Thrombosis in COVID-19 Patients

The magnitude of thrombosis in Coronavirus disease 2019 (COVID-19) patients is yet to be understood fully. Thrombosis in COVID-19 patients depends on multiple factors like the severity of the disease, presence or absence of prophylactic anticoagulants, and the number of anticoagulants prescribed. Histologically, lung tissues from COVID patients show florid capillary endothelitis with microthrombi formation in alveolar capillaries and small pulmonary vessels. Inflammation and diffuse alveolar damage, extensive pulmonary macrophage activation and diffuse interstitial inflammation play an important role in microthrombi formation in the pulmonary vessels. If antithrombotic therapy is already prescribed before the diagnosis of COVID-19, it should be continued. For all hospitalized pregnant patients, prophylactic anticoagulant therapy is prescribed unless contraindicated. Anticoagulant therapy during labor requires special care. Appropriate therapeutic and prophylactic anticoagulant regimens must be initiated as and when required including in the post discharge phase.

Advanced Tertiary Lymphoid Tissues in Protocol Biopsies are Associated with Progressive Graft Dysfunction in Kidney Transplant Recipients

Background: Tertiary lymphoid tissues (TLTs) are ectopic lymphoid tissues found in chronically inflamed organs. Although studies have documented TLT formation in transplanted kidneys, the clinical relevance of these TLTs remains controversial. We examined the impacts of TLTs on future graft function using our histological TLT maturity stages and the association between TLTs and Banff pathologic scores. We also analyzed the risk factors for the development of TLTs Methods: Serial protocol biopsy samples (0-hour, 1-, 6-, and 12-months) without rejection were retrospectively analyzed from 214 patients who underwent living donor kidney transplantation. TLTs were defined as lymphocyte aggregates with signs of proliferation and their stages were determined by the absence (stage I) or presence (stage II) of follicular dendritic cells. Results: Only 4% of patients exhibited TLTs at the 0-hour biopsy. Prevalence increased to almost 50% at the 1-month biopsy and then slightly further for 12 months. The proportion of advanced stage II TLTs increased gradually, reaching 19% at the 12-month biopsy. Presence of stage II TLTs was associated with higher risk of renal function decline after transplantation compared to patients with no TLT or stage I TLTs. Stage II TLTs were associated with more severe tubulitis and interstitial fibrosis/tubular atrophy at 12 months and predicted poorer graft function independently from the degree of interstitial inflammation. Pre-transplantation rituximab treatment dramatically attenuated the development of stage II TLTs. Conclusions: TLTs are commonly found in clinically stable transplanted kidneys. Advanced stage II TLTs are associated with progressive graft dysfunction, independent of interstitial inflammation

Comparative Histological Subtyping of Immune Cell Infiltrates in MPO-ANCA and PR3-ANCA Glomerulonephritis

BackgroundAcute kidney injury (AKI) is a common and severe complication of anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), potentially leading to chronic kidney disease (CKD), end-stage renal disease (ESRD), or death. Pathogenic ANCAs, in particular proteinase 3 (PR3) and myeloperoxidase (MPO), trigger a deleterious immune response with intrarenal immune cell infiltration resulting in a pauci-immune necrotizing and crescentic glomerulonephritis (GN). However, a systematic analysis of intrarenal immune cell subtypes concerning neutrophils, eosinophils, plasma cells, and mononuclear cell infiltrates (macrophages, lymphocytes) in ANCA GN remains elusive. Therefore, we aimed to compare distinct immune cell infiltrates in association with clinicopathological findings in ANCA GN.MethodsA total of 53 kidney biopsies with ANCA GN at the University Medical Center Göttingen were retrospectively analyzed. Histological infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the total area of inflammation.ResultsNeutrophilic infiltrates were associated with glomerular necrosis and severe kidney injury in ANCA GN. Among tubulointerstitial lesions, intrarenal neutrophils correlated with interstitial inflammation, tubulitis, and inflammation in areas of interstitial fibrosis/tubular atrophy (IFTA), representing active inflammatory lesions. Concerning eosinophils, infiltrates were associated with severe kidney injury, interstitial inflammation, and cellular casts independent of glomerular lesions, implicating a distinct role in inflammation and damage in ANCA GN. Plasma cell infiltrates correlated with tubulitis and interstitial fibrosis and were associated with renal replacement therapy during the short-term disease course. Finally, mononuclear cell infiltrates correlated with severe kidney injury and active histopathological lesions (glomerular crescents, interstitial inflammation, tubulitis, inflammation, and tubulitis in areas of IFTA) besides chronic lesions (interstitial fibrosis and tubular atrophy) in ANCA GN. Interestingly, intrarenal subtypes of immune cell infiltrates differed in MPO-ANCA versus PR3-ANCA GN and were associated with distinct glomerular and tubulointerstitial lesions, implicating different pathogenic mechanisms of kidney injury in ANCA subtypes.ConclusionOur observations imply distinct pathomechanisms contributing to inflammation and renal injury in MPO vs. PR3-associated ANCA GN and potentially contribute to new therapeutic targets in specific ANCA subtypes.

Clinicopathological Patterns and Predictors of the Functional Restoration of Immunoglobulin G4-Related Kidney Disease: A Chinese Single-Center Cohort Study

Background: Immunoglobulin G4-related disease (IgG4-RD) is a systemic immunoreactivity-based fibro-inflammatory disease. Immunoglobulin G4-related kidney disease (IgG4-RKD) is a frequently overlooked diagnosis. This study aimed to describe IgG4-RKD and examine the factors relevant to the renal outcomes of IgG4-RD.Methods: We studied a prospective IgG4-RKD cohort between January 2012 and December 2020 with close follow-up. Clinicopathologic data at kidney biopsy were collected and analyzed. We aimed to explore independent risk factors for long-term renal outcome and disease relapse. Patients with an eGFR<45 ml/min per 1.73m2 at 12 months were defined as having poor outcomes.Results: The included 42 patients with IgG4-RKD had a mean age of 58.5 ± 8.7 years (male-to-female ratio = 5:1). The IgG4-RD responder index (RI) was 12.2 ± 3.3. A total of 66.7% of the patients presented with acute on kidney disease or acute on chronic kidney disease. Eight patients (19.0%) showed nephrotic-range proteinuria, and nine (21.4%) had high-titer IgG4-autoantibodies, including antineutrophil cytoplasmic antibody and anti-phospholipase A2 receptor. A kidney biopsy was conducted in 40 patients. Thirty-seven (90.0%) patients were diagnosed with IgG4-related tubulointerstitial nephritis, and 19 (47.5%) of them had concurrent glomerular diseases (membranous nephropathy [MN], n = 3; crescentic glomerulonephritis [CrGN], n = 11; diabetic kidney disease, n = 3; and both MN and CrGN, n = 2). IgG4-RD RI had a close relationship with serum C3 (R = −0.509, P = 0.001), C4 (R = −0.314, P = 0.049) levels, and peripheral blood eosinophil count (PBEC; R = 0.377, P = 0.024), factors that were not included in RI scores. Correlation analysis disclosed that IgG4-RD RI (R = 0.422, P = 0.007), organs involved (R = 0.452, P = 0.003), and C3 (R = −0.487, R = 0.002) were correlated with the percentage decrease of serum creatinine at 1 month. However, multivariate regression analysis failed to identify any clinicopathological parameters that could predict short-term renal restoration and IgG4-RKD relapse. Ten out of 29 variables, of most importance, were identified by the least absolute shrinkage and selection operator (LASSO) regression analysis. By multivariate logistic regression a higher serum IgG4 (OR = 0.671, P = 0.010), IgG1 (OR = 1.396, P = 0.049), IgG3 (OR = 19.154, P = 0.039), and erythrocyte sedimentation rate (ESR; OR = 1.042, P = 0.032) were found to be independent factors for poor long-term outcome. Conventional immunosuppressive medications and/or rituximab were prescribed, and in 83.3% of the patients, the kidney function improved. Repeat kidney biopsies confirmed the remission of interstitial inflammation in two patients under immunosuppressive therapy. However, the disease relapse rate was as high as 31.0%.Conclusions: We strongly recommend a kidney biopsy in active IgG4-RD, especially when there is proteinuria and renal dysfunction, because concurrent glomerular involvement and active interstitial inflammation should be assessed. A higher serum IgG1, IgG3, and ESR were independent factors for the poor long-term renal outcome; however, elevated IgG4 predicted a good renal prognosis, and appropriate and timely immunosuppressive therapy can help achieve a better prognosis.

Different Patterns of Kidney Fibrosis Are Indicative of Injury to Distinct Renal Compartments

Kidney fibrosis is a common manifestation and hallmark of a wide variety of chronic kidney disease (CKD) that appears in different morphological patterns, suggesting distinct pathogenic causes. Broad macroscopically visible scars are the sequelae of severe focal injury and complete parenchymal destruction, reflecting a wound healing response as a consequence of infarction. In the kidney, chronic glomerular injury leads to atrophy of the corresponding tubule, degeneration of this specific nephron, and finally interstitial fibrosis/tubular atrophy (IF/TA). Compared to this glomerulus-induced focal replacement scar, diffuse fibrosis independent of tubular atrophy appears to be a different pathogenic process. Kidney fibrosis appears to develop in a compartment-specific manner, but whether focal and diffuse fibrosis has distinct characteristics associated with other glomerular or tubulointerstitial lesions remains elusive. In the present study, we aimed to analyze renal fibrotic patterns related to renal lesions, which directly contribute to renal fibrogenesis, to unravel fibrotic patterns and manifestations upon damage to distinct renal compartments. Patterns of kidney fibrosis were analyzed in experimental models of CKD and various renal pathologies in correlation with histopathological and ultrastructural findings. After the induction of isolated crescentic glomerulonephritis (GN) in nephrotoxic serum-nephritis (NTN), chronic glomerular damage resulted in predominantly focal fibrosis adjacent to atrophic tubules. By contrast, using unilateral ureteral obstruction (UUO) as a model of primary injury to the tubulointerstitial compartment revealed diffuse fibrosis as the predominant pattern of chronic lesions. Finally, folic acid-induced nephropathy (FAN) as a model of primary tubular injury with consecutive tubular atrophy independent of chronic glomerular damage equally induced predominant focal IF/TA. By analyzing several renal pathologies, our data also suggest that focal and diffuse fibrosis appear to contribute as chronic lesions in the majority of human renal disease, mainly being present in antineutrophil cytoplasmic antibody (ANCA)-associated GN, lupus nephritis, and IgA nephropathy (IgAN). Focal IF/TA correlated with glomerular damage and irreversible injury to nephrons, whereas diffuse fibrosis in ANCA GN was associated explicitly with interstitial inflammation independent of glomerular damage and nephron loss. Ultrastructural analysis of focal IF/TA versus diffuse fibrosis revealed distinct matrix compositions, further supported by different collagen signatures in transcriptome datasets. With regard to long-term renal outcome, only the extent of focal IF/TA correlated with the development of end-stage kidney disease (ESKD) in ANCA GN. In contrast, diffuse kidney fibrosis did not associate with the long-term renal outcome. In conclusion, we here provide evidence that a focal pattern of kidney fibrosis seems to be associated with nephron loss and replacement scarring. In contrast, a diffuse pattern of kidney fibrosis appears to result from primary interstitial inflammation and injury.

POS0331 LUNG TARGETED DELIVERY OF EVEROLIMUS AS A NEW TREATMENT OF SCLERODERMA-RELATED INTERSTITIAL LUNG DISEASE (SSc-ILD) DEVELOPED BY PSGL-1 KO MICE

Background:Interstitial lung disease (ILD), the main cause of mortality in scleroderma (SSc) patients (1), has no treatment (2). P-selectin glycoprotein ligand 1 (PSGL-1), the main ligand for P-Selectin, is expressed on leukocytes and responsible for the initial steps of extravasation (3). The absence of PSGL-1 in mice spontaneously develops an autoimmune syndrome similar to human SSc with fibrosis, vascular damage, autoantibodies and pulmonary arterial hypertension in females, and almost 60% of animals older than 12 months develop ILD with aging (4). In this work, the therapeutic action of everolimus-loaded nanomedicine given by local administration as a treatment for ILD was evaluated. The intratracheal administration of everolimus loaded into in liposomes decorated with hyaluronic acid (HA) is studied as an administration strategy to reach the inflammatory and fibrotic cells, targeting these cells and avoiding systemic effects and possible toxicity on epithelial cellsObjectives:1) To study the effect of everolimus on bronchoalveolar lavage (BAL) cell populations and in lung pathology in SSc-ILD PSGL-1 KO mice2) To analyze the intratracheal application of everolimus included in empty liposomes (Lip+Ev) vs. liposomes decorated with hyaluronic acid (Lip-HA+Ev) as an administration strategy to decrease drug toxicity and increase drug effectivityMethods:In an observational study, PSGL-1−/− C57BL/6 males older than 12 months (n=4) were treated intratracheally with 4 doses of Lip or Lip-HA (with or without everolimus included), once a week (Lip+Ev 295.67µg/mL; Lip+Ev 82.73µg/mL; Lip-HA+Ev 82.73µg/mL). Then, animals were euthanatized and BAL and lungs were obtained. BAL cells were stained for flow cytometry analysis. Lungs were embedded in paraffin blocks for blind histological analysis by a pathologist and evaluated for interstitial inflammation and fibrosis degree. Lip-HA was selected as the treatment of choice for a second experiment (n=8) following the same experimental design (86.22µg/mL)Results:The observational study showed an increase in CD45+, alveolar macrophages (AM), eosinophils (Eos), granulocytes (Gr1+) and T cells in the BAL of untreated PSGL-1-/- mice compared with WT mice. Everolimus reduced these populations to WT levels in all casesLip-HA+Ev administration was chosen for further experiments because a lower dose of the drug gave a better result than the high dose in undecorated liposomes. Reduction of CD45+, AM, eosinophils, and CD45- cells populations by Lip-HA+Ev was confirmed. Lip-HA treatment increased the number of neutrophils and T cells, but this effect is controlled by the everolimus administrationHistological lung analysis showed an increase in interstitial inflammation and fibrosis in untreated PSGL-1-/- and empty Lip-HA experimental groups. Treatment with everolimus included in Lip-HA reduced the fibrotic and inflammatory interstitial lung lesions, reaching values similar to those observed in WT miceConclusion:PSGL-1 KO mice present ILD associated with scleroderma (SSc-ILD) with an increase of CD45+, Gr1+, Eos, T cells and AM populations in the BAL. Intratracheal treatment with everolimus included in liposomes decorated with hyaluronic acid reduces immune cell infiltration and fibrosis once SSc-ILD is establishedReferences:[1]Solomon JJ, Olson AL, Fischer A, Bull T, Brown KK, Raghu G (2013). Scleroderma lung disease[2]Singh D, Parihar AK, Patel S, Srivastava S, Diwan P, Singh MR (2019). Scleroderma: An insight into causes, pathogenesis and treatment strategies. Pathophysiology, 26(2)[3]Zarbock A, McEver RP, Hidalgo A (2011). Leukocyte Ligands for Endothelial Selectins: Specialized Glycoconjugates That Mediate Rolling and Signaling Under Flow. BLOOD[4]Pérez-Frías A, Núñez-Andrade N, et al. (2014). Development of an autoimmune syndrome affecting the skin and internal organs in P-selectin glycoprotein ligand 1 leukocyte receptor-deficient mice. Arthritis RheumatolDisclosure of Interests:None declared

Author Correction: Molecular patterns of isolated tubulitis differ from tubulitis with interstitial inflammation in early indication biopsies of kidney allografts

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Polyclonal free light chains in IgA-nephropathy: correlation with clinical and morphological parameters and prognostic significance

BACKGROUND. Mechanisms of the initiation of renal interstitial inflammation and fibrosis caused by immunoglobulin monoclonal free light chains (mFLC) in monoclonal gammopathy are well established. As far as these damage pathways are considered to be universal we hypothesize that polyclonal free light chains (pFLC) could have a similar effect on tubular and interstitial tissue and lead to chronic kidney disease (CKD) progression in primary glomerulopathies. THE AIM of this retrospective study was to analyze the association of pFLC kappa (pFLC-κ) and lambda (pFLC-λ) assessed in serum by Freelite® with clinical and morphological parameters and CKD progression in IgA-nephropathy (IgAN) cohort.PATIENTS AND METHODS. In this retrospective study, we enrolled 24 patients with IgAN proven by kidney biopsy (KBx). pFLC-κ and pFLC-λ levels were assessed in all cases at the time of KBx by Freelite® method (N pFLC-κ=3.3-19.4 mg/l, N pFLC-λ=5.7-26.3 mg/l). The normal κ/λ ratio was the inclusion criterion. In all cases, we determined serum creatinine, estimated glomerular filtration rate by CKD-EPI method (eGFRCKD-EPI), and daily proteinuria. Morphological findings were defined semiquantitatively by light and immunofluorescence microscopy. Oxford MEST-C score was evaluated as well as % of glomerulosclerosis. Correlation between parameters was assessed by Spearman’s coefficient. Cox proportional hazards regression was used to analyze the association of parameters with the progression of CKD estimated as an elevation of serum creatinine ≥25 % from the initial level or the initiation of renal replacement therapy at the end of the follow-up period (median was 28 (7; 37) months).RESULTS. Median of pFLC-κ 30.2 (6.1; 67.5) mg/l, median of pFLC-λ 27.6 (11.1; 92.1) mg/l. Levels of pFLC-κ and pFLC-λ were increased in 66.7 % and 50 % of patients, respectively. eGFR CKD-EPI median was 41 (26; 65) ml/min/1.73m2. Serum creatinine correlates with pFLC-κ (R=0.62, p<0.01) and pFLC-λ (R=0.45, p=0.03). Among morphological parameters pFLC-κ correlates with interstitial inflammation (R=0.47, p=0.02), tubular atrophy (R=0.54, p<0.01), interstitial fibrosis (R=0.44, p=0.03), peritubular capillaritis (R=0.42, p=0.04), T-score (R=0.66, p<0.01) and combined MEST-C score (R=0.45, p=0.03). For pFLC-λ the correlations with tubular atrophy (R=0.45, р=0.03) and Т-score (R=0.56, p<0.01) were shown. In Univariate Cox regression analysis pFLC-κ and pFLC-λ were associated with CKD progression (Exp(ß)=1.053; 95,0 %CI 1.003-1.105; p=0.038 and Exp(ß)= 1.041; 95,0 %CI 1.002-1.082; p=0.038, respectively) CONCLUSION. Polyclonal FLC, mostly pFLC-κ, were associated with tubulointerstitial inflammation and fibrosis in patients with IgAN. Increased levels of either pFLC-κ or λ could be proposed as a predictor of CKD progression in patients with IgAN.