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Query: UMLS:C0032285 (pneumonia)
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Warnericin RK is the first antimicrobial peptide known to be active against Legionella pneumophila, a pathogen bacterium that is responsible for severe pneumonia. Strikingly, this peptide displays a very narrow range of antimicrobial activity, almost limited to the Legionella genus, and a hemolytic activity. A similar activity has been described for delta-lysin, a well-known hemolytic peptide of Staphylococci that has not been described as antimicrobial. In this study we aimed to understand the mode of action of warnericin RK and to explain its particular target specificity. We found that warnericin RK permeabilizes artificial membranes in a voltage-independent manner. Osmotic protection experiments on erythrocytes showed that warnericin RK does not form well-defined pores, suggesting a detergent-like mode of action, as previously described for delta-lysin at high concentrations. Warnericin RK also permeabilized Legionella cells, and these cells displayed a high sensitivity to detergents. Depending on the detergent used, Legionella was from 10- to 1000-fold more sensitive than the other bacteria tested. Finally, the structure of warnericin RK was investigated by means of circular dichroism and NMR spectroscopy. The peptide adopted an amphiphilic alpha-helical structure, consistent with the proposed mode of action. We conclude that the specificity of warnericin RK toward Legionella results from both the detergent-like mode of action of the peptide and the high sensitivity of these bacteria to detergents.
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PMID:Detergent-like activity and alpha-helical structure of warnericin RK, an anti-Legionella peptide. 1980 24

The results above reported lead to the conclusion that while in the degenerating cells chemical changes are taking place tending toward a diminution of the hexon bases as a whole, they affect the arginin especially. One may picture the process either as a partial or as a complete breaking down of certain proteid. material more or less rich in hexon bases, leaving behind. proteid matter poorer in bases. The meaning of these changes is, however, obscure, and with the limited number of known facts bearing upon the subject, it would seem idle even to attempt to formulate an hypothesis to explain them. Certain work of other investigators is, however, suggestive in this connection. Kossel and Dakin, for instance, as illustrated by their work upon the simple proteid body clupein, found that a partial destruction of the proteid molecule, involving the arginin group, is brought about by a ferment furnished by the animal organism. When subjected to the hydrolytic action of a mineral acid, clupein yields arginin in considerable abundance. But if the clupein is first acted upon by the ferment arginase found in the liver, and then subjected to acid hydrolysis, the yield of arginin is appreciably diminished. Among the cleavage products in the latter instance are the components of arginin, namely, omithin and urea. It would seem, therefore, as if the ferment had loosened the union between the omithin and urea in the arginin group, so that upon subsequent hydrolysis a diminution of arginin resulted. In the cases studied by me, it may be that the conditions were favorable for some such ferment action as that above described, and hence the relatively low yield of arginin. No attempt, however, was made to ascertain if omithin were present in the urine. Its presence there would seem not wholly unlikely when one considers the diminished power of oxidation of the phosphorus-poisoned cell, although Thompson has shown that arginin or omithin when administered to a healthy dog as food or by hypodermic injection is eliminated for the most part as urea, no ornithin being found. There might seem to be a conflict between this view and the results recently published by Wohlgemuth, but it must be borne in mind that the influences at work causing the breaking down of the proteid molecule are probably quite diverse in character. Wohlgemuth has recently shown for the first time that a diamino acid may actually find its way into the urine in phosphorus poisoning. He found arginin in the urine not only in rabbits poisoned with phosphorus but also in a patient suffering from phosphorus poisoning. On the other hand, he was unable to find lysin in the urine. This fact is of especial interest in view of the evidence set forth in this paper that the arginin base is lost to the proteid molecule more rapidly than the lysin base. The correspondence between the findings in the liver and in the urine is thus a close one. How much of the arginin liberated from the proteid molecule may find its way into the urine is of course uncertain. It seems reasonable to suppose that a portion of the base is acted upon by the arginase ferment in the manner already described. Of the seventeen to eighteen cleavage products of the proteid molecule thus far isolated, the hexon bases are among the most stable. One or more of these bases have been found in practically all proteid matter thus far investigated; in fact arginin is so uniformly present that Kossel has made the suggestion that it is the kernel of the proteid molecule. At all events, the question may be asked, whether, if the influences at work in the altered liver tissue were of a general character causing a diminution of the hexon bases, the monoamino acid groups would not suffer even a greater diminution; and since the pathological condition is undoubtedly associated with impaired oxidation, their presence should not be expected in the urine. As a matter of fact, Ignatowski found considerable quantities of monoamino acids in the urine of patients suffering from gout, pneumonia, and leukaemia, though under normal conditions no monoamino acids were found in the urine, indeed, not even after the subcutaneous injection of glycokoll. Furthermore, the loosening of the amino acids from the proteid molecule is suggested by the fact that Taylor found such acids in the liver of a patient who died from a hepatic disease of obscure etiology, but which he was inclined to attribute to chloroform poisoning. Taylor found not only leucin and tyrosin in the liver, but also arginin, a fact not without interest in view of the diminished arginin content found in the livers of the chloroformed dogs after acid hydrolysis. Moreover, the falling off of the hexon bases under the conditions studied seems quite in accordance with some results recently reported by Levene. He has shown that certain cleavage products obtained by the action of mineral acids upon self-digested pancreas, spleen, and liver, are much diminished when compared with the products obtained from the fresh glands. The lysin and arginin of the digested liver, for example, showed a diminution of over 50 per cent. It is now well established that in course of the process of aseptic autolysis, the proteids of the liver cell undergo decomposition into simpler substances, and Jacoby showed that during life autolysis may go on in portions of the liver in which the circulation has been hindered. But of greater significance still in this connection, is the observation made by Jacoby on the autolytic changes in the liver during phosphorus poisoning. He found that when the normal liver substance is permitted to autolyse the solution of the liver substance is a slow one. On the other hand, under similar conditions the liver of a phosphorus-poisoned animal undergoes rapid and almost complete solution. The difference in the behavior of the normal and damaged liver points to an increase of normal ferment action in the case of the poisoned organ. It thus seems reasonable to suppose that in phosphorus poisoning we have during life an exaggerated breaking down of the proteid molecule associated with an over-action of certain ferments, and among them probably arginase. The pathological process in the liver during life may, therefore, be thought of as proceeding in the same general direction as the process of post-morten autolytic decomposition. By means of further studies along lines indicated in this paper, it should be possible to gain a deeper insight into numerous pathological processes. The changes in amyloid degeneration are among those which promise to be better understood through the application of the new methods of chemical analysis. Moreover, it cannot be doubted that pharmacology as well as toxicology has much to gain from a study of what happens to the proteid molecule under the influence of poisons.
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PMID:ON THE HEXON BASES OF LIVER TISSUE UNDER NORMAL AND CERTAIN PATHOLOGICAL CONDITIONS. 1986 99

Pneumonia is one of the most prevalent Staphylococcus aureus-mediated diseases, and the treatment of this infection is becoming challenging due to the emergence of multidrug-resistant S. aureus, especially methicillin-resistant S. aureus (MRSA) strains. It has been reported that LysGH15, the lysin derived from phage GH15, displays high efficiency and a broad lytic spectrum against MRSA and that apigenin can markedly diminish the alpha-hemolysin of S. aureus. In this study, the combination therapy of LysGH15 and apigenin was evaluated in vitro and in a mouse S. aureus pneumonia model. No mutual adverse influence was detected between LysGH15 and apigenin in vitro. In animal experiments, the combination therapy showed a more effective treatment effect than LysGH15 or apigenin monotherapy (P < 0.05). The bacterial load in the lungs of mice administered the combination therapy was 1.5 log units within 24 h after challenge, whereas the loads in unprotected mice or mice treated with apigenin or LysGH15 alone were 10.2, 4.7, and 2.6 log units, respectively. The combination therapy group showed the best health status, the lowest ratio of wet tissue to dry tissue of the lungs, the smallest amount of total protein and cells in the lung, the fewest pathological manifestations, and the lowest cytokine level compared with the other groups (P < 0.05). With regard to its better protective efficacy, the combination therapy of LysGH15 and apigenin exhibits therapeutic potential for treating pneumonia caused by MRSA. This paper reports the combination therapy of lysin and natural products derived from traditional Chinese medicine.
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PMID:Combination Therapy of LysGH15 and Apigenin as a New Strategy for Treating Pneumonia Caused by Staphylococcus aureus. 2647 3

Lysins are a new and novel class of anti-infectives derived from bacteriophage (or phage ). They represent highly evolved enzymes produced to cleave essential bonds in the bacterial cell wall peptidoglycan for phage progeny release. Small quantities of purified recombinant lysin added externally to gram-positive bacteria results in immediate lysis causing log-fold death of the target bacterium. Lysins can eliminate bacteria both systemically and topically, from mucosal surfaces and biofilms, as evidenced by experimental models of sepsis, pneumonia, meningitis, endocarditis, and mucosal decolonization. Furthermore, lysins can act synergistically with antibiotics by resensitizing bacteria to non-susceptible antibiotics. The advantages over antibiotics are their specificity for the pathogen without disturbing the normal flora, the low chance of bacterial resistance, and their ability to kill colonizing pathogens on mucosal surfaces, a capacity previously unavailable. Lysins, therefore, may be a much-needed anti-infective in an age of mounting antibiotic resistance.
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PMID:Lysin Therapy for Staphylococcus aureus and Other Bacterial Pathogens. 2672 63