Decreased phagocytic capacity of rat peritoneal macrophages following photon abdominal irradiation

Modifiable contributing factors to COVID-19: A comprehensive review

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. The current study identifies eighty immune system dysfunction-enabling toxic stressors and behaviors (hereafter called modifiable contributing factors (CFs)) that also link directly to COVID-19. Each CF is assigned to one of the five categories in the CF taxonomy shown in Section 3.3.: Lifestyle (e.g., diet, substance abuse); Iatrogenic (e.g., drugs, surgery); Biotoxins (e.g., micro-organisms, mycotoxins); Occupational/Environmental (e.g., heavy metals, pesticides); Psychosocial/Socioeconomic (e.g., chronic stress, lower education). The current study shows how each modifiable factor contributes to decreased immune system capability, increased inflammation and coagulation, and increased neural damage and neurodegeneration. It is unclear how real progress can be made in combatting COVID-19 and other similar diseases caused by viral variants without addressing and eliminating these modifiable CFs.

Effect of hexane fraction of leaves of Cinnamomum tamala Linn on macrophage functions

The leaves of Cinnamomum tamala Linn (Lauraceae), component of Indian spices are associated with hypoglycemic property in Ayurveda; however, no report is available towards its immunomodulation property, which has been explored here. The dried powder of CT leaves was extracted with hexane and solvent free extract (CTH) was given orally to rats for 10 days, in various doses. Its effect was studied on peritoneal macrophage functions, and was compared with ascorbic acid (1,000 mg/kg, immune-stimulant) and cyclophosphamide (10 mg/kg, immune-suppressant). CTH significantly suppressed phagocytosis activity (EC(50) 2,355 +/- 52.45 mg/kg), reduced production of superoxide (EC(50) 275.91 +/- 10.21 microg/ml) and cellular NADPH (EC(50) 384.959 +/- 4.85 microg/ml) content in concentration dependent manner. It also inhibited LPS induced production of nitric oxide (EC(50) 143.75 +/- 3.40 microg/ml) and iNOS protein expression (EC(50) 183.132 microg/ml). Thus, it could be suggested that non-polar hexane fraction of leaves of C. tamala possesses immunosuppressive property, which is mediated through modulation of innate immunity.

Raft aggregation with specific receptor recruitment is required for microglial phagocytosis of Abeta42

Microglial phagocytosis contributes to the maintenance of brain homeostasis. Mechanisms involved, however, remain unclear. Using Abeta(42) solely as a stimulant, we provide novel insight into regulation of microglial phagocytosis by rafts. We demonstrate the existence of an Abeta(42) threshold level of 250 pg/mL, above which microglial phagocytic function is impaired. Low levels of Abeta(42) facilitate fluorescent bead uptake, whereas phagocytosis is inhibited when Abeta(42) accumulates. We also show that region-specific raft clustering occurs before microglial phagocytosis. Low Abeta(42) levels stimulated this type of raft aggregation, but high Abeta(42) levels inhibited it. Additionally, treatment with high Abeta(42) concentrations caused a redistribution of the raft structural protein flotillin1 from low to higher density fractions along a sucrose gradient. This suggests a loss of raft structural integrity. Certain non-steroidal anti-inflammatory drugs, e.g., the cyclooxygenase 2-specific nonsteroidal anti-inflammatory drugs, celecoxib, raise Abeta(42) levels. We demonstrated that prolonged celecoxib exposure can disrupt rafts in a manner similar to that seen in an elevated Abeta(42) environment: abnormal raft aggregation and Flot1 distribution. This resulted in aberrant receptor recruitment to rafts and impaired receptor-mediated phagocytosis by microglial cells. Specifically, recruitment of the scavenger receptor CD36 to rafts during active phagocytosis was affected. Thus, we propose that maintaining raft integrity is crucial for determining microglial phagocytic outcomes and disease progression.

The antioxidative and immunostimulating properties of d-glucosamine

The objective of the present study was to investigate the antioxidant activity and immunostimulating property of glucosamine (GlcN) using various in vitro and in vivo tests. Results showed that GlcN possessed excellent antioxidant activities as manifested by strong chelating effect on ferrous ions and protection of macromolecules such as protein, lipid, and deoxyribose from oxidative damage induced by hydroxyl radicals. The immunostimulating effects of GlcN were further evaluated through various immunological tests. GlcN showed excellent activity of enhancing splenocyte proliferation. Neutral red pinocytosis and NO production in mouse peritoneal macrophages were significantly augmented. Oral administration of GlcN to mice for 20 days significantly enhanced the serum antibody level in mice in response to sheep red blood cells (SRBC), increased the relative organ weight of spleen and thymus tissue, and promoted the delayed-type hypersensitivity (DTH) against SRBC as compared with control group. In conclusion, the present investigation reveals GlcN is biologically functional in antioxidative activities and immunostimulating properties.

Phagocytosis--the mighty weapon of the silent warriors

Professional phagocytes, comprising polymorphonuclear neutrophils and monocyte/macrophage cells, play an important role in the host defense. Any defect in their function exposes the organism to microbial intruders terminating in fatal diseases. The functional responses of the phagocytes to bacterial and fungal infections include chemotaxis, actin assembly, migration, adhesion, aggregation, phagocytosis, degranulation, and reactive oxygen species production. Superoxide generation by phagocytic NADPH oxidase is an imperative step toward bacterial killing. Phagocytes participate in inflammatory reactions and exert tumoricidal activity. They are supported by serum factors such as immunoglobulins, cytokines, complement, the acute phase reactant C-reactive protein, production of antibacterial proteins, and others. In addition to their principal task to eliminate bacteria, they are engaged in removing damaged, senescent, and apoptotic cells. Engulfed cell debris, large particles such as latex beads, fat, and oil droplets, are examples of phagocytic activity illustrated in the present review with transmission and scanning electron microscope micrographs. Numerous factors, such as diseases and stressful conditions, affect the engulfing activity of the professional phagocytes. Our experience regarding the impaired phagocytic capacity of cells in patients with diabetes and chronic renal failure is discussed. The results obtained in our laboratory from experiments detecting the effect of strenuous physical exercise, hypothermia, fasting, and abdominal photon irradiation on the phagocytic capacity of human polymorphonuclear neutrophils and rat peritoneal macrophages are hereby summarized and the reports on those subjects in the recent literature are reviewed. A variety of assays are applied for quantifying phagocytosis. Flow cytometry based on incubation of phagocytic cells with fluorescent conjugated particles and measuring the amount of fluorescence as an indicator of the engulfing capacity of the cells is a useful method. A direct visualization of the ingested particles using light or electron microscopy is a valuable tool for estimation of phagocytic function. In our hands, the use of semithin sections of embedded phagocytes following their incubation with latex particles provided satisfactory results for measuring the total number of phagocytic cells, as well as the internalizing capacity of each individual cell. Microbiological assays, the nitroblue tetrazolium test, quantitation of antibody- and antigen-mediated phagocytosis, as well as methods reviewed in detail in other reports are additional applications for determination of this intricate process.

Peripheral blood lymphocytes and selected serum interleukins in workers operating X-ray equipment

The objective of these studies was to determine the effect of low X-ray doses on peripheral blood lymphocytes in the workers operating X-ray equipment. In 30 workers and 18 persons who constituted the control group the absolute number of peripheral blood lymphocytes, the number of T CD4+ and T CD8+ lymphocytes, the ratio CD4+/CD8+ and the concentration of serum interleukins (IL-2, IL-4, IL-6) were tested. Subgroups with respect to sex and employment period were selected. A significant increase in IL-2 concentration in workers as compared to controls was observed and significantly decreased IL-4 level in operating X-ray equipment was revealed. The lowest levels of IL-4 were noted in the women subgroup. A high positive, statistically significant correlations between the number of lymphocytes and the concentration of IL-2 and the level of IL-4 were observed. Moreover, our studies revealed that lymphocyte number and interleukin concentrations in serum of X-ray operators do not depend on the assumed ranges of the length of employment period.