Monocyte membrane type 1-matrix metalloproteinase. Prostaglandin-dependent regulation and role in metalloproteinase-2 activation

Membrane type 1-matrix metalloproteinase (MT1-MMP)-mediated activation of MMP-2 is thought to be important in the proteolysis of extracellular matrix in pathological events in which monocytes/macrophages are found. Here we report on the induction and regulation of human monocyte MT1-MMP and its role in MMP-2 activation. Activation of monocytes by lipopolysaccharide resulted in the induction of MT1-MMP mRNA and protein that was suppressed by inhibitors of prostaglandin synthesis (indomethacin), adenylyl cyclase (SQ 22536), and protein kinase A (Rp-cAMPs). Suppression of MT1-MMP by indomethacin and SQ 22536 was reversed by prostaglandin E(2) and dibutyryl cyclic AMP, respectively, demonstrating that induction of monocyte MT1-MMP is regulated through a prostaglandin-cAMP pathway. Functional analysis revealed that pro-MMP-2 in the supernatants from human bone marrow stromal fibroblasts, normal male-derived fibroblasts and melanoma cells (A2058) was converted to active MMP-2 when cultured with activated but not control monocytes. Antibodies against MT1-MMP blocked the activation of MMP-2. Tissue inhibitor of metalloproteinase-2 regulation of MMP-2 activation was shown through the addition of varying amounts of recombinant tissue inhibitor of metalloproteinase-2 with pro-MMP-2 to MT1-MMP-expressing monocytes. These findings demonstrate that activated monocytes express functionally active MT1-MMP that may play a significant role in the activation of MMP-2 produced by other cells and as such influence developmental and pathological conditions.     

Photoactive dye insecticide formulations: adjuvants increase toxicity to Mexican fruit fly (Diptera: Tephritidae)

The efficacy of photo active dyes as insecticides depends on the ingestion of the dye by the target insect and the activity of the dye at sensitive sites or on essential chemical functions. The site of this activity in insects is not understood, but we have found that certain chemical additives enhance the toxicity of phloxine B in the Mexican fruit fly. A series oftests with commercial adjuvants was performed under laboratory conditions that demonstrated a multifold decrease in the LD50 of phloxine B concentration and a decrease in the time required for photodynamic action to kill the flies. A total of 22 commercial adjuvants was tested. Of these, six were selected for evaluation under field cage conditions in comparison with a non-insecticide control bait (no treatment) and a phloxine B check bait with no adjuvant. Mortality was estimated by counting dead flies, feeding was estimated by fly counts at feeding stations, survival was estimated by trapping flies after the treatment period. In all cases the adjuvants increased the rate of mortality and decreased numbers surviving the treatment. Significant differences between adjuvants and both check and control were observed for mortality rates and the three best adjuvants, SM-9, Kinetic, and Tween60, induced significantly more mortality than the other adjuvants, the control, or the check. Feeding rates and survival rates indicated that the adjuvants increase the effectiveness of phloxine B in a predictable manner. The adjuvants appear to be active inside the insect rather than increasing the solubility of the dye in the bait medium. We propose that the addition of 1% vol:vol of the best adjuvant, Tween60 to the proteinaceous bait with 0.5% phloxine B will enhance toxicity as well as improve mixing and other characteristics of the bait.     

Suppression of TH2-type allergic reactions by helminth infection

There is no immunological mechanism to adequately explain the sudden epidemic in allergies noted in the last 30 years in developed countries. The reduction in the development of allergic disorders observed in individuals infected with parasitic helminths, however, supports a possible role for worms in suppressing allergies. Helminths regulate the immunity of the host to ensure a mutually beneficial environment for the survival of both the parasite and the host. This interplay between helminths and allergic responses raises fundamental questions in immunobiology. Harnessing current mechanistic studies for translational research into helminth infections and atopy might have potential for the identification of novel biomarkers, and even therapeutics, in allergic diseases.     

Stem cell transplantation for metastatic breast cancer: analysis of tumor contamination

The purpose of this study was to determine the efficacy, engraftment kinetics, effect of bone marrow tumor contamination, and safety of high-dose therapy and granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood progenitor cell (PBPC) support for patients with responding metastatic breast cancer. Forty two patients underwent G-CSF (10 μg/kg) stimulated PBPC harvest. PBPC and bone marrow aspirates were analyzed by histologic and immunocytochemical methods for tumor contamination. Thirty-seven patients received high-dose therapy consisting of cyclophosphamide 6 g/m², thiotepa 500 mg/m², and carboplatin 800 mg/m² (CTCb) given as an infusion over 4 d followed by PBPC reinfusion and G-CSF (5 μg/kg) support. No transplant related deaths or grade 4 toxicity was recorded. CD34+ cells/kg infused was predictive of neutrophil and platelet recovery. With a median follow-up of 38 months, three year survival was 44% with relapse-free survival of 19%. Histological bone marrow involvement, found in 10 patients, was a negative prognostic factor and was associated with a median relapse-free survival of 3.5 months. Tumor contamination of PBPC by immunohistochemical staining was present in 22.5% of patients and found not to be correlated with decreased survival. G-CSF stimulated PBPC collection followed by a single course of high dose chemotherapy and stem cell infusion with G-CSF stimulated marrow recovery leads to rapid, reliable engraftment with low toxicity and promising outcome in women with responding metastatic breast cancer.     

Type I interferons in regulation of mucosal immunity

The mucosal system is the first line of defense against many pathogens. It is continuously exposed to dietary and microbial antigens, and thus the host must maintain a homeostatic environment between commensal microbiota and pathogenic infections. Following infections and inflammatory events, a rapid innate immune response is evoked to dampen the inflammatory processes. Type I interferons, a family of pleiotropic cytokines and major products of the innate immune response, have a key role in these early immune events at the mucosa, as reviewed here. With the emergence of new discoveries of immune cell types in mucosal tissues and their reactions to commensal and pathogenic organisms, we also review the opportunities for exciting research in this field.     

Random insertion mutagenesis of the intracellular pathogen Rhodococcus equi using transposomes

The identification of virulence factors in Rhodococcus equi has been severely hampered by the lack of a method for in vivo random insertion mutagenesis. This study reports the use of transposomes to generate random insertions of a gene conferring kanamycin resistance into the genome of R. equi ATCC 33701. Southern hybridisation using the kanamycin resistance gene as probe showed that insertion of transposome is random. This was confirmed following nucleotide sequence analysis of the junction between the transposome and chromosomal DNA. The presence of a 9 bp duplication of the target sequence showed that random integration of the transposome was due to a bona fide Tn5 transposition event.     

Persistence of sterile screwworm (Diptera: Calliphoridae) flies at a release site.

Studies to determine the persistence of released, sterile screwworms, Cochliomyia hominivorax (Coquerel), were conducted in Belize, Central America, in 1987-1988. A total of nine releases were made, each consisting of 4,000 females marked with a fluorescent dust. Previous similar studies with baited fly traps indicated that flies died or dispersed from the release site within 3-4 d. For this study, flies were recaptured at sentinel animals. Recapture rates varied greatly between releases, a result that was not correlated with any weather parameter. The pattern of recapture indicated a sharp drop in the released population after 9-10 d, with a few flies persisting in the release area for up to 3 wk. The results suggest that survival of released sterile flies is comparable with estimated survival rate and life span of wild, native flies.     

Chronic fatigue syndrome: understanding a complex illness

Chronic fatigue syndrome (CFS) is a debilitating illness that affects many people. It has been marred by controversy, from initial scepticism in the medical community about the existence of the condition itself to continuing disagreements--mainly between some patient advocacy groups on one side, and researchers and physicians on the other--about the name for the illness, its aetiology, its pathophysiology and the effectiveness of the few currently available treatments. The role of the CNS in the disease is central in many of these discussions. Nature Reviews Neuroscience asked four scientists involved in CFS research about their views on the condition, its causes and the future of research aimed at improving our understanding of this chronic illness.     

Very different performance of the power Doppler modalities of several ultrasound machines ascertained by a microvessel flow phantom

Introduction

In many patients with rheumatoid arthritis (RA) subclinical disease activity can be detected with ultrasound (US), especially using power Doppler US (PDUS). However, PDUS may be highly dependent on the type of machine. This could create problems both in clinical trials and in daily clinical practice. To clarify how the PDUS signal differs between machines we created a microvessel flow phantom.

Methods

The flow phantom contained three microvessels (150, 1000, 2000 microns). A syringe pump was used to generate flows. Five US machines were used. Settings were optimised to assess the lowest detectable flow for each US machine.

Results

The minimal detectable flow velocities showed very large differences between the machines. Only two of the machines may be able to detect the very low flows in the capillaries of inflamed joints. There was no clear relation with price. One of the lower-end machines actually performed best in all three vessel sizes.

Conclusions

We created a flow phantom to test the sensitivity of US machines to very low flows in small vessels. The sensitivity of the power Doppler modalities of 5 different machines was very different. The differences found between the machines are probably caused by fundamental differences in processing of the PD signal or internal settings inaccessible to users. Machines considered for PDUS assessment of RA patients should be tested using a flow phantom similar to ours. Within studies, only a single machine type should be used.