Anemia post-transplantation

A 20-year-old female had Henoch-Schönlein purpura since age 9 leading to ESRD. She underwent kidney transplantation in 2018 from a live donor (mother) and received induction immunosuppression with thymoglobulin (100 mg once) followed by maintenance with tacrolimus (6 mg twice a day), mycophenolate sodium (720mg twice a day) and prednisone (30mg daily). The patient was discharged 5 days after surgery, with creatinine 0.9 mg/dL with tacrolimus trough level of 9.2 ng/mL.

Before surgery, the hemoglobin level ranged from 12.1g/dL to 11.6g/dL. At the time of medical discharge Hb was 9.8g/dL. During the follow-up, the patient was asymptomatic, with no increase in creatinine level and with good trough tacrolimus level (range of 8-12 ng/ml). However, at 2 months post-transplant, she developed worsened anemia with a hemoglobin of 6.1g/dl. At this time, the patient remained asymptomatic. She was then referred to the ED.

The exams at the time showed: hemoglobin 6.2 g/dL; reticulocyte 0.29%; haptoglobin 89 mg/dL; LDH 220 U/L. Subsequently, a bone marrow aspirate was performed and showed a giant pronormoblast with prominent nuclear inclusions, characteristic of parvovirus B19 infection.(FIGURE 1)

The patient received 2 doses of intravenous immunoglobulin (1g/kg/day) and was switched from tacrolimus to everolimus.

Anemia is a very common finding during post-kidney transplant consults. It is not uncommon to have patients that remain with anemia in the first 3 moths after the procedure. Read more here. (FIGURE 2)

The lack of large case series would make us imagine that parvovirus B19 infection after kidney transplant is rare. The incidence in post-transplant is not easy to estimate (range from 1-10%) and mostly occur in the first year, suggesting donor transmission, as described here.  Also, anemia is a common finding after kidney transplant and may have many other differentials that would appear higher on the list, including drug-induced myelosuppression and bleeding. Additionally, parvovirus B19 surveillance is not performed in routine clinical practice.

 A 2006 review from Mayo Clinic showed that among 98 patients with PVB19 infection after transplantation, 54% were kidney transplants, 9% liver transplants, 12% heart or lung transplants and 24% autologous or allogeneic HSCT recipients. The mean age of the patients was 35.2 ± 17.1 years. The majority (58%) were male. The median time to onset of parvovirus B19 disease was 1.75 months (range, 1 week–96 months) after transplantation. Overall, this study suggested that kidney recipients are in particular susceptible to parvovirus infection and that timing of presentation is variable though highest in the early period post-transplant. (FIGURE 3). Finally, it is reasonable to think that the magnitude of parvovirus B19 infection is underestimated.

Dr Felipe Paste
São Paulo, Brazil

Parvovirus B19 and the Kidney

Parvovirus B19 (PVB19) is a small, non-enveloped, single-stranded DNA virus belonging to the Erythrovirus genus, named for their tropism for erythroid precursor cells. It is the only known parvovirus to infect humans. By late adulthood, most people have IgG Anti-PVB19 serology demonstrating previous exposure, often from an asymptomatic infection. However, infection with PVB19 may cause a variety of clinical syndromes including fifth disease (‘Erythema infectiosum‘, a childhood viral exanthem), a polyarthropathy, pure red cell aplasia and hydrops fetalis in utero. The nephrologist may encounter PVB19 in 3 broad settings: 

Post-Transplant 

The incidence of PVB19 infection post kidney transplantation is hard to accurately determine but is likely in the range of 1-10%. Infection tends to occur in the first year and frequently in the first few weeks, suggesting possible donor transmission but the mechanism of infection/trans mission is unknown. Clinical syndromes are mainly acute anemia and chronic pure red cell aplasia, although a pancytopenia may develop. The few cases I have seen have been easy to identify, as patient presented with a profound isolated anemia. The diagnosis of chronic anemia or pancytopenia may be more protracted as these are obviously common post-transplant complications (graft dysfunction; drugs-immunosuppressants, anti-virals, co-trimoxazole, ACE inhibitor; other infections-CMV etc.). Treatment consists of reducing immunosuppression (usually the anti-metabolite) and IVIg. Similar to other viral infections (CMV, Polyoma viruses), there is some thought that PVB19 may be associated with allograft dysfunction or even acute rejection (?injured endothelium exposing previously hidden epitopes; no hard evidence for this however). A case series of thrombotic microangiopathy with PVB19 infection post transplant isolated PVB19 DNA from graft biopsies, however, overall the evidence for PVB19-induced allograft dysfunction is weak at present. 

Glomerular Disease 

PVB19 may cause a variety of glomerular lesions in immunocompetent hosts. These were first noted as associations with PVB19 viremia, however, subsequently viral DNA has been identified in renal cells from biopsy tissue. The most well described pattern of injury is FSGS, particular a collapsing glomerulopathy (see image), where the PVB19 genome has been detected in podocytes and parietal epithelial cells by PCR. Proliferative glomerulonephritis has also been temporally associated with PVB19 infection. A syndrome similar to acute post-infectious glomerulonephritis may occur, displaying hypocomplementemia, endocapillary and mesangial proliferation with subendothelial electron dense deposits. Acute glomerulonephritis may be more common in patients with sickle cell disease after an aplastic crisis due to PVB19. Given the ubiquitous nature of PVB19, it is likely that host factors contribute to why certain individuals manifest glomerular disease, with genetic factors, as always, being implicated. Viral DNA may be found in renal tissue after the acute infection has passed and the glomerular lesions will not necessarily improve with resolution of the infection. 

Dialysis Patients 

Patient with ESRD are considered to be at risk for aplastic crisis due to PVB19, albeit with a paucity of data to support that claim. The presence of abundant immature erythroid cells (due to EPO use), a relative immunosuppressed state and some particular patient populations (e.g. sickle cell disease) lead to an increased theoretical risk of this complication. 

PVB19 may be diagnosed using serology although immunosuppressed patients may not mount an adequate antibody response so PCR viral load is commonly employed. Treatment is non-specific and is generally supportive. IVIg is often used as these pooled preparations have anti-PVB19 antibodies, although randomized controlled data supporting its use is not available. Cutting back immunosuppression in transplant patients may also be of benefit, initially by reducing/stopping the anti-metabolite (logical as mycophenolate frequently induces bone marrow suppression independently). Also, tacrolimus is considered by some to be particularly conducive to PVB19 infection and a switch to cyclosporine may be a next step. 
To summarize, PVB19 is important to the nephrologist from a clinical perspective particularly for its tendency to cause isolated severe anemia (or pancytopenia) in our immunosuppressed patients. It may also cause glomerular disease in immunocompetent patients and should be a differential diagnosis for otherwise unexplained glomerulopathy, especially collapsing FSGS. It also provides clues from a research perspective to mechanism of glomerular disease/sclerosis.

Collapsing Variant of FSGS

The collapsing form of FSGS is a histologic variant which is characterized by mesangial hypercellularity and resultant collapse of the glomerular capillaries, as illustrated in the photo to the left. Its identification is important for prognostic reasons as it is known to progress much more rapidly than garden-variety FSGS (average time to progression to ESRD 13 months from diagnosis as compared to only 65 months). Not surprisingly these patients often have profound proteinuria.

The differential diagnosis of collapsing glomerulopathy is limited, but should include HIV ("HIV Nephropathy"), parvovirus B19 infection, hepatitis C infection, therapy with the bisphophonate pamidronate, lymphoproliferative disease, and certain autoimmune disease (e.g., lupus, Still's disease, etc). The Collapsing FSGS also occur in an idiopathic form, which is interestingly much, much more common in blacks than in whites.

Pure Red Cell Aplasia

One of the rare but serious side effects of recombinant erythropoietin therapy is the possibility of pure red cell aplasia, an autoimmune condition in which antibodies against erythropoietin result in T-cell-mediated destruction of erythroid precursors.  It may be recognized by an escalating EPO requirement and need for transfusions despite adequate iron stores.  It has been reported much more frequently in Europe (with a formulation called Eprex, not used in the U.S.) and is thought to be at least partially due to the practice of subcutaneous administration there rather than in the U.S. where intravenous EPO therapy, for reasons of reimbursement, is the rule.  The diagnosis of pure red cell aplasia requires a bone marrow biopsy which demonstrates a lack of erythroid precursors with a preservation of megakaryocyte and myeloblast lineages; in a recent case at our hospital one of the major manufacturers of EPO products was contacted and performed an assay looking for EPO-specific antibodies.  Being a rare condition, there is limited data on how best to treat acquired pure red cell aplasia, but standard practice currently consists of withdrawing EPO and giving a course of immunosuppressive therapy with Cytoxan and prednisone.

  

There are other causes of pure red cell aplasia:  a genetic condition (Diamond-Blackfan Syndrome) as well as other forms of acquired disease, which include leukemia/lymphoma, viral infection (e.g., hepatitis C, HIV, parvovirus B19), or drugs.  It may also be a prodrome to a full-blown myelodysplastic syndrome.  

Post-transplant HUS

A young patient was recently transferred to our service for evaluation of acute renal failure that had developed many years following a liver transplant for PSC. She had presented to another institution with nausea, vomiting, fevers and a hemolytic anemia. While with us, she had severe hypertension and a progressive decline in her renal function. A renal biopsy showed changes characteristic of a thrombotic microangiopathy (TMA) with some underlying FSGS and signs of chronic calcineurin-inhibitor (CNI) toxicity. Unfortunately, despite stopping her CNI and receiving multiple sessions of plasma exchange, her renal function continued to deteriorate and she was discharged on hemodialysis.

As mentioned in a previous post by Viresh, the predominant cause of HUS in children is diarrhea-associated. In adults, however, atypical HUS (aHUS) is commoner and it carries a poor prognosis with 25% mortality and 50% progressing to ESRD. There is a clear link between abnormalities in complement and aHUS. It is very important to determine the specific mutation responsible for the HUS in these patients as it has important implications for the likelihood and severity of recurrence after renal transplantation. About half of patients have mutations in Factor H or Factor I. Between 70-90% of these will have recurrent HUS and more than 80% will lose their grafts. Mutations in MCP are also relatively common but much more benign, recurring in only 20% with a lower rate of graft loss. Less common causes include antibodies to factor H which can be relatively easily dealt with by plasma exchange or a gain in function mutation in C3 which although rare, carries a poor prognosis. As mentioned by Nate previously, eculizimab, a monoclonal antibody that prevents formation of the membrane attack complex, has shown great promise in the treatment of aHUS and may be useful in treating and preventing recurrence after transplantation.

What about de novo HUS after transplant? This is most commonly caused by exposure to calcineurin inhibitors although it has been reported in association with many drugs including anti-platelet drugs, anti-neoplastic agents and quinine. The first case was in 1981 in a bone marrow transplant recipient treated with cyclosporine. The reported incidence varies from 2-4% in patients treated with cyclosporine with a lower incidence (1%) in patients receiving tacrolimus. The incidence varies significantly with the criteria used for the diagnosis and has been reported as high as 15% of protocol biopsies using relatively loose criteria. Interestingly, the combination of cyclosporine and rapamycin lead to a much higher incidence (20%). This supports the idea that the HUS is a result of direct endothelial toxicity as rapamycin interferes with mechanisms for repair of the endothelium and thus exacerbates any direct toxic effect.

There are a number of important risk factors for post-transplant HUS including a prolonged warm-ischemia time, infections (CMV, HIV, Parvovirus), malignancy and Ab-mediated rejection. Interestingly, a paper was recently published that looked for complement abnormalities in patients who presented with de novo HUS after renal transplant and found that 29% had CFH, CFI or MCP abnormalities. Many of these patients had previously had native renal biopsies that showed no evidence of a TMA. One study found significantly higher levels of endothelin in renal transplants with HUS relative controls. This is not surprising given the mechanism of the disease but possibly could be a means of monitoring high-risk patients for early evidence of HUS without performing a biopsy.

What about treatment? First of all remove the offending CNI. There are some data that patients can be switched from one CNI to another without necessarily exacerbating the disease and there are some case reports of centers using belatacept for CNI-avoidance after an episode of HUS. Should these patients receive plasma exchange? There are no controlled trials but there are observational studies suggesting that plasma exchange should be used. There are a number of small studies from the 1990s where removal of the CNI alone was employed. A graft loss rate of 60-80% was reported in these series. More recently, the largest series of patients with CNI-associated HUS was reported where all of the patients received plasma exchange and 80% achieved remission. Interestingly, patients with recurrent HUS were much less likely to respond to plasma exchange; these are the patients who might benefit from treatment with eculizumab. There are no data indiciating how long plasma exchange should be continued but it is suggested that one should keep going until there is no longer any evidence of hemolysis.

This is a great, recent review on the topic of post-transplant HUS.

The use of IVIg in Kidney Disease

It’s time for a quick nephro-centric summary of immune globulin use. Immune globulin, usually administered intravenously (IVIg), is made from pooled human plasma and used for a wide variety of human disease. It contains mostly IgG with various IgA concentrations depending on the preparation and different stabilizers (see sucrose nephropathy below). IVIg has various anti-infections and anti-inflammatory effects via mechanisms that are still incompletely understood. The sphere of renal transplantation is where most nephrologists will see it being administered.

HLA Desensitization

IVIg is incorporated into various desensitization protocols which may decrease preformed anti-HLA antibodies and render a previous positive crossmatch negative. Two broad regimes are (a) high dose IVIg at 2g/kg single dose or monthly and (b) plasmapheresis with low dose IVIg 100mg/kg after each session. The latter regime is likely more beneficial when an appreciable level of sensitization is present and rituximab may be also be added. The immunomodulatory mechanisms at play may include neutralizing donor-reactive antibodies, reducing anti-HLA antibody formation and the inhibition of complement-dependent endothelial injury.

Antibody-Mediated Rejection (AMR)

IVIg is generally incorporated into a multi-targeted regimen for AMR, usually at least 1g/kg given after plasmapheresis. My own experience is with 2g/kg at the end of the final plasmapheresis sessions. It must be noted that IVIg may interfere with anti-HLA titers, causing false-positive results so it is important to send levels before administering IVIg.

Transplant Infectious Disease

BK Polyoma virus nephropathy (PVN): IVIg may have a role in the treatment of (PVN), particularly in cases where acute rejection co-exists or is suspected. IVIg presumably contains anti-BK antibodies, as the virus is ubiquitous in the general population. However, whether these antibodies are neutralizing or not is unknown. As the cornerstone of PVN treatment is immunosuppression reduction, coexistent acute rejection presents a difficult scenario with IVIg being attractive due to its anti-infective and immunomodulatory properties. Other post-transplant infectious complications where IVIg may be useful include Parvovirus B19 (which may cause severe anemia or an FSGS renal lesion) and possibly resistant CMV infection. The use of IVIg in these settings is usually in conjunction with a decrease in the burden of immunosuppression.

Glomerular disease

IVIg has been used without much convincing evidence for a variety of glomerular pathologies. These include an uncontrolled series of 11 patients with severe IgA Nephropathy given monthly doses of 2g/kg. A decrease in proteinuria and stabilization of GFR was observed. Other unconvincing reports for IVIg use in glomerular disease include a small study in idiopathic membranous nephropathy as well as in lupus nephritis and ANCA associated vasculitis (ref).

Adverse Renal Events

It should be noted that IVIg preparations may uncommonly cause AKI (<1% of infusions). This almost always happens with use of high sucrose-content preparations. IV Sucrose was used in the mid-20^th century for treatment of various edematous states and was associated with AKI, via an osmotic effect causing proximal tubular cell swelling and vacuolization (see JAMA paper from 1942!). IVIg may also cause hyponatremia, as discussed by Nate previously.

Sickle cell disease and the kidney

Since moving to Baltimore, a city with a large African-American population, earlier this year, I have had the opportunity to see several interesting patients with sickle cell SS disease and renal complications. Here is a mention of some of the kidney abnormalities that occur with SS disease, as well as some of the clinical manifestations.

The underlying pathology of renal sickle cell disease seems to be from microvascular hypoxemia: when red blood cells acquire a sickle shape and obstruct capillary flow, microinfarcts, chronic ischemic injury and medullary hypoxia can occur. Hemosiderin deposits can also be seen on biopsy. Sequelae can include:

1) hyperfiltration. Hypoxia can lead to increased prostaglandin release, which increases GFR. NO synthase may also be upregulated.

2) increased proximal tubular function. The exact causes are unknown, but the proximal tubular upregulates secretion of creatinine, as well as resorption of phosphorus. Thus, creatinine-based estimations of GFR may overestimate renal clearance in sickle cell patients.

3) microalbuminuria. Unclear if this is secondary to ischemia, or if hyperfiltration plays a role. Can progress to overt proteinuria over time. It is interesting to note that parvovirus B19 has been implicated as a cause of nephrotic syndrome in SS disease patients.

4) hyposthenuria. Otherwise known as inability to concentrate or dilute urine; possibly due to impaired water ADH response, although another possibility is that enhanced clearance of interstitial solute washes out the medullary concentration gradient.

5) impaired distal tubular function. Cause unclear. Can lead to decreased distal H+ and/or K+ secretion, and lead to an imcomplete distal RTA.

6) hematuria. Probably from capillary microinfarcts.

7) renal papillary necrosis. From medullary ischemia.

A collapsing form of FSGS as well as MPGN have been reported in conjunction with SS disease.

Amazing (and awful), that a single genetic mutation can cause so much renal havoc!