Identification of a chemotactic, MCP-1-like protein from Mycobacterium avium

Neospora caninum excreted/secreted antigens trigger CC-chemokine receptor 5-dependent cell migration

Neospora caninum, the causative agent of neosporosis, is an obligate intracellular parasite considered to be a major cause of abortion in cattle throughout the world. Most studies concerning N. caninum have focused on life cycle, seroepidemiology, pathology and vaccination, while data on host-parasite interaction, such as host cell migration, mechanisms of evasion and dissemination of this parasite during the early phase of infection are still poorly understood. Here we show the ability of excreted/secreted antigens from N. caninum (NcESAs) to attract monocytic cells to the site of primary infection in both in vitro and in vivo assays. Molecules from the family of cyclophilins present on the NcESAs were shown to work as chemokine-like proteins and NcESA-induced chemoattraction involved G(i) protein signaling and participation of CC-chemokine receptor 5 (CCR5). Additionally, we demonstrate the ability of NcESAs to enhance the expression of CCR5 on monocytic cells and this increase occurred in parallel with the chemotactic activity of NcESAs by increasing cell migration. These results suggest that during the first days of infection, N. caninum produces molecules capable of inducing monocytic cell migration to the sites of infection, which will consequently enhance initial parasite invasion and proliferation. Altogether, these results help to clarify some key features involved in the process of cell migration and may reveal virulence factors and therapeutic targets to control neosporosis.

Pulmonary infection of Mycobacterium avium-intracellulare complex with simultaneous organizing pneumonia

A 67-year-old woman presented high-grade fever and dyspnea. Sputum culture confirmed Mycobacterium avium-intracellulare complex (MAC). Transbronchial lung biopsies revealed organizing pneumonia (OP) that was rapidly improved with corticosteroid. Five months after onset, a nodule emerged in the right lung. Although MAC was confirmed, the lesion was deemed too small to merit anti-mycobacterial chemotherapy. Four months later, diffuse infiltrates developed on chest X-ray. Bronchoalveolar lavage study identified MAC and exhibited OP patterns. We commenced antimycobacterial chemotherapy. The infiltrates almost completely improved within a month without corticosteroid.

Secretion of monocyte chemotactic protein-1 by human uterine epithelium directs monocyte migration in culture

OBJECTIVE

To determine whether primary human uterine epithelial cells in culture are able to influence monocyte chemotaxis and to establish whether the causal agent of chemotaxis is monocyte chemotactic protein (MCP)-1.

DESIGN

Tissue culture study.

SETTING

University medical center.

PATIENT(S)

Women aged 23 to 53 years who were undergoing hysterectomy (n=7).

INTERVENTION(S)

Primary human endometrial epithelial cells were acquired from surgical specimens and grown to confluence and high transepithelial resistance. Conditioned media from epithelial cultures were analyzed for the presence of MCP-1 and for capacity to affect monocyte chemotaxis using the THP-1 monocyte line. Antibody neutralization of conditioned media was used to establish the role of MCP-1 in chemotaxis.

MAIN OUTCOME MEASURE(S)

Assay of conditioned media for MCP-1, quantitative measurement of monocyte chemotaxis to conditioned media, and inhibition of chemotaxis by antibody neutralization of MCP-1.

RESULT(S)

Primary endometrial epithelial cells in monolayer culture secrete MCP-1 to both the apical and basolateral compartments. Monocyte chemotactic protein-1 was identified as the primary agent of monocyte chemotaxis by antibody neutralization.

CONCLUSION(S)

These findings suggest that biologically active MCP-1 is secreted into both the uterine lumen as well as the underlying stroma and that it mediates the presence of monocytes, macrophages, and other immune cells in the uterine endometrium.

Subversion of the chemokine world by microbial pathogens

It is well known that microbial pathogens are able to subvert the host immune system in order to increase microbial replication and propagation. Recent research indicates that another arm of the immune response, that of the chemokine system, is also subject to this sabotage, and is undermined by a range of microbial pathogens, including viruses, bacteria, and parasites. Currently, it is known that the chemokine system is being challenged by a number of mechanisms, and still more are likely to be discovered with further research. Here we first review the general mechanisms by which microbial pathogens bypass mammalian chemokine defences. Broadly, these can be grouped as viral chemokine interacting proteins, microbial manipulation of host chemokine and chemokine receptor expression, microbial blockade of host chemokine receptor signalling, and the largely hypothetical mechanisms of microbial enhancement of host anti-chemokine networks (including digestion, antagonism, and neutralisation of host chemokines and chemokine receptors). We then discuss the potential results of these interactions in terms of outcome of infection.