Molecular profiling of kidney compartments from serial biopsies differentiate treatment responders from non-responders in lupus nephritis

The immune pathways that define treatment response and non-response in lupus nephritis (LN) are unknown. To characterize these intra-kidney pathways, transcriptomic analysis was done on protocol kidney biopsies obtained at flare (initial biopsy (Bx1)) and after treatment (second biopsy (Bx2)) in 58 patients with LN. Glomeruli and tubulointerstitial compartments were isolated using laser microdissection. RNA was extracted and analyzed by nanostring technology with transcript expression from clinically complete responders, partial responders and non-responders compared at Bx1 and Bx2 and to the healthy controls. Top transcripts that differentiate clinically complete responders from non-responders were validated at the protein level by confocal microscopy and urine ELISA. At Bx1, cluster analysis determined that glomerular integrin, neutrophil, chemokines/cytokines and tubulointerstitial chemokines, T cell and leukocyte adhesion genes were able to differentiate non-responders from clinically complete responders. At Bx2, glomerular monocyte, extracellular matrix, and interferon, and tubulointerstitial interferon, complement, and T cell transcripts differentiated non-responders from clinically complete responders. Protein analysis identified several protein products of overexpressed glomerular and tubulointerstitial transcripts at LN flare, recapitulating top transcript findings. Urine complement component 5a and fibronectin-1 protein levels reflected complement and fibronectin expression at flare and after treatment. Thus, transcript analysis of serial LN kidney biopsies demonstrated how gene expression in the kidney changes with clinically successful and unsuccessful therapy. Hence, these insights into the molecular landscape of response and non-response may help align LN management with the pathogenesis of kidney injury.

A Novel Inflammatory Dendritic Cell That Is Abundant and Contiguous to T Cells in the Kidneys of Patients With Lupus Nephritis

The mechanisms that promote local inflammatory injury during lupus nephritis (LN) flare are largely unknown. Understanding the key immune cells that drive intrarenal inflammation will advance our knowledge of disease pathogenesis and inform the development of new therapeutics for LN management. In this study, we analyzed kidney biopsies from patients with proliferative LN and identified a novel inflammatory dendritic cell (infDC) population that is highly expressed in the LN kidney, but minimally present in healthy human kidneys. During an agnostic evaluation of immune transcript expression in the kidneys of patients with proliferative LN, the most abundantly overexpressed transcript from isolated glomeruli was FCER1G, which encodes the Fc receptor gamma chain (FcRγ). To identify the cell types expressing FcRγ that infiltrate the kidney in LN, studies were done on kidney biopsies from patients with active LN using confocal immunofluorescence (IF) microscopy. This showed that FcRγ is abundantly present in the periglomerular (PG) region of the kidney and to a lesser extent in the tubulointerstitium (TI). Further investigation of the surface markers of these cells showed that they were FcRγ+, MHC II+, CD11c+, CD163+, CD5-, DC-SIGN+, CD64+, CD14+, CD16+, SIRPα+, CD206-, CD68-, CD123-, CD3-, and CD11b-, suggesting the cells were infDCs. Quantification of the infDCs showed an average 10-fold higher level of infDCs in the LN kidney compared to the healthy kidneys. Importantly, IF identified CD3+ T cells to be adjacent to these infDCs in the PG space of the LN kidney, whereas both cell types are minimally present in the healthy kidney. Thus, we have identified a previously undescribed DC in lupus kidneys that may interact with intrarenal T cells and play a role in the pathogenesis of kidney injury during LN flare.

Establishing a Case for Anti-complement Therapy in Membranous Nephropathy

Introduction

Membranous nephropathy (MN) is a common cause of adult nephrotic syndrome that progresses to end-stage kidney disease in up to 40% of cases. It is an autoimmune disease characterized by glomerular subepithelial deposits containing IgG. In experimental MN, these deposits activate complement and cause kidney damage. The role of complement in human MN is less clearly defined. To address this, the current study focused on the role of complement in 2 independent primary (p) MN cohorts.

Methods

Glomeruli were isolated by laser capture microdissection and analyzed by mass spectrometry, focusing on complement proteins, from kidney biopsy specimens from a pMN cohort (n = 11) and from normal controls (n = 5). Immunohistological staining of kidney biopsy specimens for complement proteins was also done. In a second pMN cohort (n = 13), urine levels of Ba, C5a, and C5b-9 (membrane attack complex [MAC]) were measured.

Results

Mass spectrometry identified 8 complement pathway components (C1q, C3, C4, C5, C6, C7, C8, and C9) and 5 complement regulators (complement receptor type 1 [CR1], factor H [FH], FH-related protein 2 [FHR2], vitronectin, and clusterin). All complement levels were significantly higher in the MN groups than in the control group, except the level of CR1, which was lower. All pMN biopsy specimens showed negative or trace staining for C1q, positive staining for C3 and C4, and positive staining for at least 1 component of the lectin pathway. Urine Ba, C5a, and MAC were present in pMN, and their levels correlated (r_Ba,C5a = 0.87, r_Ba,MAC = 0.89, and r_C5a,MAC = 0.97, P = .001 for each correlation).

Conclusion

Elevated glomerular levels of C3, C4, and components of MAC (C5b-9) and absent or decreased levels of the complement regulator CR1, along with increased levels of complement activation products in the urine, support the involvement of complement in the pathogenesis of MN. These data raise the possibility that anti-complement therapies may be effective in some forms of MN.

Limited Reliability of the Spot Urine Protein/Creatinine Ratio in the Longitudinal Evaluation of Patients With Lupus Nephritis

Introduction

Cross-sectional studies document that the spot protein/creatinine ratio (PCR) is often an inaccurate estimate of proteinuria magnitude compared with the 24-hour PCR, which is the gold standard. However, the extent to which the inaccuracy of the spot PCR varies over time and between individuals has not previously been reported. We address these crucial questions using a unique database, an National Institutes of Health trial in which lupus nephritis (LN) patients (N = 103) provided spot PCR testing each month and 24-hour PCR testing every 3 months for up to 15 months after induction therapy.

Methods

A gold standard proteinuria trend line was constructed for each patient by joining the points that represented the serial 24-hour PCR values of the patient. The spot PCR values of the patient were then plotted in relationship to the 24-hour PCR trend line. Using our previous work, which estimated the 95% confidence intervals for the 24-hour PCR at specific levels, we determined in each patient whether the spot PCR values were "reliable," "problematic," or "unreliable." The sequential spot PCR of the patients deviated widely and often from the 24-hour PCR trend line, to the extent that, if the spot PCR results were used in real time for clinical decision-making, it was likely management errors would occur.

Results

Spot PCRs were reliable in 41%, problematic in 24%, and unreliable in 35% of patients. Those with unreliable spot PCRs could not be predicted and were more likely to respond poorly to treatment.

Conclusion

The spot PCR should not be used for management of LN, and perhaps, other glomerulopathies.

Molecular imaging of the kidney in lupus nephritis to characterize response to treatment

The consequences of treatment for the kidney at the molecular level have not been explored in human lupus nephritis (LN). In this investigation, changes in intrarenal transcript expression were measured and correlated with response in a LN cohort that underwent serial kidney biopsies. The intrarenal transcript expression of 19 patients with proliferative LN (Class III or IV) was measured at diagnostic biopsy (Bx1) and after induction therapy was completed (Bx2) using Nanostring technology. Patients were segregated by clinical response into complete responders (n = 5, CR) or nonresponders (n = 4, NR). Transcript expression for each biopsy was compared with normal controls (n = 4), and the change in expression was compared in each responder group and between groups. Compared with controls, the CR group had 21 and 28, whereas NR had 45 and 103 differentially-expressed transcripts at Bx1 and Bx2, respectively. The profiles of these differentially-expressed genes indicated that the type I and II interferon, alternative complement and T cell signaling pathways discriminated CR from NR. Comparing the change in transcript expression from Bx1 to Bx2 revealed a 5-gene signature that differentiated NR from CR and included increased IL1RAP and FCAR in NR and increased NCAM1 in CR. In summary, molecular imaging of serial kidney biopsies from LN patients shows several immune and inflammatory pathways that are dysregulated in the kidneys during active disease that may serve as therapeutic targets to improve clinical response. This approach to LN biomarker development may facilitate personalized medicine in LN and improve long-term kidney outcomes.

Low copy-number of complement C4A, the presence of HLA-DR3, and the presence of HLA-DR2 are independent and additive risk factors for human systemic lupus erythematosus (SLE) (93.13)

The major histocompatibility complex (MHC) in chromosome 6p21.3 has the strongest genetic association with human SLE. This study aims to dissect the roles of MHC genes HLA-DRB1 and complement C4 in SLE. The study population includes 744 SLE patients and 760 unrelated healthy controls of European ancestry. Genomic Southern blot analyses and qPCR were used to determine the gene copy-numbers of total C4, C4A and C4B. Two-digit genotypings for HLA-DRB1 were performed by SSP-PCRs. The copy-numbers for total C4, C4A and C4B vary from 2 to 6, 0 to 5, and 0 to 4, respectively. Lower C4A copy-number (p=2.4x10-13), and increased frequencies of HLA-DRB1*03 (DR3; p=1.5x10-10) and HLA-DRB1*15 (DR2; p=0.032) are associated with SLE. Zero, 1 and ≥2 copies of C4A strongly correlate with homozygous, heterozygous and non-DR3, respectively, in controls (r2=0.435,χ2=374.0; p=1.2x10-79) and in SLE (r2=0.381, χ2=463.9; p=4.2x10-99). Comparing to subjects with non-low C4A (i.e. ≥2 copies), non-DR3 and non-DR2, the odds for SLE with low C4A only (i.e. <2 copies) was 2.22 (95% CI: 1.11-4.43; p=0.031), DR3+ only was 1.81 (1.21-2.71; p=0.004), and DR2+ only was 1.65 (1.26-2.16; p=0.0002). Notably, the odds increased to 2.80 (2.09-3.76; p=3.6x10-12) among subjects with low C4A and DR3, and 2.71 (1.10-6.64; p=0.037) among subjects with low C4A and DR2. In conclusion, low C4A gene copy-numbers, the presence of HLA-DR3 or HLA-DR2 are each independent risk factors with additive effects for SLE.

Gott time machines, BTZ black hole formation, and choptuik scaling

We study the formation of Banados-Teitelboim-Zanelli black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.