Adult Ixodes dammini on rabbits: a hypothesis for the development and transmission of Borrelia burgdorferi

A histological study of unfed Ixodes dammini adults has shown that the Lyme disease spirochete can be found in the midgut diverticula of these ticks and is presumably carried over from the nymphal stage. Sequential histology of the early stages of ticks feeding on a rabbit showed that spirochetes began to divide and were located in close proximity or attached to the epithelial cells of the diverticulae. Evidence for division was obtained by the higher number of spirochetes per tick after a three-day feeding period than in the unfed females. Although the mechanism is unclear, some spirochetes become systemic by the fifth day of feeding and can be detected in low numbers in other tick organs. Spirochetes were also noted in the feeding cavities created by I. dammini in the dermis after five days of attachment. Spirochetes were not detected in salivary glands or in the feces of I. dammini during the feeding period.     

Immunomodulatory effects of Maxadilan and Phlebotomus papatasi sand fly salivary gland lysates on human primary in vitro immune responses

Leishmaniasis is a parasitic disease transmitted by the bite of Leishmania-infected sand flies. Here we show for the first time the ability of Maxadilan (Max), a vasodilatory peptide isolated from the sand fly Lutzomyia longipalpis, and salivary gland lysate (SGL) from Phlebotomus papatasi to decrease the secretion of Type 1 cytokines and to enhance the production of the Type 2 cytokine interleukin (IL)-6 by human peripheral blood mononuclear cells (PBMC) and monocytes. We found Max decreased the secretion of interferon (IFN)-gamma and IL-12p40 by PBMC and TNF-alpha by monocytes. SGL reduced the production of IFN-gamma by PBMC. In contrast, production of the Type 2 cytokine IL-6 was increased in Max or SGL-exposed cells. Finally, we determined that Max interacts with human cells through at least the pituitary adenylate cyclase activating polypeptide receptor. These results show that sand fly salivary gland components have an immunomodulatory effect on human cells, and this has important implications for the development of vaccines against leishmaniasis for humans.     

Impairment of lachrymal and salivary secretion and cellular immune responses to salivary antigens in rheumatoid arthritis.

During a systematic investigation of 100 unselected outpatients with rheumatoid arthritis, 58 were found to have reduced lachrymal or salivary secretion. No correlation could be detected between the presence or absence of secretory abnormalities and the age or sex of the patient, the presence of nodules or salivary duct antibody, or the occurrence of vasculitis. However, there was a significant correlation between diminished salivary of lachrymal flow and the occurrence of cellular immune responses to a protein fraction of normal human saliva, sensitisation being found in 94% of those with impairment of salivary and lachrymal secretion as compared with 33% of those without.     

Lyme disease ecology in Wisconsin: distribution and host preferences of Ixodes dammini, and prevalence of antibody to Borrelia burgdorferi in small mammals

Lyme disease recently has been recognized in Wisconsin. Trapping studies were conducted at four geographically separate and ecologically distinct regions in Wisconsin to elucidate the distribution and host preferences of Ixodes dammini on small and medium sized mammals, and the occurrence of antibodies to Borrelia burgdorferi in these wild mammals. Peak I. dammini larval activity occurred from June-September. Nymphs were most active from May-August. White-footed mice (Peromyscus leucopus) and chipmunks (Tamias striatus) were important hosts for immature ticks. Mean numbers of I. dammini per mouse were highest in regions of high prevalence of Lyme disease. Antibody to B. burgdorferi was detected in sera of 60/371 (16%) white-footed mice, 5/104 (5%) chipmunks, 3/5 (60%) gray squirrels (Sciurus carolinensis), 0/8 raccoons (procyon lotor), and 0/12 opossum (Didelphis virginiana); antibody prevalence correlated positively with I. dammini occurrence, and seropositive animals were not detected in areas where I. dammini were not found. Two of 15 recaptured P. leucopus had greater than or equal to 4-fold changes in antibody titer. B. burgdorferi was cultured from blood of a P. leucopus captured in west-central Wisconsin, and was observed by direct immunofluorescence in 9/23 (39%) I. dammini nymphs. In Wisconsin, I. dammini has increased in numbers and has significantly expanded its range since its first recognition in 1968.     

Cases of Lyme disease in the United States: locations correlated with distribution of Ixodes dammini.

Lyme disease, defined by erythema chronicum migrans and sometimes followed by neurologic, cardiac, or joint involvement, is known to have affected 512 patients in the United States. The disease seems to occur in three distinct foci: along the northeastern coast, in Wisconsin, and in California and Oregon, a distribution that correlates closely with that of Ixodes dammini in the first two areas and with Ixodes pacificus in the last. The implicated tick, saved by six patients in the Northeast, was identified as nymphal I. dammini. Residence in or travel to endemic areas and history of tick bite may be important clues to diagnosis.     

Humoral immune responses of Hereford cattle vaccinated with midgut antigens of the cattle tick, Boophilus microplus

Vaccination of cattle with midgut membrane (GM) antigen derived from the cattle tick, Boophilus microplus, infected with the adjuvant Quil A, resulted in significant increases in total immunoglobulins, mainly in the IgG1 and IgG2 fractions of the serum. Analysis of the anti-GM antibody levels of vaccinated cattle showed that the levels of IgG, IgG1 and complement-fixing antibodies were significantly correlated to protection against infestation with cattle ticks. Anti-GM antibodies of the IgG2 and IgM isotype were not correlated to protection against infestation with cattle ticks. Anti-GM antibodies fixed complement (C') in the presence of GM, larval membrane antigen and live, midgut cells, but not in the presence of live, larval cells. Anti-GM antibodies were able to fix C' equally well in the presence of GM antigen and live, midgut cells. None of the antigens tested activated the alternate pathway of complement under the conditions tested. Levels of anti-GM IgG1 antibodies were used to develop a regression model for predicting levels of protection against infestation with cattle ticks in vaccinated cattle.     

Effects of antiinflammatory agents on the acute response of immune synovitis in rabbits

Immune synovitis in rabbits was investigated as a potential in vivo model for evaluating new antiinflammatory agents. Antigen-induced increases in knee width as well as β-glucuronidase and acid phosphatase activities in exudates were observed. Histologically, polymorphonuclear leukocytes appeared within hours in synovial tissues and reached maximum infiltration at about 24 hours. Subsequently, mononuclear cells, including plasma cells, appeared. The 6-hour Arthus-like phase of synovitis can be depressed by some antiinflammatory agents, colchicine and steroids being particularly effective. It is suggested that this model can be utilized to define potentially more effective antiinflammatory drugs.     

Fasciola hepatica in the rat: immune responses associated with the development of resistance to infection

F. hepatica infections were established in rats and immune responses were monitored during primary and challenge infections. Antibody levels peaked at 3 weeks post-primary infection and at 6 days post-challenge infection. No significant correlation was found between antibody titre and number of flukes recovered at autopsy. Immunoblotting revealed a limited number of immunogenic polypeptides. When antibodies from these reactive bands were eluted and tested by IFA they all gave identical binding patterns: on juvenile fluke sections tegumental syncytium, tegumental cells and gut cells were labelled, while on adult sections the same antibodies labelled gut cells, reproductive tissue, excretory ducts and flame cells. This suggested that these tissues shared a common epitope or range of epitopes. A pronounced eosinophilia was observed throughout the infection period studied and infected liver sections showed massive cellular infiltration. Histochemical and immunocytochemical investigation of infected liver revealed the presence of large numbers of eosinophils, neutrophils, lymphocytes and phagocytes. The implications of these findings, to an understanding of concomitant immunity in the rat are discussed.     

Long-term transgene expression within the anterior pituitary gland in situ: impact on circulating hormone levels, cellular and antibody-mediated immune responses

Adenoviral vectors have been identified as useful tools for gene transfer to the pituitary gland with the aim of providing therapeutic treatments for pituitary diseases. Although successful adenovirus-mediated gene transfer to the pituitary has been shown, the duration of transgene expression, local immune responses and consequences on circulating pituitary hormone levels have not been investigated. These are critical not only for the successful implementation of these gene transfer techniques both for physiological and/or therapeutic applications but also for assessing the safety of these approaches. We have therefore assessed duration and levels of transgene expression 3 days, 14 days, 1, 2, and 3 months after delivery of adenoviruses expressing herpes simplex virus type 1 thymidine kinase (HSV1-TK), under the control of the major immediate early human cytomegalovirus (RAd-hCMV/TK) or human PRL (RAd-hPrl/TK) promoters, to the anterior pituitary (AP) gland in situ. The presence of vector genome and cellular immune infiltrates within the AP gland were also studied along with the levels of circulating anti-adenovirus neutralizing antibodies and AP hormones in sera. Ubiquitous or cell-type specific expression of HSV1-TK within the AP gland was seen from RAd-hCMV/TK and RAd-hPrl/TK respectively at all time points, although a reduction in expression was seen over time. PCR amplification of HSV1-TK specific sequences showed the persistence of adenoviral genomes for up to 3 months. Analysis of the AP showed the presence of a virus-induced inflammation that peaked around day 14 and was resolved between 2-3 months. ED1-positive macrophages, CD8-positive T-cells and CD161-positive NK cells were identified up to 1 month after virus administration. A virus-induced humoral immune response was also present as anti-adenovirus neutralizing antibodies were detected from 14 days after virus administration. Levels of circulating pituitary hormones were unaffected by virus administration with the exception of the stress hormone ACTH which was increased at 3 days but normalized by 14 days. In conclusion, our data indicates that adenovirus-mediated delivery to the AP gland in situ may be a useful tool for the treatment of pituitary diseases as no major cytotoxicity or disruption of AP hormonal functions are seen. Despite of this, further developments to this approach still need to be made to combat the reduced transgene expression seen over time and the induction of virus-induced immune responses.     

Hemodynamic responses to atrial natriuretic factor in nephrectomized rabbits: attenuation of the circulatory consequences of acute volume expansion

We investigated the hemodynamic responses to three doses of atrial natriuretic factor [human atrial natriuretic factor-(99-126)] (ANF) in nephrectomized rabbits anesthetized with ketamine and acepromazine. The influence of the different doses of the peptide on the hemodynamic consequences produced by acute volume expansion (0.9% NaCl, 1.4 ml/kg/min for 60 minutes) was also studied. All three dosages of ANF (0.001, 0.01, and 0.2 micrograms/kg/min for 20 minutes) significantly reduced blood pressure. With the lowest dose, the hypotensive effect was associated with reduction in systemic vascular resistance and no significant change in heart rate, stroke volume, central venous pressure, and hematocrit. In contrast, the intermediate and high doses, which resulted in markedly higher plasma levels, caused a significant decrease in heart rate, central venous pressure, and stroke volume; a slight rise in hematocrit; and no change in systemic vascular resistance. Volume expansion produced by saline infusion in an additional group of nephrectomized rabbits increased central venous pressure and decreased hematocrit. When ANF infusion was associated to volume expansion, each dosage of ANF was able to reduce the rise in central venous pressure, while only the higher dosage attenuated the progressive fall in hematocrit caused by volume expansion. Plasma volume, measured at the end of volume expansion was lower in the group treated with the highest dose of ANF than in the control animals (28.2 +/- 9 vs. 35.1 +/- 3 ml/kg, p less than 0.05). We conclude that 1) ANF induces significant hemodynamic effects independently from its renal action.(ABSTRACT TRUNCATED AT 250 WORDS)     

Innate immunity, through late complement components activation, contributes to the development of early vascular inflammation and morphologic alterations in experimental diabetes

We previously showed that progesterone (P4) inhibits the proliferation of rat aortic smooth muscle cells (RASMC). Here, we further demonstrate that P4 at physiologic levels (5-500 nM) concentration-dependently inhibited migration of cultured RASMC. The effect is blocked by pretreatment with progesterone receptor (PR) antagonist, RU486. The P4-induced RASMC migration inhibition was through RhoA inactivation induced by cSrc-enhanced RhoA degradation. The P4-induced increases of phosphorylated Src (pSrc) and PR-pSrc complex in RASMC were observed mainly in the membrane fraction. Pre-treatment with a cSrc inhibitor (PP2) or cSrc antisense oligonucleotides prevented the P4-induced decreases of the protein levels of RhoA, phosphorylated FAK (p-FAK) and paxillin phosphorylaton and migration inhibition in RASMC. These findings expend our knowledge of the basis of P4's effect on vascular smooth muscle cell migration and highlight novel pathways of signaling transduction of P4 through PR-mediated nongenomic mechanisms.     

Human schistosomiasis mansoni: immune responses during acute and chronic phases of the infection

Schistosoma mansoni infection may occur either as an acute infection in individuals who have recently visited an endemic area, with no previous contact with the parasite, or as a lasting chronic disease, if not interrupted by specific chemotherapy. The acute phase is characterized by symptoms such as fever, cough, diarrhea, anorexia, and arthralgias in combination with leukocytosis and eosinophilia, and a high cellular immune response to schistosome antigens especially those from the parasite's eggs. In the chronic phase, most patients living in endemic areas are asymptomatic, and their immune responses to egg antigens are modulated. A few develop periportal fibrosis of the liver, which may result in the hepatosplenic form of the disease. The humoral response (IgG, IgM and IgE) in acute patients to egg and worm antigens does not differ from the chronic phase. However, a high level of IgG and IgM antibodies to KLH were detected in acute patients. Acute patients express a considerably higher in vitro cellular responsiveness than do chronic patients, especially to egg antigens. They present a mixed profile of Th1 and Th2 cytokines. Ultrasound examinations of endemic population reveal a high heterogeneity between the patients as regards the presence and intensity of periportal fibrosis. Most patients are asymptomatic and their immune responses to schistosoma egg antigens (SEA) are modulated. In contrast, a high percentage of patients with incipient fibrosis (early stage of hepatosplenic) responded strongly to SEA. Patients with advanced hepatosplenic disease were likely to be non-responders to SEA. Most of the chronic patients presented a Th2 profile with low production of interferon-gamma (IFN-gamma). The intensity of infection favors the production of interleukin (IL)-10. After adjusting for age, sex, and intensity of infection, a strong correlation was observed between the production of IL-13 and the degree of fibrosis. Chronic asymptomatic patients and those with incipient fibrosis expressed very high levels of heterogeneity of their antibody responses. IgG response to soluble worm antigen preparation (SWAP) was distinct and significantly higher in hepatosplenic patients than in those asymptomatic or with incipient fibrosis. Levels of IgG4 to SEA were significantly higher in sera from patients with incipient fibrosis as compared to uninfected and hepatosplenic groups. Polyclonal idiotypic antibodies and their fragments F(ab')2, directly stimulate in culture T cells of schistosomiasis patients in presence of IL-1. Polyclonal idiotypic antibodies are able to modulate in vitro granuloma formation around SEA-polyacrylamide. The importance of idiotypes for protection or pathology in schistosomiasis is still not clear.     

Cardiovascular responses to graded treadmill exercise during the development of doxorubicin induced heart failure in rabbits

STUDY OBJECTIVE--The aim was to examine the haemodynamic and humoral responses to graded treadmill exercise, serially during the development of congestive heart failure. DESIGN--Doxorubicin (1 mg.kg-1) was given to rabbits twice weekly intravenously over 8 weeks to induce a low output congestive cardiomyopathy. Treadmill exercise at 8 and 16 m.min-1 was performed at weeks 0, 2, 4, 6, 7, and 8. During each exercise study, continuous recordings were made of cardiac output, mean arterial pressure, and heart rate, and central venous blood was sampled at rest and during the last 10 s of exercise for plasma noradrenaline and plasma renin activity. EXPERIMENTAL MATERIAL--Six cross-bred English rabbits, mean weight 2.6 kg, received doxorubicin treatment; three control rabbits received vehicle injection. MEASUREMENTS AND MAIN RESULTS--Over the first 2 weeks, resting haemodynamic variables and responses to exercise were normal in all rabbits. Thereafter, doxorubicin treated rabbits had progressive falls in resting cardiac index and mean arterial pressure, and rises in resting heart rate and systemic vascular resistance. The normal increases in cardiac index and mean arterial pressure with exercise were progressively attenuated, despite an increase in resting and exercising heart rate. The resting levels of plasma noradrenaline and plasma renin rose after the fourth week of doxorubicin treatment. Throughout the experiment, exercise consistently raised plasma noradrenaline and renin, but the exercising levels of both hormones increased as heart failure progressed. Four of the six doxorubicin treated rabbits became exhausted in the final run and there was an intense rise in systemic vascular resistance. CONCLUSIONS--In this rabbit model of chronic heart failure, sympathetic vasoconstrictor drive is greater than normal at rest, and is greatly exaggerated during exercise. It is suggested that this abnormal response to exercise results from a combination of failure of arterial pressure to reach the elevated set point of the arterial baroreflex, increased afferent input from exercising muscles due to their underperfusion, and increase in central command due to muscle fatigue.     

Disruption of the salivary protein 14 in Ixodes scapularis nymphs and impact on pathogen acquisition.

We previously examined the physiological role of the anticoagulant salivary protein 14 (salp14) in adult Ixodes scapularis and showed that Salp14 played a role in tick feeding and engorgement. We now analyze whether the disruption of the salp14 family expression by RNA interference affects tick weight in na?ve nymph I. scapularis. Salp14 expression after dsRNA injection was significantly reduced, as shown by mRNA and protein analysis. However, nymph engorgement weight was not altered in salp9pac (salp14 paralog) dsRNA-injected ticks. We also determined Borrelia burgdorferi and Anaplasma phagocytophilum acquisition in I. scapularis nymphs that had reduced Salp14 expression. B. burgdorferi and A. phagocytophilum acquisition was not affected 72 hours after feeding. Our results suggest that different mechanisms govern nymph and adult feeding in I. scapularis.     

Intestinal epithelial responses to enteric pathogens: effects on the tight junction barrier,ion transport,and inflammation

The effects of pathogenic organisms on host intestinal epithelial cells are vast. Innumerable signalling pathways are triggered leading ultimately to drastic changes in physiological functions. Here, the ways in which enteric bacterial pathogens utilise and impact on the three major physiological functions of the intestinal epithelium are discussed: alterations in the structure and function of the tight junction barrier, induction of fluid and electrolyte secretion, and activation of the inflammatory cascade. This field of investigation, which was virtually non-existent a decade ago, has now exploded, thus rapidly expanding our understanding of bacterial pathogenesis. Through increased delineation of the ways in which microbes alter host physiology, we simultaneous gain insight into the normal regulatory mechanisms of the intestinal epithelium.     

Role of microRNAs in the immune system,inflammation and cancer

MicroRNAs,a key class of gene expression regulators,have emerged as crucial players in various biological processes such as cellular proliferation and differentiation,development and apoptosis.In addition,microRNAs are coming to light as crucial regulators of innate and adaptive immune responses,and their abnormal expression and/or function in the immune system have been linked to multiple human diseases including inflammatory disorders,such as inflammatory bowel disease,and cancers.In this review,we discuss our current understanding of microRNAs with a focus on their role and mode of action in regulating the immune system during inflammation and carcinogenesis.