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Metastasis is the leading cause of death in cancer patients, and successful colonisation of a secondary organ by circulating tumour cells (CTCs) is the rate-limiting step of this process. We used tail-vein injection of B16-F10 melanoma cells into mice to mimic the presence of CTCs and to allow for the assessment of host (microenvironmental) factors that regulate pulmonary metastatic colonisation. We found that mice deficient for the individual subunits of the NADPH oxidase of myeloid cells, NOX2 (encoded by Cyba, Cybb, Ncf1, Ncf2, and Ncf4), all showed decreased pulmonary metastatic colonisation. To understand the role of NOX2 in controlling tumour cell survival in the pulmonary microenvironment, we focused on Cyba-deficient (Cyba tm1a ) mice, which showed the most significant decrease in metastatic colonisation. Interestingly, histological assessment of pulmonary metastatic colonisation was not possible in Cyba tm1a mice, owing to the presence of large granulomas composed of galectin-3 (Mac-2)-positive macrophages and eosinophilic deposits; granulomas of variable penetrance and severity were also found in Cyba tm1a mice that were not injected with melanoma cells, and these contributed to their decreased survival. The decreased pulmonary metastatic colonisation of Cyba tm1a mice was not due to any overt defects in vascular permeability, and bone marrow chimaeras confirmed a role for the haematological system in the reduced metastatic colonisation phenotype. Examination of the lymphocyte populations, which are known key regulators of metastatic colonisation, revealed an enhanced proportion of activated T and natural killer cells in the lungs of Cyba tm1a mice, relative to controls. The reduced metastatic colonisation, presence of granulomas and altered immune cell populations observed in Cyba tm1a lungs were mirrored in Ncf2-deficient (Ncf2 tm1a ) mice. Thus, we show that NOX2 deficiency results in both granulomas and the accumulation of antitumoural immune cells in the lungs that probably mediate the decreased pulmonary metastatic colonisation. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., (© 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

Inhibition of the enzyme cyclooxygenase (COX) is the basis for the mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs). COX exists as a constitutive (COX-1) and a mitogen-inducible (COX-2) isoform. The relative contribution of COX-1 and COX-2 to inflammation is unknown. This study investigated COX activity and the distribution of COX-1 and COX-2 during the development of a murine air pouch model of chronic granulomatous inflammation. COX activity progressively rose and was maximal at day 14. Of the COX metabolites measured, PGE2 was the greatest > 6-keto PGF1a > TXB2 > PGF2a. By day 7, COX-2-labelled fibroblast- and macrophage-like cells were observed and their number and distribution increased with time. At all time points, endothelial cells of venules in the loose connective tissue of the dermis showed immunoreactivity for COX-2. After day 14, labelling of capillaries in the granuloma was also observed. This study is the first to show that COX-2 is the predominant COX isoform in all stages of the inflammatory response. These results suggest that selective inhibition of COX-2 may prove more beneficial, with fewer gastric and renal side-effects, than existing NSAID therapy for the treatment of chronic inflammatory diseases.

A study has been made on mycobacterial-induced granulomas in guinea-pig lymph nodes. Lysozyme and angiotensin-converting enzyme (ACE) were measured in the auricular lymph nodes and serum of guinea-pigs which had received live BCG (Pasteur) or Cobalt (Co)-irradiated armadillo-derived Mycobacterium leprae intradermally into the ear or dinitrofluorobenzene (DNFB) painted epicutaneously upon the ears. In the lymph nodes with granulomas induced by either live BCG or killed M. leprae, the mean concentrations of lysozyme and ACE varied directly with the mean weight of the lymph nodes but the temporal pattern of weight change differed with the two agents. In M. leprae recipients at the time of peak lymph node weight, serum lysozyme and ACE values were significantly greater than those observed in controls; in animals receiving live BCG (Pasteur), serum lysozyme but not ACE values were elevated significantly at the time of peak lymph node weight. Four days following the epicutaneous application of DNFB, where there was no granuloma, there was a similar increase in the concentration of lysozyme and ACE in the lymph nodes. At the same time, there was also significant elevation in the serum lysozyme and ACE concentrations. Thus, in the granulomatous responses, the parallel tissue and serum changes in lysozyme and ACE concentrations were consistent with increased production and secretion of each enzyme by cells of the mononuclear phagocyte series. The increased lysozyme and ACE concentrations found in the lymph nodes of DNFB sensitised animals gives further evidence that such changes are not unique to granulomas. Finally, the intradermal administration of dead M. leprae in guinea pigs also produced increased lysozyme and ACE levels similar to that found in leprosy in man.

The output of lysozyme into the venous and lymphatic drainage of a B.C.G. experimental granuloma has been studied. There is a massive output of lysozyme by both routes maximal in the lymph at 28 days, and in the serum at 35 days after induction of the granuloma. There is no similar excretion of acid phosphatase. The lactic dehydrogenase level both in blood draining the granuloma and blood draining the normal limb is elevated but not in precise synchrony with lysozyme output. Macrophages in the granuloma show ultrastructural features suggestive of secretion of dense granules, by appearance of electron dense material in the Golgi zone, and condensation therefrom. Granules are discharged on to the surface of lipid droplets, presumably representing attempted phagocytosis, but are not discharged elsewhere on the cell surface. Granules are released by cell disintegration both of macrophages and polymorphs. Lysozyme was demonstrated immunocytochemically in macrophage granules. The macrophages in the granuloma are biosynthetically active as shown by uptake of tritiated tyrosine. The findings support the view that granulomas export lysozyme and that this is due partly to exocytosis of material by macrophages on to the surface of lipid globules and partly to cell disintegration.