Lipopolysaccharide is able to bypass corticotrophin-releasing factor in affecting plasma ACTH and corticosterone levels: evidence from rats with lesions of the paraventricular nucleus.

Stimulation of the immune system or experimental conditions (bacterial lipopolysaccharide (LPS) treatment) provoke a broad spectrum of physiological responses. It was recently shown that one of them is the activation of the hypothalamic-pituitary-adrenal (HPA) axis. The mechanism and the site or sites through which LPS stimulates the HPA axis are not well understood. To establish whether the effect of bacterial LPS is related in vivo to the presence of hypothalamic hypophysiotrophic peptides (corticotrophin-releasing factor-41, arginine vasopressin, etc.), plasma ACTH and corticosterone levels were monitored in intact and sham-operated rats, and in rats with paraventricular nucleus lesions in order to remove the main source of these neuropeptides. Evidence was obtained that 4 h after treatment, LPS was able to activate the hypophysial-adrenal system in the absence of hypophysiotrophic neuropeptides of paraventricular origin. It is suggested that, in vivo, LPS could have a direct effect on the pituitary gland or that it acts through an extrapituitary, non-paraventricular pathway to activate the HPA axis.

Natural immunity and neuroimmune host defense.

Innate resistance is mediated by non-immune defense and by natural immunity. Non-immune defense includes diverse mechanisms (e.g., physico-chemical defense by bile acids). Natural killer (NK) cells, gamma delta T lymphocytes and CD5+ B lymphocytes are key mediators of natural immunity. These cells utilize germ-line coded receptors that recognize highly conserved, homologous epitopes (homotopes). Typically, it is not the antigen, but cytokines and hormones that regulate the level of NK-mediated cytotoxicity. These include interleukin-2, interferons, prolactin and growth hormone. Less is known about gamma delta T lymphocytes. CD5+ B lymphocytes produce germ-line coded antibodies (predominantly IgM) that are polyspecific, and able to recognize a great variety of microorganisms, cancer-cells and self-components. Antigen is not an effective stimulus for natural antibody (NAb), but bacterial lipopolysaccharide (LPS) is. During the acute phase response (febrile illness) the T-cell-regulated adaptive immune response is switched off and natural immune mechanisms are amplified several hundred to a thousand times within 24-48 hours (immunoconversion). This immunoconversion is initiated by immune-derived cytokines, and involves profound neuroendocrine and metabolic changes, all in the interest of host defense. Immune recognition is assured by natural antibodies and by some liver-derived acute phase proteins, such as C-reactive protein or endotoxin-binding protein, the level of which is elevated in the serum. Thus, natural immunity is essential for a first and last line of defense and the neuroendocrine system is an important promoter of this activity.

Adenylate cyclase-the more membrane associated, the less radiosensitive.

A dose dependent but not parallel decreases were observed both in SH content and catalytic activity of "free" catalytic subunit after irradiation (0-3200 Gy), while SH groups of membrane-associated adenylate cyclase were insensitive (under 3200 Gy). An initial "radioactivation" of membrane-associated enzyme was found under 800 Gy, then an inhibition above 1600 Gy. The SH alkylating agent, N-ethylmaleimide resulted in a complete inactivation, both of membrane associated form of adenylate cyclase and "free" catalytic subunit with similar inactivation profiles. These data indicate that in the radiosensitivity or "radioprotection" of adenylate cyclase, its membrane association/integration might play a more important role than the SH groups themselves.

Endotoxins and endocrine system.

There is good evidence for the interaction of neuroendocrine and immune systems. Endotoxin (LPS)-induced mediators (e.g., cytokines, prostaglandins etc) set on endocrine organs (e.g., the hypothalamo-pituitry-adrenal axis; thyroid glands etc). Endotoxin-treated, intestinal ischemic, or irradiated rats show decreased T4 levels of blood. These animals cannot respond to TSH because the TSH-receptors of follicular membranes are disturbed by LPS in the thyroid glands. Radiodetoxified endotoxin is an effective immunstimulator and does not disturb the follicular membrane of thyroid gland. Thus, the T4 production remains normal. The bile acids--as the end-product of cholesterol metabolism--play an important role in the physiological defense of macroorganisms against endotoxin and other lipid-like agents (Physico-chemical defense) and in the regulation of endocrine system, including the reproduction.

Toxicity of microbial products in cell culture.

Cytotoxicity of a mixed pyrogen preparation and its components as well as native and radiodetoxified lipopolysacharides (LPS) was determined with established HEp-2 cell cultures and by measuring plating efficiency. This proved to be more sensitive to the damaging effect of both microbe-containing LPS (Escherichia coli) and purified LPS. Microorganisms without this compound (Lactobacillus casei, Streptococcus faecalis) seem to be more infifferent on cells, even Saccharomyces cerevisiae has a marked augmenting effect on cell plating. Divergence in null-toxicity between the established cultures and plating efficiency makes it possible to presume that the primary effect of microorganisms on epithelial cells is medited by LPS, and the subsequent liberation of lysosomal proteinases is responsible for major biological effects.

[Bile acids and endotoxins: physico-chemical defense of the body]. / Epesavak és endotoxinok: a szervezet fiziko-kémiai védelme.

The toxic effects of endotoxin--the cell wall component of Gram negative intestinal bacteria--under experimental conditions can be induced only when they are administered parenterally. However, in naturally occurring enteroendotoxemic diseases (e.g. septic and various shocks, etc.), the endotoxin absorbs from the intestinal tract. The cause and mode of translocation was unknown. The generally used experimental shock models differ from natural diseases only in the mode by which endotoxin enters the blood circulation. If the common bile ducts of rats were chronically cannulated (bile deprived animals) perorally administered endotoxin was absorbed from the intestinal canal into blood circulation and provoked endotoxin shock. The translocation of endotoxins and consequent shock can be prevented by sodium deoxycholate or natural biles. The bile acids can split the endotoxin macromolecule (atoxic fragments). A similar destructive detergent action might will be a significant factor against potential infectious agents with lipoprotein outer structure (e.g. so-called "big" viruses). This defense mechanism of macrooganisms based on the detergent activity of bile acids is called as physico-chemical defense system. On the basis of this knowledge the bile acids might be used in the prevention and therapy of some clinical processes (e.g. hepatorenal syndrome; psoriasis).

[A new possibility for enhancing natural immunity: a radiation-detoxified endotoxin]. / A természetes ellenállóképesség fokozásának új lehetósége: a sugárzással méregtelenített endotoxin.

Using ionizing radiation the author and co-workers produced a detoxified endotoxin preparation (Tolerin) which seems to be a suitable product for the increase of natural immunity (nonspecific resistance)-including activation of bone marrow in immunosuppressions, immunodeficiencies-protection against various types of shocks-radiation injury, septic/endotoxic shock, etc.- and increase of immunogen effect of antigens (e.g. inactivated virus vaccines) as an immunoadjuvant in human beings and experimental animals.

[Bacterial endotoxins and their effects]. / Bakteriális endotoxinok és hatásaik.

The lipopolysaccharide endotoxin macromolecules are cell wall's components of the Gram negative bacteria. The endotoxins are produced by Gram negative bacteria of intestinal flora. If the endotoxins are translocated from the intestinal tract to the circulation or injected into bloodstream, they elicit (depending from the quantity of endotoxin), slight or serious effects (e.g. endotoxin shock). In the effects of endotoxin certain cell populations (e.g. thrombocytes, macrophages, leukocytes, etc.), certain organs and organ-systems (e.g. liver, spleen, bone marrow, endocrine and lymphoreticular systems etc.) are involved. Effects of endotoxin are produced by mediators (e.g. endotoxin binding proteins, cytokines, prostaglandins, prostacyclins, NO etc.). The endotoxin sensitivity of vertebrate organisms is dependent from the phylogenetical status of the species. Most sensitive species is the human. Generally accepted that endotoxin has an important role in the pathogenesis of septic shock. In other pathological processes (e.g. intestinal syndrome of radiation disease, Gram negative infections, various shock forms etc.) are supposed or proved the role of endotoxins. Lead acetate induced endotoxin hypersensitivity or LAL methods are good tools for demonstration of the role of endotoxin in the pathogenesis of various processes. For this reason, the experimental endotoxin shock is used a model of septic and other shocks.

[Role of bile acids and endotoxins in the pathogenesis and therapy of psoriasis]. / Epesavak és endotoxinok szerepe a pikkelysömör kórfejlódésében és kezelésében.

The authors demonstrated significant curative effect of bile acids (Suprachol; Acidum dehydrocholicum) in 551 psoriatic patients. The clinical efficiancy was evaluated by means of PASI-score (Psoriasis Area Severity Index). During this treatment (1-8 weeks) 434 patients (78.8 per cent) became asymptomatic. However, the traditional therapy resulted in 62 patients (24.9 per cent) of 249 sick persons a recovery (p < 0.05). In acute form of psoriasis (184 patients) this curative effect of bile acids was elevated (95.1 per cent). Two years later 319 patients (57.9 per cent) of bile treated 551 people were asymptomatic in contrast with 15 people (6.0 per cent) of 249 traditional treated patients (p < 0.05). In same time among the patients which were treated in acute form of psoriasis 10 (7.2 per cent) of 139 controls and 147 (79.9 per cent) of 184 bile-treated individuals were asymptomatic (p < 0.01). On the basis of their clinical observations (digestive disorders, ultrasonical confirmed gallbladder complaints, etc.) authors supposed that the deficiency of bile acids and the consecutive endotoxin translocation might play a role in the pathogenesis of psoriasis. In normal conditions the bile acids as detergent (physico-chemical defense) can protect the body against enteral endotoxins while split them to atoxic fragments and so preventing consecutive cytokin liberation.

[Plasma endotoxin level in healthy blood donors]. / Egészséges véradók plazma endotoxin szintje.

The plasma level of endotoxin was determined in 116 healthy blood donors in this laboratory. After a routine physical and laboratory investigations the endotoxin level was determined with Limulus amebocyte lysate assay (LAL test) by the chromogenic kinetic method of Bio-Whittaker Co. (USA). Its sensitivity was 0.005-50 EU/ml. The plasma level of endotoxin in most of healthy donors was less than 1 EU/ml (in the range of 0.01-1.0 EU/ml), but always measurable. The average +/- S. D. was 0.128 +/- 0.215 EU/ml. Because of the high standard deviation and high range of values, the data were distributed to two groups with the means of 0.05 +/- 0.022 EU/ml and 0.294 +/- 0.186 EU/ml. The difference between the groups was significant found (p < 0.001). In conclusion, endotoxin can be measured in plasma of healthy individuals.

[Human herpesvirus 6 A enhances HIV-1 replication in vitro by soluble mediators, this effect is diminished by endotoxin]. / Az emberi 6-os herpeszvírus A változata szolubilis mediátorok által fokozza a HIV-1 szaporodását in vitro, mely hatást az endotoxin csökkenti.

Simultaneous HHV-6A infection can activate HIV-1 latency and promote AIDS progression, but in this process the effects of HHV-6A induced soluble mediators on HIV-1 have not been studied yet. Recently, supernatants of HSB-2 cultures infected with HHV-6A and/or treated with endotoxin have been filtered virus free at time intervals until the cytopathic effect developed. Biological activity of some cytokines which might participate in HIV-1 activation was quantitated. Filtered supernatants were mixed into CEM-ss cultures, which had been HIV-1 infected at 1:1 cell:virus ratio, subsequently HIV-1 replication was quantitated and compared to controls. Supernatants filtered during the first 96 hours of HHV-6A replication without visible cytopathic effect augmented HIV-1 syncytium formation by tenfold, reverse transcriptase activity by threefold, p24 antigen production by 6-fold. Filtered supernatants obtained at onset of HHV-6A cytopathic effect did not modify HIV-1 replication. HSB-2 cultures produced no IL-2, and IFN-gamma induced by endotoxin diminished HIV-1 replication. HHV-6A delayed IFN-gamma release. An increase in the tumour necrosis factor activity upon the effect of HHV-6A and endotoxin was not parallel to HIV-1 activation. The putative mediator, different from those above which characterisation is in progress, might transmit similar transactivating effects between immune cells of lymph nodes and circulation.

[In vitro synergic lymphocyte stimulation in HIV-1 infected patients using inosine derivatives and radio-detoxified endotoxin]. / HIV-1 fertözöttek lymphocytáinak in vitro együttes serkenthetösége inozin származékokkal és sugárdetoxikált endotoxinnal.

Restoration of immune functions through promoting cell cycle might delay acquired immunodeficiency syndrome development. Therefore, stimulation of peripheral lymphocytes of human immunodeficiency virus-1 infected patients in successive clinical stages was studied by phytohaemagglutinin and other stimulants. In vitro blastogenesis was quantitated by 3H-thymidine uptake. Stimulation by phytohaemagglutinin decreased in patients with AIDS related complex to 63.1%, with AIDS to 13.6% of control values. Small amount of recombinant interleukin-2 or indomethacin solely not promoting lymphocytes, increased response to phytohaemagglutinin minimally. Alone ineffective methyl-ester and methyl-phosphonate inosine derivatives augmented phytohaemagglutinin-response of controls and patients with AIDS related complex by approx. 1.5-fold, but the effect in the case of AIDS patients was minimal. Radio-detoxified endotoxin alone or in combination with phytohaemagglutinin stimulated lymphocytes of both controls and patients with AIDS related complex slightly. Lymphocyte stimulation of patients with AIDS related complex was augmented in concentration-dependent manner, and by synergic effect it approached phytohaemagglutinin-stimulated blastogenesis of controls. Anergy due to human immunodeficiency virus-1 infection damages synchronisation of secondary messenger systems induced on cell surface receptors, therefore their selective influence by recombinant interleukin-2 or indomethacin is less efficient. Inosine derivatives promote cell cycle by inhibiting cyclic adenosine 3',5'-monophosphate production. In the early stage of virus infection, radio-detoxified endotoxin might bind to receptors of immature T cells and facilitate cell cycle through cyclic guanosine 3',5'-monophosphate stimulation. The clinical trials of radio-detoxified endotoxin (Tolerin) have already been launched.

Role of endotoxins and bile acids in the pathogenesis of septic circulatory shock.

It has long been known that the toxic effects of endotoxins under experimental conditions can be induced only when they are administered parenterally. However, in naturally occurring enteroendotoxemic diseases (e. g. septic and intestinal ischemic shocks) the endotoxins--which are produced by gram negative members of intestinal flora-, absorb from the intestinal tract to the blood circulation and can elicit pathological processes. It is an important distinction between natural and experimental endotoxin shock. If the common bile duct of rats were chronically cannulated a significant amount of perorally administered endotoxin was absorbed into the blood. This endotoxin shock can be prevented by bile acids. The physiological surfactants, the bile acids, are important facts in the defense of macroorganisms against endotoxins (physico-chemical defense). The production and passage of bile acids depend from the function of liver and the cholecystokinine (CCK) synthesis of small intestine wall. If the bile (bile acid) content of the intestinal canal decreases the endotoxin can translocate to the body and elicits toxic symptoms. So most important parts of defense against endotoxins in natural conditions are the CCK and bile acids. The consequence of damage of liver (place of bile acid synthesis) or small intestine (place of CCK synthesis) is the absorption of endotoxins.

Bacterial endotoxins and nonspecific resistance.

The stress situations, including medical intervention (e.g. operations, antitumor drugs, irradiation, etc.) decrease the nonspecific resistance of the body. In these situations patients people have greater chance to get an opportunistic infection than healthy ones. The restoration or elevation of the activity of immune system in injured patients is a very important task of medicine. Minute amounts of bacterial endotoxin (LPS)--given parenterally--can elevate the nonspecific resistance. Unfortunately this beneficial influence is associated with noxious properties. Irradiation (60 Co-gamma; 150 kGy) is a good technique for the detoxification of LPS. The radiodetoxified endotoxin (RD-LPS) preparation (so-called TOLERIN) is less toxic but its beneficial properties is preserved. On the basis of animal experiments and clinical trials TOLERIN could be a suitable preparation for regeneration of the lymphoreticular-immune system and elevation of nonspecific resistance.