with mTOR inhibitors represents an emerging strategy. Finally, it is relevant to anticipate which patients under ICIs would experience severe irAEs and from a kidney perspective, to predict patients with higher risk of AKI. Here, we provide a detailed overview of ICIs-related nephrotoxicity and the recently described multicenter studies. Several factors have been reported as biomarkers of ICIs-irAEs, in this review we speculate on potential biomarkers for ICIs-associated AKI.

Acute kidney injury during pregnancy leads to increased sFlt-1 and sEng and decreased renal T regulatory cells in pregnant rats with HELLP syndrome

BACKGROUND

The incidence of acute kidney injury (AKI) during pregnancy precedes a high maternal mortality rate of 20-40%. AKI during pregnancy has multiple etiologies; however, the more common are maternal hypertensive disorders, which include preeclampsia and HELLP (hemolysis, elevated liver enzyme, low platelet) syndrome. Therefore, we sought to assess the impact of AKI on blood pressure, kidney injury, and anti-angiogenic factors during pregnancies with and without HELLP syndrome.

METHODS

On gestational day (GD) 12, mini-osmotic pumps were inserted into a subset of normal pregnant (NP) rats infusing 4.7 μg/kg soluble fms-like tyrosine kinase-1 (sFlt-1) and 7 μg/kg soluble endoglin (sEng) to induce HELLP syndrome. On GD18, the renal pedicles were occluded for 45 min to induce AKI via bilateral ischemia reperfusion in a subset of NP (n = 18) or HELLP (n = 20) rats. Control NP (n = 20) and HELLP (n = 20) rats underwent a SHAM surgery on GD18. Plasma, urine, and maternal organs were saved for further analysis. Renal injury was assessed via renal histopathology, glomerular filtration rate (GFR), T cell infiltration, and assessment of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). Data was measured via two-way analysis of variance with Tukey's test for post hoc analysis.

RESULTS

Blood pressures were increased in HELLP+AKI rats (p = 0.0001); both NP+AKI and HELLP+AKI rats had increased lactate dehydrogenase (p < 0.0001) and aspartate aminotransferase levels (p < 0.0001), and decreased platelet levels (p < 0.001) vs. NP rats. HELLP+AKI (p = 0.002) and HELLP rats (p = 0.0002) had evidence of renal fibrosis vs. NP rats. GFR was decreased in HELLP+AKI (p = 0.01) rats vs. NP rats. Urinary KIM-1 was increased in NP+AKI rats vs. NP (p = 0.003) and HELLP rats (p = 0.01). HELLP+AKI rats had increased urinary KIM-1 vs. NP (p = 0.0008) and HELLP rats (p = 0.004) and increased NGAL vs. HELLP rats (p = 0.002). HELLP+AKI rats had increased sFlt-1 (p = 0.009) vs. NP rats. NP+AKI (p = 0.02) and HELLP+AKI (p = 0.007) rats had increased sEng vs. NP rats. CD3+CD4+ T cells were significantly increased in HELLP+AKI rats vs. NP (p = 0.0002) and NP+AKI (p = 0.05) rats. T regulatory cells were significantly decreased in HELLP+AKI (p = 0.03) and NP+AKI (p = 0.02) rats vs. NP rats; there were no changes between groups in T helper 17 cells (p = 0.34).

CONCLUSION

The findings in this study suggest that AKI during pregnancy contributes to increased blood pressure and biochemical markers for HELLP syndrome, creates an anti-angiogenic imbalance, and exacerbates kidney injury as shown on histopathology, GFR, and kidney injury markers.

Radiation recall pneumonitis induced by PD-1/PD-L1 blockades: mechanisms and therapeutic implications

BACKGROUND

The synergistic effect of radiotherapy (RT) in combination with immunotherapy has been shown in several clinical trials and case reports. The overlapping pulmonary toxicity induced by thoracic RT and programmed death 1/programmed death ligand-1 (PD-1/PD-L1) blockades is an important issue of clinical investigation in combination treatment. Thus far, the underlying mechanism of this toxicity remains largely unknown.

MAIN TEXT

In this review, we discuss the unique pattern of radiation recall pneumonitis (RRP) induced by PD-1 blockade. The clinical presentation is different from common radiation pneumonitis (RP) or RRP induced by cytotoxic drugs. The immune checkpoint inhibitors may evoke an inflammatory reaction in patients' previously irradiated fields, with infiltrating lymphocytes and potential involvement of related cytokines. All RRP patients have showed durable response to anti-PD-1/PD-L1. RRP is manageable; however, interruption of checkpoint blockades is necessary and immunosuppressive treatment should be started immediately. Further analyses of the predictive factors, including RT dosimetric parameters, tumor-infiltrating lymphocytes (TILs), and PD-L1 expression, are needed given the wide use of immune checkpoint inhibitors and high mortality from lung toxicity with the combination treatment.

CONCLUSION

Immune checkpoint inhibitors may evoke an RRP in the patients' previously irradiated fields. Interactions between immune checkpoint inhibitors and radiotherapy should be studied further.

Calcium channel Orai1 promotes lymphocyte IL-17 expression and progressive kidney injury

We hypothesized that the store-operated calcium entry (SOCE) channel, Orai1, participates in the activation of Th17 cells and influences renal injury. In rats, following renal ischemia/reperfusion (I/R), there was a rapid and sustained influx of Orai1+ CD4 T cells and IL-17 expression was restricted to Orai1+ cells. When kidney CD4+ cells of post-acute kidney injury (post-AKI) rats were stimulated with angiotensin II and elevated Na+ (10-7 M/170 mM) in vitro, there was an enhanced response in intracellular Ca2+ and IL-17 expression, which was blocked by SOCE inhibitors 2APB, YM58483/BTP2, or AnCoA4. In vivo, YM58483/BTP2 (1 mg/kg) attenuated IL-17+ cell activation, inflammation, and severity of AKI following either I/R or intramuscular glycerol injection. Rats treated with high-salt diet (5-9 weeks after I/R) manifested progressive disease indicated by enhanced inflammation, fibrosis, and impaired renal function. These responses were significantly attenuated by YM58483/BTP2. In peripheral blood of critically ill patients, Orai1+ cells were significantly elevated by approximately 10-fold and Th17 cells were elevated by approximately 4-fold in AKI versus non-AKI patients. Further, in vitro stimulation of CD4+ cells from AKI patients increased IL-17, which was blocked by SOCE inhibitors. These data suggest that Orai1 SOCE is a potential therapeutic target in AKI and CKD progression.

Orai1: CRACing the Th17 response in AKI

A strong Th17 inflammatory response aggravates ischemia reperfusion-induced (IR-induced) acute kidney injury (AKI), tissue fibrosis, and AKI-to-chronic kidney disease (CKD) progression. However, the underlying mechanisms of sustained Th17 activation following AKI and during AKI-to-CKD progression are unclear. In this issue of the JCI, Mehrotra et al. present compelling evidence that the store-operated calcium (Ca2+) channel Orai1 sustains Th17-driven inflammatory response after AKI and drives the AKI-to-CKD transition. Orai1 blockade significantly protected renal function from IR, attenuated high-salt-induced AKI-to-CKD progression in rats, and decreased Th17 response in rat and human T cells. Therapeutic targeting of Orai1 can potentially reduce AKI, AKI-to-CKD progression, and other Th17-driven diseases.

IL-17A - A regulator in acute inflammation: Insights from in vitro, in vivo and in silico studies

Acute inflammation following sterile injury is both inevitable and necessary to restore homeostasis and promote tissue repair. However, when excessive, inflammation can jeopardize the viability of organs and cause detrimental systemic effects. Identifying key-regulators of the immune cascade induced by surgery is vital to attenuating excessive inflammation and its subsequent effects. In this review, we describe the emerging role of IL-17A as a key-regulator in acute inflammation. The role of IL-17A in chronic disease states, such as rheumatoid arthritis, psoriasis and cancer has been well documented, but its significance in acute inflammation following surgery, sepsis, or traumatic injury has not been well studied. We aim to highlight the role of IL-17A in acute inflammation caused by trauma, liver ischemia, and organ transplantation, as well as in post-operative surgical infections. Further investigation of the roles of this cytokine in acute inflammation may stimulate novel therapies or diagnostic modalities.

Proteins of TNF-α and IL6 Pathways Are Elevated in Serum of Type-1 Diabetes Patients with Microalbuminuria

Soluble cytokine receptors may play an important role in development of microalbuminuria (MA) in type-1 diabetes (T1D). In this study, we measured 12 soluble receptors and ligands from TNF-α/IL6/IL2 pathways in T1D patients with MA (n = 89) and T1D patients without MA (n = 483) participating in the PAGODA study. Twelve proteins in the sera from T1D patients with and without MA were measured using multiplex Luminex assays. Ten serum proteins (sTNFR1, sTNFR2, sIL2Rα, MMP2, sgp130, sVCAM1, sIL6R, SAA, CRP, and sICAM1) were significantly elevated in T1D patients with MA. After adjusting for age, duration of diabetes, and sex in logistic regression, association remained significant for seven proteins. MA is associated with increasing concentrations of all 10 proteins, with the strongest associations observed for sTNFR1 (OR = 108.3, P < 10⁻³²) and sTNFR2 (OR = 65.5, P < 10⁻³⁷), followed by sIL2Rα (OR = 12.9, P < 10⁻¹³), MMP2 (OR = 5.5, P < 10⁻⁶), sgp130 (OR = 5.2, P < 10⁻³), sIL6R (OR = 4.6, P < 10⁻⁴), and sVCAM1 (OR = 3.3, P < 10⁻⁴). We developed a risk score system based on the combined odds ratios associated with each quintile for each protein. The risk scores cluster MA patients into three subsets, each associated with distinct risk for MA attributable to proteins in the TNF-α/IL6 pathway (mean OR = 1, 13.5, and 126.3 for the three subsets, respectively). Our results suggest that the TNF-α/IL6 pathway is overactive in approximately 40% of the MA patients and moderately elevated in the middle 40% of the MA patients. Our results suggest the existence of distinct subsets of MA patients identifiable by their serum protein profiles.