A role for tetraspanin proteins in regulating fusion induced by Burkholderia thailandensis

Burkholderia pseudomallei is the causative agent of melioidosis, a disease with high morbidity that is endemic in South East Asia and northern Australia. An unusual feature of the bacterium is its ability to induce multinucleated giant cell formation (MNGC), which appears to be related to bacterial pathogenicity. The mechanism of MNGC formation is not fully understood, but host cell factors as well as known bacterial virulence determinants are likely to contribute. Since members of the tetraspanin family of membrane proteins are involved in various types of cell:cell fusion, their role in MNGC formation induced by Burkholderia thailandensis, a mildly pathogenic species closely related to B. pseudomallei, was investigated. The effect of antibodies to tetraspanins CD9, CD81, and CD63 in MNGC formation induced by B. thailandensis in infected mouse J774.2 and RAW macrophage cell lines was assessed along with that of recombinant proteins corresponding to the large extracellular domain (EC2) of the tetraspanins. B. thailandensis-induced fusion was also examined in macrophages derived from CD9 null and corresponding WT mice, and in J774.2 macrophages over-expressing CD9. Antibodies to CD9 and CD81 promoted MNGC formation induced by B. thailandensis, whereas EC2 proteins of CD9, CD81, and CD63 inhibited MNGC formation. Enhanced MNGC formation was observed in CD9 null macrophages, whereas a decrease in MNGC formation was associated with overexpression of CD9. Overall our findings show that tetraspanins are involved in MNGC formation induced by B. thailandensis and by implication, B. pseudomallei, with CD9 and CD81 acting as negative regulators of this process.

Papanicolaou smear: A diagnostic aid in sexually transmitted infections

Background:

Sexually transmitted infections (STIs) are a major public health problem in developing countries, and treatment with the right medicine at the right time is necessary to reduce transmission and improve sexual and reproductive health. Laboratory diagnosis has undergone changes in the recent years. The new generation tests are not cost-effective in resource-poor settings. Papanicolaou smear (Pap smear) of the cervix is a simple, quick, and inexpensive screening procedure for cervical cancer that can also give a clue to the presence of STIs.

Methods:

A hospital-based cross-sectional design with fifty patients was conducted studied. The initial diagnosis based on clinical findings and routine laboratory results was compared with the final diagnosis incorporating Pap smear results.

Results:

The Pap smear was abnormal in 96%, and the abnormalities were koilocytosis (30%), endocervicitis (24%), Trichomonas vaginalis (16%), multinucleated giant cells (10%), low-grade squamous intraepithelial lesion (10%), and clue cells (8%). Pap smear could diagnose an infection in 64%, of which 38% were asymptomatic. Clinical and Pap smear correlation was found only in 26% of the patients.

Conclusion:

Along with the conventional methods, Pap smear can be a valuable tool in diagnosing STIs. This can detect asymptomatic infections, not detected by conventional methods, thus preventing complications and further spread in the community. Asymptomatic human papillomavirus (HPV) infection and trichomoniasis are the two STIs that can be easily detected by Pap smear. By detecting asymptomatic cervical HPV infection, the patients at risk for carcinoma of the cervix can be identified and referred to gynecology department for further management.

Multinucleated giant cell phenotype in response to stimulation

Macrophages fuse into multinucleated giant cells (MGC) in many pathological conditions. Despite MGC correlations with granulomas, their functional contribution to inflammation is relatively unknown. An in vitro mouse model of IL-4-induced bone marrow-derived macrophage fusion and microfiltration were used to generate enriched MGC and macrophage populations. Phenotypes were compared in response to well-known inflammatory stimuli, including lipopolysaccharide and crocidolite asbestos. Surface markers were assessed by flow cytometry: CD11b, CD11c, F4/80, and MHC II. Secreted cytokines were assessed by multiplex immunoassay: IFN-γ, IL-1β, IL-6, TNF-α, IL-10, IL-13, and IL-33. Results show that MGC maintained macrophage surface protein expression but lost the ability to produce a cytokine response. This suggests a potentially beneficial role of MGC in isolating the host from a foreign body without contributing to excessive inflammation. This study and future research using other stimulants and environments are important to gaining a fundamental MGC cell biology understanding. This will inform approaches to controlling the foreign body response to particle exposure, medical implants, and many diseases associated with granulomas.

Factors influencing multinucleated giant cell formation in vitro

Macrophages fuse together to form multinucleated giant cells (MGC) in granulomas associated with various pathological conditions. Improved in vitro methods are required to better enable investigations of MGC biology and potential contribution to disease. There is a need for standardization of MGC quantification, purification of MGC populations, and characterization of how cell culture variables influence MGC formation. This study examined solutions to address these needs while providing context with other current and alternative methods. Primary mouse bone marrow-derived macrophages were treated with interleukin-4, a cytokine known to induce fusion into MGC. This model was used to systematically assess the influence of cell stimulant timing, cell seeding density, colony stimulating factors, and culture vessel type. Results indicated that MGC formation is greatly impacted by alterations in certain culture variables. An assessment of previously published research showed that these culture conditions varied widely between different laboratories, which may explain inconsistencies in the literature. A particularly novel and unexpected observation was that MGC formation appears to be greatly increased by silicone, which is a component of a chamber slide system commonly used for MGC studies. The most successful quantification method was fluorescent staining with semi-automated morphological evaluation. The most successful enrichment method was microfiltration. Overall, this study takes steps toward standardizing in vitro methods, enhancing replicability, and guiding investigators attempting to culture, quantify, and enrich MGC.

"Osteoclastoma of Maxilla" a Rare Case

Giant cell tumour (GCT) of the bone accounts for 5 to 9 % of primary bone tumors. The most common sites are long bones. The incidence of craniofacial GCTs, involving the sphenoid (Kujas et al. Arch Anat Cytol Pathol, 47(1):7-12, 1999), ethmoid and temporal bones is rare, but they do exist, among all GCT tumors 2 % are found in craniofacial bones. Here is a report on a case of osteoclastoma of maxilla, presented to us with complains of swelling and pain over left side of cheek, nasal obstruction from last 5 months. Excision of whole mass from anterior wall was done under general anesthesia.

A case of idiopathic giant cell myocarditis with a past history of sarcoidosis

A 70-year-old woman with back pain and breathlessness was referred to our hospital for suspected myocardial infarction. Coronary angiogram was normal and endomyocardial biopsy showed inflammatory cell infiltrates consisting of eosinophils and multinucleated giant cells. The clinical course was hemodynamically fulminant, but steroid therapy improved the cardiac function. Interestingly, this patient had a past history of sarcoidosis. We diagnosed this case with idiopathic giant cell myocarditis (IGCM) from its clinical course. However, whether IGCM and cardiac sarcoidosis belong to the same histological entity has been debated. This case is important with respect to the pathogenic association between these two disorders. <Learning objective: Both idiopathic giant cell myocarditis and cardiac sarcoidosis are known to show multinucleated giant cell infiltration in the myocardium histologically. In particular, idiopathic giant cell myocarditis is a severe and fulminant disease, making its early diagnosis and treatment important. Although it is difficult to diagnose these diseases, endomyocardial biopsy is useful to decide the treatment strategy in such disorders that may assume a fulminant course.>.