Neutrophilic tubulitis as a marker for urinary tract infection in renal allograft biopsies with C4d deposition

Analysis of Cross-sectional and Longitudinal HLA and Anti-viral Responses After COVID Infection in Renal Allograft Recipients: Differences and Correlates

BACKGROUND

Characterization of anti-HLA versus anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) immune globulin isotypes in organ transplant recipients after coronavirus disease 2019 (COVID-19) infection has not been reported. We aimed to determine changes in anti-HLA antibodies in renal transplant patients with COVID-19 and compare the immunoglobulin and epitope-binding pattern versus anti-SARS-CoV-2 antibodies.

METHODS

This is a cross-sectional study of 46 kidney transplant recipients including 21 with longitudinal sampling. Using a semi-quantitative multiplex assay, we determined immunoglobulin (Ig) M, IgA, IgG, and IgG1-2-3-4 antibodies against Class I and Class II HLA, and 5 SARS-CoV-2 epitopes including the nucleocapsid protein and multiple regions of the spike protein.

RESULTS

Fourteen of 46 (30%) patients had donor-specific anti-HLA antibodies (donor-specific antibody [DSA]), 12 (26%) had non-DSA anti-HLA antibodies and 45 (98%) had anti-SARS-CoV-2 antibodies. Most DSAs targeted HLA-DQ (71%), with a dominant IgG isotype and IgG1 subtype prevalence (93%), and/or IgG3 (64%), followed by IgG2 (36%). Comparatively, there was a higher prevalence of IgA (85% versus 14%, P = 0.0001) and IgM (87%, versus 36%, P = 0.001) in the anti-SARS-CoV-2 antibody profile, when compared to DSAs, respectively. Anti-SARS-CoV-2 antibody profile was characterized by increased prevalence of IgM and IgA, when compared to DSAs. The median calculated panel reactive antibody before COVID-19 diagnosis (24%) tended to decrease after COVID-19 diagnosis (10%) but it was not statistically significant ( P = 0.1).

CONCLUSIONS

Anti-HLA antibody strength and calculated panel reactive antibody in kidney transplant recipients after COVID-19 do not significantly increase after infection. Although the IgG isotype was the dominant form in both HLA and SARS-CoV-2 antigens, the alloimmune response had a low IgA pattern, whereas anti-SARS-CoV-2 antibodies were high IgA/IgM.

Acute Allograft Pyelonephritis: Vague Symptoms, Indeterminate Laboratory Results, and the Necessity of Indication Biopsy

OBJECTIVES

In this study, we examined the clinical and biochemical features of biopsy-proven acute pyelonephritis among 769 kidney transplant recipients.

MATERIALS AND METHODS

This cohort study was performed between January 2003 and December 2019 at the University of Health Sciences (Izmir, Turkey). Acute pyelonephritis refers to urinary tract infection with acute graft dysfunction. All patients with suspected acute pyelonephritis underwent diagnostic biopsy and received antibiotic treatment for an average of 14 to 21 days. Patients with acute pyelonephritis (18/769, 2.3%) were categorized into groups of 9 patients each: group 1 developed acute pyelonephritis in the first 6 months, and group 2 developed acute pyelonephritis >6 months posttransplant.

RESULTS

All patients in group 1 had acute graft dysfunction; only 2 (22%) were symptomatic. All patients recovered baseline graft function after treatment. Patients in group 2 had at least 2 laboratory findings that included leukocytosis, neutrophilia, and high C-reactive protein values. Six patients had urine culture positivity. Recurrent pyelonephritis occurred in 3 patients. Four patients had graft loss. Over the mean follow-up of 48.0 ± 28.4 months, 14 patients (78%) were alive with a functioning graft.

CONCLUSIONS

Diagnostic biopsy is of great importance in patients with urinary tract infection accompanied by acute graft dysfunction in the first 6 months after transplant.

Antinatriuretic phenomena seen in children with acute pyelonephritis may be related to the activation of intrarenal RAAS

We investigated whether antinatriuretic phenomena [decreases in urinary sodium (uNa) and fractional excretion of sodium (FENa)] seen in children with acute pyelonephritis (APN) are associated with the renin-angiotensin-aldosterone system (RAAS).We examined 114 children experiencing their first episode of febrile urinary tract infection (fUTI) consecutively admitted to our hospital from July 2012 to June 2014. Blood tests [C-reactive protein, white blood cell count, erythrocyte sedimentation rate, and aldosterone (Aldo)] and urine tests [uNa, urine potassium (uK) and FENa] were performed upon admission. All enrolled children underwent a 99m-dimercaptosuccinic acid renal scanning (DMSA) at admission. Areas with cortical defects (AreaCD) and uptake counts (UptakeCD) on their DMSA scans were calculated. Data were compared between children with positive DMSA results (APN), lower urinary tract infection (L-UTI), and controls; and between children with high and low Aldo levels.uNa, uNa/K, and FENa negatively correlated with AreaCD%, UptakeCD, and Aldo; were significantly lower in APN patients than in LUTIs and controls regardless of Aldo level; were lower in the high Aldo group than in the low Aldo group. However, there is no difference in AreaCD% and UptakeCD between APN children with the high and low Aldo level.Decreases in uNa, uNa/K, and FENa in children with APN may result from an antinatriuretic effect of RAAS and be related to the activation of the intrarenal RAAS.

Gram-negative sepsis following biopsy of a transplant recipient with asymptomatic allograft pyelonephritis

Pyelonephritis post-renal transplantation is common and in up to 50% of cases can be asymptomatic. Transplant pyelonephritis shares a lot of histopathological features with acute cellular rejection. We present a case of asymptomatic acute graft pyelonephritis where a renal biopsy was complicated by sepsis, and discuss the difficulties in interpretation of renal histology in the setting of transplant pyelonephritis where rejection may also be a possibility, but differentiation is challenging.

Differential gene expression pattern in biopsies with renal allograft pyelonephritis and allograft rejection

Differentiating acute pyelonephritis (APN) from acute rejection (AR) in renal allograft biopsies can sometimes be difficult because of overlapping clinical and histologic features, lack of positive urine cultures,and variable response to antibiotics. We wanted to study differential gene expression between AR and APN using biopsy tissue. Thirty-three biopsies were analyzed using NanoString multiplex platform and PCR (6 transplant baseline biopsies, 8 AR, 15 APN [8 culture positive, 7 culture negative], and 4 native pyelonephritis [NP]). Additional 22 biopsies were tested by PCR to validate the results. CXCL9, CXCL10, CXCL11, and IDO1 were the top differentially expressed genes, upregulated in AR. Lactoferrin (LTF) and CXCL1 were higher in APN and NP. No statistically significant difference in transcript levels was seen between culture-positive and culture-negative APN biopsies. Comparing the overall mRNA signature using Ingenuity pathway analysis, interferon-gamma emerged as the dominant upstream regulator in AR and allograft APN, but not in NP (which clustered separately). Our study suggests that chemokine pathways in graft APN may differ from NP and in fact resemble AR, due to a component of alloreactivity, resulting in variable response to antibiotic treatment. Therefore, cautious addition of steroids might help in resistant cases of graft APN.

Renal outcome in biopsy proven cases of graft pyelonephritis

The incidence, risk factors and outcome of graft pyelonephritis are variably described in literature. All patients who had been transplanted at our center between January 2002 and November 2006 and had presented with acute graft dysfunction were subjected to biopsy. Those patients who had neutrophilic casts and interstitial inflammation with predominant neutrophils were included in the study. Out of the 265 patients, 110 were transplanted in the period and underwent biopsy for graft dysfunction. Out of the 110 patients, 26 had biopsy proven acute graft pyelonephritis (AGPN). Nine patients had early AGPN (within 6 months) and the other 17 had late AGPN. Nearly 19% of patients were culture negative and five patients had no clinical features of urinary tract infection; AGPN being a surprise finding on biopsy. Among the risk factors, only hepatitis C virus infection was significantly associated with AGPN. All patients received 4-6 weeks of antibiotics with at least 3 weeks of parenteral antibiotics. Majority (75%) of our patients experienced relapse of AGPN. Graft function was significantly lower 6 months after onset when compared to baseline, portending a poor outcome for these patients. Out of 26, 7 (27%) of our patients had biopsy features of concomitant acute cellular rejection. The treatment of acute rejection, however, did not improve the outcome.

Acute pyelonephritis in renal allografts: a new role for microRNAs?

BACKGROUND

Acute pyelonephritis (APN) versus acute rejection (AR) is a frequently encountered diagnostic and therapeutic dilemma in kidney transplants. Variable culture results, overlapping histologic features, and persistent graft dysfunction despite antibiotics are frequently encountered. Therefore, we explored the utility of intragraft microRNA profiles to distinguish between allograft APN and AR.

MATERIALS AND METHODS

Between 2003 and 2011, we identified 49 patients with biopsy features of APN, within the first 2 years posttransplant. MicroRNA profiling was performed on 20 biopsies (normal kidney, n=4; unequivocal AR, n=5; features of APN, n=11).

RESULTS

Only 32% (16/49) of the patients had concomitant positive urine cultures at biopsy, and in 8 of 16 patients, colony count was less than 10 CFU/mL. In 14 of 49 patients, positive urine culture did not coincide with the biopsy, and in 19 of 49 patients, urine cultures were negative. On microRNA profiling, good clustering was seen among the normal kidneys and among AR biopsies. Among the 11 biopsies with features of APN, 4 biopsies showed good clustering with a pattern distinct from AR; (these patients recovered graft function with antibiotics); 7 of 11 biopsies showed heterogeneity in microRNA profiles and variable outcomes with antibiotic treatment. We identified a panel of 25 microRNAs showing statistical difference in expression between AR and APN. MiR-99b, miR-23b let-7b-5p, miR-30a, and miR-145 were validated using qPCR.

CONCLUSION

Allograft pyelonephritis can be a diagnostic and therapeutic challenge. A gestalt approach is required. In addition to histology and cultures, differential intragraft microRNA expression may prove helpful to distinguish APN from AR in renal allograft biopsies.