Post COVID-19 AA amyloidosis of the kidneys with rapidly progressive renal failure

ABSTRACT

Coronavirus disease 2019 (COVID-19) pandemic has taken the world by a storm, posing a gruelling challenge to the medical fraternity globally. Besides its very high infectivityinfectivity, significant organ dysfunction occurs in critically ill COVID-19 patients, leading to severe morbidity and mortality. Pulmonary involvement is the leading cause of death in these patients to be followed by the cardiovascular involvement. Kidney involvement due to COVID-19 is becoming more discernible with AKI adversely affecting the outcome. Besides AKI, a few cases of collapsing FSGS in genetically vulnerable patients and thrombotic microangiopathies have been reported as well. We report a case of AA amyloidosis of the kidney with a rapidly progressive renal failure and congestive heart failure with preserved left ventricular functions, which complicated a moderate COVID-19 pneumonia providing some clues to a possible association of this novel virus disease with this complication, which needs to be confirmed in future studies.

KEYWORDS:

• AA- Amyloidosis
• COVID-19
• Prion-like domains in SARS-CoV-2 spike protein
• rapidly progressive renal failure: segment SK-9 of SARS CoV-2
• renal AA amyloidosis

Introduction

Coronavirus disease 2019 (COVID-19) pandemic has taken the world by a storm, posing a gruelling challenge to the medical fraternity globally. Besides its outrageous infectivityinfectivity, significant organ dysfunction occurs in critically ill patients leading to severe morbidity and mortality with more than four million deaths having been reported so far due to SARS CoV-2 infection [1]. Severe COVID-19 is characterized by a maladaptive hyper-inflammatory response and a severe endothelial injury, culminating into a multiorgan dysfunction syndrome whichsyndrome, which is a constellation of respiratory distress, multifactorial hypercoagulable state, cardiac dysfunction and even kidney injury in some [2–6]. Since this novel virus utilizes ACE2 as its route of entry into tissue cells andcells, the latter are densely distributed in the renal tissue facilitating its deleterious effects on multiple renal segments, tubulointerstitium, vasculature and podocytes causing AKI through various mechanisms. Besides acute tubular injuryinjury, a few cases of COVID-19 -induced collapsing FSGS and thrombotic microangiopathy have been reported in some genetically vulnerable patients [7–11]. In this reportreport, we present the first case of COVID-19 -associated AA amyloidosis of the kidney who developed a rapidly progressive renal failurefailure, which is otherwise uncommon in AA amyloidosis.

Case report

A 55-year old male was referred to us for evaluation of an unexplained renal dysfunction. Five months back he had developed COVID-19 infection with lung involvement requiring hospitalization. His nasal swab had tested positive for SARS CoV-2 by RT PCR. CT chest had revealed a moderate interstitial lung disease. Blood work at the time of COVID-19 infection revealed neutrophilic leukocytosis, Urea 37 mg/dl creatinine 0.9 mg/dl. albumin of 4 mg/dl. Inflammatory markers were raised CRP of 80 mg/L (normal: 0–5 mg/L), IL-6 93 pg/ml (normal:1.50 -7 pg/ml). D – dimer normal. He was managed with oxygen therapy, antibiotics, steroids and anti-coagulants After four days he was discharged and managed at home with home oxygen, antibiotics, anti-coagulants and oral steroids which were tapered over the next few days. His respiratory symptoms improved in the next few weeks. However, he complained of progressive fatigue and weakness which did not respond to a short course of paracetamol and multi vitamins. Almost four months after his recovery from COVID-19 he was evaluated for worsening malaise fatigue and anorexia and found to have advanced renal dysfunction. There was no history of oliguria, passage of high coloured or frothy urine, oedema or flank pain. He denied any past history of a chronic infective, inflammatory or a malignant disease. There was no history of substance abuse. His BUN and serum creatinine done eight months back as a routine health check-up were normal. His present medication was only an occasional intake of a proton pump inhibitor. On examination he was afebrile, with normal supine blood pressure without a postural drop. There were no clinical stigmata of chronic kidney disease. Systemic examination was unremarkable. Blood work revealed haemoglobin of 13 gm/L, WBC count of 14.68/µL. Urea 89.1 mg/dl, creatinine 6.04 mg/dl, Sodium 136 mEq/L Potassium 4.7mEq/L. Uric acid 8.3 mg/dl. Urine dipstick revealed 1+ albuminuria and no haematuria. Twenty-four-hour urine showed a proteinuria of 560 mg/24 hours. CRP was 100 mg/L, LDH 900 U/L, ANA, ANCA, rheumatoid factor, anti CCP (cyclic citrullinated peptides) and HLA B 27 were negative. Serological tests for hepatitis B, hepatitis C, HIV and CMV were negative. Serum and urine protein electrophoresis, immunofixation and free light chain ratio was negative for M protein. Ultrasound abdomen did not reveal any visceromegaly, mass lesion or lymphadenopathy. The kidneys were normal sized with a preserved cortico medullary differentiation. Given his systemic symptoms and falling GFR in absence of hypotension or exposure to nephrotoxic medicines like NSAIDS’ a possibility of an acute interstitial nephritis or some fibrotic kidney disease was considered he was given daily 500 mg IV pulses of methyl prednisone for four doses which led to a marked improvement in his fatigue, malaise and aches. Kidney biopsy was done which revealed diffuse deposition of pale eosinophilic material predominantly in the extra glomerular compartment (interstitium and vasculature) and mesangium (Figure 1a) which stained positive with congo red (Figure 1b) displaying green birefringence under polarized light (Figure 1c) consistent with the diagnosis of renal amyloidosis. The interstitial tissue displayed widespread deposits of amyloid with moderate tubular atrophy and interstitial fibrosis with scattered areas of chronic inflammation. Amyloid deposits were seen in glomerular hilar vessels as well (Figure 2). Immunofluorescence was negative for immunoglobulins and complement. Staining for LECT2 was negative. Stain (IHC) for SAA (serum amyloid associated) protein showed intense 3+ positivity along glomerular and extra glomerular sites of amyloid deposition confirming the diagnosis of renal AA amyloidosis (Figure 1d). His test for SAA levels hasve been outsourced to a laboratory outside the country, and results are pending. 2D echocardiography showed normal LV functions without cardiac hypertrophy; however, N-terminal Pro B type natriuretic peptide (NT-ProBnp) was significantly raised to 3748 pg/ml (normal:<115), which couldn’t not be explained on the basis of a reduced GFR only suggestive of myocardial injury. Skeletal muscle -specific enzymes were normal. An extensive systemic evaluation for a chronic infective, inflammatory, autoimmune and malignant diseases was negative. The patient is being managed with prednisone and a modified dose of colchicine. Four weeks post -steroids, his CRP has normalized and his creatinine is 3.8 mg/dl. Patient is being followed for response to treatment and periodic evaluation for other visceral involvement.

Figure 1. Low magnification view of kidney biopsy showing predominantly extra glomerular (vascular and interstitial) deposition of abundant eosinophilic material (a: H&Ex100), which is Congo red positive (b: Congo Red x100) showing apple green birefringence under cross -polarized light (c: PL x 100) and intensely positive for SAA {amyloid a associated protein} (d: IHCx100).

Figure 2. Congo red staining of glomerulus showing congophilic amyloid in hilar vessels and mesangium (Congo redx400red x400).

Discussion

AA amyloidosis also called secondary amyloidosis is a systemic disease due to the excessive production of serum acute phase reactant SAA (Serum Amyloid A) by the liver under the transcriptional control of IL-1 and IL-6 following certain chronic infective, inflammatory, malignant, hereditary disorders and could rarely be of an idiopathic origin. An impaired breakdown of this protein results in misfolding, of proteolytic fragments of serum amyloid A as amyloid fibrils and extracellular organ deposition and dysfunction. A persistently high concentration of SAA which after reaching a critical threshold becomes aggregation prone. This process is driven by various local and systemic factors setting into motion a perpetual process of fibrillogenesis [12,13]. Given only a minority of patients with long standing inflammation actually go on to develop AA amyloidosis a genetic vulnerability seems to be a prerequisite. SAA1 genotypes are predisposed to this complication. SAA.1 genotype is the only known genetic variable which significantly increases the susceptibility to AA amyloidosis. SAA.1.1, SAA.1.3 and SAA.1.4 are the known SAA.1 alleles. Caucasians homozygous for SAA.1.1 are seven times more predisposed to AA amyloidosis than other genotypes. SAA.1.3 homozygosity in Japanese besides predisposing them to AA amyloidosis also confers a rapidly progressive course of the disease. Renal involvement is relatively common in AA amyloidosis and adversely affects the outcome but the onset of renal failure is a slow process evolving over years. Many chronic viral infections like hepatitis B, C and HIV have been associated with AA amyloidosis. Surprisingly our patient’s disease had a very strong temporal association with COVID-19 infection. To the best of our knowledge this is the first case of COVID-19 infection (moderate though) associated AA amyloidosis reported thus far. Given the magnitude of the pandemic it sounds unreal for only one case of AA amyloidosis to have been reported till date favouring a chance association only. Besides COVID-19 is not a chronic disease. However, there are strong pointers favouring COVID-19 as a possible trigger for AA amyloidosis in this patient. Firstly, his multiple blood tests at the time of COVID-19 infection showed normal urea and creatinine without any proteinuria. Secondly it has been repeatedly demonstrated that SARS CoV-2 infection causes SAA overproduction which has a prognostic significance and SAA protein has even been regarded as a biomarker of COVID-19 infection since high levels of cytokines and this novel viral infection go hand in hand which are an important trigger for SAA overproduction by liver [14,15]. Some experts have hypothesized AA amyloidosis as an important factor causing systemic complications after COVID-19 and have even predicted the occurrence of systemic AA amyloidosis in vulnerable patients following this novel virus infection mandating long term follow up in those who have recovered from a severe COVID-19 infection [16]. In support of this hypothesis very recently molecular dynamic simulations were applied to study the amyloidogenic potential of SARS CoV-2. It was demonstrated that the presence of nine residue segment SK-9 located in SARS CoV-2-Envelope protein markedly increases the propensity of SAA fibril formation by at least three mechanisms, firstly by reducing the stability of the overproduced SAA hexamers by shifting the equilibrium towards their monomerization which assemble as amyloid fibrils. In addition, this SK-9 segment besides altering the configuration of these fragments to an aggregation prone state also enhances the stability of SAA fibrils [17]. Rapidly worsening renal failure due to AA amyloidosis is a rare occurrence but not unknown, reported in some series, and the risk factors for the same are a predominant interstitial and vascular involvement, hilar amyloid deposits and interstitial inflammation possibly cytokine mediated, which our patient’s renal biopsy displayed [18,19]. The treatment of AA amyloidosis involves effectively controlling the basic inflammatory, infective or malignant condition; however, managing post -COVID-19 amyloidosis seems to be a challenge since the amyloidogenic process evolves after the infective agent is no longer present. AA amyloidosis poses a challenge since the cause triggering the amyloidogenesis is not obvious. Comparative genomic hybridization array -based studies have shown large deletions on the long arm of chromosome 15 in some patients with the so -called idiopathic AA amyloidosis. This region hosts SELS, the gene for selenoprotein S, an endoplasmic reticulum -associated protein involved in processing and removal of misfolded protein from ER to cytosol for proteasome degradation. It also hashas also been shown that selenoprotein S besides interacting with SAA, it’s ex vivo inhibition triggers production of pro inflammatorypro-inflammatory cytokines [20].

It is worth a mentioning that some of the immune reactions triggered by this novel virus have been observed after exposure to SARS-CoV-2 vaccines too. A massive global SARS-CoV-2 vaccination drive has unveiled various vaccine -induced autoimmune phenomena including different connective tissue, neurological, cardiac and haematological diseases. In spite of a massive global vaccination program, only a relatively small number of cases of various de novo or relapsing autoimmune diseases have been and are still being reported with a strong temporal relationship to SARS-CoV-2 vaccines. These observations reiterate the existence of a small but extremely vulnerable population to thisthese vaccine -induced/triggered autoimmune phenomena. Despite the use of different vectors in mRNA and adenoviral COVID vaccines (lipid nanoparticles versus replicationdeficientreplication-deficient adenovirus), both have been associated with these immune reactions, given the common antigenic source SARSCoV2 spike protein, which could be the common denominator between both the virus- and vaccine -related syndromes. The mechanisms behind these adverse reactions possibly seem to be due to vaccine-encoded antigen distribution in the human body and possible interactions with human proteins and also a result of S protein-induced proinflammatory responses, amyloidogenic potential and unique gene expression signatures following vaccination [21].

Based on recent invitroin vitro experiments, it has been shown that S‐protein endoproteolysis by neutrophil elastase (which activates the spike protein) can render it exceptionally amyloidogenic, especially segments 193‐202, that could trigger amyloidosis [22]. Recently, prion-like domains have been demonstrated in the SARS CoV-2 S-protein, seen typically in the original Wuhan and the delta strain [23]. The same prion domain is present in the SARS-CoV-2 mRNA vaccine and has been implicated in the genesis of recently reported cases of SARS -CoV-2 vaccine -induced new form of a rapidly progressive Creutzfeldt-−Jakob disease phenotype. This further augments the notion of SARS – CoVSARS-CoV potential for inducing protein misfolding and fibrillogenesis in some vulnerable subjects [24,25].

In conclusionconclusion, it appears that COVID-19 infection could get complicated by AA amyloidosis including that of the kidneys in some genetically vulnerable patients, requiring future research. It seems prudent to follow severe COVID-19 survivors and also on a long term basis for a possible development of AA amyloidosis using persistently elevated CRP and serum AA levels as potential markers for future development of this serious complication. In newly diagnosed patients of AA amyloidosiswith AA amyloidosis, the temporal relationship with SARS -CoV-2 vaccine needs to be determineddetermined, which could again be an unsuspected culprit in some genetically vulnerable subjects, given the growing evidence of the amyloidogenic potential of the spike protein, a common denominator between both the virus and the vaccine.

Contribution

T.H.M. conceptualized the manuscript, wrote the draft, and the entire discussion and was primarily involved in the management of the patient and finalized the manuscript.

P.A.Z. did an extensive cardiac evaluation of the patient, and contributed into writing the case and approved the manuscript.

A.S. and S.S. performed the histopathology, and contributed into writing the case and approved the manuscript.

B.J. performed most of the radiological testing and the literature search, and corrected and modified the final manuscript.

S.S. did the initial histopathology and approved the manuscript.

M.O.P. collected new data for the revision and arranged it them and approved the manuscript.

S.B. contributed into writing the revised manuscript and approved it.

R.J. contributed into writing the revised manuscript and approved it.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported that there is no funding associated with the work featured in this article.