Effect of Clostridium perfringens beta toxin on blood pressure of rats

Microbiome Changes in Pregnancy Disorders

The human microbiota comprises all microorganisms, such as bacteria, fungi, and viruses, found within a specific environment that live on our bodies and inside us. The last few years have witnessed an explosion of information related to the role of microbiota changes in health and disease. Even though the gut microbiota is considered the most important in maintaining our health, other regions of the human body, such as the oral cavity, lungs, vagina, and skin, possess their own microbiota. Recent work suggests a correlation between the microbiota present during pregnancy and pregnancy complications. The aim of our literature review was to provide a broad overview of this growing and important topic. We focused on the most significant changes in the microbiota in the four more common obstetric diseases affecting women's health. Thus, our attention will be focused on hypertensive disorders, gestational diabetes mellitus, preterm birth, and recurrent miscarriage. Pregnancy is a unique period in a woman's life since the body undergoes different adaptations to provide an optimal environment for fetal growth. Such changes also involve all the microorganisms, which vary in composition and quantity during the three trimesters of gestation. In addition, special attention will be devoted to the potential and fundamental advances in developing clinical applications to prevent and treat those disorders by modulating the microbiota to develop personalized therapies for disease prevention and tailored treatments.

Changes in the Gut Microbiome and Pathologies in Pregnancy

Pregnancy is a special period in a woman's life when her organism undergoes multiple physiological changes so that the fetus has optimal conditions for growth and development. These include modifications in the composition of the microbiome that occur between the first and third trimesters of pregnancy. There is an increase in Akkermansia, Bifidobacterium, and Firmicutes, which have been associated with an increase in the need for energy storage. The growth in Proteobacteria and Actinobacteria levels has a protective effect on both the mother and the fetus via proinflammatory mechanisms. The aim of the study is to review the research on the relationship between the mother's intestinal microbiome and gestational pathologies. Changes in the maternal gut microbiome is probably one of the mechanisms that occurs in various pregnancy diseases such as preeclampsia, fetal growth restriction, gestational diabetes mellitus, excessive gestational weight gain, and premature birth. For this reason, it seems vital to pay attention to certain interventions that can benefit the affected patients both in the short term, by preventing complications during pregnancy, and in the long term, as one of the mechanisms occurring in various gestational diseases is dysbiosis of the maternal intestinal flora.

Production, immunogenicity, stability, and safety of a vaccine against Clostridium perfringens beta toxins

Background and Aim:

The beta toxin is causing the most severe Clostridium perfringens-related diseases. This work was dedicated to developing a vaccine against beta toxin using C. perfringens type C (NCTC 3180).

Materials and Methods:

The crude toxoid harvest contained 710 limits of flocculation (Lf)/mL. The vaccine was formulated. Each 1 mL of the final vaccine product contained at least 50 Lf/mL of beta toxoids, 0.2 mL 3% aluminum hydroxide gel (equivalent to 5.18 mg of aluminum), <0.001% W/V thiomersal, formaldehyde <0.05% W/V, and ~0.7 mL phosphate-buffered saline (pH 7.2). The efficacy of the vaccine was evaluated by potency, stability, and safety tests.

Results:

The vaccine demonstrated 24.36 IU/mL (standard deviation, ±0.56) and 14.74 IU/mL (±0.36) of neutralizing antibodies in rabbits and cattle, respectively. Indeed, these levels were above the minimum recommended by international protocols since the obtained antibody levels had 2.43- and 1.47-fold increase in both rabbits and cattle, respectively, over the minimum antitoxin level suggested by the United States Department of Agriculture. Interestingly, our formulation was capable of inducing 1.65-fold higher immune responses in rabbits than that stimulated in cattle (65% increase) with a significant difference (p<0.0001). The vaccine was stable up to 30 months. The vaccinated rabbits were suffered from a temporarily slight increase in temperatures in the first 10 h without any significant difference (p>0.05).

Conclusion:

The research showed a procedure for the manufacturing process of the vaccine against C. perfringens beta toxins with a feasible quantity and the vaccine described here showed to be effective in eliciting levels of neutralizing antibodies higher than required by international standards. In addition, The vaccine was stable up to 30 months. Thus, it may represent an effective and safe for preventing C. perfringens-related diseases in rabbits and cattle, although further studies to prove its efficacy in the field on other farm animals are still needed.

Remodeling of the gut microbiota and structural shifts in Preeclampsia patients in South China

Preeclampsia (PE) is one of the pregnancy metabolic diseases. Since Gut microbiota play important roles in the hosts' metabolism, it is necessary to investigate the gut microbiota in PE patients, so that some intestinal dysbiosis might be detected as a biomarker for PE early diagnosis or as a target for intervention. One hundred subjects were categorized into four groups: 26 PE patients in late pregnancy, healthy individuals in early, middle, and late pregnancy (26/24/24 women). Gut microbiota were analyzed by sequencing the V4 region of the 16S rDNA gene using Illuminal MiSeq. Data were analyzed by multivariate statistics. Bacteroidetes was the dominant bacterium (47.57-52.35%) in the pregnant women in South China. Tenericutes increased while Verrucomicrobia almost disappeared in late pregnancy. In the PE patients, there was an overall increase in pathogenic bacteria, Clostridium perfringens (p = 0.03) and Bulleidia moorei (p = 0.00) but a reduction in probiotic bacteria Coprococcus catus (p = 0.03). Our research suggests that there is a significant structural shift of the gut microbiota in PE patients, which might be associated with the occurrence and development of the disease. However, further studies are required to understand the underlying mechanisms.

Recent insights into Clostridium perfringens beta-toxin

Clostridium perfringens beta-toxin is a key mediator of necrotizing enterocolitis and enterotoxemia. It is a pore-forming toxin (PFT) that exerts cytotoxic effect. Experimental investigation using piglet and rabbit intestinal loop models and a mouse infection model apparently showed that beta-toxin is the important pathogenic factor of the organisms. The toxin caused the swelling and disruption of HL-60 cells and formed a functional pore in the lipid raft microdomains of sensitive cells. These findings represent significant progress in the characterization of the toxin with knowledge on its biological features, mechanism of action and structure-function having been accumulated. Our aims here are to review the current progresses in our comprehension of the virulence of C. perfringens type C and the character, biological feature and structure-function of beta-toxin.

The p38 MAPK and JNK pathways protect host cells against Clostridium perfringens beta-toxin

Clostridium perfringens beta-toxin is an important agent of necrotic enteritis and enterotoxemia. Beta-toxin is a pore-forming toxin (PFT) that causes cytotoxicity. Two mitogen-activated protein kinase (MAPK) pathways (p38 and c-Jun N-terminal kinase [JNK]-like) provide cellular defense against various stresses. To investigate the role of the MAPK pathways in the toxic effect of beta-toxin, we examined cytotoxicity in five cell lines. Beta-toxin induced cytotoxicity in cells in the following order: THP-1 = U937 > HL-60 > BALL-1 = MOLT-4. In THP-1 cells, beta-toxin formed oligomers on lipid rafts in membranes and induced the efflux of K(+) from THP-1 cells in a dose- and time-dependent manner. The phosphorylation of p38 MAPK and JNK occurred in response to an attack by beta-toxin. p38 MAPK (SB203580) and JNK (SP600125) inhibitors enhanced toxin-induced cell death. Incubation in K(+)-free medium intensified p38 MAPK activation and cell death induced by the toxin, while incubation in K(+)-high medium prevented those effects. While streptolysin O (SLO) reportedly activates p38 MAPK via reactive oxygen species (ROS), we showed that this pathway did not play a major role in p38 phosphorylation in beta-toxin-treated cells. Therefore, we propose that beta-toxin induces activation of the MAPK pathway to promote host cell survival.

Involvement of tumour necrosis factor-alpha in Clostridium perfringens beta-toxin-induced plasma extravasation in mice

BACKGROUND AND PURPOSE

Clostridium perfringens beta-toxin, an important agent of necrotic enteritis, causes plasma extravasation due to the release of a tachykinin NK(1) receptor agonist in mouse skin. In this study, we investigated the role of cytokines in beta-toxin-induced plasma extravasation.

EXPERIMENTAL APPROACH

Male Balb/c, C3H/HeN and C3H/HeJ mice were anaesthetized with pentobarbitone and beta-toxin was injected i.d. into shaved dorsal skin. SR140333, capsaicin, chlorpromazine and pentoxifylline were given as pretreatment when required before the injection of the toxin. Cytokines in the dorsal skin were measured by ELISA.

KEY RESULTS

Injection (i.d.) of beta-toxin induced a dose-dependent increase in dermal TNF-alpha and interleukin (IL)-1beta levels with a concomitant increase in plasma extravasation, but not the release of IL-6. SR140333 and capsaicin significantly inhibited the toxin-induced release of TNF-alpha and IL-1beta. The plasma extravasation and the release of TNF-alpha induced by beta-toxin were significantly inhibited by chlorpromazine and pentoxifylline which inhibit the release of TNF-alpha. The toxin-induced plasma extravasation in mouse skin was attenuated by pretreatment with a monoclonal antibody against TNF-alpha, but not anti-IL-1beta. Furthermore, the toxin caused an increase in plasma extravasation in both C3H/HeN (TLR4-intact) and C3H/HeJ (TLR4-deficient) mice. In C3H/HeN mice, the toxin-induced leakage was not inhibited by pretreatment with anti-TLR4/MD-2 antibody.

CONCLUSIONS AND IMPLICATIONS

These observations show that beta-toxin-induced plasma extravasation in mouse skin is related to the release of TNF-alpha via the mechanism involving tachykinin NK(1) receptors, but not via TLR4.

Clostridium infection resulting in paralysis in a child

CASE REPORT

We report an 11-year-old boy who fell from an All Terrain Vehicle and sustained multiple minor soft tissue contusions and a small midthoracic laceration. Irrigation and closure of the small wound was performed at another hospital. There was no history of a penetrating wound. Within 48 h of injury, the patient developed profound dysesthesia and paralysis of the lower extremities and was transferred to our hospital. MRI disclosed a paraspinal abnormality without bony involvement. At exploration a portion of a tree branch was removed. Wound cultures were positive for Clostridium botulinum, tetani, and perfringens.

CONCLUSIONS

To our knowledge, this is the first case of direct Clostridium intoxication of the spinal cord in man. Moreover, this report demonstrates the invasive manner in which Clostridium toxins may breach both the intact ligamentum flavum and the dura mater to deliver their toxicity to the intradural contents. Although the patient's dysesthesia resolved and paraplegia improved to ambulation he is still left with a significant motor deficit.

Involvement of tachykinin receptors in Clostridium perfringens beta-toxin-induced plasma extravasation

1 Clostridium perfringens beta-toxin causes dermonecrosis and oedema in the dorsal skin of animals. In the present study, we investigated the mechanisms of oedema induced by the toxin. 2 The toxin induced plasma extravasation in the dorsal skin of Balb/c mice. 3 The extravasation was significantly inhibited by diphenhydramine, a histamine 1 receptor antagonist. However, the toxin did not cause the release of histamine from mouse mastocytoma cells. 4 Tachykinin NK(1) receptor antagonists, [D-Pro(2), D-Trp(7,9)]-SP, [D-Pro(4), D-Trp(7,9)]-SP and spantide, inhibited the toxin-induced leakage in a dose-dependent manner. Furthermore, the non-peptide tachykinin NK(1) receptor antagonist, SR140333, markedly inhibited the toxin-induced leakage. 5 The leakage induced by the toxin was markedly reduced in capsaicin-pretreated mouse skin but the leakage was not affected by systemic pretreatment with a calcitonin gene-related peptide receptor antagonist (CGRP(8-37)). 6 The toxin-induced leakage was significantly inhibited by the N-type Ca(2+) channel blocker, omega-conotoxin MVIIA, and the bradykinin B(2) receptor antagonist, HOE140 (D-Arg-[Hyp(3), Thi(5), D-Tic(7), Oic(8)]-bradykinin), but was not affected by the selective L-type Ca(2+) channel blocker, verapamil, the P-type Ca(2+) channel blocker, omega-agatoxin IVA, tetrodotoxin (TTX), the TTX-resistant Na(+) channel blocker, carbamazepine, or the sensory nerve conduction blocker, lignocaine. 7 These results suggest that plasma extravasation induced by beta-toxin in mouse skin is mediated via a mechanism involving tachykinin NK(1) receptors.

Clostridium perfringens beta toxin and Clostridium septicum alpha toxin: their mechanisms and possible role in pathogenesis

The Clostridium septicum alpha toxin and the Clostridium perfringens beta toxin are examples of pore-forming toxins that exhibit several different features. The cell types that are targeted by these toxins reflect the effect these toxins have on the host during infection with either organism. Alpha toxin elicits a rapid shock-like syndrome, whereas beta toxin appears to induce a variety of neurological effects. The effects of the purified toxins appear to mimic some of the features of the animal and human diseases caused by C. septicum and C. perfringens. This review, examines the current state of knowledge for the cytolytic mechanism, role in pathogenesis and structure of these two toxins.

Clostridium perfringens beta-toxin forms potential-dependent, cation-selective channels in lipid bilayers

Recombinant beta-toxin from Clostridium perfringens type C was found to increase the conductance of bilayer lipid membranes (BLMs) by inducing channel activity. The channels exhibited a distribution of conductances within the range of 10 to 380 pS, with the majority of the channels falling into two categories of conductance at 110 and 60 pS. The radii of beta-toxin pores found for the conductance states of 110 and 60 pS were 12.7 and 11.1 A, respectively. The single channels and the steady-state currents induced by beta-toxin across the BLMs exhibited ideal monovalent cation selectivity. Addition of divalent cations (Zn(2+), Cd(2+), or Mg(2+)) at a concentration of 2 mM increased the rate of beta-toxin insertion into BLMs and the single-channel conductance, while application of 5 mM Zn(2+) to a beta-toxin-induced steady-state current decreased the inward current by approximately 45%. The mutation of arginine 212 of beta-toxin to aspartate, previously shown to increase the 50% lethal dose of beta-toxin for mice nearly 13-fold, significantly reduced the ability of beta-toxin to form channels. These data support the hypothesis that the lethal action of beta-toxin is based on the formation of cation-selective pores in susceptible cells.

Clostridium perfringens beta-toxin is sensitive to thiol-group modification but does not require a thiol group for lethal activity

The beta-toxin gene isolated from Clostridium perfringens type B was expressed as a glutathione S-transferase (GST) fusion gene in Escherichia coli. The purified GST-beta-toxin fusion protein from the E. coli transformant cells was not lethal. The N-terminal amino acid sequence of the recombinant beta-toxin (r toxin) isolated by thrombin cleavage of the fusion protein was G-S-N-D-I-G-K-T-T-T. Biological activities and molecular mass of r toxin were indistinguishable from those of native beta-toxin (n toxin) purified from C. perfringens type C. Replacement of Cys-265 with alanine or serine by site-directed mutagenesis resulted in little loss of the activity. Treatment of C265A with N-ethylmaleimide (NEM), which inactivated lethal activity of r toxin and n toxin, led to no loss of the activity. The substitution of tyrosine or histidine for Cys-265 significantly diminished lethal activity. In addition, treatment of C265H with ethoxyformic anhydride which specifically modifies histidyl residue resulted in significant decrease in lethal activity, but that of r toxin with the agent did not. These results showed that replacement of the cysteine residue at position 265 with amino acids with large size of side chain or introduction of functional groups in the position resulted in loss of lethal activity of the toxin. Replacement of Tyr-266, Leu-268 or Trp-275 resulted in complete loss of lethal activity. Simultaneous administration of r toxin and W275A led to a decrease in lethal activity of beta-toxin. These observations suggest that the site essential for the activity is close to the cysteine residue.

Lethal and dermonecrotic activities of Clostridium perfringens lota toxin: biological activities induced by cooperation of two nonlinked components

The effect of separate injections of two components of Clostridium perfringens iota toxin, designated Ia and Ib components, on the biological activities of the toxin was investigated. The intravenous injection of one component within 120 min after the injection of the other component killed mice. The activity of iota toxin was abolished by anti-Ia or anti-Ib antiserum. On the other hand, when Ib component was intravenously administered to mice given anti-Ia antiserum within 120 min after the intravenous injection of Ia component, the lethal activity was completely neutralized, but when Ia component was injected into mice that were given anti-Ib antiserum over 5 min after the injection of Ib component, the activity was not neutralized. The separate injections of Ia and Ib components in skin of guinea pigs indicated dermonecrosis at the injection site of Ib components, but not at the site of Ia components. Furthermore, when one component was intradermally injected in guinea pigs and then the other intraperitoneally, the dermonecrotic activity of the toxin was observed at the intradermal injection site of Ib component, but not at that of Ia component. From the data, it appears that the lethal and dermonecrotic activities of iota toxin are initiated by the binding of Ib component to specific sites on tissues.

Effect of p-chloromercuribenzoate on Clostridium perfringens beta toxin

p-Chloromercuribenzoate (PCMB) was shown to bind to Clostridium perfringens beta toxin. Treatment of the toxin with N-ethylmaleimide (NEM), 5,5'-dithio-bis(2-nitro-benzoic acid) (DTNB), o-iodosobenzoate (OIBA) and metal ions such as Cu2+ and Ag+ decreased the lethal activity, but PCMB did not affect the lethal activity. On the other hand, the binding of PCMB to the toxin was inhibited by DTNB and NEM in a dose-dependent manner. Furthermore, the lethal activity of beta toxin pretreated with PCMB was not blocked by treatment with NEM, DTNB, OIBA, Cu2+ and Ag+. However, the PCMB-treated toxin treated with reduced glutathione, dithiothreitol, 2-mercaptoethanol, liver homogenate or serum from mice was inactivated by NEM.

Toxigenic clostridia

Toxigenic clostridia belonging to 13 recognized species are discussed in this review. Each species or group of organisms is, in general, introduced by presenting the historical aspects of its discovery by early investigators of human and animal diseases. The diseases caused by each species or group are described and usually discussed in relation to the toxins involved in the pathology. Morphological and physiological characteristics of the organisms are described. Finally, the toxins produced by each organism are listed, with a presentation of their biological activities and physical and biochemical characteristics. The complete amino acid sequences for some are known, and some of the genes have been cloned. The term toxin is used loosely to include the various antigenic protein products of these organisms with biological and serological activities which have served as distinguishing characteristics for differentiation and classification. Some of these factors are not truly toxic and have no known role in pathogenicity. Some of the interesting factors common to more than one species or group are the following: neurotoxins, lethal toxins, lecithinases, oxygen-labile hemolysins, binary toxins, and ADP-ribosyltransferases. Problems in bacterial nomenclature and designation of biologically active factors are noted.

Purification and characterization of Clostridium perfringens beta toxin

A new procedure for the purification of beta toxin from culture supernatant fluid of Clostridium perfringens was established. The procedure consists of ammonium sulfate fractionation, affinity chromatography on zinc-chelate Sepharose and gel filtration on Toyopearl HW 60. Beta toxin was purified about 460-fold from the ammonium sulfate fraction with a yield of about 60% in terms of lethality of the toxin. The molecular weight of the toxin, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose gradient centrifugation, was approximately 40,000. The isoelectric point was 5.6. The minimal necrotic dose for guinea pigs was approximately 2 ng. The 50% lethal doses for adult mice were 310 ng/kg and 4.5 micrograms/kg, when injected i.v. and i.p., respectively.