Pathophysiology of IgA Nephropathy.

Immunoglobulin (Ig)A nephropathy is the most prevalent primary chronic glomerular disease in the world. Studies of molecular and cellular interactions involved in the pathogenesis of IgA nephropathy have revealed several inherent abnormalities in the production and subsequent handling of IgA1. In patients with this disease, altered glycan structures in the unique hinge region of the heavy chains of IgA1 molecules lead to the exposure of antigenic determinants, which are recognized by naturally occurring antiglycan antibodies of the IgG and/or IgA1 isotype. In addition, due to a homing abnormality there is a gradual shift of mucosal IgA1 producing lymphoplasma cells from mucosal lymphoid tissue to bone marrow resulting in excess production of mucosal-type IgA1 in the systemic circulation. As a result, nephritogenic immune complexes form in the circulation and deposit in the glomerular mesangium. Deposited immune complexes induce proliferation of resident mesangial cells with increased production of extracellular matrix proteins. A number of inflammatory cytokines produced by the mesangial cells damage the filtration barrier resulting in hematuria and proteinuria ultimately leading to progressive renal damage.

Podocyte and Parietal Epithelial Cell Interactions in Health and Disease.

The glomerulus has 3 resident cells namely mesangial cells that produce the mesangial matrix, endothelial cells that line the glomerular capillaries, and podocytes that cover the outer surface of the glomerular basement membrane. Parietal epithelial cells (PrECs), which line the Bowman's capsule are not part of the glomerular tuft but may have an important role in the normal function of the glomerulus. A significant progress has been made in recent years regarding our understanding of the role and function of these cells in normal kidney and in kidneys with various types of glomerulopathy. In crescentic glomerulonephritis necrotizing injury of the glomerular tuft results in activation and leakage of fibrinogen which provides the trigger for excessive proliferation of PrECs giving rise to glomerular crescents. In cases of collapsing glomerulopathy, podocyte injury causes collapse of the glomerular capillaries and activation and proliferation of PrECs, which accumulate within the urinary space in the form of pseudocrescents. Many of the noninflammatory glomerular lesions such as focal segmental glomerulosclerosis and global glomerulosclerosis also result from podocyte injury which causes variable loss of podocytes. In these cases podocyte injury leads to activation of PrECs that extend on to the glomerular tuft where they cause segmental and/or global sclerosis by producing excess matrix, resulting in obliteration of the capillary lumina. In diabetic nephropathy, in addition to increased matrix production in the mesangium and glomerular basement membranes, increased loss of podocytes is an important determinant of long-term prognosis. Contrary to prior belief there is no convincing evidence for an active podocyte proliferation in any of the above mentioned glomerulopathies.

Pathophysiology of ANCA-associated Vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is characterized as inflammation of small-sized to medium-sized blood vessels and encompasses several clinicopathologic entities including granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis, and renal-limited ANCA-associated vasculitis. Over the past several decades, significant progress has been made in understanding the pathophysiology of ANCA-associated vasculitis. Although neutrophils contain a multitude of granular proteins, clinically significant autoantibodies are only recognized against myeloperoxidase and proteinase 3, both of which are present in the azurophilic granules. The propensity to develop these antibodies depends on a variety of predisposing factors such as microbial infection, genetic factors, environmental agents, and therapeutic drugs among others. These factors are usually associated with production of proinflammatory cytokines with capacity to prime the neutrophils. As a result a high proportion of neutrophils in circulation may be primed resulting in exposure of cytoplasmic proteins including myeloperoxidase and proteinase 3 on the surface of the neutrophils. Primed neutrophils are activated by interaction with ANCA in circulation. Activated neutrophils attach to and transmigrate through endothelium and accumulate within the vessel wall. These neutrophils degranulate and produce reactive oxygen radicals and ultimately die, causing tissue injury. Endothelial injury results in leakage of serum proteins and coagulation factors causing fibrinoid necrosis. B cells produce ANCAs, as well as neutrophil abnormalities and imbalances in different T-cell subtypes with excess of Th17, which perpetuate the inflammatory process.

Renal involvement in monoclonal gammopathy.

Monoclonal gammopathy is produced by neoplastic or non-neoplastic expansion of a clone of plasma cells or B lymphocytes. Monoclonal gammopathy of unknown significance is characterized by low levels of the monoclonal protein and a relatively small population of clonal lymphocytes or plasma cells in the bone marrow. In these cases, the patient is asymptomatic with no evidence of overt myeloma or lymphoma. The abnormal serum protein may be present as a complete immunoglobulin molecule or may consist of ≥1 of its components such as light chains or heavy chains. These proteins may cause a variety of diseases in various tissues and organs, of which the kidney appears to be the most vulnerable. Renal involvement in monoclonal gammopathy may occur as part of a generalized disease such as amyloidosis, immunoglobulin deposition disease, and cryoglobulinemia. In addition, there may be evidence of kidney damage by processes which are renal specific. These include light chain proximal tubulopathy, light chain cast nephropathy, and a variety of glomerulopathies encompassing a wide spectrum of disease patterns.

Impact of liver biopsy on the decision to treat patients with chronic hepatitis B genotype D virus infection.

OBJECTIVES: Patients with chronic hepatitis B virus (HBV) may exhibit significant liver pathology despite alanine aminotransferase (ALT) and HBV DNA levels below the cutoff values advised by treatment guidelines. We evaluated candidacy for HBV therapy when baseline histopathological changes are taken into consideration. METHODS: Clinical, biochemical, serological, virological, and histopathological (METAVIR score) data of 117 patients with HBeAg-negative chronic HBV genotype D were collected and analyzed. RESULTS: Significant pathology (≥F2 and/or ≥A2) and fibrosis (≥F2 ± ≥A2) were found in 73 (62.4%) and 59 (50.4%) patients, respectively. Based on HBV DNA (>2,000 IU/ml) and ALT levels >2 × 40 U/l (the standard cutoff value), only 31 (26.5%) patients were candidates for therapy. This increased to 58 (49.6%) patients when the new ALT cutoff values (30 U/l for males, and 19 U/l for females) were applied. Relying on either ≥F2 and/or A ≥2 or ≥F2 ± ≥A2 increases the treatment candidacy to 73 (62.4%) and 59 (50.4%) patients, respectively. Also, when compared with standard ALT cutoff values, applying both new ALT cutoff values with either significant pathology or fibrosis increases treatment candidacy to 28 (23.9%) and 42 (35.9%) patients, respectively. CONCLUSION: Liver pathology is more reliable than ALT and HBV DNA in the decision to treat patients with HBeAg-negative chronic HBV genotype D.

Accuracy of international guidelines for identifying significant fibrosis in hepatitis B e antigen--negative patients with chronic hepatitis.

BACKGROUND & AIMS: Differing threshold levels of hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) are recommended by international guidelines for commencement of antiviral therapy. These guidelines advocate therapy for patients with significant fibrosis (METAVIR score ≥F2); we assessed the accuracy of these guideline-defined thresholds in identifying patients with ≥F2 fibrosis. METHODS: We applied the European (European Association for the Study of the Liver [EASL] 2012), Asian-Pacific (Asian-Pacific Association for the Study of the Liver [APASL] 2012), American (American Association for the Study of Liver Diseases [AASLD] 2009), and United States Panel Algorithm (USPA 2008) criteria to 366 consecutive hepatitis B e antigen-negative patients with liver biopsy samples: EASL, ALT >laboratory-defined upper limit of normal (ULN) and HBV DNA ≥2000 IU/mL (n = 171); APASL, ALT >2-fold laboratory-defined ULN and HBV DNA ≥2000 IU/mL (n = 87); AASLD, ALT >2-fold the updated ULN (0.5-fold ULN [corresponding to ≤19 U/L] for women and 0.75-fold the ULN [corresponding to ≤30 U/L] for men) and HBV DNA ≥20,000 IU/mL (n = 53); and USPA, ALT >updated ULN (>0.5-fold ULN for women and >0.75-fold ULN for men) and HBV DNA ≥2000 IU/mL (n = 173). RESULTS: Overall, 113 patients (30.9%) had ≥F2 fibrosis, which was more frequent among patients who fulfilled any guideline criteria (45.7% vs 17.9% for those who did not fulfill any criteria, P < .0001). In applying the EASL, AASLD, APASL, and USPA criteria, sensitivity and specificity values for detection of ≥F2 fibrosis were 45.6%, 58.5%, 56.3%, and 45.7% (P = .145) and 82.1%, 73.8%, 77.1%, and 82.4% (P = .366), respectively. The EASL criteria (area under the receiver operating characteristic [AUROC] curve, 0.66; 95% confidence interval [CI], 0.61-0.71) and USPA criteria (AUROC, 0.66; 95% CI, 0.58-0.73) performed better than APASL (AUROC, 0.64; 95% CI, 0.59-0.69; P = .421) and significantly better than the AASLD criteria (AUROC, 0.59; 95% CI, 0.54-0.64; P = .013). CONCLUSIONS: In hepatitis B e antigen-negative patients with chronic hepatitis, the EASL, AASLD, APASL, and USPA criteria identify patients with ≥F2 fibrosis with low levels of accuracy. However, the EASL and USPA criteria are the most accurate for identification of these patients.

Intrahepatic splenosis mimicking hepatocellular carcinoma in a cirrhotic liver.

We report a patient who has a cirrhotic liver secondary to hepatitis C virus infection with a liver lesion incidentally found on routine liver ultrasound. The patient had a history of splenectomy 30 years earlier. The magnetic resonance imaging (MRI) characteristics suggested the diagnosis of intrahepatic splenosis, which is confirmed by core needle biopsy. Knowledge of these imaging findings makes this entity important to be considered in the differential diagnosis of a hepatic tumor in the presence of a history of splenic trauma or surgery.

Calciphylaxis-associated second renal graft failure and patient loss: a case report and review of the literature.

OBJECTIVES: Calciphylaxis is a small vessel disease that affects 1% to 4% of patients undergoing dialysis. Only 21 cases of postrenal transplant calciphylaxis have been reported, but none has been associated with primary graft failure or has occurred in a second graft. We present the first case of second renal graft calciphylaxis leading to primary graft failure and death. MATERIALS AND METHODS: We reviewed the 22 cases, including ours, and assessed risk factors, management, and mortality for these cases. RESULTS: The mean age was 34.2 -/+ 10.6 years, 11 patients were males (50%), and 13 (57.9%) underwent a deceased-donor renal transplant. The mean pretransplant dialysis period was 35.7 -/+ 39.3 months, 22 patients (100%) were on steroid therapy, 8 (36.4%) had a rejection, 18 (81.8%) underwent postcalciphylaxis parathyroidectomy, and 11 patients died (50%). Acute graft rejection and its management in the presence of high parathormone and divalent ion levels may be associated with postrenal transplant calciphylaxis. CONCLUSIONS: If the high parathormone levels are not adequately suppressed with medical treatment, prerenal transplant preparation should include parathyroidectomy. In addition, steroids and other immunosuppressive medications should be tapered quickly in calciphylaxis patients, especially if a patient's life is at risk.

HER2, TOP2A, CCND1, EGFR and C-MYC oncogene amplification in colorectal cancer.

AIM: Recent studies had suggested substantial molecular differences between tumours from different ethnic groups. In this study, the molecular differences between the incidences of colorectal carcinoma in Saudi and Swiss populations are investigated. METHOD: 518 cases of colon cancer tumours (114 from Saudi Arabia and 404 from Switzerland) were analysed in a tissue microarray format. Fluorescence in situ hybridisation (FISH) was used to estimate frequencies of copy number changes of known oncogenes, including HER2, TOPO2A, CCND1, EGFR and C-MYC. RESULTS: Using FISH, amplifications were mostly low level (gene-to-centromere ratio 2 to 4), which is in contrast with other tumour types with more frequent gene amplifications. The amplifications were particularly frequent for MYC (Saudi 9% and Swiss 14.2%) but unrelated to clinical outcome and pathological information. Remarkably, there were four tumours exhibiting classic high-level gene amplification for HER2 (Swiss 1.3%), a pattern often accompanied by response to trastuzumab (Herceptin) in breast cancer. Occasional high-level amplifications were also observed for CCND1 (Saudi 1/106, 0.9%; Swiss 2/373, 0.5%) and EGFR (Swiss 2/355; 0.6%). CONCLUSIONS: Rare high-level amplifications of therapeutic target genes were found in patients with colon cancer. Although no molecular differences were found between incidences of colon cancer cases in Swiss and Saudi populations, these observations emphasise the urgent need for clinical studies investigating the effect of targeted therapies.

Clinicopathologic features of hepatic neoplasms in explanted livers: a single institution experience.

BACKGROUND: Hepatic neoplasms can be the primary indication for hepatic transplantation. The tumors can also be incidentally identified in explanted livers. We explored the clinicopathologic features of hepatic neoplasms identified in explanted livers. MATERIALS AND METHODS: All explanted livers resected between 2001 and 2006 were evaluated for the presence of neoplasms and their clinicopathologic features were examined. RESULTS: In 98 liver transplants, 15 neoplasms (15.3%) were identified. Patient ages ranged from 5 to 63 years (median, 56 years). The primary etiology of hepatic disease was hepatitis C virus in 12 cases, hepatitis B virus in 1 case, cryptigenic cirrhosis in 1 case and congenital hepatic fibrosis in 1 case. Serum alpha-fetoprotein was significantly elevated (>400 U/L) in only 2 cases. CA19-9 was not elevated in any of the cases. The tumors included hepatocellular carcinoma (HCC) in 13 cases, 1 case of choloangiocarcinoma and 1 case of combined HCC and hepatoblastoma. The tumors in size from 0.5 to 5 cm (median 1.4 cm) and were multifocal in 5 of the cases (33%). Tissue alpha-fetoprotein expression was only seen in the cases associated with elevated serum levels. CONCLUSION: In our institution hepatic neoplasms are seen in more than 15% explanted livers. They can be incidentally indentified, are frequently not associated with elevated serum levels of alpha-fetoprotein and CA19-9, are commonly multifocal but small, and are associated with good prgonosis. Elevated serum alpha-fetoprotein, albeit specific, is not a very sensitive marker in the detection of hepatic neoplasms.

Patterns of glomerulonephritis with crescents: Experience at a tertiary medical center in Saudi Arabia.

A series of 78 cases of glomerulonephritis (GN), in which renal biopsy revealed changes of GN associated with crescent formation, were reviewed. Renal pathology findings were correlated with clinical features including patient's age, renal function, and serologic findings. In most of the cases (71.8%), the crescents were due to immune complex-mediated GN. This was followed by pauci-immune GN (20.5%) and anti-glomerular basement membrane antibody (GBM) GN (7.7%). The percentage of glomeruli with crescents was the highest in cases of anti-GBM disease (mean of 93.3%), followed by pauci-immune GBM (mean of 48.2%) and immune complex GN (30.9%). In cases with the pauci- immune GN, there were additional features of glomerular injury including fibrinoid necrosis, disruption of the GBM, and rupture of Bowman's capsule. These changes were generally more pronounced in a subset of pauci-immune GN associated with serum elevation of antineutrophil cytoplasmic antibody (c-ANCA). In biopsies from patient with immune complex disease, systemic lupus erythematosus was the most common cause of crescentic GN.

Correlation between clinical characteristics, survival and genetic alterations in patients with hepatocellular carcinoma from Saudi Arabia.

Amplification of the two oncogenes ERBB2 and MYC and deletion of the tumor suppressor gene TP53 are frequently encountered in cancerous tissues. The purpose of this study was to use the fluorescence in situ hybridization (FISH) technique for the assessment of ERBB2 and MYC amplification and TP53 deletion, and to relate these molecular markers to clinical and pathologic factors in Saudi patients with hepatocellular carcinoma. The study was conducted on 40 paraffin-embedded tissue samples originally taken from either hepatitis C virus (HCV)- or HBV-infected patients using the FISH technique. The level of ERBB2, MYC, and TP53 in the malignant group was significantly increased as compared to the control group. Of the 40 patients, 3 (7.5%) had amplification of ERBB2 gene, 4 (10%) different patients had amplification of MYC, and 26 patients (65%) had evidence of deletion of at least one allele on chromosome 17 for the TP53 gene in a high proportion of cells. There was a significant correlation between amplification of MYC oncogene and the number of tumor masses. Moreover, significant correlation was observed between poorly differentiated tumors when compared with moderate or well-differentiated tumors when MYC was analyzed. On the other hand, MYC failed to reveal any significant association between oncogene amplification and other clinicopathologic variables examined. Univariate analysis revealed a strong association between deletion of TP53 and multiple tumor mass (P< 0.001). No statistical correlation could be detected between deletion of TP53 and tumor size, grade, stage, and tumor differentiation. No significant difference could be detected in the mean survival time of patients positive for the alteration of the genes compared to the patients who showed no alterations for the same genes. However, when the stage of the tumor was analyzed, there was a significant difference in the mean survival time between patients who showed gene alterations compared to patients with no changes in the studied genes. When overall survival was analyzed, only patients with MYC amplification had a lower median survival (20.75 months) than patients without MYC amplification (35.82, P = 0.009). Genetic alterations of ERBB2 and TP53 genes had no effect on survival 2 (see Results). The combination of ERBB2, MYC, and TP53 could be useful markers to stratify patients into different risk groups.

Biallelic p.R2223H mutation in the thyroglobulin gene causes thyroglobulin retention and severe hypothyroidism with subsequent development of thyroid carcinoma.

CONTEXT: Dyshormonogenesis due to genetic defect in thyroglobulin (Tg) synthesis and secretion can lead to congenital hypothyroidism. OBJECTIVES: The aim of the study was to analyze the TG gene for the presence of mutations and to study the underlying mechanisms leading to dyshormonogenesis. CASES: Two siblings aged 25 and 31 yr presented with recurrent goitrous hypothyroidism with undetectable serum Tg. The older sibling was diagnosed with follicular variant of papillary thyroid carcinoma (FVPTC) at age 21 and metastatic FVPTC 8 yr later. METHODS: The entire coding region of TG gene was sequenced. BRAF, RAS, and P53 mutations or PAX8/PPAR-gamma rearrangement were screened in the FVPTC. Tg expression was studied by immunohistochemistry. RESULTS: Biallelic c.6725G>A (p.R2223H) and c.6396C>T (p.S2113L) sequence variations were detected in both patients and monoallelic variations in their family members. The c.6396C>T (p.S2113L) sequence variation was found in 14% of 100 population controls, whereas c.6725G>A variation was not present in the controls. Two previously reported polymorphisms (c.2200T>G and c.3082A>G) were present in all the family members. Strong cytoplasmic immunostaining of Tg was observed in the hyperplastic thyroid epithelial cells and weak or no staining in the follicular lumen. Cytoplasmic staining was localized in the endoplasmic reticulum. Reduced staining was found in the FVPTC. Neither RAS, BRAF, or P53 gene mutation nor a PAX8/PPAR-gamma rearrangement was detected in the tumor tissue. CONCLUSIONS: Biallelic c.6725G>A (p.R2223H) mutation causes Tg retention in the endoplasmic reticulum, resulting in dyshormonogenesis. Prolonged TSH stimulation may promote malignant transformation and development of thyroid cancer. The c.6396C>T (p.S2113L) is a novel polymorphism.

Intravascular papillary endothelial hyperplasia of renal vein: report of 2 cases.

Intravascular papillary endothelial hyperplasia is a benign intravascular process thought to arise from an organizing thrombus. The lesion may present clinically as an abnormal mass and, depending on the location, may be confused with benign or malignant neoplasms. It has been described in a variety of locations. Involvement of the renal vein by papillary endothelial hyperplasia is extremely rare, with only 4 cases reported in the literature. We describe 2 additional cases. In both cases, the radiologic examination revealed a well-circumscribed mass in the hilar region of the kidney, which was considered to be a renal neoplasm. Nephrectomy specimen in each case revealed characteristic features of intravascular papillary endothelial hyperplasia. It is suggested that intravascular papillary endothelial hyperplasia should be included in the differential diagnosis of a hilar renal mass.

Molecular basis of proteinuria.

The glomerular filtration barrier is composed of endothelial cells, basement membrane, and podocytes. In recent years, remarkable progress has been made in our understanding of the molecular structure of the filtration barrier and its relation to the effectiveness of the barrier function. The glomerular basement membrane is composed of a multitude of proteins, including collagen IV, heparan sulfate proteoglycans, and laminin, among others. The slit diaphragm, which is seen as a membrane covering the space between adjacent foot processes close to the basement membrane, is an extremely important structure with a crucial role in permselectivity of the filtration barrier. Its composition is now understood to consist primarily of a unique protein called nephrin. Mutations in the gene-encoding nephrin are known to result in the Finnish type of nephrotic syndrome. The exact mechanism by which nephrin controls permselectivity is not yet clear, but it is known to interact with several podocyte proteins including CD2AP, podocin, and alpha-actinin-4. Abnormalities of any of these proteins may result in proteinuria. The role of nephrin and its associated proteins in the pathogenesis of common acquired glomerulopathies in humans is still under investigation. Normal function of podocyte also depends upon maintaining a fully mature and terminally differentiated phenotype. A host of transcription factors, especially WT1 and PAX2, play a significant role in modulating podocyte function.