Psychoneuroimmunology: the example of psoriasis

The relationship between the central nervous system (CNS) and the endocrine system have been known for many years. Indeed some of the hormone secreting glands are actually located in the brain. The notion that the CNS and hormones are also involved in the bi-directional cross-talk with the Immune System has been the target of intense research in the recent decades. In this manner, for example, psychological states can be closely related to changes in immune mediators, and not only they may influence the evolution of human diseases, but may in the future lead to novel therapeutic interventions. This is the subject of this review, with particular emphasis on the role of psychoneuroimmunology (PNI) in psoriasis.

Positional cloning of zebrafish ferroportin1 identifies a conserved vertebrate iron exporter

Defects in iron absorption and utilization lead to iron deficiency and overload disorders. Adult mammals absorb iron through the duodenum, whereas embryos obtain iron through placental transport. Iron uptake from the intestinal lumen through the apical surface of polarized duodenal enterocytes is mediated by the divalent metal transporter, DMTi. A second transporter has been postulated to export iron across the basolateral surface to the circulation. Here we have used positional cloning to identify the gene responsible for the hypochromic anaemia of the zebrafish mutant weissherbst. The gene, ferroportin1, encodes a multiple-transmembrane domain protein, expressed in the yolk sac, that is a candidate for the elusive iron exporter. Zebrafish ferroportin1 is required for the transport of iron from maternally derived yolk stores to the circulation and functions as an iron exporter when expressed in Xenopus oocytes. Human Ferroportin1 is found at the basal surface of placental syncytiotrophoblasts, suggesting that it also transports iron from mother to embryo. Mammalian Ferroportin1 is expressed at the basolateral surface of duodenal enterocytes and could export cellular iron into the circulation. We propose that Ferroportin1 function may be perturbed in mammalian disorders of iron deficiency or overload.

Enhanced expression of inducible nitric oxide synthase without vasodilator effect in chronically infected lungs

We hypothesized that abnormal ventilation-perfusion matching in chronically infected lungs was in part due to excess nitric oxide (NO) production after upregulation of inducible NO synthase (iNOS) expression. Rats were anesthetized and inoculated intratracheally with Pseudomonas aeruginosa incorporated into agar beads (chronically infected) or with sterile agar beads (placebo inoculated) and killed 10-15 days later. Immunohistochemistry demonstrated increased expression of iNOS and reduced expression of endothelial NOS (eNOS) in chronically infected compared with placebo-inoculated or noninoculated lungs. In isolated lungs from chronically infected rats, NOS inhibition with N(omega)-nitro-L-arginine methyl ester increased the mean perfusion pressure (14.4 +/- 2.7 mmHg) significantly more than in the placebo-inoculated (4.8 +/- 1.0 mmHg) or noninoculated (5.3 +/- 0.8 mmHg) lungs (P < 0.01). Although the chronically infected lungs were more sensitive to NOS inhibition, further evidence suggested that the increased iNOS expression was not associated with enhanced iNOS activity. Selective inhibitors of iNOS did not produce an increase in vascular resistance similar to that produced by nonselective inhibitors. Accumulation of nitrate/nitrite in the perfusate of isolated lungs was unchanged by chronic infection. Thus although iNOS expression was increased in chronic pulmonary infection, iNOS activity in the intact lung was not. Nonetheless, endogenous NO production was essential to maintain normal vascular resistance in these lungs.

Thrombolysis in Myocardial Infarction frame count in saphenous vein grafts

BACKGROUND

Although the Thrombolysis in Myocardial Infarction flow grade system is a widely used index of coronary blood flow, it has important limitations. We recently described a new continuous measure of blood flow in native coronary arteries, the Thrombolysis in Myocardial Infarction frame count (TFC), and sought to extend this method to coronary artery bypass grafts.

METHODS

We retrospectively analyzed cinefilms of patients' status after coronary artery bypass grafting, excluding patients with recent myocardial infarction and grafts with stenoses in the graft or native vessel. We counted the cineframes required for dye to travel from the ostium of the graft to the graft anastomotic site (TFCg) and to a standardized distal coronary landmark (TFC).

RESULTS

For all vein grafts combined, TFCg was 19.2+/-5.7 frames (mean+/-SD, n = 93) and the TFC was 33.9+/-8.0 frames (n = 67). The upper limits for "normal" flow, calculated from the 95% confidence intervals, were 31 frames for TFCg and 50 frames for TFC.

CONCLUSIONS

The Thrombolysis in Myocardial Infarction frame counting method has now been extended to normal saphenous vein grafts, and normal reference values are provided.

Exhaled nitric oxide and bronchoalveolar lavage nitrite/nitrate in active pulmonary sarcoidosis

Increased exhaled nitric oxide (NO) may reflect respiratory tract inflammation in untreated asthmatics. We compared exhaled NO and bronchoalveolar lavage (BAL) nitrate/nitrite (NO3-/NO2-) in 10 patients who had untreated, active pulmonary sarcoidosis with those of normal control subjects. Exhaled NO concentrations, determined by chemiluminescence, were similar in patients and control subjects (peak NO concentration of patients [mean +/- SD]: 13.6 +/- 5.9 parts per billion [ppb], peak NO concentration of control subjects: 11.2 +/- 5.7 ppb, p = 0.32; mean alveolar NO concentration of patients: 7.8 +/- 4.4 ppb, mean alveolar NO concentration of control subjects: 7.1 +/- 4.2 ppb, p = 0.70; end-tidal NO concentration of patients: 6.9 +/- 4.5 ppb, end-tidal NO concentration of control subjects: 6.6 +/- 4.0 ppb, p = 0.60). BAL NO2- was assayed using a modified Griess reaction after reduction of NO3- to NO2-. There was no significant difference in mean BAL NO2- concentrations, expressed as nanomoles per milliliter of epithelial lining fluid (patients: 544 nmol/ml, control subjects: 579 nmol/ml, p = 0.81) or as nanomoles per milliliter of BAL fluid (patients: 6.7 nmol/ml, control subjects: 5.7 nmol/ml, p = 0.41). These data suggest that excess NO generation does not accompany the respiratory tract inflammation of pulmonary sarcoidosis.

Relation between injections before 90-minute angiography and coronary patency: results of the thrombolysis in myocardial infarction 4 trial

The current goal of thrombolytic therapy is to achieve both full (Thrombolysis in Myocardial Infarction [TIMI] grade 3) and early reperfusion. Newer reperfusion strategies may now achieve a high degree of reperfusion even earlier than the traditional 90-minute end point. To determine whether injections before 90 minutes affect this traditional end point, the relation between the number of injections before 90-minute angiography and patency was examined in the TIMI 4 trial. The number of injections before 90-minute angiography was no different between occluded arteries (TIMI grade 0/1 flow) (2.46 +/- 1.78; n = 94) and patent arteries (TIMI grade 2/3 flow) (2.71 +/- 2.42; n = 295) (p = 0.24). The incidence of any injections before 90 minutes was no different in patent versus closed arteries (80.6% [77/98] vs 72.4% [22/304]; p = 0.10). The number of injections before 90 minutes was insignificantly smaller in patients with TIMI grade 3 flow (2.53 +/- 2.53 [n = 184] vs 2.76 +/- 2.03 [n = 204]; p = 0.31), but the incidence of any injections before 90 minutes was significantly smaller in patients with TIMI grade 3 flow (68.8% [132/192] vs 79.5% [167/210]; p = 0.01). No relation was identified between the number of injections before 90-minute angiography and patency at this traditional time point. This observation justifies the judicious use of a limited number of "earlier snapshots" of the infarct-related artery before 90 minutes to ascertain just how rapidly newer thrombolytic regimens achieve patency. Patients with TIMI grade 3 flow had a slightly lower incidence of injections before 90 minutes, perhaps because they did not require as urgent a definition of coronary anatomy.

Conditioned increase in peripheral blood mononuclear cell (PBMC) number and corticosterone secretion in the rat

Femoral artery catheters were surgically implanted into male Lewis/N rats to allow blood sampling and drug infusion in the freely moving animal. After recovery, conditioned animals received four pairings of a peppermint odor, the conditioned stimulus (CS), and an infusion of 0.1 mg/kg nicotine bitartrate, an unconditioned stimulus (US) for an increase in the number of peripheral blood mononuclear cells (PBMC) and an increase in corticosterone concentration. When reexposed to the peppermint odor, conditioned animals showed a significant increase in PBMC number and corticosterone secretion when compared to saline and unpaired control groups and previously conditioned animals that were not reexposed to the CS. Increased PBMCs were found on the fifth unreinforced CS trial. Conditioned CORT responses were lost after the initial test trial. The data indicate that the distribution of immune cells can be influenced by learning processes and support the role of learning in the regulation of corticosterone secretion.

Adjuvant effects of freely ingested cholera toxin on systemic antibody and DTH responses to protein antigen

Recent evidence suggests that immunological handling of antigen in the gut may be different when animals voluntarily ingest antigen in their drinking fluid. Therefore, we investigated whether the adjuvant effects of CT were evident in mice that voluntarily ingested CT together with keyhole limpet hemocyanin (KLH) in 1.0 ml chocolate milk. Initially, it was found that ingestion of 2 mg KLH for up to four times (one ingestion per week) did not induce serum IgG anti-KLH antibody; however, KLH-specific IgG was detected if KLH was ingested together with 10 micrograms CT. Furthermore, 50 days after only one ingestion of CT+KLH, the serum IgG response to intraperitoneal challenge with 100 micrograms KLH was significantly elevated with respect to the response of mice who previously had ingested either KLH alone, CT alone, or drinking fluid only. This observation was repeated in further experiments showing an enhanced IgG response to 100 micrograms KLH ip given 7 or 14 days after a single ingestion of 2 or 5 mg KLH mixed with different doses (0.5-20 micrograms) CT. The lowest effective CT dose for serum IgG anti-KLH adjuvanticity was found to be 1 microgram; the highest effective dose was 10 micrograms, there being no additive effect with 20 micrograms CT. It was also found that simultaneous ingestion of KLH (2 or 5 mg) with CT (0.5-20 micrograms) followed 7 or 14 days later by 100 micrograms KLH ip, increased the 24 hr footpad DTH response to 50 micrograms KLH administered 43 days after the ip challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of handling on antibody production, mitogen responses, spleen cell number, and lymphocyte subpopulations

The effects of a simple psychosocial manipulation, handling, on immune function in BALB/c.ByJ mice were studied. Handling for two minutes/day prior to immunization was shown to be associated with a decreased primary IgG antibody response to the protein antigen keyhole limpet hemocyanin. Handling was also associated with decreased T cell proliferative responses to Concanavalin A. No reliable changes in spleen cell number or lymphocyte subsets were found. These findings demonstrate that simply picking up an animal results in modulation of the immune response. These data are also of interest for their obvious methodological implications.

Autoreactive T-cell response to resting or activated B cells

Cloned autoreactive T-cell lines and hybridomas have been selected in many laboratories. A number of observations have suggested that activation of Ia-positive stimulators may be required for optimal induction of an autoreactive response. We have examined the ability of small resting B cells fractionated by centrifugal elutriation to stimulate the proliferative response of seven cloned autoreactive T-cell lines. Of these, six were efficiently stimulated by resting B cells. One I-Ed-specific Th2-type T-cell clone failed to be stimulated by resting B cells. This clone did, however, respond to this same cell fraction following lipopolysaccharide (LPS) activation. An independent I-E-specific Th2 clone was stimulated by resting B cells. It appears, therefore, that a requirement for activated stimulators is not a general property of either autoreactive T cells or the Th2 helper T-cell subset.

Repeated intraperitoneal injections of saline attenuate the antibody response to a subsequent intraperitoneal injection of antigen

The results of two experiments with male C3H/HeJ mice indicated that repeated intraperitoneal (ip) injections of sterile saline over a 2-week period resulted in an attenuated antibody response to the subsequent ip injection of a soluble protein antigen, keyhole limpet hemocyanin. There were no differences among experimental groups that received a different number of preimmunization injections of saline, and comparable effects were obtained simply by the daily handling of mice. Neither repeated ip injections nor handling altered preimmunization (baseline) corticosterone levels, and only previously unmanipulated mice showed an elevation in corticosterone levels 30 min after ip immunization. These latter results suggest that the depressed IgM and IgG responses were not due to the immunosuppressive effects of endogenously elevated adrenocortical steroids.

The kinetics of recovery of leukocyte number and lymphocyte function following an injection of a single high dose of cyclophosphamide in C3H/HeJ mice

The short-term effects of the immunosuppressive drug cyclophosphamide (Cy) are well-documented, but the long-term consequences are not as well studied. Here we report on the kinetics of leukocyte number and immune function recovery following a single intraperitoneal injection of 100 mg/kg or 300 mg/kg Cy. The leukocyte number in spleen, lymph node, bone marrow and thymus was unchanged in C3H/HeJ mice injected with the lower dose of Cy, and was severely but transiently depressed in mice injected with 300 mg/kg Cy. Recovery was complete by day 21. Humoral immunity was unchanged with the lower dose of Cy; mice injected with 300 mg/kg recovered normal antibody production after 3-5 weeks. Natural killer cell function was also transiently depressed in animals receiving the higher but not the lower concentration of Cy. Surprisingly, splenic mitogen responses were markedly inhibited in mice injected with either concentration of Cy. The T-cell proliferative response remained depressed even after 5 weeks in mice injected with 300 mg/kg Cy. Lymphocyte subpopulations in spleen were examined by flow cytometry, and, although some deviations were observed, it is unlikely that these changes are responsible for the highly depressed mitogen response. Thus, there is a loss of the proliferative response to mitogens in Cy-treated mice long after recovery of other lymphocyte functions.