Extrarenal complications of cystinosis

Cystinosis is a rare autosomal recessive disease with an incidence 1 per 100,000-200,000 live births. It is caused by pathogenic variants of the cystinosin (CTNS) gene that lead to impaired cystine transport from lysosomes to cystosol, resulting in cystine accumulation in lysosomes and subsequent cellular dysfunction. The initial manifestation, cystine accumulation in proximal tubular cells (PTCs), causes renal Fanconi syndrome, which presents with proximal renal tubular acidosis and generalized dysfunction of the proximal tubule, including the presence of polyuria, glycosuria, phosphaturia, aminoaciduria, tubular proteinuria, growth retardation, and rickets. Eventually, glomerular involvement, glomerular proteinuria, focal segmental glomerulosclerosis (FSGS), and progression to kidney failure occur. Although the kidneys are the first organs affected, and play a key role in morbidity and mortality, extrarenal multiorgan involvement can occur in patients with cystinosis, which is seen not only in adults but in early ages in untreated patients, patients with insufficient treatment, and in those that don't comply with treatment. The treatment of cystinosis consists of supportive treatment for Fanconi syndrome, and specific lifelong cystine-depleting therapy using oral cysteamine. There is strong evidence that as early as possible, initiation and ongoing appropriate therapy with cysteamine are essential for delaying the progression to kidney failure, end-organ damage, and extrarenal involvement. The present review aimed to evaluate the extra renal complications of cystinosis.

Autoinflammatory diseases and the kidney

The kidney represents an important target of systemic inflammation. Its involvement in monogenic and multifactorial autoinflammatory diseases (AIDs) vary from peculiar and relatively frequent manifestations to some rare but severe features that may end up requiring transplantation. The pathogenetic background is also very heterogeneous ranging from amyloidosis to non-amyloid related damage rooted in inflammasome activation. Kidney involvement in monogenic and polygenic AIDs may present as renal amyloidosis, IgA nephropathy, and more rarely as various forms of glomerulonephritis (GN), namely segmental glomerulosclerosis, collapsing glomerulopathy, fibrillar, or membranoproliferative GN. Vascular disorders such as thrombosis or renal aneurysms and pseudoaneurysms may be encountered in patients with Behcet's disease. Patients with AIDs should be routinely assessed for renal involvement. Screening with urinalysis, serum creatinine, 24-h urinary protein, microhematuria, and imaging studies should be carried out for early diagnosis. Awareness of drug-induced nephrotoxicity, drug-drug interactions as well as addressing the issue of proper renal adjustment of drug doses deserve a special mention and should always be considered when dealing with patients affected by AIDs. Finally, we will explore the role of IL-1 inhibitors in AIDs patients with renal involvement. Targeting IL-1 may indeed have the potential to successfully manage kidney disease and improve long-term prognosis of AIDs patients.

Profiling of kidney involvement in systemic lupus erythematosus by deep learning using the National Database of Designated Incurable Diseases of Japan

BACKGROUND

Kidney involvement frequently occurs in systemic lupus erythematosus (SLE), and its clinical manifestations are complicated. We profiled kidney involvement in SLE patients using deep learning based on data from the National Database of Designated Incurable Diseases of Japan.

METHODS

We analyzed the cross-sectional data of 1655 patients with SLE whose Personal Clinical Records were newly registered between 2015 and 2017. We trained an artificial neural network using clinical data, and the extracted characteristics were evaluated using an autoencoder. We tested the difference of population proportions to analyze the correlation between the presence or absence of kidney involvement and that of other clinical manifestations.

RESULTS

Data of patients with SLE were compressed in a feature space in which the anti-double-stranded deoxyribonucleic acid (anti-dsDNA) antibody titer, antinuclear antibody titer, or white blood cell count contributed significantly to distinguishing patients. Many SLE manifestations were accompanied by kidney involvement, whereas in a subgroup of patients with high anti-dsDNA antibody titers and low antinuclear antibody titers, kidney involvement was positively and negatively correlated with hemolytic anemia and inflammatory manifestations, respectively.

CONCLUSION

Although there are various combinations of SLE manifestations, our study revealed that some of them are specific to kidney involvement. SLE profiles extracted from the objective analysis will be useful for categorizing SLE manifestations.

The Investigation of Kidney Involvement in 430 Hospitalized Patients with Omicron COVID-19 in Tianjin, China

INTRODUCTION

This study evaluated the incidence, clinical characteristics, and risk factors of kidney involvement in patients with the Omicron variant infection in the post-acute treatment phase in Tianjin, China.

METHODS

Data were collected from 430 patients with Omicron variant infection in Tianjin, China. Demographics, comorbidities, laboratory blood tests, urinalysis, vaccination status, and COVID-19 clinical classification were assessed. Patients were grouped based on kidney involvement, and associated risk factors of kidney involvement were also investigated.

RESULTS

Asymptomatic, mild, ordinary, and severe patients with Omicron COVID-19 variant comprised 1.5%, 49.1%, 48.9%, and 0.5% of the sample population, respectively, without critical illness or death. The incidences of hematuria, proteinuria, and concurrent hematuria and proteinuria were 14.7%, 14.2%, and 5.1%, respectively. Patients with and without kidney involvement differed in age, body mass index (BMI), comorbidity, creatinine levels, estimated glomerular filtration rate, and C-reactive protein (CRP) levels. Age, hypertension, higher CRP levels, and higher BMI were linked with kidney involvement.

CONCLUSION

The majority of the patients suffered from mild or ordinary symptoms of Omicron COVID-19 infection. The primary kidney involvement was hematuria and proteinuria. Proteinuria was significantly associated with Omicron variant infection, and patients with hypertensive comorbidity, higher CRP, and higher creatinine levels were at increased risk of proteinuria after Omicron variant infection.

Cyclin-D1 positive B cell lymphoma with intravascular and interstitial involvement of kidney and bone marrow

Kidney involvement is rare in non-Hodgkin's lymphomas (NHL), and can be caused by direct lymphoid infiltration, paraneoplastic glomerulonephritis (GN), or both. Herein, we present a case of acute kidney injury (AKI) due to renal cyclin-D1 positive B cell lymphoma infiltration. To our knowledge, this is the first case where a renal biopsy revealed intravascular neoplastic cells along with parenchymal infiltration.

Clinical associations of renal involvement in ANCA-associated vasculitis

OBJECTIVE

Renal involvement in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis is associated with significant morbidity and higher mortality rates. This study examined clinical manifestations associated with renal involvement in ANCA-associated vasculitis within a large, international cross-sectional cohort.

METHODS

Univariate and multivariate analyses were performed to identify clinical factors associated with renal disease, which was defined as i) a serum-creatinine >30% above normal and a fall in creatinine-clearance >25%; or ii) haematuria attributable to active vasculitis.

RESULTS

The study cohort include 1230 patients from 31 countries; 723 (58.8%) presented with renal involvement: microscopic polyangiitis (82.2%), granulomatosis with polyangiitis (58.6%), and eosinophilic granulomatosis with polyangiitis (26.4%). The following clinical and laboratory factors were more common among patients with renal disease: age (OR 1.01, 95% CI 1.01-1.02), fever (OR 1.97, 95% CI 1.35-2.88), fatigue (OR 1.55, 95% CI 1.14-2.10), weight loss (OR 1.62, 95% CI 1.23-2.12), polyarthritis (OR 1.39, 95% CI 1.02-1.89), petechiae/purpura (OR 1.47, 95% CI 1.06-2.05), pulmonary haemorrhage (OR 5.23, 95% CI 1.39-19.63), gastrointestinal symptoms (OR 2.19, 95% CI 1.34-3.58), seizures (OR 3.42, 95% CI 1.26-9.30), lower serum albumin (OR 2.42, 95% CI 1.64-3.57), higher CRP (OR 2.06, 95% CI 1.04-4.06), low serum C3 at baseline (OR 3.86, 95% CI 1.30-11.53), myeloperoxidase- (OR 7.97, 95% CI 2.74-23.20) and proteinase 3-ANCA (OR 3.40, 95% CI 1.22-9.50). The following clinical factors were less common among patients with renal disease: mononeuritis multiplex (OR 0.63, 95% CI 0.41-0.98), proptosis/exophthalmos (OR 0.19, 95% CI 0.06-0.59), nasal polyps (OR 0.32, 95% CI 0.19-0.55), septal defect/perforation (OR 0.29, 95% CI 0.14-0.60), respiratory distress/pulmonary fibrosis/asthma (OR 0.08, 95% CI 0.04-0.19), and wheeze/obstructive airway disease (OR 0.29, 95% CI 0.16-0.52).

CONCLUSION

In this large international study, several clinical and laboratory factors were identified as associated with renal involvement in ANCA-associated vasculitis.

Concurrent Kidney Glomerular and Interstitial Lesions Associated with Kimura's Disease

BACKGROUND

Kimura disease (KD) is a chronic benign inflammatory disorder that is usually manifested as a deep, subcutaneous mass with or without regional lymphadenopathy in the head and neck region. Various types of glomerulonephritis are associated with KD, including minimal change disease (MCD), membranous glomerulopathy (MN), and immunoglobulin (Ig)A-nephropathy. Kidney interstitial lesion associated with KD is rarely reported. The aim of this study was to expand the spectrum of kidney lesions associated with KD.

METHODS

From 2007 to 2016, 12 cases of KD with kidney lesions were retrospectively reviewed. Pathological examinations included hematoxylin and eosin staining, periodic acid-schiff staining, periodic acid-methenamine silver staining, and Masson staining, immunofluorescence, and electron microscope analyses.

RESULTS

Anatomic sites of subcutaneous involvement included head and neck area, arm, and groin. Most cases had elevated IgE level and peripheral eosinophilia. Nephrotic syndrome was the most common kidney manifestation. Pathological results showed 3 types of glomerulonephritis, including 9 cases of MCD, 2 cases of IgA nephropathy, and 1 case of MN. Of note, 4 MCD cases showed concurrent glomerular and interstitial lesions associated with KD, including 2 distinct patterns: (1) a diffusely eosinophilic and lymphatic infiltration similar to KD lesion developed elsewhere and (2) exclusively eosinophilic infiltration in the interstitium. Eight out of 10 patients were responsive to steroid treatment and had complete remission of proteinuria and recovery of kidney function.

CONCLUSION

Our report suggested that, in addition to glomerulonephritis, interstitial lesions may also be associated with KD. Pathologist should pay special attention to differentiated diagnosis when such pathological changes are identified in patients with subcutaneous mass or cervical lymphadenopathy with concurrent kidney manifestation.

Increased renal damage in hypocomplementemic patients with ANCA-associated vasculitis: retrospective cohort study

INTRODUCTION

The complement system has an important role in the pathogenesis of vasculitis associated with antineutrophilic cytoplasmic antibody (AAV) mainly at the level of the kidneys because patients with complement deposits on the glomerular basal membrane present more aggressive disease compared with those with pauci-immune vasculitis.

AIM

To analyze the association of hypocomplementemia with the clinical manifestations, laboratory data, renal histology, progress to renal insufficiency, and mortality of patients with AAV.

METHODS

Retrospective cohort study (2000-2007) included 93 patients with AAV. Hypocomplementemia is defined as having C3 values lower than 80 mg/dL or C4 values below 15 mg/dL. Demographic, statistical, clinical, hematological, serological, and histopathological characteristics of all the patients with and without diagnosis of hypocomplementemia were compared. In order to evaluate variable independence, a logistic regression analysis was used.

RESULTS

Ninety-three patients were studied of whom 63 (67.7%) had complement dosage at the moment of AAV diagnosis. Seven patients (11.1%) presented hypocomplementemia and a greater kidney involvement compared with normocomplementemic patients. Thirty renal biopsies were analyzed and 4 (13.3%) showed immunocomplex (IC) or complement deposits by an immunofluorescence test (IFT). Patients with "non-pauci-immune" AAV also presented terminal chronic renal disease (TCRD).

CONCLUSION

There is an association between low complement and the degree of renal damage in patients with AAV. Patients with renal biopsies confirming IC and/or complement deposits showed more aggressive renal disease. Key Points • The complement system has an important role in the pathogenesis of vasculitis associated to antineutrophilic cytoplasmic antibody. • The studies in murine models confirming the complement activation by alternative pathway and particularly the receptor C5a (C5aR) is necessary for the development of glomerulonefritis. • Complement deposit observed in the renal biopsies of patients diagnosed with AAV was correlated to greater kidney damage, greater proteinuria and major disease activity compared to patients diagnosed with typical pauci-immune vasculitis. • The presence of hypocomplementemia at the onset of the disease was also associated with a greater organ involvement, poor prognosis and greater mortality.

Clinical features of acute kidney injury in patients with Kawasaki disease

Although acute kidney injury (AKI) is a common complication in hospitalized children, AKI has rarely been reported in patients with Kawasaki disease (KD). Herein, we review the clinical trajectories of AKI in patients with KD. A total of 39 patients with KD who developed AKI have been reported in 28 publications as case reports. The causes of AKI include prerenal AKI associated with acute heart failure (AHF), intrinsic AKI caused by tubulointerstitial nephritis (TIN), acute nephritic syndrome (ANS), hemolytic uremic syndrome (HUS), immune complex-mediated nephropathy, rhabdomyolysis, and KD shock syndrome (KDSS). Six of the 39 patients (15.4%) underwent renal replacement therapy. While AHF and multiple organ dysfunction syndrome developed in 41% and 68% of KD patients with AKI, respectively, all patients recovered without any renal sequelae. Although the precise pathogenic mechanism underlying the development of AKI in patients with KD is unknown, several possible mechanisms have been proposed, including T-cell-mediated immunologic abnormalities for TIN, renal and glomerular endothelial injury resulting from vasculitis for HUS, immune complex-mediated kidney injury for immune complex-mediated nephropathy and ASN, and capillary leak and an increased release of cytokines with myocardial dysfunction for KDSS.

Kidney involvement in psoriasis: a case-control study from China

PURPOSE

Kidney involvement secondary to psoriasis is still a controversial issue. In this study, we aimed to evaluate the prevalence of urinary abnormalities in psoriasis patients and to find out whether the abnormality is related to the severity of psoriasis.

METHODS

Ninety-seven psoriasis patients (62 females, 35 males, mean age 35.74 ± 13.45 years) and ninety-six age- and gender-matched control subjects (58 males, 38 females, mean age 35.82 ± 13.48 years) without hypertension or diabetes were enrolled in this study. Psoriasis area and severity index (PASI) was used to assess the severity of psoriasis. Twenty-four-hour proteinuria, albuminuria, RBP, and NAG were measured in all patients and controls. Pathologic proteinuria was defined as the total protein excretion of more than 0.4 g/24 h, as measured by the turbidimetric assay. Pathologic albuminuria was defined as albumin excretion of more than 17 mg/24 h. Pathologic NAG and RBP were defined as the excretion of more than 16.5 u/g cr and 0.5 mg/L, respectively.

RESULTS

Increased 24-h microalbuminuria (11.53 ± 7.29 vs. 9.79 ± 3.72, P = 0.039) and 24-h proteinuria (0.24 ± 0.21 vs. 0.18 ± 0.09, P = 0.002) were found in patients with psoriasis compared with controls. Patients with psoriasis had an increased prevalence of pathological albuminuria (15.46 vs. 5.21%, P = 0.019), NAG (10.31 vs. 3.13%, P = 0.046), and RBP (9.28 vs. 2.08%, P = 0.031) compared with controls. PASI scores in patients with psoriasis correlated positively with 24-h albuminuria (χ ² = 10.75, P = 0.005).

CONCLUSIONS

The prevalence of abnormal urinalysis was more common in patients with psoriasis than in controls. The positive correlation between the prevalence of pathological albuminuria and psoriasis severity may indicate a subclinical renal dysfunction in patients with psoriasis.

Pyuria in patients with Kawasaki disease

Kawasaki disease (KD) is an acute, febrile vasculitis that predominantly develops in children ≤ 5 years of age and can lead to multiple organ injuries including the kidneys. Of these injuries, pyuria is a common feature of patients with KD, occurring in 30%-80% of patients. Sterile pyuria is most common in KD patients ≤ 1 year of age. KD patients with sterile pyuria exhibit more severe inflammatory reactions and may have sub-clinical renal injuries. Sterile pyuria in KD is associated with mononuclear cells (not neutrophils) in the urine. Although sterile pyuria in KD was at one time thought to be due to urethritis caused by a non-specific vasculitis of the urethra, recent studies suggest that sterile pyuria in KD originates from the urethra, the kidney as a result of mild and sub-clinical renal injuries, and/or the bladder due to cystitis. Pyuria is not always sterile in KD, but can result from a urinary tract infection (UTI). As causative pathogens, Escherichia coli and Klebsiella oxytoca have been reported. The clinical phenotypes do not differ between those with or without UTI. Because some KD patients with UTIs have urinary tract abnormalities such as vesicoureteral reflux, a complete UTI workup including renal ultrasound, voiding cystourethrogram and/or dimercaptosuccinic acid renal scan recommended in KD patients with UTIs.