Biomarkers for predicting the outcome of Puumala hantavirus infection

Hantaviruksiin kuuluva Puumala-virus aiheuttaa lievän munuaisoireisen verenvuotokuumeen, myyräkuumeen. Taudin vaikeusaste vaihtelee oireettomasta kuolemaan johtaviin tapauksiin, jotka ovat kuitenkin harvinaisia. Myyräkuumeen taudin kehittymistä ei täysin tunneta, mutta immunologisilla reaktioilla on arveltu olevan siinä tärkeä osuus. Väitöstutkimuksessa selvitettiin erilaisten immunologisten tekijöiden yhteyttä myyräkuumeen vaikeusasteeseen sekä arvioitiin niiden mahdollista osuutta taudin kehittymisessä. Korkean IL-6-pitoisuuden todettiin liittyvän vaikeaan myyräkuumeeseen ja olevan itsenäinen riskitekijä munuaisten vajaatoiminnalle. Pitkän pentraksiinin PTX3:n pitoisuus oli koholla akuutissa myyräkuumeessa ja korkea pitoisuus oli yhteydessä vaikeaan taudinkuvaan, erityisesti matalaan verihiutaletasoon sekä myös komplementtijärjestelmän aktivaatioon. Tutkimuksen perusteella PTX3 voisi vaikuttaa matalan trombosyyttitason kehittymiseen myyräkuumeessa aktivoituneen komplementtijärjestelmän kautta. Tryptofaania kataboloivan entsyymin IDO:n pitoisuuden todettiin olevan koholla akuutissa myyräkuumeessa ja korkea IDO oli yhteydessä vaikeaan tautiin sekä osoittautui merkittävän munuaisten vajaatoiminnan itsenäiseksi riskitekijäksi. IDO saattaa vaikuttaa munuaisten vajaatoiminnan kehittymiseen myyräkuumepotilailla aiheuttamalla tubulaaristen epiteelisolujen apoptoosia tai lamaamalla immuunijärjestelmää T-soluja estämällä. Soluvapaa DNA on peräisin apoptoottisista tai nekroottisista soluista ja siten kuvastaa solutuhon määrää erilaisissa sairauksissa. Plasman soluvapaan DNA:n pitoisuus todettiin koholla olevaksi akuutissa myyräkuumeessa. Se myös korreloi taudin vaikeuteen mm. sairaalahoidon kestolla arvioituna. Virtsan soluvapaan DNA:n eritys puolestaan ei ollut myyräkuumeessa koholla eikä se korreloinut taudin vaikeusasteeseen. Siten virtsan soluvapaan DNA:n eritys ei kuvasta tulehduksen määrää munuaisissa. Korkea plasman CRP ei liittynyt vaikeampaan akuuttiin myyräkuumeeseen vaan päinvastoin osoittautui mahdolliseksi munuaisten toimintaa suojaavaksi tekijäksi. CRP ei siten sovellu seurantamerkkiaineeksi arvioitaessa taudin vaikeusastetta ja ennustetta myyräkuumepotilailla.Puumala hantavirus (PUUV) causes a mild type of hemorrhagic fever with renal syndrome called nephropathia epidemica (NE). After an incubation period of 1-8 weeks, NE presents with sudden high fever, headache, nausea, abdominal pain, backache, visual disturbances, and impaired renal function. The severity of NE varies from asymptomatic to rare fatal cases, and its pathogenesis is not completely understood. An important feature in hantaviral infections is capillary leakage due to increased capillary permeability. The mechanisms behind this phenomenon are unclear, although immunological responses have been suggested to be important. In the present study, the association of immunological factors, i.e. interleukin (IL)-6, C-reactive protein (CRP), pentraxin-3 (PTX3), indoleamine 2,3-dioxygenase (IDO), and cell-free DNA (cf-DNA), with the severity of NE was analyzed. Furthermore, their possible role in the pathogenesis was assessed. Pentraxins are a family of acute-phase proteins. CRP is a short pentraxin mainly produced in the liver in response to inflammatory signals. IL-6, in turn, is a multifunctional cytokine involved in immune responses and inflammation. Increased cytokine levels have previously been found in the plasma, urine, and tissues of patients with hantavirus infection. In Study I, plasma IL-6 and CRP as well as their association with disease severity reflecting variables were studied in 118 hospital-treated patients with acute NE. High plasma IL-6 levels were found to associate with clinically severe acute NE. High IL-6 levels were also found as an independent risk factor for impaired renal function. High plasma CRP, in turn, did not have an association with a more severe course of the disease. On the contrary, high CRP levels turned out to be a possible protective factor for renal function. PTX3 is a long pentraxin produced at the site of inflammation. In Study II, 61 hospitalized PUUV-infected patients were studied to assess the associations of plasma PTX3 with variables reflecting the severity of acute NE. PTX3 levels were shown to be elevated during the acute phase of the disease. High PTX3 associated with a more severe course of NE and, most of all, with significant thrombocytopenia. It also associated with the activation of the complement system. Thus, PTX3 could possibly be involved in the pathogenesis of thrombocytopenia in NE through the activated complement cascade. IDO is the rate-limiting enzyme in tryptophan catabolism to kynurenine leading to depletion of tryptophan as well as T cell suppression. In Study III, 102 hospitalized patients were studied to establish the association of serum IDO enzyme with the variables reflecting the severity of acute NE. Serum tryptophan and kynurenine levels were determined by reverse-phase high-performance liquid chromatography, and tryptophan/kynurenine ratio reflecting IDO activity was calculated. IDO levels were found to be elevated during acute NE. High IDO was revealed to associate with clinically severe NE and it presented as an independent risk factor for significant renal insufficiency. Furthermore, serum IDO levels were shown to peak before serum creatinine levels. It is conceivable that IDO is involved in the pathogenesis of renal insufficiency in PUUV infection. The possible mechanisms are promotion of tubular epithelial cell apoptosis or immunosuppression through T cell suppression. Elevated levels of cf-DNA have been previously reported in different clinical disorders. The current view is that, in these conditions, cf-DNA originates from apoptotic or necrotic cells and therefore reflects the amount of cellular damage. In Study IV, total cf-DNA was studied in the plasma of 61 patients and urine of 20 patients with acute NE. Also, a qualitative high-sensitivity lab-on-a-chip DNA assay was carried out in 20 patients to elucidate the appearance of cf-DNA in plasma and urine. The plasma levels of cf-DNA were found to be elevated during acute PUUV infection and correlate with the apoptotic band (150-200 base pairs) intensity. The total plasma cf-DNA concentration also correlated with leukocytosis, thrombocytopenia, and the length of hospitalization. The urinary excretion of cf-DNA, in turn, was not elevated during the acute infection and it did not correlate with any of the disease severity reflecting variables. In conclusion, high plasma IL-6, PTX3, cf-DNA, and serum IDO levels reflect the clinical severity of NE, while high CRP concentration seems to protect against renal failure and does not predict a severe course of NE. Neither does urinary excretion of cf-DNA reflect the degree of inflammation in the kidney. Furthermore, PTX3 might be involved in the pathogenesis of thrombocytopenia and IDO, in turn, could act in the pathogenesis of renal insufficiency

Severity Biomarkers in Puumala Hantavirus Infection

Annually, over 10,000 cases of hemorrhagic fever with renal syndrome (HFRS) are diagnosed in Europe. Puumala hantavirus (PUUV) causes most of the European HFRS cases. PUUV causes usually a relatively mild disease, which is rarely fatal. However, the severity of the infection varies greatly, and factors affecting the severity are mostly unrevealed. Host genes are known to have an effect. The typical clinical features in PUUV infection include acute kidney injury, thrombocytopenia, and increased vascular permeability. The primary target of hantavirus is the endothelium of the vessels of different organs. Although PUUV does not cause direct cytopathology of the endothelial cells, remarkable changes in both the barrier function of the endothelium and the function of the infected endothelial cells occur. Host immune or inflammatory mechanisms are probably important in the development of the capillary leakage. Several immunoinflammatory biomarkers have been studied in the context of assessing the severity of HFRS caused by PUUV. Most of them are not used in clinical practice, but the increasing knowledge about the biomarkers has elucidated the pathogenesis of PUUV infection.Peer reviewe

Flash-Like Albuminuria in Acute Kidney Injury Caused by Puumala Hantavirus Infection

Transient proteinuria and acute kidney injury (AKI) are characteristics of Puumala virus (PUUV) infection. Albuminuria peaks around the fifth day and associates with AKI severity. To evaluate albuminuria disappearance rate, we quantified albumin excretion at different time points after the fever onset. The study included 141 consecutive patients hospitalized due to acute PUUV infection in Tampere University Hospital, Finland. Timed overnight albumin excretion (cU-Alb) was measured during the acute phase in 133 patients, once or twice during the convalescent phase within three months in 94 patients, and at six months in 36 patients. During hospitalization, 30% of the patients had moderately increased albuminuria (cU-Alb 20–200 μg/min), while 57% presented with severely increased albuminuria (cU-Alb >200 μg/min). Median cU-Alb was 311 μg/min (range 2.2–6460) ≤7 days after fever onset, 235 μg/min (range 6.8–5479) at 8–13 days and 2.8 μg/min (range 0.5–18.2) at 14–20 days. After that, only one of the measurements showed albuminuria (35.4 μg/min at day 44). At six months, the median cU-Alb was 2.0 μg/min (range 0.6–14.5). Albuminuria makes a flash-like appearance in PUUV infection and returns rapidly to normal levels within 2–3 weeks after fever onset. In the case of AKI, this is a unique phenomenon

Coagulopathy in Acute Puumala Hantavirus Infection

Puumala hantavirus (PUUV) causes a hemorrhagic fever with renal syndrome (HFRS), also called nephropathia epidemica (NE), which is mainly endemic in Europe and Russia. The clinical features include a low platelet count, altered coagulation, endothelial activation, and acute kidney injury (AKI). Multiple connections between coagulation pathways and inflammatory mediators, as well as complement and kallikrein-kinin systems, have been reported. The bleeding symptoms are usually mild. PUUV-infected patients also have an increased risk for disseminated intravascular coagulation (DIC) and thrombosis.Peer reviewe

Flash-Like Albuminuria in Acute Kidney Injury Caused by Puumala Hantavirus Infection

Transient proteinuria and acute kidney injury (AKI) are characteristics of Puumala virus (PUUV) infection. Albuminuria peaks around the fifth day and associates with AKI severity. To evaluate albuminuria disappearance rate, we quantified albumin excretion at different time points after the fever onset. The study included 141 consecutive patients hospitalized due to acute PUUV infection in Tampere University Hospital, Finland. Timed overnight albumin excretion (cU-Alb) was measured during the acute phase in 133 patients, once or twice during the convalescent phase within three months in 94 patients, and at six months in 36 patients. During hospitalization, 30% of the patients had moderately increased albuminuria (cU-Alb 20–200 μg/min), while 57% presented with severely increased albuminuria (cU-Alb >200 μg/min). Median cU-Alb was 311 μg/min (range 2.2–6460) ≤7 days after fever onset, 235 μg/min (range 6.8–5479) at 8–13 days and 2.8 μg/min (range 0.5–18.2) at 14–20 days. After that, only one of the measurements showed albuminuria (35.4 μg/min at day 44). At six months, the median cU-Alb was 2.0 μg/min (range 0.6–14.5). Albuminuria makes a flash-like appearance in PUUV infection and returns rapidly to normal levels within 2–3 weeks after fever onset. In the case of AKI, this is a unique phenomenon

Glycoprotein YKL-40 Is Elevated and Predicts Disease Severity in Puumala Hantavirus Infection

Most cases of hemorrhagic fever with renal syndrome (HFRS) in Europe are caused by the Puumala hantavirus (PUUV). Typical features of the disease are increased vascular permeability, acute kidney injury (AKI), and thrombocytopenia. YKL-40 is an inflammatory glycoprotein involved in various forms of acute and chronic inflammation. In the present study, we examined plasma YKL-40 levels and the associations of YKL-40 with disease severity in acute PUUV infection. A total of 79 patients treated in Tampere University Hospital during 2005–2014 were studied. Plasma YKL-40 was measured in the acute phase, the recovery phase, and one year after hospitalization. Plasma YKL-40 levels were higher during the acute phase compared to the recovery phase and one year after hospitalization (median YKL-40 142 ng/mL, range 11–3320, vs. 45 ng/mL, range 15–529, vs. 32 ng/mL, range 3–213, p < 0.001). YKL-40 level was correlated with the length of hospital stay (r = 0.229, p = 0.042), the levels of inflammatory markers—that is, blood leukocytes (r = 0.234, p = 0.040), plasma C-reactive protein (r = 0.332, p = 0.003), and interleukin-6 (r = 0.544, p < 0.001), and maximum plasma creatinine level (r = 0.370, p = 0.001). In conclusion, plasma YKL-40 levels were found to be elevated during acute PUUV infection and correlated with the overall severity of the disease, as well as with the degree of inflammation and the severity of AKI

Glycoprotein YKL-40 Is Elevated and Predicts Disease Severity in Puumala Hantavirus Infection

Most cases of hemorrhagic fever with renal syndrome (HFRS) in Europe are caused by the Puumala hantavirus (PUUV). Typical features of the disease are increased vascular permeability, acute kidney injury (AKI), and thrombocytopenia. YKL-40 is an inflammatory glycoprotein involved in various forms of acute and chronic inflammation. In the present study, we examined plasma YKL-40 levels and the associations of YKL-40 with disease severity in acute PUUV infection. A total of 79 patients treated in Tampere University Hospital during 2005–2014 were studied. Plasma YKL-40 was measured in the acute phase, the recovery phase, and one year after hospitalization. Plasma YKL-40 levels were higher during the acute phase compared to the recovery phase and one year after hospitalization (median YKL-40 142 ng/mL, range 11–3320, vs. 45 ng/mL, range 15–529, vs. 32 ng/mL, range 3–213, p < 0.001). YKL-40 level was correlated with the length of hospital stay (r = 0.229, p = 0.042), the levels of inflammatory markers—that is, blood leukocytes (r = 0.234, p = 0.040), plasma C-reactive protein (r = 0.332, p = 0.003), and interleukin-6 (r = 0.544, p < 0.001), and maximum plasma creatinine level (r = 0.370, p = 0.001). In conclusion, plasma YKL-40 levels were found to be elevated during acute PUUV infection and correlated with the overall severity of the disease, as well as with the degree of inflammation and the severity of AKI

Puumala Hantavirus Infections Show Extensive Variation in Clinical Outcome

The clinical outcome of Puumala hantavirus (PUUV) infection shows extensive variation, ranging from inapparent subclinical infection (70–80%) to severe hemorrhagic fever with renal syndrome (HFRS), with about 0.1% of cases being fatal. Most hospitalized patients experience acute kidney injury (AKI), histologically known as acute hemorrhagic tubulointerstitial nephritis. Why this variation? There is no evidence that there would be more virulent and less virulent variants infecting humans, although this has not been extensively studied. Individuals with the human leukocyte antigen (HLA) alleles B*08 and DRB1*0301 are likely to have a severe form of the PUUV infection, and those with B*27 are likely to have a benign clinical course. Other genetic factors, related to the tumor necrosis factor (TNF) gene and the C4A component of the complement system, may be involved. Various autoimmune phenomena and Epstein-Barr virus infection are associated with PUUV infection, but hantavirus-neutralizing antibodies are not associated with lower disease severity in PUUV HFRS. Wide individual differences occur in ocular and central nervous system (CNS) manifestations and in the long-term consequences of nephropathia epidemica (NE). Numerous biomarkers have been detected, and some are clinically used to assess and predict the severity of PUUV infection. A new addition is the plasma glucose concentration associated with the severity of both capillary leakage, thrombocytopenia, inflammation, and AKI in PUUV infection. Our question, “Why this variation?” remains largely unanswered

Glucosuria Predicts the Severity of Puumala Hantavirus Infection

Introduction: Puumala hantavirus (PUUV) causes a mild type of hemorrhagic fever with renal syndrome characterized by acute kidney injury (AKI), increased capillary leakage, and thrombocytopenia. Albuminuria and hematuria in dipstick urine test at hospital admission are known to predict the severity of upcoming AKI. Methods: We analyzed dipstick urine glucose in 195 patients with acute PUUV infection at hospital admission, and divided them into 2 categories according to the presence or absence of glucose in the dipstick urine test. Determinants of disease severity were analyzed in glucosuric and nonglucosuric patients. Results: Altogether, 24 of 195 patients (12%) had glucosuria. The patients with glucosuria had more severe AKI than patients without glucosuria (median maximum creatinine concentration 459 mmol/l, range 78-1041 mmol/l vs. 166 mmol/l, range 51-1499 mmol/l; P <0.001). The glucosuric patients had more severe thrombocytopenia (median minimum platelet count 41 x 10(9)/l, range 5-102 x 10(9)/l vs. 62 x 10(9)/l, range 3249 x 10(9)/l; P = 0.006), and more pronounced signs of increased capillary leakage (change in weight, maximum plasma hematocrit, minimum plasma albumin). The glucosuric patients were more often in clinical shock at admission (20.8% vs. 1.2%; P <0.001) and the length of hospital stay was longer (median 7.5 days, range 4-22 days vs. 6 days, range 2-30 days; P = 0.009). Conclusion: Glucosuria is relatively rare, but when present it predicts a more severe disease course in patients with acute PUUV infection.Peer reviewe

Plasma Levels of Soluble Urokinase-Type Plasminogen Activator Receptor Associate with the Clinical Severity of Acute Puumala Hantavirus Infection

Peer reviewe