APMIS

Statins, 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase inhibitors, have been shown to ameliorate a number of vascular diseases. We evaluated the inflammatory and angiogenic components of the fibrovascular tissue induced by subcutaneous implants in mice and their modulation by fluvastatin. Our results showed that the statin (0.6 and 6 mg/kg/day) inhibited hemoglobin (Hb) content (51%) and vascular endothelial growth factor (VEGF) levels (71%) in the treated group compared with the control group. The inflammatory component, as assessed by N‐acetyl‐β‐D‐glucosaminidase activity and tumor necrosis factor‐α (TNF‐α) level was also decreased by the compound. In the treated group; the inhibition of the enzyme activity was 33% and the cytokine was 67% relative to the control. In these implants the statin was also able to decrease nitric oxide (NO) production, detected with an NO‐sensitive electrode. To our knowledge this is the first study demonstrating an inhibitory role of fluvastatin on the production of NO in inflammatory angiogenesis of newly formed fibrovascular tissue.

Teeth are colonized by oral bacteria from saliva containing more than 700 different bacterial species. If removed regularly, the dental biofilm mainly comprises oral streptococci and is regarded as resident microflora. But if left undisturbed, a complex biofilm containing up to 100 bacterial species at a site will build up and may eventually cause development of disease. Depending on local ecological factors, the composition of the dental biofilm may vary considerably. With access to excess carbohydrates, the dental biofilm will be dominated by mainly gram‐positive carbohydrate‐fermenting bacteria causing demineralization of teeth, dental caries, which may further lead to inflammation and necrosis in the pulp and periapical region, i.e., pulpitis and periapical periodontitis. In supra‐ and subgingival biofilms, predominantly gram‐negative, anaerobic proteolytic bacteria will colonize and cause gingival inflammation and breakdown of supporting periodontal fibers and bone and ultimately tooth loss, i.e., gingivitis, chronic or aggressive periodontitis, and around dental implants, peri‐implantitis. Furthermore, bacteria from the dental biofilm may spread to other parts of the body by bacteremia and cause systemic disease. Basically, prevention and treatment of dental biofilm infections are achieved by regular personal and professional removal of the dental biofilm.

Lipofuscin (age pigment) is a brown‐yellow, electron‐dense, autofluorescent material that accumulates progressively over time in lysosomes of postmitotic cells, such as neurons and cardiac myocytes. The exact mechanisms behind this accumulation are still unclear. This review outlines the present knowledge of age pigment formation, and considers possible mechanisms responsible for the increase of lipofuscin with age. Numerous studies indicate that the formation of lipofuscin is due to the oxidative alteration of macromolecules by oxygen‐derived free radicals generated in reactions catalyzed by redox‐active iron of low molecular weight. Two principal explanations for the increase of lipofuscin with age have been suggested. The first one is based on the notion that lipofuscin is not totally eliminated (either by degradation or exocytosis) even at young age, and, thus, accumulates in postmitotic cells as a function of time. Since oxidative reactions are obligatory for life, they would act as age‐independent enhancers of lipofuscin accumulation, as well as of many other manifestations of senescence. The second explanation is that the increase of lipofuscin is an effect of aging, caused by an age‐related enhancement of autophagocytosis, a decline in intralysosomal degradation, and/or a decrease in exocytosis.

YKL‐40, a cellular glycoprotein isolated from the human osteosarcoma (OS) cell line MG63, is increased in the blood of patients with various types of cancer, and is found as an independent prognostic variable for survival. YKL‐40 is also present with variable intensity in the tumor cells of some cancer types, but survival results have been conflicting. The aim of this study was to investigate the tissue expression of YKL‐40 and its possible role as a predictive marker in patients with OS. Forty‐eight patients were included in the study. Diagnostic biopsies were analyzed by immunohistochemistry; YKL‐staining scores as well as CD14 and CD163 scores were determined, and survival data were determined statistically. A universal intense immunostaining for YKL‐40 was found in all tumor cells, but tumor cell/stroma ratio varied, and this ratio (%) served as staining score. Using 24% as mean score to divide the material, patients with tumors of high YKL‐40 score had a better survival than patients with low score (p = 0.05). YKL‐positive macrophages had no influence on the result. Unexpectedly and contrary to some other findings in cancer tissues, this study has shown a correlation between high YKL‐40 tumor cell/matrix ratio and longer overall survival in OS.

Christensen AD, Haase C. Immunological mechanisms of contact hypersensitivity in mice. APMIS 2012; 120: 1–27.

Contact hypersensitivity (CHS) is an animal model in which the immunological mechanisms of allergic contact dermatitis (ACD) in humans can be studied but is also widely used in the study of many basic immunological mechanisms. In CHS, a pre‐sensitized animal is re‐exposed to an antigen, thereby eliciting an immunological reaction at the site of antigen exposure. CHS consists of two phases: sensitization and elicitation phase. In the sensitization phase, the first contact of the skin with a hapten leads to binding of the hapten to an endogenous protein in the skin where they form hapten‐carrier complexes which are immunogenic. The hapten‐carrier complex is taken up by Langerhans cells (LCs) and dermal dendritic cells (dDCs) which migrate from the epidermis to the draining lymph node. Here, they present the haptenated peptides to naive T cells which are subsequently activated. The newly activated T cells proliferate and migrate out of the lymph node and into circulation. In the elicitation phase, re‐exposure of the skin to the hapten activates the specific T cells in the dermis and triggers the inflammatory process responsible for the cutaneous lesions. Originally CHS was regarded as being solely driven by T cells but recently other cell types such as B1 cells, natural killer (NK) T cells and NK cells have shown to mediate important functions during the response as well. Here, we have described the molecular and cellular pathways in the development of CHS and have focused on recent advances and novel knowledge in the understanding of the immunoregulatory mechanisms involved in CHS.

Groups of CBA mice immunosuppressed with antithymocyte serum (ATS) treatment were xeno‐transplanted with either HeLa human cervical carcinoma cells or genetically modified cells expressing the human tumor necrosis factor‐α (TNF) gene (All cells). Both cell lines were highly resistant to the cytotoxic effects of TNF. If 3 times 10⁶ tumor cells were inoculated s.c. into female mice, HeLa cells grew progressively into large tumors and killed 74% of the recipients, while TNF‐expressing All cells caused fatal tumor growth only in 22% of the mice. 3times 10⁶ or 1.5times 10⁷ All cells produced progressive tumor growth and lethality in all male recipients. In sera of all the All‐cell‐transplanted mice, biologically active TNF was detected shortly (4.5 h) after tumor inoculation (6–39 U/ml), decreasing to below detection level in the circulation by day 3. In recipients of 15 million All cells, circulating TNF reappeared and reached high levels (12–1000 U/ml) 3 to 7 weeks later, when the animals bore large tumors (14–23 mm). Generally, such mice became cachectic, severely anemic, hypothermic, and soon died. On account of calcium mobilization from bones, their serum Ca levels were high. Electron microscopy revealed severe liver damage, but there were no signs of chronic arthritis. These results suggest that ATS‐treated mice xenotransplanted with TNF‐gene‐transfected All human tumor cells provide a new model for studying the pathophysiological and anti‐tumor effects of TNF.

The role of the immune response in rheumatoid arthritis (RA) is a subject of debate, although it is widely believed to be a T‐cell‐driven disease. Progress is being hindered by lack of convincing evidence of a defined specific antigen initiating or perpetuating the response. Clinical trials using monoclonal antibodies directed against T‐cell surface molecules such as CD4, CD5, and CD7 have thus far not provided evidence of efficacy. The negative data may reflect inadequate dosing or could suggest that indiscriminate depletion of T cells is insufficient by itself as a therapeutic strategy. Blocking proinflammatory cytokines (e.g. TNFα, IL‐1) or augmenting anti‐inflammatory cytokines (e.g. IL‐10) offers an alternative approach to therapy. Clinical trials using monoclonal anti‐TNFα have been particularly successful in controlling inflammation and markedly reducing acute phase proteins and cellular ingress. However, because disease invariably relapses, repeated therapy is necessary. Preliminary experience suggests that this is possible. Anti‐TNF therapy for RA has defined a molecular target and new approach for treating immuno‐inflammatory disorders.

To study the structure and function of the Legionella flagellum, we screened a genomic L. micdadei library in Escherichia coli for expression of the flagellin (Fla) subunit. One recombinant clone, JM105 (pHI5588), producing a truncated Fla protein of 40.5 kDa was identified. The plasmid pHI5588 carried a L. micdadei DNA insert of 5 kb, containing ca 95% of the fla gene. The complete DNA sequence of the L. micdadei fla gene was obtained by combining sequence data from pHI5588 with results using a polymerase chain reaction‐based system for genome walking (vectoretle PCR). The L. micdadei fla gene shared a high degree of homology with other flagellin genes in the amino‐ and carboxy termini, whereas the central region was found to be nonconserved. The fla sequence will facilitate the cloning of Fla proteins from other Legionella species and the study of flagella in the pathogenesis of Legionnaires' disease.