Myelofibrosis and focal segmental glomerulosclerosis associated with toluene poisoning

Myelofibrosis-associated complications: pathogenesis, clinical manifestations, and effects on outcomes

Myelofibrosis (MF) is a rare chronic BCR-ABL1 (breakpoint cluster region-Abelson murine leukemia viral oncogene homologue 1)-negative myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, inefficient hematopoiesis, and shortened survival. The clinical manifestations of MF include splenomegaly, consequent to extramedullary hematopoiesis, cytopenias, and an array of potentially debilitating abdominal and constitutional symptoms. Dysregulated Janus kinase (JAK)-signal transducer and activator of transcription signaling underlies secondary disease-associated effects in MF, such as myeloproliferation, bone marrow fibrosis, constitutional symptoms, and cachexia. Common fatal complications of MF include transformation to acute leukemia, thrombohemorrhagic events, organ failure, and infections. Potential complications from hepatosplenomegaly include portal hypertension and variceal bleeding, whereas extramedullary hematopoiesis outside the spleen and liver - depending on the affected organ - may result in intracranial hypertension, spinal cord compression, pulmonary hypertension, pleural effusions, lymphadenopathy, skin lesions, and/or exacerbation of abdominal symptoms. Although allogeneic stem cell transplantation is the only potentially curative therapy, it is suitable for few patients. The JAK1/JAK2 inhibitor ruxolitinib is effective in improving splenomegaly, MF-related symptoms, and quality-of-life measures. Emerging evidence that ruxolitinib may be associated with a survival benefit in intermediate- or high-risk MF suggests the possibility of a disease-modifying effect. Consequently, ruxolitinib could provide a treatment backbone to which other (conventional and novel) therapies may be added for the prevention and effective management of specific MF-associated complications.

Myelofibrosis-associated complications: pathogenesis, clinical manifestations, and effects on outcomes

Myelofibrosis (MF) is a rare chronic BCR-ABL1 (breakpoint cluster region-Abelson murine leukemia viral oncogene homologue 1)-negative myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, inefficient hematopoiesis, and shortened survival. The clinical manifestations of MF include splenomegaly, consequent to extramedullary hematopoiesis, cytopenias, and an array of potentially debilitating abdominal and constitutional symptoms. Dysregulated Janus kinase (JAK)-signal transducer and activator of transcription signaling underlies secondary disease-associated effects in MF, such as myeloproliferation, bone marrow fibrosis, constitutional symptoms, and cachexia. Common fatal complications of MF include transformation to acute leukemia, thrombohemorrhagic events, organ failure, and infections. Potential complications from hepatosplenomegaly include portal hypertension and variceal bleeding, whereas extramedullary hematopoiesis outside the spleen and liver - depending on the affected organ - may result in intracranial hypertension, spinal cord compression, pulmonary hypertension, pleural effusions, lymphadenopathy, skin lesions, and/or exacerbation of abdominal symptoms. Although allogeneic stem cell transplantation is the only potentially curative therapy, it is suitable for few patients. The JAK1/JAK2 inhibitor ruxolitinib is effective in improving splenomegaly, MF-related symptoms, and quality-of-life measures. Emerging evidence that ruxolitinib may be associated with a survival benefit in intermediate- or high-risk MF suggests the possibility of a disease-modifying effect. Consequently, ruxolitinib could provide a treatment backbone to which other (conventional and novel) therapies may be added for the prevention and effective management of specific MF-associated complications.

Advances in the management of myelofibrosis

BACKGROUND

Myelofibrosis (MF) is a rare and serious hematologic malignancy classified as a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN). The disease is more common in males and in older individuals. Of the MPNs, MF presents with the most severe morbidity and greatest mortality. Although the cause of MF is unknown, it is thought to occur from acquired mutations that target the hematopoietic stem cell.

METHODS

We reviewed the current literature pertaining to the pathophysiology, clinical presentation, diagnosis, risk stratification, and treatment of MF. The strengths and limitations of present treatment options as well as the emerging clinical experience with Janus kinase 2 (JAK2) inhibitors are explored.

RESULTS

Diagnosis is often one of exclusion and is facilitated using the World Health Organization or International Working Group for Myelofibrosis Research and Treatment criteria, depending on whether primary or secondary MF is suspected. Treatment is complicated by a lack of disease familiarity of general practitioners and the advanced age of presenting patients. Although allogeneic stem cell transplant offers a potential cure, most treatments for this condition are limited to symptomatic management, with little to no effect on survival. Appropriate patient assessment and risk stratification are essential for predicting outcomes and allowing treating physicians to tailor therapy accordingly.

CONCLUSIONS

Significant advances have been made in understanding the pathophysiology of MF, leading to novel therapeutic approaches. The discovery of the JAK2 mutation and the development of JAK2 inhibitors provide clinicians with a new effective treatment option. Ruxolitinib is the first JAK1/2 inhibitor approved by the Food and Drug Administration (FDA) for the treatment of patients with intermediate- or high-risk MF. In clinical studies, ruxolitinib produced a significantly greater reduction in spleen size and improved quality of life compared with placebo or best available therapy. Several future therapies, including combination therapies with ruxolitinib, are currently under investigation.

Volatile solvent abuse caused glomerulopathy and tubulopathy in street children

Substance misuse among street children is a significant problem in developing countries. Volatile substances are the most abused agents. According to case reports, chronic renal diseases are common among substance-abusing street children. In this study, we examined the renal findings of 42 volatile substance–abusing street children and compared them with results from 49 healthy children (control). The street children’s weight, height, and blood pressure were lower than the controls’ ( P < 0.05). However, their blood alkaline phosphatase and creatinine phosphokinase levels were higher ( P < 0.05), and total blood protein, creatinine, and phosphorus levels were lower than the controls’ ( P < 0.05). Furthermore, the street children’s glomerular filtration rates were within normal limits ( P < 0.05), their urinary N-acetyl-beta-glucosaminidase (NAG), β2-microglobulin, microalbumin, protein, calcium, phosphorus, sodium, potassium, and chloride excretions were higher, and tubular phosphate reabsorption were lower than the controls’ ( P < 0.05). Volatile substances have been charged with causing distal tubular disease, but increased urinary protein, NAG, β2-microglobulin, microalbumin, and electrolyte excretions also result from glomerular, proximal, and distal tubular influences. We believe that increased volatile substance products in the renal parenchyma are responsible for glomerular and tubular damage. Volatile substance–abusing street children should be examined for glomerular and proximal tubular function and distal tubular acidosis.

Effect of organic solvent exposure on chronic kidney disease progression: the GN-PROGRESS cohort study

It has been suggested that solvent exposure may have a role in the progression of glomerulonephritis (GN) to ESRD, but this has never been tested with an appropriate cohort study design. A total of 338 non-ESRD patients with a first biopsy for primary GN between 1994 and 2001 were included: 194 IgA nephropathies (IgAN), 75 membranous nephropathies (MN), and 69 FSGS. ESRD, defined as an estimated GFR <15 ml/min per 1.73 m2 or dialysis, was registered during a mean follow-up period of 5 yr. Patients' lifelong solvent exposures before and after diagnosis were recorded by interview and assessed by industrial hygienist experts. Cox models were used to estimate adjusted hazard ratios (HR) of ESRD related to exposures. Overall, 15 and 14% of the patients had been exposed at a low and a high level before diagnosis, respectively. Forty-two with IgAN, 12 with MN, and 22 with FSGS reached ESRD. A graded relationship was observed for MN (age- and gender-adjusted HR [95% confidence interval] for low exposure versus none was 3.1 [0.5 to 18.2] and for high exposure versus none was 8.2 [1.9 to 34.7]) and for IgAN (1.6 [0.7 to 3.9] and 2.2 [1.0 to 4.8]) but not for FSGS. Solvent risk was mediated only partly by baseline proteinuria: Adjusted HR for high exposure versus none was 5.5 (1.3 to 23.9) for MN and 1.8 (0.8 to 3.9) for IgAN. In patients with IgAN, there was a trend in increasing HR with exposure duration before and its persistence after diagnosis. These findings support the hypothesized association of solvent exposure with the progression of GN to ESRD. They should prompt clinicians to give greater attention to patients' occupational exposures and possibly to consider professional reclassification.

Nephrotoxicity of organic solvents: biomarkers for early detection

OBJECTIVES

Evidence for a relationship between chronic kidney diseases or progression of already existing diseases (glomerulonephritides) and occupational solvent exposure has been found in case reports, in case-control studies and also in cross-sectional studies. An analysis of the available literature was performed with respect to markers measured in cross-sectional studies that might be useful for an early detection of solvent-induced effects on the kidney.

METHODS

The relevant cross-sectional studies were evaluated and the following markers were analyzed with respect to their suitability as biomarker for renal damage: total protein, albumin, transferrin, IgG, beta(2)-microglobulin, retinol-binding protein, N-acetyl-beta-D: -glucosaminidase, alanine aminopeptidase, beta-galactosidase, beta-glucuronidase, leucin aminopeptidase, alkaline phosphatase, lysozyme, Tamm-Horsfall protein and laminin fragments in urine as well as E-selectin, laminin and anti-laminin antibodies and anti-glomerular basement membrane antibodies in serum.

RESULTS

An increased albumin excretion was observed more frequently in groups of workers exposed to various solvents (like toluene, styrene, aliphatic/aromatic hydrocarbon mixtures, tetrachloroethene, mixtures of chlorinated hydrocarbons) than in controls. No clear pattern emerged for the other markers.

CONCLUSIONS

The determination of albumin excretion in the urine appears to be a useful parameter for monitoring solvent-exposed workers.

Occupational hydrocarbon exposure and chronic nephropathy

This review aims at discussing the questions raised by the hydrocarbon-related chronic nephropathy and its possible consequence, the hydrocarbon-related chronic renal failure. It has been attempted to adopt the point of view of the clinician. Therefore, the most important part of the review is devoted to a presentation and an analysis of the available data on humans. The main features of the available studies on human subjects are presented, their conclusions discussed in the light of the possible methodological flaws, and practical conclusions drawn. After a discussion of the main difficulties encountered for selecting the suitable exposure indicator, the studies are discussed in order of decreasing quality of the study design (cohort, case-control, cross-sectional studies, and the case reports). It is concluded that a great deal of controversies about chronic hydrocarbon-related nephropathy is explained by differences in the study design and that hydrocarbon-induced nephropathy is probably more than a mere hypothesis, although a causal relationship has not yet been proven. Finally, some practical consequences for dealing with a hydrocarbon-exposed patient diagnosed with a kidney disease and the need for further research are discussed.