Immune-camouflaged graphene oxide nanosheets for negative regulation of phagocytosis by macrophages

Signal regulatory protein alpha (SIRPα) is highly expressed in macrophages of the reticuloendothelial system and in tumor-associated macrophages, whereas tumor cells express the surface membrane protein, CD47, which interacts with SIRPα to negatively regulate phagocytosis. In this study, we modified the surfaces of graphene oxide (GO) nanosheets with a CD47-like SIRPα-binding peptide (SP). The presence of SP on GO nanosheets reduced the macrophage uptake to a greater extent than the PEGylation of such nanosheets. This reduced uptake was found to be mediated by the activation of Src homology region 2 domain-containing phosphatase 1 (SHP-1) and the downstream inhibition of myosin assembly, which is necessary for phagosome formation. Unlike SP-coated GO nanosheets, PEGylated GO nanosheets did not affect myosin assembly or phagocytosis. After in vivo systemic administration, the clearance of SP-coated GO nanosheets was slower than that of PEGylated GO nanosheets, and this difference increased with repeated administration. Finally, SP-coated GO nanosheets showed a higher distribution to tumor tissues than PEGylated GO nanosheets or a physical mixture of SP and GO nanosheets. Our findings indicate that immune-camouflaged GO nanosheets with natural CD47-like SIRPα-binding molecules can reduce the nonspecific loss of such nanosheets through macrophage uptake, thereby enhancing their blood circulation and tumor delivery after multiple injections.

Paraneoplastic pemphigus without an underlying neoplasm

We describe a 52-year-old man with paraneoplastic pemphigus (PNP) without any evidence of an underlying neoplasm over an 8-year follow-up period. He had a chronic relapsing vesiculobullous eruption for approximately 7 years (from April 1998 to May 2005). Initially, scattered flaccid vesicles with crusts developed on the face and trunk, which waxed and waned several times. Our patient was diagnosed as having PNP based on immunopathological criteria for PNP, i.e. histopathological, immunoblotting and immunoprecipitation analyses. However, physical and laboratory examinations including serial blood tests with peripheral blood smear, whole-body positron emission tomography/computed tomography and abdominal ultrasound were unable to detect any underlying neoplasm over an 8-year follow-up period.

Sera from patients with toxic epidermal necrolysis contain autoantibodies to periplakin

BACKGROUND

The pathophysiological mechanism of toxic epidermal necrolysis (TEN) with extensive bullae that is induced suddenly by drugs is not well understood. The individual patterns and distribution of the widespread mucocutaneous reactions of TEN often show striking similarities with those of paraneoplastic pemphigus (PNP), which is known to involve autoantibodies (aAbs) to members of the plakin family.

OBJECTIVES

To investigate the existence of circulating aAbs to periplakin in the sera of patients with TEN.

METHODS

The presence of circulating aAbs to periplakin was examined using immunoblotting, immunoabsorption and indirect immunofluorescence (IF) analyses. Recombinant protein expression was used to determine the interaction between periplakin and aAbs in the sera of patients with TEN.

RESULTS

Indirect IF studies revealed circulating aAbs in the intercellular area in the epidermis. Interestingly, on rat bladder the staining pattern of the IgG deposits was similar to that observed in patients with PNP. Immunoblotting analysis of the epidermal extracts was used to identify the aAbs in the sera of patients with TEN. These contained circulating aAbs to a 190-kDa protein corresponding to periplakin. Recombinant periplakin and domains of periplakin were prepared in order to confirm the existence of aAbs to periplakin. Immunoblotting with these proteins demonstrated that the sera from patients with TEN reacted with each domain as well as with the full-length periplakin.

CONCLUSIONS

We found that circulating aAbs in the sera of patients with TEN target periplakin. These aAbs might play a role in the pathogenesis of TEN as a humoral autoimmune mechanism.

Tob is a potential marker gene for the basal layer of the epidermis and is stably expressed in human primary keratinocytes

BACKGROUND

Epidermis consists of multiple layers, from the proliferating basal layer to terminal differentiated cornified layers, and these layers are defined by differentiation status. Tob gene product is known to be a member of the BTG antiproliferative protein family. We investigated the expression pattern of Tob gene product to understand the possible role in differentiation of keratinocytes and epidermis.

OBJECTIVES

In this study, we examined the expression of Tob gene product in the primary cultured human keratinocytes and in the in vivo epidermis.

METHODS

The expression of Tob gene product was assessed by Western blotting analysis. Cellular localization of Tob was detected using the green fluorescent protein-tagged Tob cDNA expression construct. In vivo expression of Tob gene product in the epidermis was determined by immunohistochemistry with paraffin sections.

RESULTS

Tob family members are degraded by the ubiquitine-proteasome system triggered by the growth signal. Tob is stably and abundantly expressed in primary cultured human keratinocytes. Furthermore, the expression of Tob in the keratinocytes persists during the differentiation induced by calcium; however, it was not detected in primary cultured fibroblasts. Also, the subcellular localization of Tob is mainly in the cellular membrane in the primary human keratinocytes. We evaluated Tob expression in normal skin, oral mucosa and different diseases, such as psoriasis, X-linked ichthyosis and squamous cell carcinoma (SCC). Using immunohistochemical analysis, we observed that Tob was selectively expressed in the basal layer of X-linked ichythyosis and the hyperproliferative basal layer of psoriasis and oral mucosa as well as in normal epidermis. In SCC, the expression of Tob gene product was relatively decreased.

CONCLUSIONS

Tob is stably expressed in primary human keratinocytes and it is specifically expressed in the basal layer of in vivo epidermis.

Sporadic inclusion body myositis correlates with increased expression and cross-linking by transglutaminases 1 and 2

Sporadic inclusion body myositis (SIBM) is characterized by vacuolar degeneration of muscle fibers and intrafiber clusters of paired helical filaments with abnormal amyloid deposition. Because of their potential involvement in other degenerative disorders, we have examined the expression of transglutaminases (TGases) in normal and SIBM tissues. We report that at least two different enzymes, the ubiquitous TGase 2 as well as the TGase 1 enzyme, are present in muscle tissues. However, in comparison with normal tissue, the expression of TGases 1 and 2 was increased 2.5- and 4-fold in SIBM, accompanied by about a 20-fold higher total TGase activity. By immunohistochemical staining, in normal muscle, TGase 2 expression was restricted to some endomysial connective tissue elements, whereas TGase 1 and beta-amyloid proteins were not detectable. In SIBM muscle, both TGases 1 and 2 as well as amyloid proteins were brightly expressed and co-localized in the vacuolated muscle fibers, but none of these proteins colocalized with inflammatory cell markers. Next, we isolated high molecular weight insoluble proteins from SIBM muscle tissue and showed that they were cross-linked by about 6 residues/1000 residues of the isopeptide bond. Furthermore, by amino acid sequencing of solubilized tryptic peptides, they contain amyloid and skeletal muscle proteins. Together, these findings suggest that elevated expression of TGases 1 and 2 participate in the formation of insoluble amyloid deposits in SIBM tissue and in this way may contribute to progressive and debilitating muscle disease.

Interaction of hepatitis B viral X protein and CCAAT/ enhancer-binding protein alpha synergistically activates the hepatitis B viral enhancer II/pregenomic promoter

The hepatitis B viral X protein (HBx) is known to exert its transactivation activity by the interaction with several cellular transcription factors. Here we report the interaction of HBx and CCAAT/enhancer-binding protein alpha (C/EBPalpha) and their effects on the enhancer/promoters of hepatitis B virus (HBV). A chloramphenicol acetyltransferase assay showed that the cotransfection of HBx and C/EBPalpha strongly activated the enhancer II/pregenomic promoter of HBV in a synergistic manner. This effect was also observed in the heterologous expression system with promoters of SV40 and herpes simplex virus thymidine kinase genes. Serial deletion analysis of the enhancer II/pregenomic promoter identified the responsible region (nucleotides 1639-1679), in which two C/EBP-binding sites are located. An in vitro interaction assay and electrophoretic mobility shift assay showed that HBx augmented the DNA binding activity of C/EBPalpha by direct interaction with it, and its basic leucine zipper domain was responsible for the interaction with HBx. Domain analysis of HBx showed that the central region (amino acids 78-103) was necessary for direct interaction with C/EBPalpha. However, the complete form of HBx was necessary for the synergistic activation of the HBV pregenomic promoter. These results suggest that the interaction of HBx and C/EBPalpha enhances the transcription of the HBV pregenomic promoter for the effective life cycle of HBV in hepatocytes.

A case of pancytopenia secondary to low-dose pulse methotrexate therapy in a patient with rheumatoid arthritis and renal insufficiency

Most reports on serious MTX toxicity have focused on hepatic abnormalities, while other effects, including hematologic reactions, have not been emphasized. We experienced a case of pancytopenia secondary to MTX therapy in a patient with RA and renal insufficiency. A 67-year-old woman with a 12-year history of active seropositive RA that was a response to non-steroidal anti-inflammatory drugs, hydroxychloroquinine and intra-articular steroid injections, had been followed up and was diagnosed as early chronic renal failure in October, 1993. Recently, because of significant morning stiffness and polyarthralgia, the decision was made to institute MTX treatment. This was begun as a single oral dose of 5mg/week. After 2 doses, the patient was admitted to the hospital with general weakness. Laboratory tests showed a hemoglobin level of 7.9 g/dl, WBC count 1800/mm3 and platelet count of 64000/mm3. The serum creatinine level was 6.1 mEq/dl and the BUN level was 82 mEq/dl. Liver function test results were normal, but the serum albumin level was 2.7 g/dl. The patient subsequently developed fever and blood transfusions, granulocyte colony stimulating factor (G-CSF) and intravenous prophylactic antibiotic therapy were required. Her condition was improved. In summary, Low-dose MTX-related adverse hematologic side effects, including fatal pancytopenia, are rare but are a cause of increasing concern in patients with RA and renal insufficiency. Close monitoring of associated risk factors, particularly impaired renal function, should be mandatory for all patients who are receiving MTX therapy.

A case of type IIa early gastric cancer developed in pernicious anemia

Pernicious anemia is an autoimmune disease characterized by a gastric mucosal defect which results in an insufficiency of intrinsic factor to facilitate the absorption of the physiologic amount of cobalamin. Increased risk of cancers of the stomach has been reported for patients with pernicious anemia. We report here a case of a 65 year old woman who had been diagnosed as having pernicious anemia 16 months previously, was receiving monthly vitamin B12 injections, and developed early gastric cancer type IIa by routine follow-up gastroscopic examination. This patient underwent endoscopic mucosal resection for an early gastric cancer lesion with a free resection margin.

A negative regulatory element and its binding protein in the upstream of enhancer II of hepatitis B virus

The hepatitis B virus (HBV) core/pregenomic promoter is regulated by enhancer I (ENI) and enhancer II (ENII) which are located upstream of the initiation sites of core/pregenomic transcripts. In this study, we identified a negative regulatory element (NRE) (nt 1576 to 1639) upstream of ENII by serial deletion analysis; a 33 kDa cellular protein in HepG2 cells binds to this element. The NRE has a significant activity if it is located upstream of ENII in HepG2 cells. Mutational analysis showed that the sequence (5'-CCAC-3') from nt 1612 to 1615 is responsible for the repression activity of NRE. Southwestern blotting and UV-crosslinking assays with HepG2 nuclear extracts also demonstrated that the 33 kDa protein in HepG2 cells binds to the sequence. It, thus, appears that the 33 kDa protein is responsible for the repression activity of NRE.

Activating transcription factor 2 (ATF2) down-regulates hepatitis B virus X promoter activity by the competition for the activating protein 1 binding site and the formation of the ATF2-Jun heterodimer

The hepatitis B viral X promoter is known to be positively autoregulated by its own HBx protein, which also interacts with many cellular regulatory proteins. We investigated the effect of activating transcription factor 2 (ATF2) on the activity of the X promoter. Cotransfection of the ATF2 expression vector with a X promoter-chloramphenicol acetyltransferase plasmid repressed the X promoter activity in HepG2 cells. HBx activated activating protein 1 (AP-1)-mediated transcription through the hepatitis B virus E element by 35-fold, while its activation activity was inhibited in the presence of ATF2, suggesting that ATF2 inhibited the autoactivation of X promoter by HBx and basal transcription mediated by AP-1. Since the binding sites of AP-1 and ATF2 in the hepatitis B virus E element overlap, the repression of X promoter activity by ATF2 is exerted by the competition for the AP-1 binding site and the formation of the ATF2-Jun heterodimer as in the case of the consensus AP-1 element. However, the small X promoter had a ATF2 binding site and was activated by ATF2. These results suggest that the syntheses of X proteins are differentially regulated by ATF2.

Renal potassium wasting and hypocalciuria ameliorated with magnesium repletion in Gitelman's syndrome

A woman aged 45 years was presented with hypokalemic metabolic alkalosis and hypomagnesemia associated with renal potassium and magnesium wasting. Her 24-hour urinary calcium excretion was strikingly low despite normocalcemia and normal creatinine clearance, which is one of characteristic findings of Gitelman's syndrome (GS). She was evaluated for the responses following Mg supplementation for 10 days, which showed marked increments in serum potassium and magnesium as well as improvements of the degree of renal potassium wasting and hypocalciuria. This amelioration of abnormal biochemical pictures in this patient after Mg supplementation proposes that the hypokalemia with renal potassium wasting and hypocalciuria may be caused by abnormal Mg metabolism.

The retinoblastoma gene product activates transcription of the hepatitis B virus pregenomic promoter through the Sp1 binding sites

The hepatitis B virus (HBV) pregenomic promoter is regulated by two enhancers and cis-elements. We have studied whether the retinoblastoma susceptibility gene product (Rb) modulates the activity of the HBV pregenomic promoter. Cotransfection of the Rb expression vector, phRB, with pCENCAT (containing the pregenomic promoter region: nt 248-1874) increased transcription from the HBV pregenomic promoter in HepG2 cells. Deletion analysis of the pregenomic promoter indicated that the region between nt -96 and -66, which contains two Sp1 binding sites, is responsible for activation by Rb. Mutation of the Sp1 binding sites abolished activation of the pregenomic promoter by Rb in the heterologous and natural promoter context. Therefore, our results suggest that Rb can activate the HBV pregenomic promoter through the Sp1 binding sites.

A positive regulatory sequence of hepatitis B viral small X promoter

Hepatitis B viral X protein (HBx) and small X proteins (HBSx) are known to transactivate promoters for RNA polymerase II and RNA polymerase III. Small X promoter has been mapped in the 5'-distal half of the X open reading frame. A 5'-serial deletion analysis showed that there was a positive regulatory sequence for the efficient transcription of the small X promoter. Two cellular proteins of 110 kDa (p110) and 33 kDa (p33) bound at the 3' and 5' regions of the regulatory sequence, respectively. Mutation of p33-binding and p110-binding sites led to diminution and elevation, respectively, of activation properties of the positive element, suggesting that p33 participates in the transactivation and that p110 has an inhibitory effect on the function of p33. This possibility was further supported by the result demonstrating that in vitro phosphorylation of p110 reduced its target DNA-binding capability.

Upper gastrointestinal endoscopy in an urban hospital in northern Nigeria: association of presenting features with endoscopic findings

In 326 fibreoptic upper gastrointestinal (GI) endoscopies performed in Evangel Hospital (Jos, Nigeria), pathology was found in 210 patients, and of a major nature such as peptic ulcer disease or cancer in 129 of these. The three most useful features to predict the presence of major pathology were epigastric tenderness (the single most useful feature), loss of weight and epigastric pain of a burning nature. These features were selected by stepwise discriminant analysis, which also led to the conclusion that the presence of at least two of these three features is an even more powerful predictor of major pathology.