Quantitative Immunohistochemistry

Metallothionein and Dendritic Cells in Skin of End-Stage Renal Disease Patients not on Dialysis, or on Hemodialysis or Peritoneal Dialysis

♦ Objective

Renal failure leads to a variety of defects in immune function. The skin, as a major player in the immune system network, also exhibits multiple derangements. The pathogenesis of these defects and derangements are poorly understood; therefore, we studied immune competent cells, dermal dendrocytes (DC), and a special proinflammatory protein, metallothionein (MT), in the skin of these patients.

♦ Design

22 patients with end-stage renal disease (ESRD) but not on dialysis, 18 patients on hemodialysis (HD), 14 patients on peritoneal dialysis (PD), and 35 healthy controls were included in the study. Immunohistochemical staining of skin biopsies for DC and MT was performed with the following antibodies: for DC, antibody against factor XIIIa; and for MT, Dako-MT, E9 (Dako, Carpinteria, California, USA). Measurements were made by counting stained DC per square millimeter, and by optical density (OD) for MT (mean ± SEM).

♦ Results

Metallothionein was increased in the skin of HD (OD 0.42 ± 0.05, p < 0.01) and PD patients (OD 0.33 ± 0.04, p < 0.05) compared to controls (OD 0.23 ± 0.02) and ESRD patients not on dialysis (OD 0.22 ± 0.05). In contrast, numbers of DC were reduced in patients on PD compared to controls (59 ± 13 vs 96 ± 59 DC/mm2, p < 0.01) and increased in patients with ESRD prior to dialysis (141 ± 13 DC/mm2, p < 0.05). Patients on HD were in-between (105 ± 20 DC/mm2), with a significant difference versus patients on PD ( p < 0.05).

♦ Conclusions

Our data show that the mode of dialysis influences the number of antigen-presenting cells in the dermis. However, in both dialysis modes, a proinflammatory immune status of the skin (MT) was present and, therefore, other regulatory elements for dermal dendrocytes apart from proinflammation exist.

Renal effects of metallothionein induction by zinc in vitro and in vivo

BACKGROUND

Metallothionein (MTT) is an endogenous antioxidant that can be induced by both zinc (Zn) and ischemia. In kidneys, increased MTT expression exerts a putative protective role in diabetes and hypoxia. Our goal was to further investigate the behavior of MTT under the influence of Zn and hypoxia in vitro and in vivo.

METHODS

MTT expression was measured in vitro in cell cultures of proximal tubular cells (LCC-PK1) by immune-histochemistry and real-time PCR after incubation with increasing concentrations of Zn under hypoxic and non-hypoxic conditions. In addition, in vivo studies were carried out in 54 patients to study MTT induction through Zn. This is a sub-study of a prospective, randomized, double-blind trial on prevention of contrast-media-induced nephropathy using Placebo, Zn and N-Acetylcysteine. Blood samples were obtained before and after 2 days p.o. treatment with or without Zn (60 mg). ELISA-based MTT level measurements were done to evaluate the effects of Zn administration. For in vivo analysis, we considered the ratio of MTT to baseline MTT (MTT₁/MTT₀) and the ratio of eGFR (eGFR₁/eGFR₀), correspondingly.

RESULTS

In vitro quantitative immuno-histochemical analysis (IHC) and real-time PCR showed that at increasing levels of Zn (5, 10, and 15 μg/ml) led to a progressive increase of MTTs: Median (IQR) expression of IHC also increased progressively from 0.10 (0.09-0.12), 0.15 (0.12-0.18), 0.25 (0.25-0.27), 0.59 (0.48-0.70) (p < 0.0001). Median (IQR) expression of PCR: 0.59 (0.51-1.72), 1.62 (1.38-4.70), 3.58 (3.06-10.42) and 10.81 (9.24-31.47) (p < 0.0001). In contrast, hypoxia did not change MTT-levels in vitro (p > 0.05). In vivo no significant differences (p = 0.96) occurred in MTT-levels after 2 days of Zn administration compared with no Zn intake. Nevertheless, there was a significant correlation between MTT (MTT₁/MTT₀) and eGFR (eGFR₁/eGFR₀) in case of Zn administration (rho = -0.49; 95%-CI: -0.78 to -0.03; p = 0.04).

CONCLUSIONS

We found that Zn did induce MTTs in vitro, whereas hypoxia had no significant impact. In contrast, no significant increase of MTTs was detected after in vivo administration of Zn. However, there was a significant negative correlation between MTT and eGFR in vivo in case of Zn administration, this could indicate a protective role of MTTs in a setting of reduced kidney function, which is possibly influenced by Zn.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00399256 . Retrospectively registered 11/13/2006.

Peritoneal mast cells in peritoneal dialysis patients, particularly in encapsulating peritoneal sclerosis patients

BACKGROUND

We assumed that increased mast cell numbers contribute substantially to the fibrosis often seen in the peritoneum of peritoneal dialysis (PD) patients, particularly those with encapsulating peritoneal fibrosis (EPS). Therefore, we investigated mast cells in different pathological conditions of the peritoneum.

METHODS

One hundred fifteen tissue probes with different peritoneal pathological states were selected (normal, n = 20; chronic appendicitis, n = 25; herniotomy, n = 24; fibrosis, n = 11; PD, n = 26; and EPS, n = 9). For staining of mast cells, we used alpha-naphtol-AS-d-chloracetate-esterase and mast cell tryptase. Next, we counted numbers of mast cells per square millimeter. Tryptase was measured by using image analysis.

RESULTS

Measurements by means of both methods correlated well (r = 0.812). Numbers of mast cells per square millimeter were as follows: normal, 26 +/- 16; chronic appendicitis, 241 +/- 217; herniotomy, 115 +/- 88; fibrosis, 99 +/- 66; PD, 81 +/- 64, and EPS, 24 +/- 23 (P = 0.00006). Amounts of tryptase present were 2.900 +/- 0.118, 2.871 +/- 0.150, 2.733 +/- 0.183, 3.041 +/- 0.176, 2.780 +/- 0.184, and 2.609 +/- 0.234, respectively (P = 0.00002).

CONCLUSION

We found upregulation of mast cells in specimens of chronic inflammatory diseases of the peritoneum. This also was true for PD patients, with the exclusion of patients with EPS. Therefore, loss-of-control functions of mast cells may contribute to the ill-understood disease entity of EPS.

Induction of metallothionein in proximal tubular cells by zinc and its potential as an endogenous antioxidant

BACKGROUND

This study was undertaken to gain further insights into the expression of metallothionein (MT) in kidney, to define the necessary dosage of a metal (zinc) to achieve induction of MT and to evaluate the antioxidative potential of MT in comparison to other more common antioxidative therapeutics, like N-acetyl-L-cysteine (NAC), and endogenous molecules, like glutathione.

METHODS

MT was measured in renal specimens from cadaver kidneys from patients with chronic diseases (n = 76) and controls (n = 21) by immunohistochemistry. In addition, induction experiments were performed in cell cultures of proximal tubular cells (LCC-PK1) and MT measured on the RNA and protein level (immunohistochemistry, Western and dot blotting). Antioxidative potential of MT was compared to NAC and glutathione.

RESULTS

MT was restricted to tubular cells with no differences between controls and patients. Zn caused a dose-dependent increase of MT on the RNA as well as on the protein level (RNA (ratio MT/histone 3.3): control 0.34 +/- 0.12; Zn 17 microM 0.65 +/- 0.26; Zn 35 microM 1.25 +/- 0.43 (p < 0.05), Zn 52 microM 1.35 +/- 0.46 (p < 0.05), and protein: 5.8-fold increase from 47 +/- 13 mg/g total protein (n = 6) to 272 +/- 140 mg/g total protein (n = 6)). The antioxidative effect of MT was equal to NAC and glutathione.

CONCLUSIONS

Induction of renal MT by zinc is easily achievable and might be an interesting therapeutic and preventive tool against oxidative stress.

Constants and variables in immunohistochemistry

Many efforts have been made to develop reliable methods for the quantification of immunohistochemical reaction products. Most of the corresponding studies have dealt with problems related to the development of adequate hardware and software, while fewer investigations have focused on variables of histotechnical or immunohistochemical methods. The present paper summarizes findings and experience obtained over many years in this latter field, and a total of 14 corresponding parameters were considered. The studies were performed with methods well established in the author's laboratory; namely immunohistochemistry for various pancreatic hormones and chromogranin A applying the peroxidase anti-peroxidase method on serial semithin sections from the mammalian endocrine pancreas. Optical densities of immunoreactivities were determined using an appropriate measuring program by the interactive image analysis system IBAS. All parameters investigated were found to influence densities of immunoreactivities, and those with major significance were: 1) the thickness of histologic sections; 2) the dilution range of the antisera used as first layers; 3) the type or composition of the buffers used for dilution of the antisera and of the chromogen di-aminobenzidine or as the rinsing solution. All these variables could be standardized in appropriate ways. It was not possible, however, to prevent batch-to-batch (inter-assay) variations. Finally, the results of the present investigations served to increase the efficiency of immunohistochemical staining by the applied methods.

Microarray as a model for quantitative visualization chemistry

For visualization of proteins or nucleic acids, direct and indirect in situ fluorescence and absorption methods (immunohistochemistry and cytochemistry) have existed for many years. The authors describe a new experimental approach using microarray as a model to quantitatively compare both visualization methods. The spots obtained with the microarray robot had a progressive twofold decrease in concentrations and are used as objects with known amounts of DNA. Subsequent hybridization resulted in a direct fluorescence (DF) label or in hapten for indirect fluorescence (IF) and absorption. The results show that the image of the object in the IF method is larger than that in the DF method because of an edge effect, with stronger staining at the circumference. This leads to a higher plateau level and an 8- to 10-fold reduction in the detection threshold for IF compared with DF. These features are especially useful for one-color DNA-related microarray analysis, such as single nucleotide polymorphism, loss of heterozygosity, and mutation analysis, provided that the spots are not designed directly adjacent to each other, so that the edge effect is taken into account. The slope of the linear range for the IF method is much steeper than for the DF method, pointing to a narrow dynamic range in immunohistochemistry. It is noteworthy that the detection limit for absorption images after indirect immunoenzyme visualization is lower than for the DF images. The indirect immunohistochemistry semiquantitative absorption signal was at least similar compared with the DF fluorescence. In conclusion, an explanation for the difficulties experienced in quantitative immunohistochemistry is provided, and the data emphasize that in general, for daily pathology, semiquantitative patterns should suffice. Indirect labeling of DNA has useful characteristics for application in microarray analyses because of the large signal enhancement.

Targeted expression of tetanus neurotoxin interferes with behavioral responses to sensory input in Drosophila

Targeted inactivation of neurons by expression of toxic gene products is a useful tool to assign behavioral functions to specific neurons or brain structures. Of a variety of toxic gene products tested, tetanus neurotoxin light chain (TNT) has the least severe side effects and can completely block chemical synapses. By using the GAL4 system to drive TNT expression in a subset of chemo- and mechanosensory neurons, we detected walking and flight defects consistent with blocking of relevant sensory information. We also found, for the first time, an olfactory behavioral phenotype associated with blocking of a specific subset of antennal chemoreceptors. Similar behavioral experiments with GAL4 lines expressing in different subsets of antennal chemoreceptors should contribute to an understanding of olfactory coding in Drosophila. To increase the utility of the GAL4 system for such purposes, we have designed an inducible system that allows us to circumvent lethality caused by TNT expression during early development.

A central neural circuit for experience-independent olfactory and courtship behavior in Drosophila melanogaster

We have studied the function of the major central olfactory pathway in fruit flies. Key elements of this pathway, the projection neurons (PNs), connect the antennal lobes with the lateral protocerebrum both directly and indirectly, the latter via the mushroom bodies (MBs). Transgenic expression of tetanus toxin in the majority of PNs and few MB neurons leads to defects in odor detection and male courtship. Considering behavioral data from flies lacking MBs, our results argue that the direct PN-to-lateral protocerebrum pathway is necessary and sufficient to process these experience-independent behaviors. Moreover, the involvement of an olfactory pathway in male courtship suggests a role of volatile attractive female pheromones in Drosophila.

Integrin receptors and their relationship to cellular proliferation and differentiation of oral squamous cell carcinoma. A quantitative immunohistochemical study

The expression of extracellular matrix (ECM) proteins (fibronectin, laminin, collagen IV) and ECM receptors of integrin type (alpha 2 beta 1, collagen receptor; alpha 6 chain of the fibronectin receptor; alpha 6 chain of the laminin receptor) were examined in normal oral squamous epithelium and in invasive areas of squamous cell carcinomas with various differentiation and proliferation activities (Ki-67 antigen labelling), evaluating the presence, quantity (using an image analysis system) and distribution of the integrin subunits. In the mucosa, there was uniform immunostaining for alpha 2 beta 1 and alpha 6 concentrated at the cell membrane in the basal/supra basal cell zone, whereas, alpha 5 showed a discontinuous staining of the basal cell-basement membrane interface. alpha 2 and alpha 6 could be visualized in all carcinomas. alpha 5 showed low expression preferentially in less differentiated carcinomas. In contrast to normal mucosa, there was an increase in alpha 6 staining in well-differentiated carcinomas. Dedifferentiation of oral carcinomas was accompanied by an increase in cellular proliferation and with a decrease in alpha 2 beta 1 and alpha 6 staining. This reduction of alpha 6 staining was shown to be statistically significant, suggesting that this integrin may be a valuable grading parameter for oral squamous cell carcinoma.