Effect of adjuvant chemotherapy on localized dedifferentiated low-grade osteosarcoma: a systematic review

PURPOSE

Dedifferentiated low-grade osteosarcomas, which are considered high grade malignancies, can arise from the dedifferentiation of parosteal and low-grade osteosarcomas. Usually, localized dedifferentiated low-grade osteosarcomas are treated by wide resection, and the efficacy of adjuvant chemotherapy is controversial. We conducted a systematic review of studies that investigated the rates of mortality and significant events, such as recurrence and metastases, in localized dedifferentiated low-grade osteosarcoma patients who received wide resection only and in those who received wide resection and (neo-)adjuvant chemotherapy.

METHODS

We identified 712 studies through systematic searches of Embase, PubMed, and the Cochrane Central Register of Controlled Trials databases. Of those studies, seven were included in this review and none were randomized controlled trials. In the seven studies, 114 localized dedifferentiated low-grade osteosarcoma patients were examined.

RESULTS

Mortality rates of the resection plus chemotherapy (R + C) and the resection only (Ronly) groups were 20.3% and 11.4%, respectively [overall pooled odds ratio, 1.59 (P = 0.662); heterogeneity I2, 0%]. The local recurrence or distant metastasis rate in the R + C group was 36.7% and that in the Ronly group was 28.6% [overall pooled odds ratio, 1.37 (P = 0.484); heterogeneity I2 was 0%].

CONCLUSIONS

Results show a limited efficacy of adjuvant chemotherapy for localized dedifferentiated low-grade osteosarcoma. However, because this was a systematic review of retrospective studies that examined a small number of patients, future randomized controlled trials are needed.

Current Concepts in the Treatment of Giant Cell Tumor of Bone: An Update

Curettage is recommended for the treatment of Campanacci stages 1-2 giant cell tumor of bone (GCTB) in the extremities, pelvis, sacrum, and spine, without preoperative denosumab treatment. In the distal femur, bone chips and plate fixation are utilized to reduce damage to the subchondral bone and prevent pathological fracture, respectively. For local recurrence, re-curettage may be utilized when feasible. En bloc resection is an option for very aggressive Campanacci stage 3 GCTB in the extremities, pelvis, sacrum, and spine, combined with 1-3 doses of preoperative denosumab treatment. Denosumab monotherapy once every 3 months is currently the standard strategy for inoperable patients and those with metastatic GCTB. However, in case of tumor growth, a possible malignant transformation should be considered. Zoledronic acid appears to be as effective as denosumab; nevertheless, it is a more cost-effective option. Therefore, zoledronic acid may be an alternative treatment option, particularly in developing countries. Surgery is the mainstay treatment for malignant GCTB.

Is perioperative chemotherapy effective in patients with localized myxoid liposarcoma?

BACKGROUND

This study aimed to compare the local recurrence, distant metastasis and disease-specific survival rates of patients with localized myxoid liposarcoma in the surgery and adjuvant chemotherapy group versus the surgery alone group.

METHODS

A total of 456 patients in the Japanese National Bone and Soft Tissue Tumour Registry database who had localized myxoid liposarcoma and underwent surgery and adjuvant chemotherapy or surgery alone between 2001 and 2019 were included in this retrospective study. The study adjusted for background differences between patients who underwent surgery and adjuvant chemotherapy (n = 228) or surgery alone (n = 228) using propensity score matching.

RESULTS

Univariate analysis showed no significant difference in local recurrence rate between the two groups (5-year local recurrence-free survival: 98.6% [95% confidence interval: 95.9-99.6] vs. 94.0% [95% confidence interval: 89.7-96.6], P = 0.052). Univariate analysis showed no difference in the incidence of distant metastases between the two groups (5-year distant metastasis-free survival: 80.5% [95% confidence interval: 73.9-85.8] vs. 75.1% [95% confidence interval: 67.7-81.2], P = 0.508). Univariate analysis showed no difference in disease-specific survival between the two groups (5-year disease-specific survival: 92.6% [95% confidence interval: 86.1-96.2] vs. 93.2% [95% confidence interval: 87.6-96.4], P = 0.804). In the high-risk group (n = 203) with high-grade tumours and tumour size ≥10 cm, there were no significant differences in the local recurrence, distant metastasis and disease-specific survival rates between the surgery and adjuvant chemotherapy group and the surgery alone group.

CONCLUSION

The effect of adjuvant chemotherapy on localized myxoid liposarcoma appears to be limited.

A Systematic Review of Adjuvant Chemotherapy in Localized Dedifferentiated Chondrosarcoma

Dedifferentiated chondrosarcoma (DDCS) is a high-grade subtype of chondrosarcoma with the bimorphic histological appearance of a conventional chondrosarcoma component with abrupt transition to a high-grade, non-cartilaginous sarcoma. DDCS can be radiographically divided into central and peripheral types. Wide resection is currently the main therapeutic option for localized DDCS. Moreover, the effectiveness of adjuvant chemotherapy remains controversial. Therefore, we performed a systematic review of available evidence to evaluate the effect of adjuvant chemotherapy on localized DDCS. The purpose was to compare the 5-year survival rate among patients treated with surgery plus adjuvant chemotherapy or surgery alone for localized DDCS. The search was conducted in PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Of the 217 studies shortlisted, 11 retrospective non-randomized studies (comprising 556 patients with localized DDCS) were selected. The 5-year survival rates were similar between the two treatment groups (28.2% (51/181) vs. 24.0% (90/375), respectively). The overall pooled odds ratio was 1.25 (95% confidence interval: 0.80-1.94; p = 0.324), and heterogeneity I2 was 2%. However, when limited to peripheral DDCS, adjuvant chemotherapy was associated with prolonged survival (p = 0.03). Due to the paucity of included studies and the absence of prospective comparative studies, no conclusions can be drawn regarding the effectiveness or ineffectiveness of adjuvant chemotherapy for localized DDCS.

Comparison of pre-operative and post-operative radiotherapy in patients with localized myxoid liposarcoma

BACKGROUND

Myxoid liposarcoma is more radiosensitive than other soft tissue sarcomas, and radiotherapy has been reported to reduce tumour size. This study was performed to compare the rates of local recurrence, survival and wound complications between pre- and post-operative radiotherapy for localized myxoid liposarcoma.

METHODS

From the Japanese Nationwide Bone and Soft Tissue Tumor Registry database, 200 patients with localized myxoid liposarcoma who received pre- (range, 30-56 Gy) or post-operative (range, 45-70 Gy) radiotherapy and surgery were included in this retrospective study. Propensity score matching was used to adjust for background differences between patients who received pre- and post-operative radiotherapy.

RESULTS

Local recurrence occurred in five (5.0%) and nine (9.0%) patients in the pre- and post-operative radiotherapy groups, respectively (both n = 100). The median follow-up time from diagnosis was 40.5 months (IQR, 26.3-74). Univariate analysis showed a similar risk of local recurrence between the pre- and post-operative radiotherapy groups (5-year local recurrence-free survival 94.9% [95% CI 87.0-98.1] vs. 89.0% [95% CI 79.6-94.3]; P = 0.167). Disease-specific survival was similar between the pre- and post-operative radiotherapy groups (5-year disease-specific survival 88.1% [95% CI 75.5-94.6] vs. 88.4% [95% CI 77.3-94.5]; P = 0.900). The incidence of wound complications was similar between the pre- and post-operative radiotherapy groups (7.0% vs. 12.0%; P = 0.228).

CONCLUSIONS

There was no difference in local recurrence, survival or incidence of wound complications between pre- and post-operative radiotherapy for localized myxoid liposarcoma. Therefore, pre-operative radiotherapy for myxoid liposarcoma provides clinical results equivalent to post-operative radiotherapy.

Megaprosthetic reconstruction of the distal femur with a short residual proximal femur following bone tumor resection: a systematic review

BACKGROUND

To investigate the risk of postoperative function and complications associated with reconstruction methods in patients with short residual proximal femurs (< 12 cm) after resection of distal femoral bone tumors, we performed a systematic review of studies reporting postoperative function and complications in these patients.

METHODS

Of the 236 studies identified by systematic searches using the Medline, Embase, and Cochrane Central Register of Controlled Trials databases, eight were included (none were randomized controlled trials). In these studies, 106 (68.4%), 12 (7.7%), and 37 (23.9%) patients underwent reconstruction with custom-made megaprostheses with extracortical plates or cross-pins, allograft prosthetic composite (APC), and Compress^® compliant pre-stress (CPS) implants, respectively.

RESULTS

Aseptic loosening occurred slightly more frequently in the APC group than in the other reconstruction methods (APC group, 21%; custom-made megaprosthesis group, 0-17%; CPS implant group, 14%). No differences were noted in the frequencies of implant breakage, fractures, or infections between the three reconstruction methods. Mechanical survival, where endpoint was set as implant removal for any reason, was 80% at seven years in the APC group, 70-77% at 10 years in the custom-made megaprosthesis group, and 68% at nine years in the CPS implant group. Therefore, there appeared to be no difference among the three reconstruction methods with respect to mechanical survival.

CONCLUSIONS

During megaprosthetic reconstruction of the distal femur with a short residual proximal femur after bone tumor resection, similar results were obtained using custom-made megaprostheses, APCs, and CPS implants.

A cryogenic linear ion trap beamline for providing keV ion bunches

A new cryogenic linear ion trap beamline has been constructed and commissioned, which serves to inject cold molecular and cluster ions into the RIKEN cryogenic electrostatic ring (RICE). Ions are created with an electrospray ion source, and a quadrupole mass filter is used for mass-selection prior to trap injection. The radio frequency octupole ion trap can be continuously loaded with ions and features a fast ion extraction mode to create short ion bunches with tens of μs duration. We report here on the simulations and development of the ion trap beamline and validate performance with the moderately heavy molecular cation methylene blue. Characterization of the novel trap design with additional wedge-shaped electrodes was carried out, which includes the determination of the temporal and spatial shape of the ion bunch and the total number of ions after extraction. Finally, these ion bunches are synchronized with the switching of a pulsed high-voltage acceleration device downstream of the trap, where the ions obtain a kinetic energy of up to 20 keV. The preparation and control of the keV ion beam are demonstrated for the ion injection into RICE.

Design and commissioning of the RIKEN cryogenic electrostatic ring (RICE)

A new electrostatic ion storage ring, the RIKEN cryogenic electrostatic ring, has been commissioned with a 15-keV ion beam under cryogenic conditions. The ring was designed with a closed ion beam orbit of about 2.9 m, where the ion beam is guided entirely by electrostatic components. The vacuum chamber of the ring is cooled using a liquid-He-free cooling system to 4.2 K with a temperature difference of 0.4 K at most within all the positions measured by calibrated silicon diode sensors. The first cryogenic operation with a 15-keV Ne⁺ beam was successfully performed in August 2014. During the measurement, the Ne⁺ beam was stored under a ring temperature of 4.2 K with a residual-gas lifetime of more than 10 min. This permits an estimation of the residual gas density at a few 10⁴ cm^-3, which corresponds to a room-temperature-equivalent pressure of around 1×10^-10 Pa. An effect of longitudinal pulse compression at the bunching cavity in the ring was clearly identified by monitoring the pick-up beam detector. The detailed design and mechanical structure of the storage ring, as well as the results from the commissioning run, are reported.

A Japanese-specific recurrent mutation and a novel splice site mutation in the LAMC2 gene identified in two Japanese families with Herlitz junctional epidermolysis bullosa

BACKGROUND

Herlitz junctional epidermolysis bullosa (H-JEB) is an extremely rare genodermatosis characterized by lethality owing to severe blister formation. We report two unrelated Japanese patients with H-JEB. Genetic analyses detected a single nonsense mutation on the LAMC2 gene in these two patients.

AIM

To identify the mutation involved and describe the first reported Japanese recurrent mutation in the LAMC2 gene.

METHODS

Direct sequencing was performed of DNA from either peripheral blood or fetal cells in amniotic fluid. Reverse transcriptase PCR was used to confirm that an aberrant transcript resulted from the splice site mutation. A haplotype analysis was performed to define the origin of the recurrent mutation.

RESULTS

Both patients had blisters and erosions on the trunk and limbs at birth, with nail dystrophy. Patient 1 died as a result of sepsis at 30 weeks of age, and patient 2 died as a result of disseminated intravascular coagulation at 20 weeks of age. Mutation analysis of the LAMC2 gene revealed that patient 1 was compound heterozygous for a nonsense mutation (p.Cys553X) and a novel splice site mutation (c.2868+1delG), and patient 2 was a homozygous for p.Cys553X. Prenatal diagnosis performed during a subsequent pregnancy in family 2 revealed that this second child was heterozygous for p.Cys553X, and was thus not affected. Haplotype analysis suggested that a p.Cys553X allele derived from the same origin had been independently inherited by these two unrelated families.

CONCLUSIONS

p.Cys553X in the LAMC2 gene may be a Japanese-specific recurrent mutation as a result of a founder effect, and it may therefore be useful for initial screening in the mutation analysis of H-JEB.

FK506 (tacrolimus) improves lung injury through inhibition of Fas-mediated inflammation

OBJECTIVE

To investigate whether FK506 (tacrolimus) can inhibit Fas- or A23187-induced interleukin (IL)-8 expression and cell death in A549 human alveolar epithelial cells, plus Fas-mediated acute lung injury in vivo.

METHODS

Assays for IL-8, cell death, and caspase-3 activity were performed. A549 cells were treated with 25 micromol A23187 or 0.2 microg/ml agonistic anti-Fas antibody plus 5 ng/ml interferon-gamma (IFN-gamma). Tacrolimus was treated at 0.1-10 ng/ml. For in vivo experiment, agonistic anti-Fas antibody (Jo2) at 2.5 microg/g was intratracheally instilled into C57BL/6 mice. Neutrophils and protein contents in bronchoalveolar lavage (BAL) fluid were measured within 24 h of instillation. Mice were orally treated with 32 mg/kg of tacrolimus 24 h and 1 h prior to instillation.

RESULTS

Both Fas and A23187 caused significant IL-8 expression and cell death in A549 cells. Tacrolimus inhibited A23187-induced IL-8 expression alone while it protected all Fas-mediated responses. Mice instilled intratracheally with Jo2 at 2.5 microg/g had significant increases in neutrophils, protein contents in BAL fluid and in expression of chemoattractants for neutrophils. These increases were reversed by tacrolimus.

CONCLUSIONS

Tacrolimus serves as a therapeutic option for improving lung injury through inhibition of Fas-mediated inflammation.

Immunomolecular mapping of adherens junction and desmosomal components in normal human epidermis

Adherens junctions (AJs) are cell-cell and cell-matrix junctions that are known to comprise the transmembrane and cytoplasmic components linked to the f-actin cytoskeleton. Although the presence of AJs han been confirmed in normal human epidermis, previous studies immunolocalizing AJ-related antigens have been controversial. The purpose of this study was to produce a more precise molecular mapping of AJs and their constituents in relation to desmosomes in normal human epidermal keratinocytes. Using an electron microscope (EM) method to optimally fix plasma membranes. AJ structures were typically seen as a narrowing of the intercellular space between two keratinocytes that was distinct from desmosomes and gap junctions. Such structures were consistently found more frequently in the upper epidermis than in the basal layer. Immunogold electron microscopy showed an absence of the AJ components (E-cadherin and beta-catenin) from desmosomal areas but they were present at interdesmosomal areas at sites of close membrane association. Conversely, the desmosomal components plakoglobin and plakophilin 1 were restricted only to the outer attachment plaque of the desmosome. These results further confirm that AJs have a distinct molecular composition and distribution from desmosomes and that they regularly occur between desmosomes along the keratinocyte plasma membrane to provide alternative cell-cell adhesion mechanisms.

Bone-specific delivery and sustained release of diclofenac, a non-steroidal anti-inflammatory drug, via bisphosphonic prodrug based on the Osteotropic Drug Delivery System (ODDS)

We have newly synthesized osteotropic diclofenac with bisphosphonic moiety (DIC-BP) based on the concept of Osteotropic Drug Delivery System (ODDS) and investigated its potency of site-specific and controlled delivery of diclofenac to the bone in rats. After intravenous injection into rats, DIC-BP was predominantly distributed in the skeleton. DIC-BP once incorporated in the bone was gradually eliminated (t(1/2)=9.7 days), releasing diclofenac into the bone compartment. As a result, the bone concentration of regenerated diclofenac was apparently constant over 28 days. Furthermore, we evaluated the anti-inflammatory effects of DIC-BP compared with diclofenac (sodium salt) in adjuvant-induced arthritic rats. The mean effective doses (ED(50)) were 0.55 mg/kg and 1.3 mg/kg for daily oral administration of diclofenac and weekly intravenous injection of DIC-BP, respectively. Considering the frequency of medication of 17 times for diclofenac and 4 times for DIC-BP in the experimental period, ED(50) was corrected to 9.4 and 5.2 mg/kg (per experimental period) for diclofenac and DIC-BP, respectively. Moreover, DIC-BP exhibited no side effects of gastrointestinal damage, typical of non-steroidal anti-inflammatory drugs. Thus, ODDS of diclofenac shows promise as an approach for highly potent and non-toxic therapy of diclofenac, with less frequent medication.

The extracellular domain of BPAG2 has a loop structure in the carboxy terminal flexible tail in vivo

The 180 kDa bullous pemphigoid antigen is a hemidesmosome-associated transmembranous protein with a molecule length estimated to be 190-230 nm, which is much longer than the transverse length of the lamina lucida and lamina densa. The purpose of this study was to clarify the precise in vivo structure of the 180 kDa bullous pemphigoid antigen in normal human skin. We used three monoclonal antibodies directed to (i) the intracellular globular head of the 180 kDa bullous pemphigoid antigen, (ii) the mid-portion of the flexible tail of the antigen, corresponding approximately to amino acids 1000-1320, and (iii) the carboxyl terminal end, corresponding approximately to amino acids 1320-1500 of the antigen. Using low temperature postembedding immunoelectron microscopy, we quantitated the distribution of immunogold labeling of these monoclonal antibodies in normal human skin. The results showed that the monoclonal antibodies (i) bound to the intracellular portion of the hemidesmosome at a mean distance of 20 nm from the plasma membrane, (ii) bound to the lamina densa beneath the hemidesmosome at a mean distance of 65 nm from the plasma membrane, and (iii) bound to the lamina densa-lamina lucida interface at a mean distance of 39 nm from the plasma membrane. Considering the reported size of the 180 kDa bullous pemphigoid antigen, our results indicate that the extracellular domain of the antigen has at least one loop structure in the lamina densa in vivo. This unique structure of the antigen is thought to contribute to dermo- epidermal adhesion by intertwining with other basement membrane components.

Glycine substitution mutations by different amino acids in the same codon of COL7A1 lead to heterogeneous clinical phenotypes of dominant dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB), caused by mutations in the gene encoding type VII collagen (COL7A1), is known to show heterogeneous clinical phenotypes. Certain correlations between the nature or position of COL7A1 mutations and the resultant DEB phenotypes have been suggested, although such relationships may be more complex than initially thought. The purpose of the present study was to clarify the molecular basis of two different subtypes of dominant DEB (DDEB), EB pruriginosa and classical type. Interestingly, we found that both cases were caused by a missense glycine substitution mutation by different amino acids in the same codon of COL7A1 (G2028R and G2028A). These results further support the notion that different glycine substitution mutations in the same codon can lead to heterogeneous clinical phenotypes of DDEB, EB pruriginosa and classical type.

Expression of plectin and HD1 epitopes in patients with epidermolysis bullosa simplex associated with muscular dystrophy

Plectin, a widespread cytoskeletal linker protein, is prominently expressed in basal keratinocytes of the epidermis. HD1, originally identified as a hemidesmosomal protein, has been suggested to be an isoform of or closely related to plectin, but the exact relationship between these proteins is unknown. Plectin has recently been identified as the gene/protein system at fault in epidermolysis bullosa simplex associated with muscular dystrophy (EBS-MD; OMIM# 226670). In this study, we examined the expression patterns of plectin and HD1 epitopes in the skin of four unrelated patients with EBS-MD confirmed to be caused by plectin gene mutations. By indirect immunofluorescence, all monoclonal antibodies (mAbs) to plectin (5B3, 10F6) or to HD1 (121, E2, K15, 156) bound to the epidermal basement membrane zone (BMZ) of normal human skin. In addition, immunostaining along the periphery of keratinocytes was detected with mAbs 5B3, 10F6 (antiplectin), K15 and 156 (anti-HD1), but not with mAbs 121 and E2 (anti-HD1). Immunolabeling for mAbs 5B3 and 10F6 (antiplectin) was absent in the skin of three patients who had premature termination codon mutations in the plectin gene in both alleles. In contrast, labeling was only slightly reduced in a patient who was homozygous for a 9-bp in-frame deletion mutation in the same gene. Interestingly, peripheral labeling of keratinocytes using mAbs K15 and 156 (anti-HD1) was clearly present in all the patients despite the disappearance of BMZ labeling. Quantitative analysis by postembedding immunoelectron microscopy demonstrated that both plectin and HD1 epitopes were localized in the inner plaque of hemidesmosomes with a mean distance of 110 and 120 nm from the plasma membrane, respectively. These results confirm the molecular heterogeneity of EBS-MD in terms of the expression patterns of plectin and HD1 epitopes which correlate with clinical severity, the pattern of plectin gene mutations and their consequences.

In vitro characteristics and in vivo plasma disposition of cisplatin conjugated with oxidized and dicarboxymethylated dextrans

In vitro release behavior and cytotoxic activity, and in vivo plasma disposition of newly synthesized macromolecular derivatives of cisplatin (CDDP) were investigated and compared with CDDP. The derivatives included oxidized dextran conjugate of CDDP (OX-Dex/CDDP) and dicarboxymethylated dextran conjugate of CDDP (DCM-Dex/CDDP). In vitro release of platinum complex from dextran conjugated CDDP was determined by an equilibrium dialysis method. These dextran conjugates showed sustained release of the platinum complex. In vitro release half-life for DCM-Dex/CDDP was significantly longer (4.5 times) than that for OX-Dex/CDDP. In vitro cytotoxic activity of CDDP and dextran conjugated CDDP against colon 26, mouse colon cancer cell line, was measured using the MTT assay method. OX-Dex/CDDP showed a similar cytotoxic activity to CDDP. However, both cytotoxic activities were markedly decreased when preincubated with the medium containing serum. On the other hand, DCM-Dex/CDDP retained residual cytotoxic activity at a significantly higher level than OX-Dex/CDDP after preincubation with the medium containing serum, although it showed the lowest cytotoxic activity. This indicated longer maintenance of the in vitro antitumor activity of DCM-Dex/CDDP in serum compared with OX-Dex/CDDP. Plasma disposition of CDDP and dextran conjugated CDDP was determined by intravenous administration to rats. Although the total platinum plasma concentration-time profile for OX-Dex/CDDP was similar to that for CDDP, its markedly higher profile was achieved when DCM-Dex/CDDP was administered. The values of the total platinum AUC and MRT, where AUC is the area under the platinum concentration-time curve and MRT is the mean residence time, for DCM-Dex/CDDP were 11.2 times and 4.8 times significantly higher than with OX-Dex/CDDP in plasma, respectively. DCM-Dex/CDDP also showed a significantly lower total clearance compared with OX-Dex/CDDP. These results from the in vivo experiments revealed that retention of DCM-Dex/CDDP in blood circulation was much greater than that for OX-Dex/CDDP. DCM-Dex/CDDP thus has potential as a macromolecular derivative of CDDP for passive tumor targeting.

Detection of antigens by immunofluorescence on ultrathin cryosections of skin

Cryoultramicrotomy was originally established to provide ultrathin cryosections as substrates for on-section immunolabeling in immunoelectron microscopy. Recently, we recognized that ultrathin cryosections of skin (0.2 micrometer thick) could serve as substrates for immunofluorescence (IF) with excellent resolution. To assess the advantages and the limitations of IF on ultrathin cryosections, we compared the labeling of IF on 0.2-micrometer ultrathin cryosections of skin with those of routine IF on 6-micrometer cryostat sections, confocal laser scanning microscopy (LSM), and immunogold electron microscopy using several markers of keratinocyte cell surface and basement membrane zone molecules. IF on ultrathin cryosections clearly demonstrated a lack of bullous pemphigoid antigens beneath the melanocytes, desmosomal antigens as discontinuous dot-like labeling, and nondesmosomal plasma membrane antigen as a ladder-like pattern. IF on ultrathin cryosections provided convincing images with higher resolution than confocal LSM, which corresponded well to those of immunogold electron microscopy. IF on ultrathin cryosections had superior resolution compared to routine IF or confocal LSM and should serve as a powerful tool in future studies for the analysis of skin antigens. (J Histochem Cytochem 46:1455-1460, 1998)

Evaluation of immunoelectron microscopic techniques in the study of basement membrane antigens

Recent technical advances in immunoelectron microscopy (IEM), including methods of pre- and postembedding IEM and cryoultramicrotomy, have helped to elucidate the precise ultrastructural localization of various basement membrane-related molecules. Our objective was to evaluate the advantages and disadvantages of several different techniques for studying the ultrastructural organization of basement membrane components. We found that, while "on-surface" immunolabeling of postembedding IEM and cryoultramicrotomy with anti-type IV collagen or anti-laminin-5 antibody clearly demonstrated dense labeling on the lamina densa, preembedding IEM with a 1-nm ultra-small gold probe showed labeling only on the epidermal and/or dermal surfaces of the lamina densa, with no specific gold particles being seen within the lamina densa itself. These results indicate that even ultra-small colloidal gold-labeled antibody fails to penetrate the lamina densa in preembedding IEM. However, labeling with a GB3 monoclonal antibody against laminin-5 was demonstrable with preembedding IEM and cryoultramicrotomy, but not with postembedding IEM, probably due to a loss of antigenicity. These results confirm the advantages and limitations of these techniques of IEM and emphasize the importance of using different techniques of IEM in determining the precise ultrastructural distribution of basement membrane antigens.

97 kDa linear IgA bullous dermatosis antigen localizes in the lamina lucida between the NC16A and carboxyl terminal domains of the 180 kDa bullous pemphigoid antigen

Linear IgA bullous dermatosis is an autoimmune blistering disease characterized by circulating IgA anti-basement membrane autoantibodies. A 97 kDa protein (97-LAD), which localizes at the basement membrane zone of normal human skin, is one of the major autoantigens associated with this disease and possesses multiple regions of amino acid identity with the extracellular domain of the 180 kDa bullous pemphigoid antigen, BPAG2. To investigate further the relationship between 97-LAD and BPAG2, immunogold electron microscopy was performed on cryo-ultrathin sections of normal human skin using a series of polyclonal and monoclonal antibodies. Gold particles immunolabeling two newly developed monoclonal antibodies against 97-LAD were localized to the lamina lucida. This immunolabeling pattern was associated with hemidesmosomes and localized at a mean distance of 28 nm beneath the plasma membrane of basal keratinocytes. In contrast, polyclonal antibodies against a fusion protein containing the NC16A domain of BPAG2 immunolabeled the plasma membrane of the hemidesmosomal complex, whereas polyclonal antibodies against the carboxyl terminus mainly immunolabeled the lower lamina lucida with a mean distance of 42 nm beneath the plasma membrane. By double immunolabeling, 97-LAD was localized as if being sandwiched between the NC16A and the carboxyl terminal domains of BPAG2. These results clearly demonstrated the co-localization of 97-LAD and the extracellular portion of BPAG2 in the lamina lucida, and suggested that 97-LAD is closely related to, and/or forms a complex with, the extracellular domain of BPAG2.

Precise ultrastructural localization of in vivo deposited IgG antibodies in fresh perilesional skin of patients with bullous pemphigoid

Bullous pemphigoid (BP) is a blistering skin disease in which the patient develops autoantibodies to the epidermal basement membrane zone. Using postembedding immunogold electron microscopy, we previously demonstrated that autoantibodies against the 230-kDa BP antigen (BPAG1) bind to the intracellular hemidesmosomal component of normal skin, whereas those against the 180-kDa BP antigen (BPAG2) bind only along the plasma membrane of hemidesmosomes. The purpose of the present study was to elucidate the precise localization of the in vivo deposited IgG antibodies in fresh perilesional skin of patients with BP. Samples of fresh perilesional skin were obtained from three patients with BP whose sera reacted only with BPAG1, only with BPAG2, and with both BPAG1 and BPAG2 upon immunoblotting using epidermal extracts. Cryofixed and cryosubstituted skin samples were used as a substrate for on-surface immunolabelling. In all three cases, most of the gold particles were observed close to the plasma membrane of the basal keratinocytes. A quantitative analysis revealed that most (> 80%) of the in vivo deposited IgG antibodies in the three cases were localized within 10 nm inside to 50 nm outside of the cell membrane, with a single peak observed 0-10 nm outside of the cells (> 50%). This distribution corresponded to the location of BPAG2, but not to that of BPAG1. These findings suggest that most, if not all, of the in vivo deposited IgG antibodies in the perilesional skin of BP are directed against BPAG2, rather than against BPAG1, thus further supporting the crucial role of anti-BPAG2 autoantibody in the initial stage of blister formation in BP.

Cross-linking of collagen by singlet oxygen generated with UV-A

Singlet oxygen (1O2), a highly reactive and toxic intermediate, may play a role in photo-induced aging. We examined singlet oxygen generation from hematoporphyrin (HP) with UV-A, by monitoring the emission at 1,268 nm corresponding to 1O2 --> 3O2. Singlet oxygen was formed HP-dose-dependently in this system. We then investigated the reaction of singlet oxygen generated by UV-A irradiation with collagen, which is related to skin elasticity and softness. Collagen from skin was rapidly and dose-dependently cross-linked by singlet oxygen. The reaction was inhibited by NaN3, a selective quencher of singlet oxygen. In contrast, SOD (superoxide dismutase) and mannitol had no effect. These results suggested that cross-linking of collagen was caused by UV-A-generated singlet oxygen, not by any other reactive oxygen species. Compared with another multisubunit protein, alcohol dehydrogenase, collagen was cross-linked much more efficiently. Further, the finding that semicarbazide inhibited cross-linking of collagen showed that cross-links were formed between photooxidized histidyl residues and amino groups. Singlet oxygen generated by UV-A irradiation may contribute to cross-linking of collagen in the process of skin photoaging.

The extracellular domain of BPAG2 localizes to anchoring filaments and its carboxyl terminus extends to the lamina densa of normal human epidermal basement membrane

Bullous pemphigoid antigen 2 (BPAG2) is a 180 kDa type II transmembrane protein associated with hemidesmosomes (HDs) in basal keratinocytes. To better understand how BPAG2 promotes keratinocyte adhesion to epidermal basement membrane (BM), purified IgG against a baculovirus-encoded recombinant was used to localize its carboxyl terminus in human skin by immunogold electron microscopy (IEM). A 2.1-kb BPAG2 cDNA encoding the distal extracellular domain and carboxyl terminus of BPAG2 was used in a baculovirus expression system to create virus that produced a 70-kDa recombinant form of BPAG2 (BV4). BV4 was purified, characterized, and used to raise high-titer specific rabbit IgG. Purified anti-BV4 IgG bound the epidermal side of 1 M NaCl split skin and bound only BPAG2 on immunoblots containing extracts of human keratinocytes. In IEM studies of pre- and post-embedded skin, the distal ectodomain of BPAG2 localized beneath HDs in basal keratinocytes; there was no evidence of BPAG2 beneath melanocytes. Anti-BV4 IgG extensively bound anchoring filaments on the epidermal side of 1 M NaCl split skin; this staining extended along anchoring filaments to their ends. In post-embedded skin, the carboxyl terminus of BPAG2 was localized within the lamina densa, 41 nm (mean of 400 determinations) beneath plasma membranes of basal keratinocytes. BPAG2 thus extends from the intracellular HD plaque of basal keratinocytes to the lamina densa of human epidermal BM.

Most anchoring fibrils in human skin originate and terminate in the lamina densa

Anchoring fibrils (AF) at the dermo-epidermal junction are well characterized as ultrastructural entities. They are composed mainly of collagen VII and play a key role in dermo-epidermal adhesion. Previous studies have suggested that AF originate in the lamina densa (LD), extend perpendicularly into the dermis, and insert into amorphous elements, called "anchoring plaques," in the dermal connective tissue. To elucidate the precise structural organization of the AF network in human skin, we analyzed quantitatively the distribution of different domains of collagen VII in the epidermal basement membrane zone, using various techniques of immunoelectron microscopy with a range of domain-specific antibodies that we prepared. Some electron-dense amorphous structures (ie, anchoring plaques) that were positive with aminoterminal end of collagen VII could be recognized only by pre-embedding en bloc labeling, and not by postembedding section labeling of immunoelectron microscopy. Quantitative analysis of surface labeling with postembedding immunoelectron microscopy demonstrated that most (> 90%) gold particles labeling the epitopes in the aminoterminal (NC-1 domain) of collagen VII were precisely localized to the LD, whereas no specific labeling was observed in the dermis. Most (> 90%) of the gold particles labeling the carboxyterminal end of collagen VII localized at a 160- to 360-nm distance from the LD, and most (> 90%) of the labeling epitopes in the central triple-helical collagenous domain were distributed between the LD and up to 360 nm from it; no specific labelings were observed beyond this area. These results suggest that most (> 90%), if not all, of the AF in human skin do not extend perpendicularly into the dermis, but instead originate and terminate in the LD, forming individual semicircular loops that constitute a network of AF.

Pheochromocytoma in a long-term hemodialysis patient, discovered as an adrenal incidentaloma

A case of pheochromocytoma was discovered incidentally during long-term hemodialysis for chronic renal failure due to acquired cystic kidney disease. A 52-year-old male patient was examined for weight loss of 3 kg during over a period of 3 months. Abdominal computed tomography (CT) revealed a left adrenal mass (3.0 cm in size). Plasma adrenaline and noradrenaline were increased to 521 pg/ml and 1,341 pg/ml, respectively, and the metoclopramide provocative test was positive. Further, in the scintiscan using 123I-metaiodobenzylguanidine (MIBG), an accumulation of the radionuclide in the left adrenal tumor region was confirmed. The patient is currently under observation and conservative treatment due to the possible occurrence of arterial hypotension after resection of the tumor and to lesser possibility of the malignancy.

Localization of laminin-5 in the epidermal basement membrane

Laminin-5 (kalinin/nicein/BM600) is a component of the epidermal basement membrane zone. Previous en bloc pre-embedding immunogold electron microscopy (EM) has shown that the epitope of GB3, a monoclonal antibody against laminin-5, is present in the lamina lucida (LL). However, precise localization of the entire laminin-5 molecule was unclear because of uneven and limited penetration of gold-labeled antibody in pre-embedding immunolabeling. In addition, the location of the GB3 epitope may not directly represent the location of the laminin-5 moelcule itself. To elucidate the precise ultrastructural distribution of the entire laminin-5 molecule, we used polyclonal antibodies against different sites of laminin-5. Dual staining immunofluorescence with anti-laminin-5 and anti-melanocyte antibodies and immunoperoxidase EM showed that laminin-5 was present only beneath keratinocytes and not beneath melanocytes. Both cryoultramicrotomy and postembedding immunogold EM demonstrated that laminin-5 was localized to the lamina densa (LD) and the lower LL, with major labeling beneath the hemidesmosome. Quantitative analysis showed that 67-69% of gold particles were distributed to the LD and 88-90% were distributed beneath the hemidesmosome. Our results indicate that laminin-5 is localized mainly to the LD and partially to the lower LL, and is associated predominantly with hemidesmosomes.

Application of non-radiolabeled in situ hybridization system for the detection of polyadenylated RNA to normal and psoriatic human skin

The concentration and distribution of total mRNA is thought to reflect cellular activity. To clarify the distribution of total mRNA in normal and psoriatic human skin, in situ hybridization with a digoxigenin-labeled poly(dT) probe was carried out. In normal skin, polyadenylated RNA was distributed uniformly throughout the epidermis, including the basal, spinous, and granular layers. The nucleus and cytoplasm of skin appendages were stained more strongly than those of epidermal cells. The concentration of total mRNA in the epidermis of psoriatic skin was thought to be increased because of strong staining, especially in the basal layer, compared with that in normal epidermis, possibly reflecting hyperproliferation of keratinocytes. Results suggest that in situ hybridization with a poly(dT) probe is a useful strategy to study total mRNA distribution in human skin.

Singlet oxygen (1 delta g) generation from coproporphyrin in Propionibacterium acnes on irradiation

Although singlet oxygen has been postulated to be a highly reactive and toxic intermediate, there has been no evidence of considerable generation of singlet oxygen in vivo level except for special cases. In this work, we firstly measured the near-infrared emission spectra corresponding to the O2(1 delta g) --> O2(3 epsilon g-) transition of singlet oxygen of cutaneous Propionibacterium acnes (P. acnes) porphyrin under laser excitation. A comparison of the singlet oxygen production of coproporphyrin, which is produced predominantly from P. acnes, with that of other photosensitizers revealed coproporphyrin to be a highly efficient singlet oxygen generator under ultraviolet light A irradiation on the skin. These results suggest that singlet oxygen can be generated on the skin surface from P. acnes porphyrin under ultraviolet irradiation and induce serious damage to the skin.

97-kDa linear IgA bullous dermatosis (LAD) antigen localizes to the lamina lucida of the epidermal basement membrane

Linear IgA bullous dermatosis (LAD) is an autoimmune blistering disease in which IgA autoantibodies develop against the epidermal basement membrane zone. Target antigens of the circulating autoantibodies are thought to be heterogeneous, and their ultrastructural localization has not been fully elucidated. Previous studies with immunoblotting have demonstrated that the 97-kDa autoantigen is detected most frequently in patients' sera and is thought to be a major LAD antigen. Although a recent report suggests that the 97-kDa antigen localized to the hemidesmosomal plaques and the adjacent lamina lucida, discrepancies still exist among previous immunoelectron microscopic findings. To identify the precise localization of the 97-kDa LAD antigen, we used two different low-temperature immunoelectron microscopic techniques. For immunolabeling, we selected five LAD sera that had a high titer of autoantibodies against the 97-kDa LAD antigen. A post-embedding method with cryofixation and freeze substitution failed to immunolabel the 97-kDa LAD antigen. Cryoultramicrotomy with immunoelectron microscopy succeeded in preserving the antigenicity of the 97-kDa LAD antigen. In all cases, the majority of labeling occurred in the lamina lucida beneath the hemidesmosomes. No specific labeling was observed in the hemidesmosomal attachment plaques or the lamina densa or sublamina densa region, including anchoring fibrils. These results indicate that the 97-kDa LAD antigen is a component of the lamina lucida.

Synthesis and cytotoxic activity of dextran carrying cis-dichloro(cyclohexane-trans-l-1,2-diamine)platinum(II) complex

cis-Dichloro(cyclohexane-trans-l-1,2-diamine)platinum(II) (Dach-Pt(chlorato)), is a platinum complex which is expected to exhibit higher antitumor activity than, and show no cross resistance with, cisplatin. However, its strong side-effects and low water-solubility have also been cited. We report that polymer/antitumor drug conjugates shows reduced side-effects and high antitumor activity. In order to provide a macromolecular prodrug of Dach-Pt having reduced side-effects and high water-solubility, we synthesized polymer conjugates of Dach-Pt and dextran derivatives having carboxylic acid groups, oxidized-dextran (OX-Dex)/Dach-Pt conjugate, and carboxymethyl-dextran(CM-Dex)/Dach-Pt conjugate. The cytotoxic activities of the conjugates were investigated against p388D1 lymphocytic leukemia cells in vitro. The OX-Dex/Dach-Pt conjugate showed almost the same level of cytotoxic activity as free Dach-Pt(chlorato). Although the cytotoxic activity of free Dach-Pt(chlorato) was decreased by incubation in medium with serum, the OX-Dex/Dach-Pt conjugate kept its cytotoxic activity in higher level after 24 h incubation in medium with serum. These results suggested that the stability of Dach-Pt molecule in the medium was increased and cytotoxic activity of Dach-Pt was not decreased by fixing to OX-Dex.

Measurement of 1268 nm emission for comparison of singlet oxygen (1 delta g) production efficiency of various dyes

Singlet oxygen generation from laser-excited photosensitive dyes was measured directly using a sensitive near-infrared emission spectrometer to monitor the O2(1 delta g)-->O2(3 sigma -g) transition at 1268 nm. The emission intensity was proportional to both the laser power and the concentration of the dyes. The singlet oxygen producing ability of the dyes was compared with that of eosin YS as a standard in methanol. The relative efficiencies of singlet oxygen generation were determined for rose bengal, erythrosine B, phloxine B and eosin YS as 2.39, 1.73, 1.38, 1.00, respectively, while uranine showed no emission in this spectral region. Using rose bengal, erythrosine B, phloxine B and eosin YS, the efficiency of singlet oxygen generation correlated with the photobleaching reaction rate of azo-dyes by these dyes, suggesting singlet oxygen to be a species responsible for causing the photobleaching of azo-dyes. The halogen substituent effect on the efficiency of singlet oxygen generation from laser-excited photosensitive dyes was also examined systematically.

Dystrophic form of inherited epidermolysis bullosa in a dog (Akita Inu)

We report a dog with dystrophic epidermolysis bullosa. This 4-year-old female Akita Inu, a species of Canis familiaris var. japonicus Temminck, had a 3-year-history of ulcers and scars over the pressure areas on the limbs, and dystrophic nails, since the age of 1 year, which corresponds to early adulthood in humans. Electron microscopy of a blister revealed separation beneath the lamina densa, and a reduction in the number of anchoring fibrils. The NC-1 domain of type VII collagen was positively stained with monoclonal antibody LH7.2 at the basement membrane zone. These findings indicate that humans and dogs have a similar response to antibody LH7.2, which may aid the development of an animal model for this disease.

Pemphigus vulgaris and pemphigus foliaceus sera show an inversely graded binding pattern to extracellular regions of desmosomes in different layers of human epidermis

We analyzed the location of binding sites for pemphigus vulgaris (PV) antigen and pemphigus foliaceus (PF) antigen in the human epidermis using serum samples obtained from three patients with PV and three patients with PF. Confocal laser scanning microscopy, immunofluorescent examination of ultrathin cryosections, and immunoperoxidase electron microscopy demonstrated discontinuous dots along the epidermal cell surfaces. Immunogold electron microscopy of ultrathin cryosections showed specific binding of PV and PF autoantibodies only to desmosomes. Post-embedding immunogold electron microscopy using cryofixation and cryosubstitution enabled the whole depth of the epidermis to be examined and the binding of PV and PF autoantibodies to be quantitated by counting gold particles. Both PV and PF autoantibodies bound to all desmosomes in the epidermis, but not to the surface of the non-desmosomal keratinocytes. The majority of auto-antibody binding occurred in the extracellular domain (PV, 62%; PF, 69%). The statistical analysis of two-way analysis of variance regarding the number of gold particles labeling a single desmosome confirmed a significant interaction between subtypes of pemphigus (PV and PF) and the different epidermal cell layers (p < 0.044). The results indicate that the number of gold particles bound to individual desmosomes with PV sera was significantly higher in the lower epidermis than in the upper epidermis, and that of PF sera showed reciprocal pattern. This inversely graded binding pattern suggests heterogeneity of the composition of the desmosomes, which may explain the differences in level of acantholysis between PV and PF.

Desmoyokin/AHNAK protein localizes to the non-desmosomal keratinocyte cell surface of human epidermis

Desmoyokin, a high-molecular-weight protein of 680 kD with a 170-nm-long dumbbell shape, was originally thought to be localized to the desmosomal attachment plaque and to work as a kind of stabilizer of desmosomes. Recently, desmoyokin was shown to be widely detected in many types of cells that do not possess desmosomes. The purpose of the present study was to elucidate the precise localization and possible function of desmoyokin in human epidermis. In 0.2-micron ultrathin cryosections of human skin for immunofluorescence, anti-desmoyokin antibody showed a ladder-like staining pattern along the cell surface, whereas anti-desmocollin and anti-desmoplakin antibodies as controls showed a discontinuous dotted staining pattern, indicating their distinct localization. Post-embedding immunoelectron microscopy with cryofixation and cryosubstitution revealed that desmoyokin was localized mainly along the non-desmosomal and non-hemidesmosomal plasma membrane, but not to the desmosomes and hemidesmosomes themselves. This localization was further confirmed by double-labeling immunoelectron microscopy with antibodies against desmocollin, desmoplakin, or bullous pemphigoid antigen. Results indicate that desmoyokin was not localized to the desmosomes themselves as previously considered. Desmoyokin was localized to the non-desmosomal and non-hemidesmosomal epidermal keratinocyte cell surface as a plasma membrane-associated protein, and might play a role in cell adhesion that is not directly associated with desmosomes or hemidesmosomes.

Autoantibodies from patients with cicatricial pemphigoid target different sites in epidermal basement membrane

Indirect immunogold electron microscopy studies of cryofixed, freeze-substituted, and post-embedded normal human skin were performed to localize precisely the ultrastructural binding site of circulating autoantibodies from two groups of patients with cicatricial pemphigoid. One group of patients had circulating IgG autoantibodies that bound the dermal side of 1 M NaCl-split skin and immunoprecipitated epiligrin. The other group of patients had circulating IgG autoantibodies directed against the epidermal side of 1 M NaCl-split skin and showed no specific reactivity to any keratinocyte polypeptide by immunoprecipitation. IgG autoantibodies from all patients with anti-epiligrin cicatricial pemphigoid bound the lowermost aspect of the lamina lucida at its interface with the lamina densa; the greatest staining was seen beneath and beside hemidesmosomes. In contrast, IgG from cicatricial pemphigoid patients whose autoantibodies bound the epidermal side of 1 M NaCl-split skin localized to hemidesmosomes and the junction between hemidesmosomes and the plasma membranes of basal keratinocytes. Although the latter staining pattern is similar to that observed with anti-BPAG2 autoantibodies, sera from our patients with cicatricial pemphigoid did not bind BPAG2 in immunoprecipitation studies of radiolabeled human keratinocyte extracts or show immunoblot reactivity to a fusion protein corresponding to the immunodominant epitope of this polypeptide. These studies demonstrate the following: 1) Autoantibodies from patients with anti-epiligrin cicatricial pemphigoid consistently bind the lower lamina lucida at its interface with the lamina densa; and 2) other patients with the same phenotype may have IgG autoantibodies against yet-unknown epitopes in basal keratinocytes.

Delayed assembly of desmosomes in keratinocytes with disrupted classic-cadherin-mediated cell adhesion by a dominant negative mutant

We examined whether classic cadherins play a role in the formation of desmosomes using a mouse keratinocyte, PAMcN390 delta cell, which shows disrupted classic-cadherin-mediated cell adhesion by introduction of a dominant-negative mutant of N-cadherin. The expression of the mutant did not alter that of endogenous E-cadherin or desmoplakin. In control cells with functional classic cadherins, we observed redistribution of desmoplakin to cell-cell borders with insertions of keratin filaments at the contact sites as soon as 2 h after calcium elevation, after an earlier event of E-cadherin translocation to the cell-cell contact sites. In contrast, in the PAMcN390 delta cells, which showed retarded translocation of E-cadherin, the redistribution of desmoplakin and the rearrangement of keratin filaments were delayed as late as 24 h after the calcium elevation. The acquisition of Nonidet P-40 insolubility of desmoplakins also was found to be delayed in the PAMcN390 delta cells. These findings indicate that the disruption of classic cadherin affected the organization of desmosomes upon calcium elevation and suggest that the proper function of classic cadherins is a prerequisite for desmosome assembly in keratinocytes.

Septic pulmonary emboli secondary to pyogenic liver abscess in a diabetic patient

A 70-year-old woman with poorly controlled diabetes mellitus was admitted because of persistent remittent fever. Soon a liver abscess was detected as the cause of the fever by ultrasonography, and antibiotic therapy was started. However, suddenly serious dyspnea with chest and back pain developed. The morbid condition was definitely diagnosed as septic pulmonary emboli (SPE) with pulmonary perfusion scan. It should be recognized that liver abscess can be a latent focus of systemic metastatic complications such as SPE, and not only early detection but also prompt appropriate drainage of liver abscesses is essential.