Alpha 1-adrenoceptor activity in arterial smooth muscle following congestive heart failure

The interactions between yohimbine (selective alpha 2-antagonist) with noradrenaline (mixed agonist) and phenylephrine (selective alpha 1-agonist) were studied in the canine dorsal pedal artery in an attempt to characterize the peripheral vascular response to adrenergic agents before and after the development of congestive heart failure in the dog. The contractile responses of the dorsal pedal artery to potassium chloride were also examined. Both noradrenaline and phenylephrine contracted the dorsal pedal artery in a concentration-dependent manner before and at peak heart failure, the responses to the agonists being enhanced at heart failure. The responses of the artery to potassium were not modified by congestive heart failure. Yohimbine caused concentration-dependent antagonism of noradrenaline, without altering the magnitude of the maximum response, providing pA2 values ranging from 8.26 to 7.06 against low and high concentrations of noradrenaline, respectively, before heart failure development. Following heart failure, the pA2 values for yohimbine against noradrenaline remained unchanged, but slopes from the Arunlakshana-Schild plots were significantly different from unity, implying a noncompetitive antagonism. The pA2 values of yohimbine against phenylephrine were at least 10 orders of magnitude lower than those against noradrenaline. After congestive heart failure, yohimbine was even less effective against high concentrations of phenylephrine. These findings suggest that enhanced vasoconstriction during heart failure results, in part, from increased alpha 1-adrenoceptor mechanisms in peripheral arterial smooth muscle.     

Molecular pathogenesis of rheumatic fever and rheumatic heart disease

Molecular mimicry between streptococcal and human proteins has been proposed as the triggering factor leading to autoimmunity in rheumatic fever (RF) and rheumatic heart disease (RHD). This article summarises studies on genetic susceptibility markers involved in the development of RF/RHD. It also focuses on the molecular mimicry in RHD mediated by the responses of B and T cells of peripheral blood, and T cells infiltrating heart lesions, against streptococcal antigens and human tissue proteins. The molecular basis of T-cell recognition is assessed through the definition of heart-crossreactive antigens. The production of cytokines from peripheral and heart-infiltrating mononuclear cells suggests that T helper 1 (Th1)-type cytokines are the mediators of RHD heart lesions. An insufficiency of interleukin 4 (IL-4)-producing cells in the valvular tissue might contribute to the maintenance and progression of valve lesions.     

Human T lymphocyte responses against lung cancer induced by recombinant truncated mouse EGFR

The induction of active cellular responses against EGFR should be a promising approach for the treatment of those receptor-positive tumors. However, the immunity against EGFR is presumably difficult to elicit by vaccine based on self or syngeneic EGFR due to the immune tolerance acquired during the development in immune system. We proposed a model to break immune tolerance against self-EGFR through an altered immunogen source based on xenogeneic homologous EGFR. We have previously shown human EGFR as a xenoantigen could induce specific immune responses in mouse and cross-react with mouse EGFR, and resulted in therapeutic benefits for EGFR-positive mouse tumor. Here, we show a recombinant form of extracellular domain of mouse EGFR, in the presence of DCs, could activate human peripheral T cells to proliferate, secret IFN-γ, the induced responses could cross-react with human EGFR and kill autologous EGFR-positive lung cancer cells which could be blocked by anti-CD8 and anti-MHC class I antibody. There is no detectable cytotoxical activity against lung tissue, liver tissue and kidney tissue derived from paracancerous normal tissue. These observations suggest that antitumor immunity induced by the truncated mouse EGFR may be provoked in a cross-reaction between mouse EGFR and self-EGFR, and may provide insight into treatment of EGFR-positive tumors through induction of the autoimmune responses against EGFR.     

MsrA protects cardiac myocytes against hypoxia/reoxygenation induced cell death

Reactive oxygen species (ROS) are critical in tissue responses to ischemia-reperfusion. The enzyme methionine sulfoxide reductase-A (MsrA) is capable of protecting cells against oxidative damage by reversing damage to proteins caused by methionine oxidation or by decreasing ROS through a scavenger mechanism. The current study employed adenovirus mediated over-expression of MsrA in primary neonatal rat cardiac myocytes to determine the effect of this enzyme in protecting against hypoxia/reoxygenation in this tissue. Cells were transduced with MsrA encoding adenovirus and subjected to hypoxia/reoxygenation. Apoptotic cell death was decreased by greater than 45% in cells over-expressing MsrA relative to cells transduced with a control virus. Likewise total cell death as determined by levels of LDH release was dramatically decreased by MsrA over-expression. These observations indicate that MsrA is protective against hypoxia/reoxygenation stress in cardiac myocytes and point to MsrA as an important therapeutic target for ischemic heart disease.     

Stage-specific immunogens of Hymenolepis nana in mice

Treatment with praziquantel at the beginning of the lumen phase of Hymenolepis nana in mice showed conclusively that: (i) the mouse given eggs of H. nana produces two separate immune responses against reinfection, one directed exclusively against the tissue phase of egg challenge (early response), the other against the lumen phase of cysticercoid challenge (late response); (ii) a tissue phase of egg inoculation is not necessary for initiating the late response but is necessary to provoke the early response; and (iii) H. nana expresses several stage-specific immunogens through its development in the mouse host.     

Autoanti-idiotypes exhibit mimicry of myocyte antigens in virus-induced myocarditis.

Mice infected with coxsackievirus B develop immunologically mediated inflammatory myocarditis in heart tissue that results in the development of autoantibodies with multiple idiotypes. The specificity and temporal development of autoantibodies produced during coxsackievirus B3 infection were assessed. Antiviral idiotypes and anti-idiotypic antibodies against coxsackievirus B3 idiotypes were detected and quantitated over 21- and 42-day periods, respectively. Both polyclonal and monoclonal anti-idiotypes exhibited greater but nonspecific binding to heart, liver, kidney, and spleen cells from virus-exposed animals and normal tissue. Binding of anti-idiotypes was also demonstrated to myosin and to solubilized heart-associated antigens but not to virus. Western immunoblot analysis revealed that monoclonal and polyclonal anti-idiotypes selectively bound to hypertonic, salt-extracted, solubilized proteins of myocyte extracts of virus-exposed animals.     

Bacillus Calmette-Guérin and TLR4 agonist prevent cardiovascular hypertrophy and fibrosis by regulating immune microenvironment

Hypertension-induced cardiovascular hypertrophy and fibrosis are critical in the development of heart failure. The activity of TLRs has been found to be involved in the development of pressure overload-induced myocardial hypertrophy and cardiac fibrosis. We wondered whether vaccine bacillus Calmette-Guérin (BCG), which activated TLR4 to elicit immune responses, modulated the pressure overload-stimulated cardiovascular hypertrophy and cardiac fibrosis in the murine models of abdominal aortic constriction (AAC)-induced hypertension. Before or after AAC, animals received BCG, TLR4 agonist, IFN-gamma, or TLR4 antagonist i.p. BCG and TLR4 agonist significantly prevented AAC-induced cardiovascular hypertrophy and reactive cardiac fibrosis with no changes in hemodynamics. Moreover, TLR4 antagonist reversed the BCG- and TLR4 agonist-induced actions of anti-cardiovascular hypertrophy and cardiac fibrosis. BCG decreased the expression of TLR2 or TLR4 on the heart tissue but TLR4 agonist increased the expression of TLR2 or TLR4 on the immune cells that infiltrate into the heart tissue. This led to an increased expression ratio of IFN-gamma/TGF-beta in the heart. The cardiac protective effects of BCG and TLR4 agonist are related to their regulation of ERK-Akt and p38-NF-kappaB signal pathways in the heart. In conclusion, the activity of TLR4 plays a critical role in the mediation of pressure overload-induced myocardial hypertrophy and fibrosis. The regulation of immune responses by BCG and TLR4 agonist has a great potential for the prevention and treatment of hypertension-induced myocardial hypertrophy and cardiac fibrosis.     

Muscarinic Acetylcholine Receptors from Avian Retina and Heart Undergo Different Patterns of Molecular Maturation

Muscarinic acetylcholine receptors (mAChRs) from the avian CNS exist in two molecular weight forms whose concentrations change during development. Here, we have compared the development of mAChRs from embryonic hearts with those of the CNS. Analysis of [3H]-propylbenzilylcholine mustard (PrBCM)-labeled retina and heart mAChRs by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two atropine-sensitive peaks for each tissue. Apparent molecular masses of retina mAChRs, 86 +/- 0.7 kilodaltons (kDa) and 72 +/- 0.7 kDa, were different from those of heart mAChRs, 77 +/- 1.0 kDa and 52 +/- 0.9 kDa. During retina development, the major receptor type changed from 86 kDa to 72 kDa. No such change occurred during heart development. Furthermore, the 52-kDa species appeared to be generated by endogenous proteolysis, as prolonged incubation of heart membranes at 37 degrees C increased the amount of 52-kDa peptide with a decrease of 77-kDa peptide. Protease inhibitors blocked this conversion. Incubation of retina membranes at 37 degrees C did not result in a conversion of the 86-kDa peptide into the 72-kDa peptide, but it did cause the appearance of a minor amount of 52-kDa peptide. The proteolysis of retina mAChRs was not enhanced by cohomogenizing them with heart tissue, arguing against the presence of releasable proteases in heart. Membrane-bound retina and heart mAChRs displayed similar sensitivity to exogenous (Staphylococcus aureus V8) protease, indicating that heart receptors were not unusually susceptible to proteolytic attack; analysis of the labeled polypeptides with the V8 protease showed different patterns of digestion for the retina and heart receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biochemical and ultrastructural evidence for the association of basic fibroblast growth factor with cardiac gap junctions

Basic fibroblast growth factor (bFGF) is a ubiquitous and multifunctional polypeptide that is believed to have a role in tissue repair and to act as a morphogen in embryonic development. Here, we have used immunohistochemical and biochemical methods with antibodies directed against the amino-terminal domain of bFGF, designated IS2, which recognize native and denatured bFGF, to demonstrate that in addition to its known intracellular and extracellular localization in heart, bFGF is also associated with cardiomyocyte gap junctions. In tissue sections, IS2 labeled regions of intercalated discs, producing an immunofluorescence pattern virtually indistinguishable from that obtained with antibodies against the heart gap junction protein connexin-43. By electron microscopy, gap junctions but not other regions of plasma membrane were heavily immunolabeled with this antibody. By solid phase immunoassay, bFGF was found to be more concentrated in a fraction enriched in cardiac gap junctions than in whole sarcolemmal preparations. Finally, an 18-kDa protein was recognized by several different antibodies specific for bFGF on Western blots of heart subcellular fractions enriched in gap junctions. We suggest that bFGF-like peptides are either an integral part of, or exist in close association with, cardiac gap junctions and thus may play a role in modulating gap junctional intercellular communication.     

Autoimmunity in heart disease: mechanisms and genetic susceptibility

Recent studies of heart disease suggest that immunologically mediated processes often accompany cardiac injury and can contribute to pathogenesis. Murine models of myocarditis have provided insight into the mechanisms by which autoimmune responses to cardiac antigens arise and cause tissue pathology. It is now evident that T cells, cytokines and antibodies can all contribute to cardiac injury. Furthermore, murine models have demonstrated that both the propensity to develop autoreactivity following cardiac injury and the vulnerability of the heart to these responses are under genetic control. Continued studies will help to identify susceptibility genes and might aid in the development of strategies to protect individuals at risk from immunologically mediated damage following cardiac injury.     

The role of cardiac resident macrophage in cardiac aging

Advancements in longevity research have provided insights into the impact of cardiac aging on the structural and functional aspects of the heart. Notable changes include the gradual remodeling of the myocardium, the occurrence of left ventricular hypertrophy, and the decline in both systolic and diastolic functions. Macrophages, a type of immune cell, play a pivotal role in innate immunity by serving as vigilant agents against pathogens, facilitating wound healing, and orchestrating the development of targeted acquired immune responses. Distinct subsets of macrophages are present within the cardiac tissue and demonstrate varied functions in response to myocardial injury. The differentiation of cardiac macrophages according to their developmental origin has proven to be a valuable strategy in identifying reparative macrophage populations, which originate from embryonic cells and reside within the tissue, as well as inflammatory macrophages, which are derived from monocytes and recruited to the heart. These subsets of macrophages possess unique characteristics and perform distinct functions. This review aims to summarize the current understanding of the roles and phenotypes of cardiac macrophages in various conditions, including the steady state, aging, and other pathological conditions. Additionally, it will highlight areas that require further investigation to expand our knowledge in this field.     

C-Terminal Clostridium perfringens Enterotoxin-Mediated Antigen Delivery for Nasal Pneumococcal Vaccine

Efficient vaccine delivery to mucosal tissues including mucosa-associated lymphoid tissues is essential for the development of mucosal vaccine. We previously reported that claudin-4 was highly expressed on the epithelium of nasopharynx-associated lymphoid tissue (NALT) and thus claudin-4-targeting using C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) effectively delivered fused antigen to NALT and consequently induced antigen-specific immune responses. In this study, we applied the C-CPE-based vaccine delivery system to develop a nasal pneumococcal vaccine. We fused C-CPE with pneumococcal surface protein A (PspA), an important antigen for the induction of protective immunity against Streptococcus pneumoniae infection, (PspA-C-CPE). PspA-C-CPE binds to claudin-4 and thus efficiently attaches to NALT epithelium, including antigen-sampling M cells. Nasal immunization with PspA-C-CPE induced PspA-specific IgG in the serum and bronchoalveolar lavage fluid (BALF) as well as IgA in the nasal wash and BALF. These immune responses were sufficient to protect against pneumococcal infection. These results suggest that C-CPE is an efficient vaccine delivery system for the development of nasal vaccines against pneumococcal infection.     

Blood pressure and cardiac tissue responses to prostacyclin (PGI2) in various species

The effect of prostacyclin (PGI2) on blood pressure and heart rate (in vivo) and on isolated heart tissue has been investigated in different species. Isolated cardiac tissue had limited responses to PGI2 tested at 10(-13) to 10(-5) M. Cultured neonatal rat heart cells did not respond to PGI2, neither did intact rat hearts or rabbit cardiac tissue. Guinea pig and rat atria showed limited dose-dependent responses to PGI2 at concentrations greater than 10(7) M. In rat atria, 10(-5) M PGI2 produced a limited elevation of tissue cAMP content. When given by intravenous injection or infusion, PGI2 produced hypotension in anaesthetized primates (three species), rat, rabbit, pig, and dog. As a vasodepressor in all species, PGI2 (on a weight basis) was more active than prostaglandins of the B or E type and, in most species tested, it was approximately five times more active than PGE2. Heart responses in intact animals were often paradoxical in that decreases in heart rate often accompanied blood pressure falls.     

Hymenolepis nana: Survival in the immunized mouse

Mice initially infected with Hymenolepis nana eggs became completely immune to challenge with mouse-derived cysticercoids (cysts) after more than 10 days. The host possessed at least two separated immune responses, one directed exclusively against reinfection with eggs (early response) and the other against cyst infection (late response). In two different mouse strains the responses showed markedly different duration both for the time lag prior to acquisition of the late response and for the survival of the initially infected worms, but were otherwise similar. The mice became immune to adult tapeworms and expelled the initially infected, destrobilated worms; this third immune response determines the longevity of H. nana in the mouse host. Thus, there is a strong indication that H. nana successively changes its immunogenicity during development, each stage stimulating immunity after a time lag. It is possible that the longevity of H. nana in a mouse strain depends on the length of time prior to acquisition of immune responses directed not against the tissue stage (early response), but against the lumen stages (late response and worm expulsion response).     

Cardiac regeneration as an environmental adaptation

Heart failure is a devastating disease that affects more than 26 million individuals worldwide and has a 5-year survival rate of less than 50%, with its development in part reflecting the inability of the adult mammalian heart to regenerate damaged myocardium. In contrast, certain vertebrate species including fish and amphibians, as well as neonatal mammals, are capable of complete cardiac regeneration after various types of myocardial injury such as resection of the ventricular apex or myocardial infarction, with this regeneration being mediated by the proliferation of cardiomyocytes, dissolution of temporary fibrosis, and revascularization of damaged tissue. In an effort to identify regulators of cardiac regeneration and to develop novel therapeutic strategies for induction of myocardial regeneration in the adult human heart, recent studies have adopted an approach based on comparative biology. These studies have pointed to cellular or tissue responses to environmental cues—including activation of the immune system, the reaction to mechanical stress, and the adoption of oxidative metabolism—as key determinants of whether the heart undergoes regeneration or nonregenerative scar formation after injury. We here summarize recent insight into the molecular mechanisms as well as environmental and systemic factors underlying cardiac regeneration based on the findings of inter- or intraspecific comparisons between regenerative and nonregenerative responses to heart injury. We also discuss how recent progress in understanding the molecular, systemic, and environmental basis of cardiac regeneration in a variety of organisms may relate to multiple scientific fields including ecology, evolutionary as well as developmental biology.     

Purinergic modulation of cardiac activity in the flounder during hypoxic stress

Summary The interaction of adrenaline and adenosine was examined in cardiac tissue of the flounderPlatichthys flesus.When applied alone both agents increased contractility in both auricular and ventricular myocardial strips. This positive inotropic effect was associated with a small depolarization in the tissues examined by the sucrose gap technique. Simultaneous application of adrenaline and adenosine gave an inhibition of the control responses seen with either agent alone in both auricle and ventricle.Radiocalcium flux studies on ventricular tissue showed that influx was increased by adrenaline or adenosine alone above control values, but when applied together radiocalcium influx was reduced. Radiocalcium efflux from cardiac microsomes was stimulated by challenge with adrenaline or adenosine alone. This stimulation was not seen following simultaneous challenge by both agents.The effect of adrenaline on responses of hypoxic flounder hearts was less than that seen in normoxic hearts. This situation was reversed by pretreatment with the purine receptor blocker caffeine. Caffeine pretreatment also reduced the positive inotropic effect seen in normoxic hearts challenged with adenosine.TLC studies gave strong evidence that hearts perfused with hypoxic salines produced both adenosine and adrenaline.The results are discussed as evidence for a mechanism of heart regulation which the flounder may use as a defence against severe acute hypoxic stress.     

T-cell responses associated with resistance to Leishmania infection in individuals from endemic areas for Leishmania (Viannia) braziliensis

Subclinical or asymptomatic infection is documented in individuals living in endemic areas for leishmaniasis suggesting that the development of an appropriate immune response can control parasite replication and maintain tissue integrity. A low morbidity indicates that intrinsic factors could favor resistance to Leishmania infection. Herein, leishmanial T-cell responses induced in subjects with low susceptibility to leishmaniasis as asymptomatic subjects were compared to those observed in cured cutaneous leishmaniasis (CCL) patients, who controlled the disease after antimonial therapy. All of them have shown maintenance of specific long-term immune responses characterized by expansion of higher proportions of CD4+ as compared to CD8+ Leishmania reactive T-lymphocytes. Asymptomatic subjects had lower indexes of in vitro Leishmania induced lymphoproliferative responses and interferon-gamma (IFN-gamma) production in comparison to CCL patients. On the other hand, interleukin (IL-10) production was much higher in asymptomatics than in CCL, while no differences in IL-5 levels were found. In conclusion, long lived T-cell responses achieved by asymptomatic individuals differed from those who had developed symptomatic leishmaniasis in terms of intensity of lymphocyte activation (proliferation or IFN-gamma) and regulatory mechanisms (IL-10). The absence of the disease in asymptomatics could be explained by their intrinsic ability to create a balance between immunoregulatory (IL-10) and effector cytokines (IFN-gamma), leading to parasite destruction without producing skin tissue damage. The establishment of profiles of cell-mediated immune responses associated with resistance against Leishmania infection is likely to make new inroads into understanding the long-lived immune protection against the disease.     

抗组织纤维化多肽药物研究进展

组织纤维化是一种慢性疾病,多发于肝、肺、心脏、肾脏等部位,全球有 1/3 的人死于组织纤维化以及由其产生的器官衰竭。当组 织受到损伤后,损伤部位发生一系列细胞反应,最终导致细胞外基质过度沉积,发生组织纤维化。纤维化治疗的策略和药物开发围绕着抑 制纤维化过程中关键细胞通路和蛋白的分泌而展开。在药物开发过程中,多肽药物因其高效性、毒副作用低,可以根据治疗目的进行针对 性设计,成为研究人员进行抗纤维化药物开发的良好选择,现已有部分药物进入临床研究。综述抗纤维化治疗中的多肽药物及其治疗的机制, 为其他相关药物开发提供思路。     

肠道菌群及其代谢产物对心肌纤维化影响与治疗的研究进展

心肌纤维化是多种心血管疾病,如冠心病、心肌梗死和心力衰竭等的终末期表现和主要致病因素。研究发现,免疫和炎症过程在心肌纤维化的发病机制中起决定性作用。近年来,人们发现肠道微生物在心肌纤维化的发病机制和发展中起着至关重要的作用。肠道菌群的失调可导致微生物的代谢产物转移到血液循环中,如短链脂肪酸、脂多糖和氧化三甲胺等。这些代谢物直接或间接地诱导组织损伤免疫和激活全身炎症反应,进而影响心肌纤维化。如何改变肠道菌群来改善心肌纤维化已成为当前的研究重点,包括饮食干预、使用抗生素、补充益生菌和益生元,以及粪便微生物群移植等。本综述旨在回顾肠道菌群及其代谢产物与心肌纤维化的相互作用,介绍通过干预肠道菌群改善心肌纤维化的研究进展,为心肌纤维化的治疗提供新思路。     

Mitochondrial myopathy involving ubiquinol-cytochrome c oxidoreductase (complex III) identified by immunoelectron microscopy

The distribution of respiratory chain complexes in bovine heart and human muscle mitochondria has been explored by immunoelectron microscopy with antibodies made against bovine heart mitochondrial proteins in conjunction with protein A-colloidal gold (12-nm particles). The antibodies used were made against NADH-coenzyme Q reductase (complex I), ubiquinol cytochrome c oxidoreductase (complex III), cytochrome c oxidase, core proteins isolated from complex III and the non-heme iron protein of complex III. Labeling of bovine heart tissue with any of these antibodies gave gold particles randomly distributed along the mitochondrial inner membrane. The labeling of muscle tissue from a patient with a mitochondrial myopathy localized by biochemical analysis to complex III was quantitated and compared with the labeling of human control muscle tissue. Complex I and cytochrome c oxidase antibodies reacted to the same level in myopathic and normal muscle samples. Antibodies to complex III or its components reacted very poorly to the patient's tissue but strongly to control muscle samples. Immunoelectron microscopy using respiratory chain antibodies appears to be a promising approach to the diagnosis and characterization of mitochondrial myopathies when only limited amounts of tissue are available for study.