Functional and metabolic properties of polymorphonuclear leucocytes. I. Observations on the requirements and consequences of particle ingestion

Mechanic study based on untargeted metabolomics of Pi-pa-run-fei-tang on pepper combined with ammonia induced chronic cough model mice

ETHNOPHARMACOLOGICAL RELEVANCE

Pi-pa-run-fei-tang (PPRFT), a traditional Chinese medicine formula with long-standing history, demonstrated beneficial effect on chronic cough. However, the mechanism underlying efficacy unclear. In current research, we explored the impact and molecular mechanism of chronic cough mouse stimulating with capsaicin combined with ammonia.

AIM OF THE STUDY

To investigate the metabolic modulating effects, and potential mechanisms underlying the therapeutic effect of PPRFT in chronic cough.

MATERIALS AND METHODS

Chronic cough mouse models were created by stimulating mice by capsaicin combined with ammonia. Number of coughs and cough latency within 2 min were recorded. With lung tissue and serum samples collected for histopathology, metabolomics, RT-qPCR, immunohistochemistry, and WB analysis. Lymphocytes were isolated and flow cytometric assays were conducted to evaluate the differentiation between Th17 and Treg cell among CD4+ cells.

RESULTS

Results indicated that PPRFT obviously reduced the number of coughs, prolonged cough latency, reduced inflammatory cell infiltration and lung tissues damage, and decreased the serum level of IL-6, IL-1β, TNF-α, and IL-17 while increasing IL-10 levels. Notably, PPRFT suppressed Th17 cell divergence and promoted Treg cell divergence. Furthermore, serum metabolomic assays showed that 46 metabolites differed significantly between group, with 35 pathways involved. Moreover, mRNA levels of IL-6, NF-κB, IL-17, RORγT, JAK2, STAT3, PI3K and AKT in lung tissues remarkably reduced and mRNA levels of IL-10 and FOXP3 were elevated after PPRFT pretreatment. Additionally, PPRFT treatments decreased the protein levels of IL-6, NF-κB, IL-17, RORγT, p-JAK2, p-STAT3, p-PI3K, and p-AKT and increased the protein levels of IL-10 and FOXP3, but no significantly effects to the levels on JAK2, STAT3, PI3K, and AKT in the lungs.

CONCLUSION

Conclusively, our result suggested the effect with PPRFT on chronic cough may be mediated through IL-6/JAK2/STAT3 and PI3K/AKT/NF-κB pathway, which regulate the differentiation between Th17 and Treg cell. This beneficial effect of PPRFT in capsaicin and ammonia-stimulated chronic cough mice indicates its potential application in treating chronic cough.

The emerging role for neutrophil mitochondrial metabolism in lung inflammation

Recent advances shed light on the importance of mitochondrial metabolism in supporting essential neutrophil functions such as trafficking, NETosis, bacterial killing, and modulating inflammatory responses. Mitochondrial metabolism is now recognized to contribute to a number of lung diseases marked by neutrophilic inflammation, including bacterial pneumonia, acute lung injury, and chronic obstructive pulmonary disease. In this mini review, we provide an overview of neutrophil metabolism focusing on the role of mitochondrial programs, discuss select neutrophil effector functions that are directly influenced by mitochondrial metabolism, and present what is known about the role for mitochondrial metabolism in lung diseases marked by neutrophilic inflammation.

Shouhui Tongbian Capsules induce regression of inflammation to improve intestinal barrier in mice with constipation by targeted binding to Prkaa1: With no obvious toxicity

Constipation arising from the poor bowel movement is a rife enteric health problem. Shouhui Tongbian Capsule (SHTB) is a traditional Chinese medicine (TCM) which effectively improve the symptoms of constipation. However, the mechanism has not been fully evaluated. The purpose of this study was to evaluate the effect of SHTB on the symptoms and intestinal barrier of mice with constipation. Our data showed that SHTB effectively improved the constipation induced by diphenoxylate, which was confirmed by shorter first defecation time, higher internal propulsion rate and fecal water content. Additionally, SHTB improved the intestinal barrier function, which was manifested by inhibiting the leakage of Evans blue in intestinal tissues and increasing the expression of occludin and ZO-1. SHTB inhibited NLRP3 inflammasome signaling pathway and TLR4/NF-κB signaling pathway, reduced the number of proinflammatory cell subsets and increased the number of immunosuppressive cell subsets to relieve inflammation. The photochemically induced reaction coupling system combined with cellular thermal shift assay and central carbon metabolomics technology confirmed that SHTB activated AMPKα through targeted binding to Prkaa1 to regulate Glycolysis/Gluconeogenesis and Pentose Phosphate Pathway, and finally inhibited intestinal inflammation. Finally, no obvious toxicity related to SHTB was found in a repeated drug administration toxicity test for consecutive 13 weeks. Collectively, we reported SHTB as a TCM targeting Prkaa1 for anti-inflammation to improve intestinal barrier in mice with constipation. These findings broaden our knowledge of Prkaa1 as a druggable target protein for inflammation inhibition, and open a new avenue to novel therapy strategy for constipation injury.

In memoriam: Filippo Rossi (1926-2022)

Description of the scientific life of Filippo Rossi, who died in October 2022.

Specific and Complex Reprogramming of Cellular Metabolism in Myeloid Cells during Innate Immune Responses

Renewed interest in immune cell metabolism has led to the emergence of a research field aimed at studying the importance of metabolic processes for an effective immune response. In addition to the adaptive immune system, cells of the myeloid lineage have been shown to undergo robust metabolic changes upon activation. Whereas the specific metabolic requirements of myeloid cells after lipopolysaccharide/TLR4 stimulation have been extensively studied, recent evidence suggested that this model does not represent a metabolic blueprint for activated myeloid cells. Instead, different microbial stimuli, pathogens, or tissue microenvironments lead to specific and complex metabolic rewiring of myeloid cells. Here we present an overview of the metabolic heterogeneity in activated myeloid cells during health and disease. Directions for future research are suggested to ultimately provide new therapeutic opportunities. The uniqueness of metabolic signatures accompanying different conditions will require tailor-made interventions to ultimately modulate aberrant myeloid cell activation during disease.

Amoeboid neutrophils with few granules in childhood acute precursor B cell leukemia

BACKGROUND

We sometimes treat children with acute lymphoblastic leukemia in whom neutrophil function is impaired at diagnosis. Transmission electron microscopy enables more accurate assessment by providing greater morphological detail. Using transmission electron microscopy, we have found 2 types of neutrophils in the peripheral blood of children: 1) amoeboid neutrophils, which are characterized as amoeboid cells with pseudopodia and few granules, and 2) round neutrophils with many granules at different stages and glycogen particles.

AIM

To assess the pathological role of amoeboid neutrophils, we investigated amoeboid neutrophils in the peripheral blood of children with leukemia.

METHODS

Amoeboid neutrophils were examined in peripheral blood from 12 children with acute B-cell precursor lymphoblastic leukemia (BCP-ALL). Eight children with short stature served as healthy control subjects.

RESULTS

The percentage of amoeboid neutrophils (per total neutrophil count) at onset or relapse of BCP-ALL was significantly higher than at remission. Children with short stature showed a lower percentage of amoeboid neutrophils than did children with acute leukemia.

CONCLUSION

The presence of fewer intracellular granules in amoeboid neutrophils suggests lower neutrophil activity. These results indicate that amoeboid neutrophils in patients with BCP-ALL have lower function at onset and relapse.

Metabolic event involved in the bactericidal activity of normal mouse macrophages

The intracellular bactericidal activity of normal mouse peritoneal macrophages requires a viable, actively metabolizing cell. The killing mechanism is apparently dependent upon an intact respiratory electron chain since inhibition of activity is achieved by anaerobiosis, cyanide, antimycin A, or amytal. By way of contrast, inhibitors of oxidative phosphorylation, glycolysis, the Krebs citric acid cycle, and the phosphogluconate oxidative pathway are without influence on this antibacterial activity. Various dyes and electron acceptors with selected reduction-oxidation values also inhibit killing. Although the bactericidal substance was not identified, the data are consistent with the hypothesis that the primary agent is hydrogen peroxide.

Role of cell wall structure of salmonella in the interaction with phagocytes

Wild-type and cell wall mutants of Salmonella were examined for sensitivity to ingestion and intracellular killing in vitro by mouse peritoneal macrophages and guinea pig polymorphonuclear leukocytes. A complete polysaccharide core of the cell wall is important for resisting ingestion and intracellular killing, and the presence of the O-specific side chains contributes further resistance. Uridine diphosphate-gal-4-epimeraseless mutants grown on galactose-supplemented medium, rendering them smooth phenotypes, showed resistance to ingestion and intracellular killing similar to the wild type.

STUDIES ON THE EFFECT OF CERTAIN MACROMOLECULAR SUBSTANCES ON THE RESPIRATORY ACTIVITY OF THE LEUCOCYTES OF PERIPHERAL BLOOD

The oxygen, uptake of lightly heparinized human blood was found to increase markedly upon the addition of bacterial endotoxins, soluble antigen-antibody complexes, or polystyrene latex particles. The effect apparently reflects a transitory stimulation of respiratory activity of the blood leucocytes. The effect did not occur in the presence of anticoagulant amounts of citrate or ethylenediaminetetraacetate, was inhibited by iodoacetate and fluoride ions, and may be related to the energy-yielding processes involved in histamine release or phagocytosis.

Degranulation of polymorphonuclear leucocytes following phagocytosis of microorganisms

A marked reduction in numbers of cytoplasmic granules in rabbit and human polymorphonuclear leucocytes takes place following ingestion of various microorganisms or of a yeast cell wall preparation. The degranulation occurs within 30 minutes of phagocytosis, and is directly related to the quantity of material engulfed. White cells completely degranulated following phagocytosis of large numbers of microorganisms remain viable for at least 1 hour. The granules of polymorphonuclear leucocytes contain the antimicrobial agent, phagocytin, and various digestive enzymes. These substances thus are released into the cytoplasm or into vacuoles following ingestion of foreign material. The granule system and granule lysis mechanism may well play a central role in the primary function of these specialized cells; namely, that of destroying invading microorganisms.

Studies on the pathogenesis of fever. X. The effect of certain enzyme inhibitors on the production and activity of leucocvtic pvrogen

The production of endogenous pyrogen by intact granulocytes obtained from acute peritoneal exudates is blocked by arsenite, iodoacetate, p-chloromercuribenzoate, and N-ethylmaleimide in concentrations of 2 x 10^–4M. When the concentration of these sulfhydryl-reactive enzyme inhibitors is increased to 2 x 10^–2M, only the iodoacetate inactivates the pyrogen molecule, whereas the arsenite, the p-chloromercuribenzoate, and the N-ethylmaleimide have no gross effect upon its thermogenic activity. Both diisopropyl fluorophosphate and dinitrofluorobenzene are even more potent inactivators of the pyrogen molecule than iodoacetate, although the action of the DFP cannot be blocked or reversed by known antagonists such as 2-pyridine aldoxime methiodide and hydroxylamine. Proteolytic enzymes, potentially capable of degrading leucocytic pyrogen, are released from polymorphonuclear leucocytes, along with the pyrogen, when the cells are incubated in normal salt solution. These enzymes are readily activated by a sufficient concentration of glutathione (2 x 10^–2M). They are not present in preparations of partially purified leucocytic pyrogen from which much of the non-pyrogenic protein has been removed. Glutathione by itself, even at concentrations as high as 2 x 10^–1M, does not affect in the gross the thermogenic activity of the purified pyrogen. The implications of these findings in relation to both the production and the chemical characteristics of leucocytic pyrogen are discussed.

The isolation and properties of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes

A method has been described for isolation of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes. Homogeneous suspensions of leucocytes were disrupted by lysis in 0.34 M sucrose. This procedure liberated the cytoplasmic contents of the cell and dissolved a considerable proportion of the nuclei. Following disruption, the sucrose lysate was separated into three fractions by differential centrifugation, i.e. 400 g or nuclear pellet, 8,200 g or granule pellet and the postgranule supernate. Microscopic examination revealed that the 8,200 g pellet was composed of intact granules as well as occasional mitochondria. The other two fractions were morphologically heterogeneous. Studies with isolated granules demonstrated their lysis by a variety of weak acids and surface-active agents. When buffered solutions were employed between the ranges of pH 2.0 and 9.0, granule lysis began at pH 5.5 and was complete at pH 4.0. Chemical analysis disclosed that the granule pellet contained protein and phospholipid with only traces of nucleic acids. Approximately 70 to 80 per cent of the total cellular antimicrobial agent phagocytin was present in the granule fraction. This material was liberated from the granules by acid (pH 5.0 or lower). Studies on selected enzymes showed that acid phosphatase, alkaline phosphatase, nucleotidase, ribonuclease, deoxyribonuclease, and beta glucuronidase were predominantly localized in the granule fraction. Approximately 50 per cent of total cellular lysozyme and cathepsin were also present in the 8,200 g pellet. Disruption of the granules was associated with the release of the majority of granule protein and enzymes in a non-sedimentable form. The properties and composition of rabbit polymorphonuclear leucocyte granules seem to be analogous to those of liver lysosomes.

The fate of bacteria within phagocytic cells. II. The modification of intracellular degradation

The influence of immune serum, PMN leucocytes, and macrophages from immunized animals and metabolic inhibitors on the intraphagocytic degradation of isotopically labeled bacteria has been evaluated. Immune serum specifically delayed the degradation of a variety of P(32)- and C(14)-labeled organisms within both types of phagocytic cells. The active principle in immune serum was found to be a globulin which could be removed by adsorption with the homologous organism. The inhibiting action of immune serum was thought to be related to its combination with the bacterial surface and the subsequent temporary protection of the bacteria from leucocyte enzymes. PMN leucocytes and macrophages obtained from immune hosts did not differ from normal cells in their ability to degrade homologous, labeled bacteria. Immune serum had the same inhibiting influence in the presence of "immune" cells as with cells from non-immunized hosts. Iodoacetate, arsenite, and cyanide at concentrations which inhibited the glycolysis and respiration of both PMN leucocytes and macrophages had no influence on the rate of degradation of isotopically labeled bacteria engulfed by these cells. This implied that following the initial phagocytic events, the degradation of bacteria within leucocytes is not dependent upon the major pathways of energy metabolism.

Metabolic patterns in three types of phagocytizing cells

Some chemical and metabolic characteristics of polymorphonuclear leukocytes and monocytes from peritoneal exudates of the guinea pig, and of alveolar macrophages from the same animal, have been compared. Changes in the metabolic patterns of these three types of cell have been followed during the act of phagocytosis. The effect of conventional inhibitors of metabolism, and of anaerobiosis on the phagocytic ability of each of the three cell types mentioned has also been determined. From these studies it was found that alveolar macrophages depend to a considerable degree upon oxidative phosphorylation to provide energy for phagocytosis. The other two types of cell depend only on glycolysis as the source of metabolic energy for that function. In some experiments aimed at obtaining information on the possible role of complex lipids in the function of the cell membrane, it was noted that phagocytosis stimulated the incorporation of inorganic phosphate-P³² into the phosphatides of both types of cell from peritoneal exudates—whether these were free-swimming or adherent to a surface. This phenomenon has not yet been detected in the case of alveolar macrophages.

Effect of osmolarity on phagocytosis

Sbarra, Anthony J. (St. Margaret's Hospital, Boston, Mass.), William Shirley, and John S. Baumstark. Effect of osmolarity on phagocytosis. J. Bacteriol. 85:306-313. 1963.-The effect of a number of different compounds on phagocytosis was studied. Phagocytosis was monitored by morphological and biochemical means. It was found that the addition of compounds such as KCl, NaCl, sodium or potassium malonate, and K(2)SO(4) to the phagocytic system inhibited phagocytosis. The increased salt concentration specifically inhibited the respiratory activity associated with phagocytosis. The endogenous respiration of the leukocytes was unaffected. Glycolysis and the increased flow of glucose through the hexose monophosphate pathway were also inhibited by the elevated concentration of salts. In addition, cells exposed to high salt concentrations appeared to be reduced in size as compared with normal cells. The inhibition can be reversed by lowering the salt concentration. It was suggested that the increased osmotic pressure of the system was responsible for the inhibition.

Cinemicrophotographic observations on granule lysis in polymorphonuclear leucocytes during phagocytosis

Phagocytosis of yeast cell walls and of Bacillus megaterium by human, rabbit, and chicken polymorphonuclear leucocytes has been observed by phase contrast microscopy and recorded on motion picture film. In suitably thin preparations intracellular events could be visualized well. Lysis of cytoplasmic granules began early in the course of the ingestion process, rupture occurring only in granules adjacent to the microorganism being engulfed. Formation of a visible vacuole about the ingested particle frequently followed degranulation. Chicken polymorphonuclear leucocytes, with their large phase-dense granules, were particularly suitable subjects for observations on detailed morphologic aspects of granule lysis. Rupture took place rapidly (0.1 second or less); in place of the granule there appeared a clear zone, often with a small phase-dense round structure in its center. Also accompanying granule lysis was an increase in phase density of the adjacent surface of the microorganism. Over the course of the following few seconds the darkening on the organism faded, the dense small body disappeared from view, and the clear zone contracted towards the engulfed particle. The observations are discussed in relation to the hypothesis that fusion takes place between the granule membrane and the invaginated cell membrane overlying the ingested particle, with discharge of granule contents directly into the phagocytic vacuole.

Fate of staphylococci within human leukocytes

Direct observations by phase microscopy have demonstrated that small numbers of pathogenic staphylococci survive prolonged periods of time within living human polymorphonuclear leukocytes. Non-pathogenic microorganisms are rapidly destroyed in similar preparations. Leukocytes in which staphylococci remained viable often appeared less vigorous after ingesting microorganisms, but intracellular survival could not be correlated with obvious leukocyte damage with any consistency. Both pathogenic and non-pathogenic cocci were seen to divide within living granulocytes during the first few minutes after ingestion. Occasionally pathogenic staphylococci multiplied in dying cells after long periods of intracellular residence. Phagocytosis of more than one pair of staphylococci by a single leukocyte appeared to act as a stimulus to bacterial destruction. Multiple ingestions of pathogenic staphylococci reduced the incidence of survival of the total microbiol population contained within the cell.

Functional and metabolic properties of polymorphonuclear leucocytes. II. The influence of a lipopolysaccharide endotoxin

The effects of a purified bacterial lipopolysaccharide endotoxin on homogenous populations of rabbit polymorphonuclear leucocytes have been studied in vitro under defined conditions. Employing a 500-fold range of concentration (0.1 to 50.0 µg./ml.), it was shown that endotoxin enhanced the rate at which staphylococci were killed by leucocytes. The mechanism underlying the increased killing was found to be a direct stimulation of the phagocytic activity of the leucocyte and not mediated by the release of bactericidins or opsonins from the treated cells. In the presence of 10 per cent serum all concentrations of endotoxin enhanced phagocytosis, whereas at lower serum concentrations, the higher doses of lipopolysaccharide inhibited the phagocytic activity of the cells. Similar concentrations of endotoxin were capable of increasing the utilization of glucose and the production of lactic acid. Endotoxin treated leucocytes exhibited no change in oxygen consumption, and only a slight depression in glycogen synthesis. It appeared that endotoxin could interact and alter the functional and metabolic properties of leucocytes in the absence of serum. The demonstration of enhanced phagocytic activity of endotoxin-treated cells was dependent upon the particular opsonic requirements for the organism under study.

STUDIES ON THE PATHOGENESIS OF FEVER. 13. THE EFFECT OF PHAGOCYTOSIS ON THE RELEASE OF ENDOGENOUS PYROGEN BY POLYMORPHONUCLEAR LEUKOCYTES

1. Phagocytosis promotes the release of endogenous pyrogen from polymorphonuclear leucocytes. 2. The release of pyrogen, though initiated by the phagocytic event, is not synchronous with it. 3. The postphagocytic release mechanism is not inhibited by sodium fluoride and, therefore, appears not to require continued production of energy by the cell. 4. The release process, on the other hand, is inhibited by arsenite, suggesting the participation of one or more sulfhydryl-dependent enzymes in the over-all reaction. 5. Particle for particle, the ingestion of heat-killed rough pneumococci causes the release of approximately 100 times as much pyrogen as the ingestion of polystyrene beads of the same size. 6. The pyrogen release mechanism of polymorphonuclear leucocytes separated directly from blood, unlike that of granulocytes in acute inflammatory exudates, is not readily activated by incubation of the cells in K-free saline. Despite this difference, both blood and exudate leucocytes following phagocytosis release large amounts of pyrogen, even in the presence of K(+). The fact that the postphagocytic reaction is uninhibited by the concentrations of K(+) which are present in plasma and extracellular fluids, suggests that this mechanism of pyrogen release may well operate in vivo. 7. As might be expected from the foregoing observations, the intravenous injection of a sufficiently large number of heat-killed pneumococci causes fever in the intact host. Intravenously injected polystyrene beads, on the other hand, are significantly less pyrogenic. Evidence is presented to support the conclusion that the fever in both instances is caused by pyrogen released from the circulating leucocytes which have phagocyted the injected particles. 8. The possible relationships of these findings to the pathogenesis of fevers caused by acute bacterial infections are discussed.

Acetylcholinesterase activation of peritoneal macrophages is independent of catalytic activity

1. In diverse tissues, acetylcholinesterase appears to play a critical role in the functional state of cells completely dependent of cholinergic transmission. However, very little is known about the mechanisms and actual molecular structures mediating the fundamental interactions between this protein and the cellular membrane. 2. In this study, peritoneal macrophages were used as a model system to study the possible interaction between acetylcholinesterase, acting in a non-cholinergic capacity, and the cellular membrane. 3. When acetylcholinesterase was incubated with macrophages harvested from rat peritoneum, the rate of oxygen consumption was increased in a concentration-dependent manner that was independent of mitochondrial block with sodium cyanide. Furthermore, heat inactivation of enzymatic activity or application of BW 284C51 at a concentration which totally blocks catalytic activity did not eliminate the effect. 4. In contrast, incubation with bovine serum albumin or butyrylcholinesterase actually retarded oxygen consumption. 5. The effect of acetylcholinesterase depended on the presence of divalent cations and was inhibited by mannan and D-mannose, but not D-galactose. It is concluded that acetylcholinesterase can induce a "respiratory burst" in macrophages independent of its conventional catalytic site but involving either the mannose receptor of the monocyte-derived macrophage or a possible sugar binding site on acetylcholinesterase itself.

Zanvil Alexander Cohn 1926-1993

Zanvil Alexander Cohn, an editor of this Journal since 1973, died suddenly on June 28, 1993. Cohn is best known as the father of the current era of macrophage biology. Many of his scientific accomplishments are recounted here, beginning with seminal studies on the granules of phagocytes that were performed with his close colleague and former editor of this Journal, James Hirsch. Cohn and Hirsch identified the granules as lysosomes that discharged their contents of digestive enzymes into vacuoles containing phagocytosed microbes. These findings were part of the formative era of cell biology and initiated the modern study of endocytosis and cell-mediated resistance to infection. Cohn further explored the endocytic apparatus in pioneering studies of the mouse peritoneal macrophage in culture. He described vesicular inputs from the cell surface and Golgi apparatus and documented the thoroughness of substrate digestion within lysosomal vacuoles that would only permit the egress of monosaccharides and amino acids. These discoveries created a vigorous environment for graduate students, postdoctoral fellows, and junior and visiting faculty. Some of the major findings that emerged from Cohn's collaborations included the radioiodination of the plasma membrane for studies of composition and turnover; membrane recycling during endocytosis; the origin of the mononuclear phagocyte system in situ; the discovery of the dendritic cell system of antigen-presenting cells; the macrophage as a secretory cell, including the release of proteases and large amounts of prostaglandins and leukotrienes; several defined parameters of macrophage activation, especially the ability of T cell-derived lymphokines to enhance killing of tumor cells and intracellular protozoa; the granule discharge mechanism whereby cytotoxic lymphocytes release the pore-forming protein perforin; the signaling of macrophages via myristoylated substrates of protein kinase C; and a tissue culture model in which monocytes emigrate across tight endothelial junctions. In 1983, Cohn turned to a long-standing goal of exploring host resistance directly in humans. He studied leprosy, focusing on the disease site, the parasitized macrophages of the skin. He injected recombinant lymphokines into the skin and found that these molecules elicited several cell-mediated responses. Seeing this potential to enhance host defense in patients, Cohn was extending his clinical studies to AIDS and tuberculosis. Zanvil Cohn was a consummate physician-scientist who nurtured the relationship between cell biology and infectious disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Parenteral nutrition in patients with diabetes mellitus: theoretical and practical considerations

It is estimated that there are 11 million diabetics in the United States. Increasing recognition of the importance of nutrition in clinical medicine coupled with the frequent hospitalizations of the diabetic patient has heightened interest in their nutritional therapy. Patients with diabetes mellitus exhibit many abnormalities in the regulation of carbohydrate metabolism which may be accentuated during illness as part of the metabolic response to injury. An understanding of the effect of injury/illness, parenteral nutrition, and diabetes mellitus on carbohydrate metabolism is essential for the development of a rational approach to the initiation and maintenance of nutritional support in the diabetic patient.

Brain acidosis in experimental pneumococcal meningitis

Purulent meningitis is a serious disease that often has a lethal outcome or gives lasting complications due to brain damage. The processes causing brain dysfunction or damage are still not uncovered nor are the reasons for the characteristic increase of CSF lactate, or the decrease of glucose levels and of pH. We studied rabbits with experimentally induced purulent meningitis (Streptococcus pneumoniae). Ten hours after the inoculation into cisterna magna the rabbits developed symptoms of meningitis, with stiffness of the neck, tachypnea, and fever. The CSF level of lactate and the number of leukocytes were significantly increased and the glucose level was decreased. Brain interstitial pH, as measured by ion selective microelectrodes, was significantly decreased from the normal level of 7.4 to 6.9. The levels of energy metabolites in brain cortex, including glucose, were not different between controls and infected animals, and the lactate level was not elevated more than could have been explained by passive diffusion from the CSF. This shows that the brain tissue is not the source of CSF lactate nor the sink for glucose in CSF. The marked acidification of brain interstitial space and CSF demonstrates that purulent meningitis causes a significant disturbance of brain ion homeostasis that could be, at least in part, responsible for the brain dysfunction. We suggest that activated leukocytes consume CSF glucose and produce lactic acid and secrete protons, which causes the CSF and interstitial acidosis.

The superoxide-forming enzymatic system of phagocytes

The formation of oxygen-derived free radicals by the phagocytes (neutrophils, eosinophils, monocytes and macrophages) is catalysed by a membrane-bound NADPH oxidase which is dormant in resting cells and becomes activated during phagocytosis or following interaction of the cells with suitable soluble stimulants. This enzyme is under investigation in many laboratories but its molecular structure remains to be clarified. Possible components such as flavoproteins, cytochrome b558, and quinones have been proposed on the basis of enzyme purification studies, effects of inhibitors, kinetic properties and analysis of genetic defects of the oxidase. An extensive discussion of the evidence for the participation of these constituents is reported. On the basis of the available information on the structure and the catalytic properties of the NADPH oxidase, a series of possible models of the electron-transport chain from NADPH to O2 is presented. Finally, the triggering mechanism of the respiratory burst is discussed, with particular reference to the stimulus-response coupling and the final modification(s) of the oxidase (phosphorylation, assembly, change of lipid environment, etc.) which are involved in its activation.

Pleural fluid pH: diagnostic, therapeutic, and prognostic value

Measurement of pleural fluid pH has diagnostic, therapeutic, and prognostic implications in exudative pleural effusions (Table II). A parapneumonic effusion with a pleural fluid pH below 7.2 indicates an empyema is forming which necessitates chest tube drainage in all patients, whereas a pleural fluid pH over 7.3 does not require drainage. If the pH of a parapneumonic effusion is 7.2 to 7.3, serial pleural fluid pH measurements with clinical observation will help to determine the need for chest tube drainage. A pleural fluid glucose level of below 60 mg/dl and a lactic dehydrogenase level over 1,000 IU/dl in conjunction with a pleural fluid pH of 7.2 to 7.3 indicate an impending empyema. These findings are consistent with our clinical experience in patients with parapneumonic effusion. Tuberculous pleural effusions had a pleural fluid pH below 7.4 in all reported patients. This pH may be of value in distinguishing tuberculous pleural effusions from recent malignant effusions, which tend to have a higher pleural fluid pH, particularly if used in conjunction with other pleural fluid values, cell counts, and other clinical parameters. In patients with malignant pleural effusions, a pH of less than 7.3 is usually seen in those effusions present for several months and is associated with a lower glucose level and a higher white cell count and lactic dehydrogenase level. Results of cytologic study of the pleural fluid and pleural biopsy are often positive, there is poor response to sclerosing agents, and the prognosis is poor. A rheumatoid pleural effusion most often has a pleural fluid pH below 7.3. A pleural fluid pH below 6 is seen almost exclusively in esophageal rupture but rarely with empyemas, whereas a pleural fluid pH below 7 occurs in esophageal rupture, empyema, and rheumatoid pleural effusions. In pleural effusions secondary to congestive heart failure, the pH is almost always greater than 7.4 unless systemic acidemia coexists, in which case the pleural fluid pH is within 0.04 units of the simultaneous arterial pH. The major value of pleural fluid pH is to determine the need for chest tube drainage in parapneumonic effusions and to determine the response to sclerosing agents in patients with malignant pleural effusions. As with all diagnostic tests, the results should be interpreted in the context of other diagnostic tests of the pleural fluid and clinical aspects before diagnostic or therapeutic decisions are made.

Assessment of attachment, ingestion, and killing of Escherichia coli by bovine polymorphonuclear cells with combined micromethods

A set of microassays separately measuring attachment, ingestion, and overall killing of Escherichia coli by bovine granulocytes was devised and its analytical potential used to test the effect of drugs which block intracellular killing: sodium azide, phenylbutazone, chloroquine phosphate were all inactive, suggesting that O2-dependent systems were not the sole pathway involved in the killing of E.coli by granulocytes. The microtechniques were also used to investigate the opsonic requirements for phagocytosis of two E.coli strains. Absorption of normal bovine serum with the homologous and the heterologous strains showed that specific antibodies were necessary to induce attachment of bacteria to phagocytes. Once bound to granulocytes, the unencapsulated strain P4 was engulfed, whereas for the encapsulated strain B117, complement was required for the internalization step of phagocytosis. With immune serum the need for complement was not absolute.

Stimulating effect of fructose 1-6 diphosphate on the phagocytic function of rat RES and on human leukocyte carbohydrate metabolism

The phagocytic behavior of the reticuloendothelial system in the rat was assessed by a quantitative technique following fructose-1,6-diphosphate (FDP) administration. In addition, the effect of FDP on the carbohydrate metabolism of human leukocytes was investigated. The rate of colloidal carbon clearance from the blood was increased significantly in the FDP-treated rats as compared to dextrose and saline controls (p less than 0.001). FDP also attenuated the hepatic decrease of ATP (p less than 0.005) and creatine phosphate (p less than 0.005) that has been observed after intravenous administration of colloidal carbon. Carbohydrate metabolism in human leukocytes was enhanced by FDP, with a concomitant increase in ATP content (p less than 0.001). Experimental evidence suggests that FDP intervenes in the Embden-Meyerhof pathway both as a metabolic regulator and as a high energy substrate. These properties of FDP in stimulating the carbohydrate metabolism have recently been described in man.

Measurement of intracellular calcium ions and oxygen radicals in polymorphonuclear leucocyte-erythrocyte 'ghost' hybrids

Sendai virus induced fusion between rat polymorphonuclear leucocytes and human erythrocyte 'ghosts' containing the Ca-activated photoprotein obelin. This resulted in the production of more than 90% of the cell population as viable hybrid cells, containing active photoprotein. Substances entrapped originally within the 'ghosts' could be transferred to the hybrids as shown morphologically by fluorescence microscopy, and immunologically by the use of antibodies specific for each of the cell types. Resting free Ca2+ in the hybrids was estimated to be 0.1-0.3 microM. The relationship between intracellular Ca2+ within the hybrids and the production by the hybrids of oxygen radicals, as measured by luminol chemiluminescence, was investigated. The Ca ionophore A23187 stimulated both a rise in intracellular Ca2+ and oxygen radical production, the maximum rate of oxygen radical production being dependent upon the intracellular Ca2+ concentration. Complement activation at the cell surface, chemotactic peptide, and concanavilin A stimulated a rise in intracellular Ca2+, each with different characteristics: complement activation increased intracellular Ca2+ to 8 microM for at least 60 sec; chemotactic peptide raised it to approximately 0.6 microM for a prolonged period (at least 10 min) and concanavilin A stimulated a transient (t1/2 = approximately 80 sec) rise to approximately 0.6 microM. Un-opsinized particles, latex beads (diam. approximately equal to 1 micron), which stimulate oxygen radical production, did not produce a detectable rise in intracellular Ca2+. Intracellular EGTA (approximately, 2.5 mM) inhibited both the oxygen radical production and the rises in intracellular Ca2+ induced by chemotactic peptide and concanavilin A, and delayed both the rise in intracellular Ca2+ and the onset of oxygen radical production induced by complement. Intracellular EGTA had no effect on oxygen radical production stimulated by latex particles. An increase in intracellular Ca2+ triggered oxygen radical production by the hybrids in response to the following stimuli: concanavilin A, chemotactic peptide, complement and the Ca ionophore A23187. However, the extent and duration of the increase in cytoplasmic Ca2+ was different for each stimulus, and the apparent relationship between cytoplasmic Ca2+ and oxygen radical production was different for each stimulus. Un-opsinized particles stimulated oxygen radical production without requiring a rise in intracellular Ca2+ concentration.

Modulation of bacterial association to HeLa cell cultures by cell density and by chlamydial infection

The effect of cell density on the rate of association of Escherichia coli and Staphylococcus aureus by monolayer cultures of HeLa 229 cells was investigated. Radioactively labeled bacteria were incubated with sparsely and densely plated cells. The rate of bacterial uptake was 10- to 20-fold higher in sparse cultures. Kinetic analysis of data with different multiplicities of input bacteria showed that the Km of the reaction was unaltered, whereas the Vmax was inversely related to cell density. Pretreatment of HeLa cultures with dibutyryl adenosine 3',5'-phosphate had little effect on the rate of bacterial association. The simultaneous presence of an obligately parasitic bacterium, Chlamydia trachomatis LGV434, enhanced the Vmax of association of E. coli and S. aureus. This effect was more pronounced in dense HeLa cell cultures. Heat-inactivated chlamydiae were unable to modify the association. Enhanced association persisted for at least 3 h after infection with chlamydiae.

Study of phagocytic function with a quantitative nitroblue-Tetrazolium (NBT) reduction test in diabetes mellitus

In 40 patients suffering from diabetes mellitus and in 18 healthy volunteers the phagocytic function was investigated using a quantitative NBT test. The NBT reduction was significantly lower in diabetes than in healthy donors irrespective of affliction with other dermatoses. A significant correlation was found between the severity and hence the insulin dependency of diabetics and the NBT-reductive capacity.

Gonococci-human polymorphonuclear leukocyte interactions: metabolic studies associated with attachment and ingestion

Utilizing monolayers of human polymorphonuclear leukocytes, optimal conditions for attachment and ingestion of Neisseria gonorrhoeae were determined. Both attachment and ingestion were optimal at 36 degrees C when a bacteria-leukocyte ratio of 100:1 was employed. After 30 min of incubation, log-phase viable type 2 gonococci were attached to 90% of leukocytes, whereas log-phase viable type 4 gonococci were ingested by 80 to 90% of cells. Respiratory inhibitors had no effect on attachment or ingestion, whereas glycolytic inhibitors blocked ingestion but did not affect attachment of gonocci to the leukocyte surface. Inhibition was dose dependent and partially reversible. The oxidative metabolism of leukocytes with gonococci attached or ingested was also examined. Attachment of log-phase type 2 gonococci stimulated a minimal increase in glucose oxidation and oxygen consumption by leukocytes in contrast to marked increases by leukocytes that had ingested viable type 4 or heat-killed typed 2 organisms. These results demonstrate that attachment of log-phase type 2 gonococci to the surface membrane does not stimulate significant leukocyte oxidative metabolism nor initiate the phagocytic process.

Depressed immunological defence mechanisms in mice with experimentally induced diabetes

Persistent diabetes mellitus with marked hyperglycemia was induced in mice by the administration of streptozotocin. In these streptozotocin-induced diabetic mice, resistance to tubercle bacillus challenge and primary as well as secondardy humoral immune responses against foreign erythrocytes were markedly depressed. The T-cell function in delayed hypersensitivity to 2,4-dinitro-1-fluorobenzene and bacterial phagocytic activity or peritoneal macrophages were markedly depressed. In contrast, the B-cell function in antibody production against T-independent antigen and the intracellular killing of bacteria in peritoneal macrophages were intact. We concluded that depression of the T-cell function or the phagocytic activity of macrophages or both may be the main immunological defect in these mice.