Development of Collapsing Focal and Segmental Glomerulosclerosis After Receiving Intravitreal Vascular Endothelial Growth Factor Blockade

Renal Glomerular Expression of WT-1, TGF-β, VEGF, and ET-1 Immunostains in Murine Models of Focal and Segmental Glomerulosclerosis

Primary focal segmental glomerulosclerosis (FSGS) is a type of chronic renal disease that commonly progresses to renal failure as the treatments are not particularly effective. Glomerular podocyte injury and loss are pivotal to the pathogenesis of FSGS. This study aims to explore the glomerular immunohistochemistry stain expression of Wilms tumor-1 (WT-1) (podocyte-specific protein), transforming growth factor beta (TGF-β) (cytokine protein), vascular endothelial growth factor (VEGF) (angiogenic protein), and endothelin-1 (ET-1) (profibrotic growth factor), in rats with adriamycin nephropathy, which represents the murine model of human FSGS. By the end of 8 and 12 weeks, the kidneys of adriamycin-treated rats and control rats were harvested and the histomorphology was studied. Both 8- and 12-week test groups developed proteinuria, and hypoalbuminemia and showed FSGS on hematoxylin and eosin-stained slides. The renal tissue samples were also treated with immunostains for WT-1, TGF-β, VEGF, and ET-1. The glomeruli in all the FSGS kidneys showed loss of WT-1 expression with a concomitant notable increased expression of TGF-β, VEGF, and ET-1 immunostains. These results demonstrate that as FSGS evolves, the WT-1-expressing podocytes are lost and it correlates inversely with the overexpression of TGF-β, VEGF, and ET-1, suggesting that during the pathogenesis of FSGS, podocyte damage triggers the activation of these proteins. The findings in the current study echo the theory hypothesized in world literature that TGF-β, VEGF, and ET-1 play an integral part in the evolution of FSGS. More research is needed to further detail the pathogenic role of these proteins as it may open routes to more targeted and effective treatment modalities.

State of the art in childhood nephrotic syndrome: concrete discoveries and unmet needs

Nephrotic syndrome (NS) is a clinical entity characterized by proteinuria, hypoalbuminemia, and peripheral edema. NS affects about 2-7 per 100,000 children aged below 18 years old yearly and is classified, based on the response to drugs, into steroid sensitive (SSNS), steroid dependent, (SDNS), multidrug dependent (MDNS), and multidrug resistant (MRNS). Forms of NS that are more difficult to treat are associated with a worse outcome with respect to renal function. In particular, MRNS commonly progresses to end stage renal failure requiring renal transplantation, with recurrence of the original disease in half of the cases. Histological presentations of NS may vary from minimal glomerular lesions (MCD) to focal segmental glomerulosclerosis (FSGS) and, of relevance, the histological patterns do not correlate with the response to treatments. Moreover, around half of MRNS cases are secondary to causative pathogenic variants in genes involved in maintaining the glomerular structure. The pathogenesis of NS is still poorly understood and therapeutic approaches are mostly based on clinical experience. Understanding of pathogenetic mechanisms of NS is one of the 'unmet needs' in nephrology and represents a significant challenge for the scientific community. The scope of the present review includes exploring relevant findings, identifying unmet needs, and reviewing therapeutic developments that characterize NS in the last decades. The main aim is to provide a basis for new perspectives and mechanistic studies in NS.

Membranoproliferative glomerulonephritis after intravitreal vascular growth factor inhibitor injections: A case report and review of the literature

Systemic administration of agents that inhibit vascular endothelial growth factor (VEGF) and therefore vascular proliferation is often used to treat various cancers. However, these agents are associated with a number of side effects, including proteinuria and renal injury. Intravitreal injection of anti-VEGF agents has become the cornerstone of macular disease treatment. Since these agents cross the blood-retina barrier and enter the circulation, systemic side effects have been reported. We report the novel case of a 57-year-old patient who presented with macular oedema secondary to central retinal vein occlusion, underwent three monthly loading-dose injections with the anti-VEGF agent ranibizumab, and 2 weeks after the second injection presented with biopsy-verified membranoproliferative glomerulonephritis. Twelve weeks after presenting with renal failure and 10 weeks after his last anti-VEGF injection, the patient demonstrated spontaneous recovery of his kidney function. The patient had a history that promoted renal fragility, including hypertension, liver transplantation 6 years earlier for alcohol-related cirrhosis and new-onset diabetes mellitus after transplant. Our literature review and case suggest that although adverse renal events after intravitreal anti-VEGF injections are very rare, ophthalmologists and nephrologists should be aware of this risk.

Renal thrombotic microangiopathy and nephrotic proteinuria induced by intravitreal injection of aflibercept for diabetic macular edema

BACKGROUND

Vascular endothelial growth factor inhibitors (VEGFIs) are used to treat malignant neoplasms and ocular diseases by inhibiting angiogenesis. Systemic use of VEGFIs has various side effects, including hypertension, proteinuria, and thrombotic microangiopathy, but adverse events due to intravitreal injection of VEGFIs have not been fully clarified. Although age-related macular degeneration was initially the most common target of intravitreal injection of VEGFIs, it has also been applied sporadically for diabetic macular edema in recent years. Proteinuria following intravitreal injection of VEGFIs would be reversible. In patients with diabetes mellitus (DM), however, it would be difficult to determine whether kidney damage arises from the clinical course of DM or from intravitreal injection of VEGFIs for diabetic macular edema.

CASE PRESENTATION

A 55-year-old woman with a 20-year history of type 2 DM began intravitreal injection of VEGFI (aflibercept, 2 mg every 4 weeks) for treatment of diabetic macular edema 2 years previously. She presented with leg edema, hypertension, and nephrotic-range proteinuria 14 months after the first injection. Histological examination of renal biopsy specimens revealed diabetic nephropathy with renal thrombotic microangiopathy probably associated with intravitreal injection of VEGFI. The patient's nephrotic syndrome completely improved at 6 months after simply discontinuing aflibercept.

CONCLUSIONS

This is a precious report of pathologically investigated renal thrombotic microangiopathy leading to nephrotic syndrome due to intravitreal injection of aflibercept for diabetic macular edema in a patient with type 2 DM. Renal function and proteinuria should be monitored in diabetic patients who receive intravitreal injection of a VEGFI. If kidney damage develops independent of the clinical course of DM during intravitreal injection of a VEGFI, renal biopsy should be performed and intravitreal VEGFI injection discontinued.

Changes of Estimated Glomerular Filtration Rate and Glycated Hemoglobin A1c in Diabetic Macular Edema Patients Treated by Ranibizumab and Aflibercept in the Tertiary Referral Hospital

Background and Objectives: Intravitreal injections (IVI) of vascular endothelial growth factor (VEGF) inhibitors are guideline-indicated treatments for diabetic macular edema (DME). However, some recent data have suggested that IVI VEGF inhibitors might, through systemic absorption, lead to a reduction in renal function. Our study aims to compare changes in glycated hemoglobin A1c (HbA1c) and estimated glomerular filtration rate (eGFR) between patients who received IVI ranibizumab and aflibercept treatment and patients who have not received IVI treatments. Materials and Methods: There were 17,165 DME patients with documented ophthalmology visits in the China Medical University Hospital-Clinical Research Data Repository. Those with a history of ESRD or bevacizumab treatment history, and those with missing information on HbA1c or eGFR, were excluded. After matching by age (±2 years), gender, and the year of clinical visit, 154 patients with medical treatment (including ranibizumab and aflibercept) and 154 patients without medical treatment were included in the study. The difference between HbA1c and eGFR at baseline and 3 and 12 months after the index date between the two groups was assessed. Results: Mean HbA1c and eGFR decreased between baseline and 12 months after the index date in both groups (p < 0.05). Compared with the non-treatment group, the treatment group had significantly lower HbA1c 3 and 12 months after the index date. There was no significant difference in eGFR between the two groups. In the generalized estimating equations (GEE) model, HbA1c in the treatment group was lower than the non-treatment group (−0.44%, 95% CI = −0.75, −0.14), but eGFR was similar after adjusting for age, gender, and index-year. HbA1c and eGFR decreased with the time in the adjusted GEE model (p < 0.0001) in both groups. Conclusions: This study showed that eGFR decreased with age and time and was not related to IVI anti-VEGF treatments in our tertiary referral hospital. IVI anti-VEGF therapy was also associated with better HbA1c control. It is suggested that DME patients can receive intravitreal VEGF inhibitors without inducing more renal impairment.

Thrombotic Microangiopathy Syndromes-Common Ground and Distinct Frontiers

Thrombotic microangiopathies (TMAs) have in common a terminal phenotype of microangiopathic hemolytic anemia with end-organ dysfunction. Thrombotic thrombocytopenic purpura results from von Willebrand factor multimerization, Shiga toxin-mediated hemolytic uremic syndrome causes toxin-induced endothelial dysfunction, while atypical hemolytic uremic syndrome results from complement system dysregulation. Drug-induced TMA, rheumatological disease-induced TMA, and renal-limited TMA exist in an intermediate space that represents secondary complement activation and may overlap with atypical hemolytic uremic syndrome clinically. The existence of TMA without microangiopathic hemolytic features, renal-limited TMA, represents an undiscovered syndrome that responds incompletely and inconsistently to complement blockade. Hematopoietic stem cell transplant-TMA represents another more resistant form of TMA with different therapeutic needs and clinical course. It has become apparent that TMA syndromes are an emerging field in nephrology, rheumatology, and hematology. Much work remains in genetics, molecular biology, and therapeutics to unravel the puzzle of the relationships and distinctions apparent between the different subclasses of TMA syndromes.

Intravitreal vascular endothelial growth factors hypertension, proteinuria, and renal injury: a concise review

PURPOSE OF REVIEW

Nearly 20 years ago, vascular endothelial growth factor (VEGF)inhibitors (VEGFi) were adapted from systemic use from antiangiogenesis roles to intravitreal uses. Initially bevacizumab a murine immunoglobulin was injected 'off label' as a treatment for diabetic macular edema and age-related macular degeneration. Throughout the following decade aflibercept and finally ranibizumab were adapted and obtained Food and Drug Administration approval for intravitreal use. Initially systemic absorption was thought to be quite low after intravitreal injections and was quoted as being 200-fold lower than levels postulated to induce significant VEGF inhibition. Pharmacodynamic studies obtained in 2014 and again in 2017 revealed significant systemic absorption and detectable VEGF inhibition, this has since been confirmed in multiple subsequent studies.

RECENT FINDINGS

A few case reports of renal dysfunction and glomerular disease related to VEGFi were initially identified. Mixed findings on effects on blood pressure were noted in studies. More recently, 32 cases of de-novo glomerular disease and/or proteinuria exacerbation were identified. New studies have corroborated increased blood pressure, proteinuria exacerbation in patients with pre-existing nephrotic syndrome, and systemic VEGF depletion. Further, the most common lesion of systemic VEGFi nephrotoxicity, thrombotic microangiopathy, has recently been reported by our group.

SUMMARY

We will review the pharmacokinetic, translational, and epidemiological data that year upon year establish the finite-yet real risk of intravitreal VEGFi.

Review of intravitreal VEGF inhibitor toxicity and report of collapsing FSGS with TMA in a patient with age-related macular degeneration

Intravitreal vascular endothelial growth factor (VEGF) receptor blockade is used for a variety of retinal pathologies. These include age-related macular degeneration (AMD), diabetic macular edema (DME) and central retinal vein obstruction. Reports of absorption of intravitreal agents into systemic circulation have increased in number and confirmation of depletion of VEGF has been confirmed. Increasingly there are studies and case reports showing worsening hypertension, proteinuria, renal dysfunction and glomerular disease. The pathognomonic findings of systemic VEGF blockade, thrombotic microangiopathies (TMAs), are also being increasingly reported. One lesion that occurs in conjunction with TMAs that has been described is collapsing focal segmental glomerulosclerosis (cFSGS). cFSGS has been postulated to occur due to TMA-induced chronic glomerular hypoxia. In this updated review we discuss the mechanistic, pharmacological, epidemiological and clinical evidence of intravitreal VEGF toxicity. We review cases of biopsy-proven toxicity presented by our group and other investigators. We also present the third reported case of cFSGS in the setting of intravitreal VEGF blockade with a chronic TMA component that was crucially found on biopsy. This patient is a 74-year-old nondiabetic male receiving aflibercept for AMD. Of the two prior cases of cFSGS in the setting of VEGF blockade, one had AMD and the other had DME. This case solidifies the finding of cFSGS and its association with chronic TMA as a lesion that may be frequently encountered in patients receiving intravitreal VEGF inhibitors.

Worsening proteinuria and renal function after intravitreal vascular endothelial growth factor blockade for diabetic proliferative retinopathy

Systemic vascular endothelial growth factor (VEGF) inhibitions can induce worsening hypertension, proteinuria and glomerular diseases of various types. These agents can also be used to treat ophthalmic diseases like proliferative diabetic retinopathy, diabetic macular edema, central retinal vein occlusion and age-related macular degeneration. Recently, pharmacokinetic studies confirmed that these agents are absorbed at levels that result in biologically significant suppression of intravascular VEGF levels. There have now been 23 other cases published that describe renal sequela of intravitreal VEGF blockade, and they unsurprisingly mirror known systemic toxicities of VEGF inhibitors. We present three cases where stable levels of proteinuria and chronic kidney disease worsened after initiation of these agents. Two of our three patients were biopsied. The first patient's biopsy showed diabetic nephropathy and focal and segmental glomerulosclerosis (FSGS) with collapsing features and acute interstitial nephritis (AIN). The second patient's biopsy showed AIN in a background of diabetic glomerulosclerosis. This is the second patient seen by our group, whose biopsy revealed segmental glomerulosclerosis with collapsing features in the setting of intravitreal VEGF blockade. Though FSGS with collapsing features and AIN are not the typical lesions seen with systemic VEGF blockade, they have been reported as rare case reports previously. In addition to reviewing known elements of intravitreal VEGF toxicity, the cases presented encompass renal pathology data supporting that intravitreal VEGF blockade can result in deleterious systemic and renal pathological disorders.

A Review on Drug-Induced Nephrotoxicity: Pathophysiological Mechanisms, Drug Classes, Clinical Management, and Recent Advances in Mathematical Modeling and Simulation Approaches

A variety of marketed drugs belonging to various therapeutic classes are known to cause nephrotoxicity. Nephrotoxicity can manifest itself in several forms depending on the specific site involved as well as the underlying pathophysiological mechanisms. As they often coexist with other pathophysiological conditions, the steps that can be taken to treat them are often limited. Thus, drug-induced nephrotoxicity remains a major clinical challenge. Prior knowledge of risk factors associated with special patient populations and specific classes of drugs, combined with early diagnosis, therapeutic drug monitoring with dose adjustments, as well as timely prospective treatments are essential to prevent and manage them better. Most incident drug-induced renal toxicity is reversible only if diagnosed at an early stage and treated promptly. Hence, diagnosis at an early stage is the need of the hour to counter it. Significant recent advances in the identification of novel early biomarkers of nephrotoxicity are not beyond limitations. In such a scenario, mathematical modeling and simulation (M&S) approaches may help to better understand and predict toxicities in a clinical setting. This review summarizes pathophysiological mechanisms of drug-induced nephrotoxicity, classes of nephrotoxic drugs, management, prevention, and diagnosis in clinics. Finally, it also highlights some of the recent advancements in mathematical M&S approaches that could be used to better understand and predict drug-induced nephrotoxicity.

Thrombotic Microangiopathy and Acute Kidney Injury Induced After Intravitreal Injection of Vascular Endothelial Growth Factor Inhibitors VEGF Blockade-Related TMA After Intravitreal Use

Vascular endothelial growth factor (VEGF) inhibition can cause worsening hypertension, proteinuria, chronic kidney injury, and glomerular disease. Thrombotic microangiopathy (TMA) and other nephrotic disorders have been reported with systemic VEGF blockade. These same agents are given intravitreally for age-related macular degeneration (AMD) and diabetic retinopathy (DR), albeit at lower doses than those given for systemic indications. Systemic absorption of anti-VEGF agents when given intravitreally has been shown consistently along with evidence of significant intravascular VEGF suppression. While worsening hypertension has only been seen in some large-scale studies, case reports show worsening proteinuria and diverse glomerular diseases. These include TMA-associated lesions like focal and segmental glomerulosclerosis with collapsing features (cFSGS). In this paper, we report three cases of TMA likely associated with the use of intravitreal anti-VEGF therapy. These patients developed the signature lesion of VEGF blockade in a 6 to 11 month time frame after starting intravitreal VEGF inhibitors. The literature is reviewed showing similar cases. Intravitreal VEGF blockade may cause these adverse events in a hitherto unidentified subgroup of patients. Well-controlled prospective observational trials are needed to determine the event rate and identify which subgroups of patients are at increased risk. A registry for patients who develop worsening hypertension, proteinuria exacerbation, and glomerular diseases from intravitreal VEGF blockade is proposed.

Refractory scleroderma renal crisis precipitated after high-dose oral corticosteroids and concurrent intravitreal injection of bevacizumab

Scleroderma renal crisis is a serious complication that can develop in certain patients with systemic sclerosis. Some risks have been identified as potential triggers of scleroderma renal crisis, including the high-dose oral corticosteroids. Here, we present a patient who developed clinically severe systemic sclerosis and scleroderma renal crisis after exposure to oral corticosteroids and intravitreal vascular endothelial growth factor blockade with bevacizumab for cotton wool spots. The patient's scleroderma renal crisis was severe, progressive, and refractory to the standard of care therapy: oral captopril. Biopsy showed a diffuse thrombotic microangiopathy and findings consistent with scleroderma renal crisis. We hypothesize that depletion of systemic vascular endothelial growth factor with intravitreal anti-vascular endothelial growth factor injections likely contributed to the particularly severe presentation seen in this case. Though the finding of a monoclonal gammopathy of undetermined significance is another complicating factor, this case suggests that vascular endothelial growth factor inhibition may be a newly recognized trigger of scleroderma renal crisis.