Interstitial Mast Cell Research Articles

Validation of dermatopathological criteria to diagnose cutaneous lesions of mastocytosis: importance of KIT D816V mutation analysis.

Cutaneous lesions of mastocytosis (CLM) are often subtle and may require biopsy. However, dermatohistopathological criteria for CLM remain undefined. To establish criteria for CLM by validating histological and molecular parameters. In skin samples from Caucasian patients with CLM and controls (atopic dermatitis, chronic urticaria, pruritus, tissue from tumor safety margin excisions), mast cell (MC) numbers, size, shape, distribution, immunostainability with a large panel of markers, pigmentation and presence of KIT D816V mutation were analysed. Forty-seven CLM patients (32 maculopapular cutaneous mastocytosis (MPCM), 15 mastocytomas) and 36 controls were included. Mastocytomas were easily identified by densely packed cuboidal MCs. In MPCM, skin MC density in CD117 stains was higher in CLM patients than in controls (P < 0.0001) and values correlated closely (r = 0.65, P < 0.0001) to results in tryptase stains. The optimized upper dermis cut-off number of 62 MC/mm2 had a sensitivity and specificity of 92% in both stainings, corresponding to approximately 12 MC/high power field (HPF). MC size was larger in MPCM than in controls (P = 0.01). Interstitial (= not perivascular or periadnexal) MCs and stronger basal pigmentation of the epidermis were indicative of MPCM (P < 0.0001 each) and clusters of >3 nucleated MC/HPF exclusively found in MCPM. Surface markers CD2, CD25 and CD30 stained T-lymphocytes, but only negligibly CLM MC. The KIT D816V mutation in formalin fixed paraffin embedded (FFPE) skin was evaluable in 87.5% of MCPM patients and had both 100% sensitivity and specificity. MPCM can be predicted by major and minor criteria combined in a scoring model. Presence of D816V mutation in FFPE skin and MC density > 27/HPF are >95%-specific major criteria for MPCM. MC densities 12/HPF, interstitial MC, clusters and basal pigmentation are minor criteria.

Renal interstitial mast cell counts differ across classes of proliferative lupus nephritis.

Systemic lupus erythematosus frequently involves the kidneys leading to significant morbidity and mortality. It is classified according to glomerular involvement pattern but tubulointerstitial lesions are also important for progression and prognosis, as seen in other kidney glomerular diseases. One of the cell types which participate in this process are mast cells. The aim of the study was to analyze the counts of tryptase-positive and chymase-positive mast cells in lupus nephritis classes II, III and IV. Material consisted of 42 renal biopsies from patients with lupus nephritis; 11 class II, 9 class III and 22 class IV. Chymase- and tryptase-containing cells were stained by immunohistochemistry and counted microscopically. Mean count of chymase-positive mast cells was 9.8/10 high power fields (hpf) for the whole group, 4.66 for class II, 11.89 for class III, and 11.51 for class IV. The mean count of tryptase-positive cells was 18.6/10 hpf for the whole group, 7.65 for class II, 25.57 for class III, and 21.23 for class IV. The differences between lupus nephritis classes were significant both for chymase- and tryptase-positive cells. Tryptase- but not chymase-positive cell counts showed a correlation with the creatinine level (R = 0.35). These results suggest that mast cells are involved to a different degree in the pathogenesis of lupus nephritis depending on the class of the disease.

Do Variations in Mast Cell Hyperplasia Account for Differences in Radiation-Induced Lung Injury among Different Mouse Strains, Rats and Nonhuman Primates?

The role of mast cell infiltrates in the pathology of radiation damage to the lung has been a subject of continuing investigation over the past four decades. This has been accompanied by a number of proposals as to how mast cells and the secretory products thereof participate in the generation of acute inflammation (pneumonitis) and the chronic process of collagen deposition (fibrosis). An additional pathophysiology examines the possible connection between mast cell hyperplasia and pulmonary hypertension through the release of vasoactive mediators. The timing and magnitude of pneumonitis and fibrosis are known to vary tremendously among different genetic mouse strains and animal species. Therefore, we have systematically compared mast cell numbers in lung sections from nine mouse strains, two rat strains and nonhuman primates (NHP) after whole thorax irradiation (WTI) at doses ranging from 10-15 Gy and at the time of entering respiratory distress. Mice of the BALB/c strain had a dramatic increase in interstitial mast cell numbers, similar to WAG/Rij and August rats, while relatively low levels of mast cell infiltrate were observed in other mouse strains (CBA, C3H, B6, C57L, WHT and TO mice). Enumeration of mast cell number in five NHPs (rhesus macaque), exhibiting severe pneumonitis at 17 weeks after 10 Gy WTI, also indicated a low response shared by the majority of mouse strains. There appeared to be no relationship between the mast cell response and the strain-dependent susceptibility towards pneumonitis or fibrosis. Further investigations are required to explore the possible participation of mast cells in mediating specific vascular responses and whether a genetically diverse mast cell response occurs in humans.

Mast Cells, TGF‐β1 and α‐SMA Expression in IgA Nephropathy

IgA nephropathy (IgAN) is a kidney disease with a varying renal prognosis. Recently, many studies have demonstrated that renal α-smooth muscle actin (α-SMA) and transforming growth factor (TGF-β1) expression, as well interstitial mast cell infiltrates could represent a prognostic marker in several renal diseases. The aim of our study was to analyze the prognostic value of mast cell, TGF-β1 and α-SMA expression in IgAN. A survey of the medical records and renal biopsy reports of 62 patients with a diagnosis of IgAN followed-up from 1987 to 2003 was performed. The mean follow-up time was 74.7 ± 50.0 months. The immunohistochemical studies were performed using a monoclonal antibody anti-human mast cell tryptase, a polyclonal antibody anti-human TGF-β1, and a monoclonal antibody anti-human α-SMA. An unfavorable clinical course of IgAN was related to interstitial mast cell infiltrates and α-SMA expression in the tubulointerstitial area. Expression of glomerular TGF-β1 and α-SMA, and interstitial TGF-β1 is not correlated with clinical course in IgAN. In conclusion, the increased number of mast cells and higher α-SMA expression in the tubulointerstitial area may be predictive factors for the poor prognosis of patients with IgAN.

Hyperhomocysteinemia and Myocardial Expression of Brain Natriuretic Peptide in Rats

Hyperhomocysteinemia (HHcy) has been linked to impaired left ventricular function and clinical class in patients with chronic heart failure. We hypothesized that HHcy stimulates myocardial brain natriuretic peptide (BNP) expression and induces adverse left ventricular remodeling. We randomized 50 rats into 5 groups. Groups Co1 and Co2 (controls) received a typical diet. Groups Meth, Hcy1, and Hcy2 were fed the same diet supplemented with 2.4% methionine, 1% homocystine, and 2% homocystine, respectively. After 12 weeks, we measured total plasma homocysteine (tHcy) and BNP in plasma and tissue, and we performed histomorphometric analyses. All animals had comparable baseline body weight [mean (SD) 234 (26) g] and total circulating Hcy [4.7 (1.7) micromol/L]. After 12 weeks of treatment, total circulating Hcy increased in Meth, Hcy1, and Hcy2 [27.3 (8.8), 40.6 (7.0), and 54.0 (46.0) micromol/L, respectively] and remained unchanged in Co1 and Co2. Serum BNP significantly increased in 1 of 10 animals in Meth, 3 of 10 animals in Hcy1, and 3 of 10 animals in Hcy2. Median (25th-75th percentile) BNP tissue concentrations in Hcy1 and Hcy2 were 55% higher than in the corresponding controls [Co1 vs Hcy1, 225 (186-263) vs 338 (262-410) pg/mg protein, P = 0.05; Co2 vs Hcy2, 179 (107-261) vs 308 (192-429) pg/mg protein, P = 0.12]. In the Meth group, BNP expression was comparable to that of controls [200 (159-235) vs 225 (186-263) pg/mg protein, P = 0.32]. The percentage of perivascular and interstitial collagen and mast cell infiltration were comparable in all groups, indicating no adverse cardiac remodeling. Three months of intermediate HHcy stimulated increased cardiac BNP expression that was not accompanied by adverse cardiac remodeling.

Extracellular superoxide dismutase has a highly specific localization in idiopathic pulmonary fibrosis/usual interstitial pneumonia

Recent studies suggest the importance of oxidant stress in the progression of pulmonary fibrosis. The aim of this study was to investigate extracellular superoxide dismutase (ECSOD), the major antioxidant enzyme of the extracellular matrix of human lung, in biopsy-proven idiopathic pulmonary fibrosis (IPF) related to usual interstitial pneumonia (UIP). Fibrotic areas and fibroblastic foci in UIP lungs were notable for absence of ECSOD by immunohistochemistry. Western blotting showed significantly lowered immunoreactivity of ECSOD in fibrotic compared with non-fibrotic areas of the diseased lung. The only cell type that showed intense ECSOD positivity in UIP was the interstitial mast cell. In order to investigate the mechanism for ECSOD depletion in fibrotic areas, alveolar epithelial cells were exposed to tumour necrosis factor-alpha and transforming growth factor (TGF)-beta1; TGF-beta suggested a trend towards decreased synthesis. Patients with UIP were also assessed to determine whether this disease is associated with a naturally occurring mutation in ECSOD (Arg213Gly) which leads to a loss of tissue binding of ECSOD. No significant differences could be found in the allele or genotype frequencies of this polymorphism between 63 UIP patients and 61 control subjects. Overall, consistent with several other antioxidant enzymes, ECSOD is very low in fibrotic areas of UIP, which may further increase the oxidant burden in this disease.

Mast cells and fibrosis on testicular biopsies in male infertility.

Testicular dysfunction correlates with increased testicular mast cells. Mast cells can activate fibroblasts and promote collagen synthesis. The aim of the study was to examine testicular mast cells containing tryptase, and the relationship between mast cells and different fibrosis stages of interstitium and peritubular region of testes. Testicular biopsies obtained from 33 infertile men were assigned to 2 groups: normal spermatogenesis (n = 10) and defective spermatogenesis (n = 23). Total, interstitial, and peritubular mast cells were examined immunohistochemically using antihuman tryptase. The fibrosis stage was evaluated using vimentin and alpha-smooth muscle actin. The ratio of tubules with sclerosis to total tubules was also calculated. In all cases, mast cells were mainly localized in the interstitium. The number of total mast cells was significantly higher in defective spermatogenesis than in normal spermatogenesis (p = .048). In both groups, interstitial mast cells were higher than peritubular mast cells. However, the increase in peritubular region was much higher than the increase in interstitium. Total, peritubular, and interstitial mast cell counts were not different from each other, according to the changing fibrosis stages. Total and interstitial mast cells were significantly higher in the cases with sclerosing seminiferous tubules than in the cases with no sclerosis (p = .04 and p = .024, respectively). The mast cells and the mast cell product tryptase could be involved in the etiology of defective spermatogenesis, especially whenever the last stage (tubular hyalinization and sclerosis) takes place.

Quantitative analysis of interstitial mast cells in AA and AL renal amyloidosis.

Eighteen renal biopsy specimens obtained from patients with AA-type renal amyloidosis (AA) and 11 from patients with AL-type renal amyloidosis (AL), for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available, were examined quantitatively. The cases were selected on the basis of immunohistochemical studies. As a control, we used 10 biopsy specimens from the kidneys removed because of trauma. Morphometric investigations were carried out by a computer image analysis system to find an answer to the question of whether mast cells can correlate with tubulointerstitial fibrosis in AA and AL renal amyloidosis, and to examine the relationship between mast cells and interstitial alpha-smooth muscle actin (alpha-SMA) expression and interstitial infiltrates. The morphometric study revealed that the mean values of the interstitial tryptase-positive cells, expression of alpha-SMA, interstitial volume, CD68+, CD45RB+, CD43+ and CD20+ cells were increased in AA as compared with the AL group, most of them significantly. Most of these parameters were also significantly increased in both AA and AL patients as compared with the control group. In both the AA group and the AL group, there existed some significant positive correlations between interstitial tryptase-positive cells and interstitial expression of alpha-SMA, interstitial volume and CD68+ cells. Interestingly, in AA cases, but not in AL cases, we noted a significant relationship between interstitial tryptase-positive cells and CD43+ cells. Our findings demonstrate that mast cells belong to the constitutive cell types in the interstitium in renal amyloidosis, in particular in amyloid type A. In addition, in both the AA group and the AL group, the significant positive correlations between interstitial mast cell count and relative interstitial volume and interstitial expression of alpha-SMA suggest that these cells play a role in the development of interstitial fibrosis.