Blocking substance P signaling reduces musculotendinous and dermal fibrosis and sensorimotor declines in a rat model of overuse injury

Purpose/Aim: Substance P-NK-1R signaling has been implicated in fibrotic tendinopathies and myositis. Blocking this signaling with a neurokinin 1 receptor antagonist (NK1RA) has been proposed as a therapeutic target for their treatment.Materials and Methods: Using a rodent model of overuse injury, we pharmacologically blocked Substance P using a specific NK1RA with the hopes of reducing forelimb tendon, muscle and dermal fibrogenic changes and associated pain-related behaviors. Young adult rats learned to pull at high force levels across a 5-week period, before performing a high repetition high force (HRHF) task for 3 weeks (2 h/day, 3 days/week). HRHF rats were untreated or treated in task weeks 2 and 3 with the NK1RA, i.p. Control rats received vehicle or NK1RA treatments.Results: Grip strength declined in untreated HRHF rats, and mechanical sensitivity and temperature aversion increased compared to controls; these changes were improved by NK1RA treatment (L-732,138). NK1RA treatment also reduced HRHF-induced thickening in flexor digitorum epitendons, and HRHF-induced increases of TGFbeta1, CCN2/CTGF, and collagen type 1 in flexor digitorum muscles. In the forepaw upper dermis, task-induced increases in collagen deposition were reduced by NK1RA treatment.Conclusions: Our findings indicate that Substance P plays a role in the development of fibrogenic responses and subsequent discomfort in forelimb tissues involved in performing a high demand repetitive forceful task.

Comparative Efficacy of Eletriptan vs. Naratriptan in the Acute Treatment of Migraine

This was a randomized, double-blind study designed to evaluate the comparative efficacy and tolerability of the 40-mg dose of eletriptan and the 2.5-mg dose of naratriptan. Patients ( n = 548) meeting International Headache Society (IHS) criteria for migraine were randomized to treat a single migraine attack with either eletriptan 40 mg, naratriptan 2.5 mg, or placebo. Headache response rates at 2 h and 4 h, respectively, were 56% and 80% for eletriptan, 42% and 67% for naratriptan ( P < 0.01 for both time-points vs. eletriptan), and 31% and 44% for placebo ( P < 0.0001 vs. both active drugs at both time-points). Eletriptan also showed a significantly greater pain-free response at 2 h (35% vs. 18%; P < 0.001) as well as lower use of rescue medication (15% vs. 27%; P < 0.01) and higher sustained headache response at 24 h (38%) compared with naratriptan (27%; P < 0.05) and placebo (19%; P < 0.01). Both eletriptan and naratriptan were well tolerated. The results confirm previous meta-analyses that have suggested the superiority of eletriptan vs. naratriptan in the acute treatment of migraine.

Eletriptan Treatment of Migraine in Patients Switching from Barbiturate-Containing Analgesics: Results from a Multiple-Attack Study

The aim of this study was to examine efficacy and tolerability of eletriptan in patients switched from barbiturate-containing combinations (Fiorinal®, Fioricet®). Migraineurs ( n = 160) meeting IHS criteria, with unsatisfactory response in the past year to butalbital-containing combinations, treated up to 16 attacks over 3 months with eletriptan 40 mg. Assessments included headache response and pain-free rates and functional impairment at baseline and 2 h postdose, and global ratings of treatment satisfaction at 24 h. At 2 h postdose, average headache response and pain-free rates were 71% (95% CI, 69-74%) and 37% (95% CI, 35-40%), respectively; 68.5% of patients (95% CI, 65-72%) reported functional response. Within-patient analysis found no efficacy diminution over time (no tolerance). Average headache recurrence rate was 20% (95% CI, 18-23%). Eletriptan was well-tolerated; 6 (3.7%) patients discontinued due to adverse events. There were no serious treatment-related adverse events. We conclude that in poor responders to butalbital-caffeine combinations, switching to eletriptan 40 mg was well-tolerated and efficacious.

Roles of TNF-related apoptosis-inducing ligand in experimental autoimmune encephalomyelitis

TRAIL, the TNF-related apoptosis-inducing ligand, induces apoptosis of tumor cells, but not normal cells; the roles of TRAIL in nontransformed tissues are unknown. Using a soluble TRAIL receptor, we examined the consequences of TRAIL blockade in an animal model of multiple sclerosis. We found that chronic TRAIL blockade in mice exacerbated experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein. The exacerbation was evidenced primarily by increases in disease score and degree of inflammation in the CNS. Interestingly, the degree of apoptosis of inflammatory cells in the CNS was not affected by TRAIL blockade, suggesting that TRAIL may not regulate apoptosis of inflammatory cells in experimental autoimmune encephalomyelitis. By contrast, myelin oligodendrocyte glycoprotein-specific Th1 and Th2 cell responses were significantly enhanced in animals treated with the soluble TRAIL receptor. Based on these observations, we conclude that unlike TNF, which promotes autoimmune inflammation, TRAIL inhibits autoimmune encephalomyelitis and prevents activation of autoreactive T cells.

Modulation of susceptibility and resistance to an autoimmune model of multiple sclerosis in prototypically susceptible and resistant strains by neutralization of interleukin-12 and interleukin-4, respectively

Experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, is mediated by Th1 cells. The major Th1 inducer, IL-12, enhances EAE, while its blockade suppresses it. IL-4 suppresses EAE. Here, we determined IFN-gamma and IL-4 production by myelin basic protein-stimulated lymphocytes from prototypically EAE-susceptible SJL/J and EAE-resistant BALB/c mice, 9 days after immunization with spinal cord homogenate. While lymphocytes from SJL/J mice produce IFN-gamma and no IL-4, lymphocytes from BALB/c mice produce IL-4 and no IFN-gamma. Since early endogenous production of IL-12/IFN-gamma or IL-4 is linked to Th1 or Th2 responses, respectively, we determined whether neutralization of IL-12 or IL-4 at immunization modifies susceptibility or resistance to EAE. SJL/J mice given neutralizing anti-IL-12 mAb are protected from EAE. BALB/c mice given neutralizing anti-IL-4 mAb develop EAE, while those treated with control antibody remain resistant. These studies confirm the pivotal role of IL-12 in EAE development and show that endogenous IL-4 is important for determining the genetic resistance to EAE.

Experimental allergic neuritis in the SJL/J mouse: induction of severe and reproducible disease with bovine peripheral nerve myelin and pertussis toxin with or without interleukin-12

We report a reproducible model of experimental allergic neuritis (EAN) with severe clinical signs and consistent pathological features in mice. Pertussis toxin (PT) in the presence or absence of murine recombinant interleukin-12 (mrIL-12) was used as an adjuvant with bovine peripheral nerve myelin (BPNM) to induce clinical EAN in SJL/J mice. After immunization with a combination of BPNM in complete Freund's adjuvant (CFA) and PT, mice developed severe consistent signs of EAN. The additional treatment of immunized mice with mrIL-12 prolonged the course of EAN characterized by earlier clinical signs of the disease and delayed the recovery stage. Mice injected with BPNM and CFA without PT developed mild clinical signs. Histological examination of the caudae equinae and the sciatic nerves taken from mice with clinical signs of EAN during the recovery stage revealed severe demyelination, remyelination and remnants of mononuclear cell infiltration. Moderate to severe EAN can be induced in SJL/J mice by the injection of a combination of BPNM in CFA and PT. This model can provide a better understanding of mechanism of demyelination in infiltrating peripheral neuropathy.

Murine macrophages stimulated with central and peripheral nervous system myelin or purified myelin proteins release inflammatory products

Macrophage inflammatory products including tumor necrosis factor (TNF) and interleukin-12/p40 are implicated in demyelinating diseases such as multiple sclerosis (MS), Guillain-Barré syndrome, and animal models experimental autoimmune encephalomyelitis and neuritis. The macrophage product angiotensin converting enzyme (ACE) is released during inflammation. ACE can also be elevated in MS. We investigated the ability of central (CNS) and peripheral nervous system (PNS) myelin to stimulate TNF, interleukin-12, and ACE production by murine macrophages. Both CNS and PNS myelin and purified myelin basic protein and P2 protein induced release of these products. Direct stimulation by myelin may represent a mechanism of inducing release of macrophage products in inflammatory demyelination or neural injury.

Differential roles of Fas ligand in spontaneous and actively induced autoimmune encephalomyelitis

To determine the roles of Fas/Fas ligand (FasL) in autoimmunity, we studied spontaneous and actively induced autoimmune encephalomyelitis in 541 myelin basic protein-specific T cell receptor transgenic mice. We found that spontaneous autoimmune encephalomyelitis, which was initiated by unidentified microbial factors, was dramatically exacerbated in mice carrying Fas or FasL gene mutation. The exacerbation of autoimmune encephalomyelitis was reflected primarily by an increase in disease incidence and a decrease in spontaneous disease recovery. By contrast, actively induced encephalomyelitis, which was initiated by pertussis toxin, was significantly inhibited by Fas or FasL gene mutation. These results suggest that environmental factors that trigger autoimmune disease may determine not only whether disease will occur but also whether an immune molecule such as FasL will promote or inhibit the autoimmune process.

IL-12 reverses the suppressive effect of the CD40 ligand blockade on experimental autoimmune encephalomyelitis (EAE)

Blockade of the CD40 ligand (CD40L)-CD40 interaction suppresses experimental autoimmune encephalomyelitis (EAE). Since this interaction induces IL-12, an essential cytokine for EAE induction, we hypothesized that CD40L blockade may suppress EAE through IL-12 inhibition. Here we show that exogenous IL-12 abolishes the ability of anti-CD40L monoclonal antibodies to prevent EAE. Anti-IL-12 antibodies prevent this reversal and protect from EAE. These results show that IL-12 is sufficient to overcome CD40L blockade and suggest that, of the multiple consequences of the CD40L-CD40 interaction, IL-12 induction is an essential one for induction of EAE.

Experimental autoimmune encephalomyelitis in NF-kappa B-deficient mice:roles of NF-kappa B in the activation and differentiation of autoreactive T cells

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the CNS, which has long been used as an animal model for human multiple sclerosis. Development of autoimmune disease requires coordinated expression of a number of genes that are involved in the activation and effector functions of inflammatory cells. These include genes that encode costimulatory molecules, cytokines, chemokines, and adhesion molecules. Activation of these genes is regulated at the transcriptional level by several families of transcription factors. One of these is the NF-kappa B family, which is present in a variety of cell types and becomes highly activated at sites of inflammation. To test the roles of NF-kappa B in the development of autoimmune diseases, we studied EAE in mice deficient in one of the NF-kappa B isoforms, i.e., NF-kappa B1 (p50). We found that NF-kappa B1-deficient mice were significantly resistant to EAE induced by myelin oligodendrocyte glycoprotein. The resistance was primarily evidenced by a decrease in disease incidence, clinical score, and the degree of CNS inflammation. Furthermore, we established that the resistance to EAE in NF-kappa B1-deficient mice was associated with a deficiency of myelin oligodendrocyte glycoprotein-specific T cells to differentiate into either Th1- or Th2-type effector cells in vivo. These results strongly suggest that NF-kappa B1 plays crucial roles in the activation and differentiation of autoreactive T cells in vivo and that blocking NF-kappa B function can be an effective means to prevent autoimmune encephalomyelitis.

Effect of timing of intravenous administration of myelin basic protein on the induction of tolerance in experimental allergic encephalomyelitis

Immunological tolerance and suppression of clinical and histological experimental allergic encaphalomyelitis (EAE) can be induced by the intravenous (i.v.) administration of myelin basic protein (MBP). In this report we have characterized the effect of the time of i.v. administration of MBP on the course of EAE in Lewis rats. Rats were treated with the i.v. administration of one or two 500 micrograms doses of MBP either before or after active immunization. Results indicated that i.v. administration of MBP in rats before active immunization with MBP/CFA (naïve rats) was most effective when given 14 days before active immunization, but treatment of rats actively immunized with MBP (immunized rats) was most effective at the onset of disease. Treatment at other times was less effective. The i.v. administration of the peptide MBP 68-88 (p68-88) containing the dominant encephalitogenic epitope could also suppress MBP-induced EAE in a dose dependent manner. Intravenous administration of two injections of p68-88 to naïve rats on days 10 and 3 before, or on days 0 and 7 after, active immunization with MBP suppressed the development of EAE in a dose dependent manner. Treatment of rats with i.v. MBP after, but not before, the transfer of MBP-reactive EAE effector cells suppressed the development of EAE in the recipient rats. Transfer of lymphoid cells from tolerized naïve rats failed to protect recipient rats against development of active or passive EAE. These results indicate the importance of timing and dose of the antigen on the induction of tolerance and suggests different mechanisms of tolerance induction by intravenous MBP in immunized and naïve rats. They also emphasize the importance of timing in designing efficient treatment strategies when i.v. tolerance is contemplated in EAE and possibly multiple sclerosis.

IL-6-deficient mice are resistant to experimental autoimmune encephalomyelitis: roles of IL-6 in the activation and differentiation of autoreactive T cells

Although autoreactive T cells recognizing self myelin Ags are present in most individuals, autoimmune disease of the central nervous system is a relatively rare medical condition. Development of autoimmune disease may require not only the presence of autoreactive T cells but also that autoreactive T cells become activated. Activation of T cells may require a minimum of two signals: an Ag-specific signal delivered by MHC-peptide complex and a second signal delivered by costimulatory molecules or cytokines. Although in vitro studies have suggested that cytokines, especially proinflammatory cytokines such as IL-1, IL-6, and TNF are involved in T cell activation, their precise roles in vivo are not clear. To determine the roles of proinflammatory cytokines in T cell activation in vivo and in the development of autoimmune disease, we have studied experimental autoimmune encephalomyelitis (EAE) in mice deficient in IL-6. We found that IL-6-deficient mice were completely resistant to EAE induced by myelin oligodendrocyte glycoprotein (MOG), whereas IL-6-competent control mice developed EAE characterized by focal inflammation and demyelination in the central nervous system and deficiency in neurologic functions. Furthermore, we established that the resistance to EAE in IL-6-deficient mice was associated with a deficiency of MOG-specific T cells to differentiate into either Th1 or Th2 type effector cells in vivo. These results strongly suggest that IL-6 plays a crucial role in the activation and differentiation of autoreactive T cells in vivo and that blocking IL-6 function can be an effective means to prevent EAE.

Antibodies against IL-12 prevent superantigen-induced and spontaneous relapses of experimental autoimmune encephalomyelitis

Immunization of (PL/J x SJL/J)F1 mice with myelin basic protein (MBP) induces relapsing experimental autoimmune encephalomyelitis (EAE). Relapses occur 7 to 10 days after recovery from the initial paralysis. Staphylococcal enterotoxins (SE) A or B, administered after recovery from the initial paralysis, induce immediate relapses. IL-12 is involved in the induction of EAE. Here, we show that SEA and SEB induce IL-12 in splenocytes from (PL/J x SJL/J)F1 mice in vitro and increase the level of IL-12 in the sera of mice treated with these superantigens. IL-12 administration mimics SE in inducing spontaneous relapses and in enhancing the severity and frequency of spontaneous relapses. IL-12 neutralization blocks SE-induced and subsequent relapses of EAE, and, when instituted after recovery from the initial attack, prevents spontaneous relapse. This is the first report of prevention of relapses of EAE with anti-IL-12 Ab, an approach which may prove useful in the prevention of exacerbations in multiple sclerosis.

Pathogenesis of neuroimmunologic diseases. Experimental models

Animal models of autoimmune diseases have greatly improved our current understanding of the pathogenesis of human autoimmunity and have provided the potential for therapies based on manipulation of the immune system. In our laboratory, we have investigated the immunopathogenesis of autoimmune diseases of the nervous system and muscle. We have developed immune-based approaches for the suppression of experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS), and experimental autoimmune neuritis (EAN), a model for the Guillain-Barré syndrome (GBS). These approaches included induction of peripheral tolerance, immunotoxin targeting of activated T cells, and cytokine manipulations. In addition, we identified the antigen and characterized immunopathologically an autoimmune inflammatory disease of skeletal muscle, experimental autoimmune myositis (EAM), a model for the human inflammatory muscle disease polymyositis.

Luzindole, a melatonin receptor antagonist, suppresses experimental autoimmune encephalomyelitis

Melatonin has immune-enhancing effects and can exacerbate autoimmunity. Pinealectomy or light exposure, which suppress melatonin, inhibit T cell autoimmunity. To investigate the involvement of melatonin in experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated autoimmune demyelinating disease, we tested the effect of luzindole, a melatonin receptor antagonist, on EAE. Luzindole-treated mice did not develop EAE after immunization with spinal cord homogenate, whereas control mice developed EAE. This study suggests that pharmacological inhibition of the immunoenhancing effects of melatonin may prevent autoimmune demyelination.

Suppression of experimental autoimmune neuritis by phosphodiesterase inhibitor pentoxifylline

Phosphodiesterase inhibitor pentoxifylline (POX) has been shown to have multiple immunomodulatory effects in vitro and in vivo. It inhibits T cell proliferation, T helper 1-type cytokines, and tumor necrosis factor. We postulated that POX might have an in vivo immunomodulatory effect on a T-cell-mediated autoimmune peripheral nervous system disease, experimental autoimmune neuritis (EAN). We investigated the effect of POX on EAN in rats immunized with peripheral nerve myelin containing neuritogenic peptide SP26. At 200 mg/kg/day, there was significant suppression of clinical EAN, weight loss, and T cell proliferation to SP26 compared to controls. Proliferation of T cells from immunized rats to SP26 was suppressed by POX in vitro. These studies demonstrate a beneficial role for POX in EAN, with potential applicability to human autoimmune demyelination.

Effects of the angiotensin converting enzyme inhibitor captopril on experimental autoimmune encephalomyelitis

Angiotensin converting enzyme (ACE)1 mediates inflammation, participates in T cell stimulation by certain antigenic peptides, and influences the permeability of the blood brain barrier (BBB). ACE is elevated in multiple sclerosis (MS), an autoimmune disease of the central nervous system (CNS), characterized by increased BBB permeability. ACE inhibitor captopril suppresses certain immune functions and inhibits inflammatory or autoimmune diseases. We studied the effect of captopril on Lewis rat EAE, an animal model of MS. Fourteen rats with EAE were treated with captopril 30 mg/kg daily from immunization to day 21 post-immunization, and compared with 14 untreated rats. Severity scores and lymphocyte reactivity to myelin basic protein and mitogen were measured. There was a statistically significant (p < 0.05) difference between the mean and cumulative clinical scores of captopril-treated and untreated animals. Lymphocytes from captopril treated EAE rats at the peak of disease severity had diminished responses to MBP and concanavalin A. The data suggest a significant beneficial effect of captopril in Lewis rat EAE. Further studies including other inhibitors of ACE or of other peptidases with immune, inflammatory or BBB role, may identify potentially valuable immunopharmacologic agents.

Help-seeking for AIDS high-risk sexual behavior among gay and bisexual African-American men

Help-seeking for AIDS high-risk sexual behavior and its association with HIV status were examined among 318 gay and bisexual men in the San Francisco Bay Area who participated in the African American Men's Health Project, a longitudinal survey of gay and bisexual African-American men. A third (36%) of the sample reported seeking help regarding their concerns about HIV high-risk sexual behavior. Peers and professionals were the most widely sought sources of help and the sources perceived to be the most helpful. Men (39%) who had received the HIV antibody test and who were HIV seropositive were more likely to seek help than men who were HIV seronegative or did not know their HIV status (25%). Furthermore, gay men who were HIV seropositive or who knew their serostatus were more likely to seek help from professionals and peers. Explanations for the differences in help-seeking by HIV-seropositive men are discussed with implications for the development of social support for HIV risk reduction among gay and bisexual African-American men.

High-risk sexual behavior and condom use among gay and bisexual African-American men

OBJECTIVES

Little is known about the human immunodeficiency virus (HIV) high-risk sexual practices of gay and bisexual African-American men. These data are needed so that better interventions can be developed and implemented in this population.

METHODS

The frequency and correlates of unprotected anal intercourse were examined among 250 gay and bisexual African-American men in the San Francisco Bay Area. The cohort was recruited in 1990 from bars, bathhouses, and erotic bookstores, and through African-American gay organizations, street outreach, advertisements in gay mainstream and African-American newspapers, health clinics, and personal referral from other participants.

RESULTS

More than 50% of the men in our sample reported having unprotected anal intercourse in the past 6 months, a considerably higher percentage than that among gay White men in San Francisco through 1988 and 1989. Men who practiced unprotected anal intercourse were more likely to be poor, to have been paid for sex, or to have used injection drugs; to have a higher perceived risk of HIV infection; and to report less social support for concerns about risky sexual behavior. Condom norms, condom efficacy, and negative expectations about using condoms predicted these men's failure to use them.

CONCLUSION

In the second decade of the acquired immunodeficiency syndrome epidemic, risk reduction programs are still needed for gay and bisexual African-American men.

Retroviral sequences related to human T-lymphotropic virus type II in patients with chronic fatigue immune dysfunction syndrome

Chronic fatigue immune dysfunction syndrome (CFIDS) is a recently recognized illness characterized by debilitating fatigue as well as immunological and neurological abnormalities [Straus, S.E. (1988) J. Inf. Dis. 157, 405-412]. Once thought to be caused by Epstein-Barr virus, it is now thought to have a different but unknown etiology. We evaluated 30 adult and pediatric CFIDS patients from six eastern states for the presence of human T-lymphotropic virus (HTLV) types I and II by Western immunoblotting, polymearse chain reaction, and in situ hybridization of blood samples. The majority of patients were positive for HTLV antibodies by Western blotting and for HTLV-II gag sequences by polymerase chain reaction and in situ hybridization. Twenty nonexposure healthy controls were negative in all assays. These data support an association between an HTLV-II-like virus and CFIDS.