Lactobacillus rhamnosus strain JB-1 reverses restraint stress-induced gut dysmotility.

BACKGROUND: Environmental stress affects the gut with dysmotility being a common consequence. Although a variety of microbes or molecules may prevent the dysmotility, none reverse the dysmotility. METHODS: We have used a 1 hour restraint stress mouse model to test for treatment effects of the neuroactive microbe, L. rhamnosus JB-1™ . Motility of fluid-filled ex vivo gut segments in a perfusion organ bath was recorded by video and migrating motor complexes measured using spatiotemporal maps of diameter changes. KEY RESULTS: Stress reduced jejunal and increased colonic propagating contractile cluster velocities and frequencies, while increasing contraction amplitudes for both. Luminal application of 10E8 cfu/mL JB-1 restored motor complex variables to unstressed levels within minutes of application. L. salivarius or Na.acetate had no treatment effects, while Na.butyrate partially reversed stress effects on colonic frequency and amplitude. Na.propionate reversed the stress effects for jejunum and colon except on jejunal amplitude. CONCLUSIONS & INFERENCES: Our findings demonstrate, for the first time, a potential for certain beneficial microbes as treatment of stress-induced intestinal dysmotility and that the mechanism for restoration of function occurs within the intestine via a rapid drug-like action on the enteric nervous system.

IgA polymorphism in mice: individual light chains can pair covalently with some alpha heavy chains and non-covalently with others.

The molecular basis for the two different forms of IgA in mice, distinguished by the covalent or non-covalent association of light (L) and heavy (H) chains, is unknown. In this communication, we show, using somatic cell hybridization to construct cells producing new combinations of alpha and L chains, that individual L chains probably can pair both covalently and non-covalently depending on the alpha chain.

IgA polymorphism in mice: NZB and BALB/c mice produce two forms of IgA.

There are two different forms of mouse IgA immunoglobulins, one in which light chains are disulfide-linked to each other (IgAL-L) and the second where light chains are linked to heavy chains (IgAH-L). IgA myeloma proteins from BALB/c mice are IgAL-L and those from NZB are IgAH-L. To determine whether these two forms of IgA represent allotypic or isotypic variants, we purified serum IgA and prepared IgA-secreting somatic cell hybrids from mitogen-stimulated BALB/c and NZB mice and determined the pattern of light chain linkage. It was found that each strain produces both forms of IgA and that both forms share the allotypic determinants characteristic of the mouse strain.

Are lymphocytes a target for substance P modulation in arthritis?

The contribution of the neuropeptide substance P to the pathogenesis of rheumatoid arthritis (RA) has recently been suggested. The presence of immunoreactive substance P in the serum and joint fluid of RA patients was significantly increased compared with age-matched control patients. To investigate the ability of substance P to alter lymphocyte activity during the disease, lymphocytes were isolated from the synovial fluid and blood of RA patients and their ability to respond to substance P as measured by [3H]thymidine uptake was characterized. Upon exposure of RA synovial fluid and peripheral blood lymphocytes to various concentrations of substance P in vitro, no increase in proliferation was witnessed. To the contrary, control peripheral blood lymphocyte proliferation was significantly enhanced by various concentrations of substance P. However, synoviocytes from the joints of RA patients were responsive to substance P stimulation. These data suggest that substance P receptors may be desensitized on systemic and local lymphocytes in RA, or the proinflammatory activities of substance P may be mediated via the synovial membrane during chronic inflammation.

Novel cellular interactions and networks involving the intestinal immune system and its microenvironment.

The interactions we have described enable the intestine to respond appropriately to antigenic challenge in an effective and coordinated way. This is of vital importance when one considers the dual role of the intestine as a first line of defence against harmful microorganisms and as the route by which the animal obtains nutrition. Under normal circumstances, these interactions select for an appropriate cell phenotype by providing a network of interactions that contribute to intestinal homeostasis. If there is dysfunction of any component, then other cells will be affected. For example, if down-regulation of the mucosal immune response is not effective, damage to the epithelium, nerves and muscle may occur during an inflammatory response. Similarly, if the integrity of the epithelium is disrupted, damage to the elements of the mucosal immune system may occur. This model would suggest that these interactions must be considered if one wishes to adequately explain diseases such as IBD and design innovative therapeutic regimens. Future interdisciplinary research will shed light on the web of interactions occurring in the intestinal environment and provide a novel view of the respective contributions of the immune system and its local environment to cell differentiation, function and regulation.

Nerve growth factor and neuroimmune interactions in inflammatory diseases.

Discovered almost 50 years ago, nerve growth factor (NGF) has been extensively studied in various biological systems. NGF has recently been suggested to play an important role in mediating and/or regulating immune response, in addition to its trophic and tropic effects on nerve growth and regeneration It is clear that in complex interactions between immune cells and nervous system NGF plays a central role. We have only just begun to identify and understand the direct mechanisms by which NGF activates target cells, the precise identity of the target cells, and the particular factors released from target cells. Nerve growth factor together with possibly other neurotrophins such as BDNF (brain-derived nerve growth factor), GDNF (glial-derived nerve growth factor) or NT3 are important modulators of immunity. More detailed studies are needed at the receptor, mediator and cellular levels to better understand the neuroimmunomodulatory properties of neurothrophins and NGF. The nature of the involvement of NGF in inflammation and inflammatory diseases remains a particularly interesting question. By blocking NGF or mediators released upon NGF activation, we are able to control the progress of inflammation, thereby opening many therapeutic opportunities for the future.

Immunomodulatory activities of the somatostatin analogue BIM 23014c: effects on murine lymphocyte proliferation and natural killer activity.

We have examined the effect of somatostatin and its octapeptide analogue BIM 23014c on concanavalin A-induced lymphocyte proliferation and target-specific natural killer activity both in vitro and in vivo. Using Peyer's patches and spleen as a source of lymphocytes, we found that both peptides modulated immunity in a dose-dependent manner. Comparatively, there was no significant difference between the activity of somatostatin or BIM 23014c in the modulation of immunity. Proliferation, both in vitro and in vivo, was significantly inhibited by both peptides in each organ with a higher specificity towards the Peyer's patch lymphocytes. Natural killer activity was also inhibited in both organs in vivo and in vitro. Thus, not only did somatostatin and BIM 23014c have similar effects on proliferation and natural killer activity, but their effect was organ specific. Preliminary data suggest that BIM 23014c works via the same receptor as somatostatin, therefore intimating that these two peptides are both clinically and immunologically similar.

Spatiotemporal maps reveal regional differences in the effects on gut motility for Lactobacillus reuteri and rhamnosus strains.

BACKGROUND: Commensal bacteria such as probiotics that are neuroactive acutely affect the amplitudes of intestinal migrating motor complexes (MMCs). What is lacking for an improved understanding of these motility effects are region specific measurements of velocity and frequency. We have combined intraluminal pressure recordings with spatiotemporal diameter maps to analyze more completely effects of different strains of beneficial bacteria on motility. METHODS: Intraluminal peak pressure (PPr) was measured and video recordings made of mouse ex vivo jejunum and colon segments before and after intraluminal applications of Lactobacillus rhamnosus (JB-1) or Lactobacillus reuteri (DSM 17938). Migrating motor complex frequency and velocity were calculated. KEY RESULTS: JB-1 decreased jejunal frequencies by 56% and 34% in colon. Jejunal velocities increased 171%, but decreased 31% in colon. Jejunal PPr decreased by 55% and in colon by 21%. DSM 17938 increased jejunal frequencies 63% and in colon 75%; jejunal velocity decreased 57%, but increased in colon 146%; jejunal PPr was reduced 26% and 12% in colon. TRAM-34 decreased frequency by 71% and increased velocity 200% for jejunum, but increased frequency 46% and velocity 50% for colon; PPr was decreased 59% for jejunum and 39% for colon. CONCLUSIONS & INFERENCES: The results show that probiotics and other beneficial bacteria have strain and region-specific actions on gut motility that can be successfully discriminated using spatiotemporal mapping of diameter changes. Effects are not necessarily the same in colon and jejunum. Further research is needed on the detailed effects of the strains on enteric neuron currents for each gut region.

Neuronal factors modulating immunity.

In this minireview we will discuss some evidence suggesting that the immune response is under neuronal regulation. In particular, we will concentrate on the effects that various neuropeptides have on immunity both in vitro and in vivo. Of these, vasoactive intestinal peptide, substance P, somatostatin, and calcitonin gene related peptide will be discussed in detail. In addition, the effects of nerve growth factor on the immune system will be presented. Finally, a possible role for these neuropeptides in various diseases and its clinical relevance will be suggested.

Inhibition of murine intestinal inflammation by anti-substance P antibody.

Several neuropeptides have recently been shown to affect various aspects of the inflammatory process. Among these, the neuropeptide substance P possesses a host of immune modifying actions, which include the enhancement of lymphocyte activity, macrophage function, and neutrophil chemotaxis. The role of substance P during inflamed states has, as yet, not been fully described. Here, in T. spiralis-infected mice, we parallel increased levels of substance P both locally, (the gut) and peripherally (serum) with decreased lymphocyte responsiveness. Upon the introduction of in vivo antisubstance P antibody during the infection, levels of substance P, gastrointestinal inflammation, and lymphocyte proliferation are significantly restored to baseline (noninfected) levels. These findings suggest that the neuropeptide substance P plays an important role in promoting inflammation. It also offers the basis for future pharmacological interventions.

Neuroimmunomodulation: classical and non-classical cellular activation.

As neuroimmunologists, we are often faced with the fact that some substances can either enhance or inhibit particular immune/inflammatory cell functions. This 'duality' could only partially be explained by dose-dependency and the fact that in a variety of systems, heterogenous cell populations are commonly used. For example it has been repetitively shown that cell proliferation, immunoglobulin synthesis and NK (natural killer) activity could be enhanced, inhibited or not affected at all by such neuropeptides as somatostatin (SOM) or vasoactive intestinal peptide (VIP), depending on the experimental conditions. Even substance P (SP), which, in general, stimulates lymphocyte activity, can, under certain conditions, possess an inhibitory activity. These apparent discrepancies between various groups and experimental conditions met with a strong reservation among 'classical' immunologists as they questioned the true physiological role that neuro-immune interactions play in normal and disease states. However, upon a detailed analysis of the data, it become obvious why such discrepancies abounded. Not only are we comparing totally different responses in different species, but almost always we compare different experimental conditions. In lieu of this, the reproducibility of the experiments within the same laboratory is in fact very high. One fundamental and striking observation is the fact that at the level of a homogeneous cell population, a differential response could be evoked by the same neuropeptide over a range of concentrations. For the purpose of this brief report we will focus on the cellular responses to the neuropeptide substance P and we will try to illustrate why such differential responses are possible. Some of the physiological data relating to the effects of SP on cell function will be discussed. This will be followed by a synopsis of SP receptor mechanisms on effector cells and finally the mechanism by which SP activates secondary messenger systems in these cells.

Substance-P-mediated intestinal inflammation: inhibitory effects of CP 96,345 and SMS 201-995.

The proinflammatory peptide substance P (SP) has been shown to be intimately involved in the local inflammatory processes of Trichinella-spiralis-induced murine intestinal inflammation. Significant increases in SP, increased myeloperoxidase levels coupled with local morphological deterioration of the jejunum and impaired lymphocyte responses to exogenous SP in vitro have been associated with the model. We have recently determined that the elimination of increased levels of SP via anti-SP antibody therapy can spare the murine gastrointestinal tract much of the pathologies associated with the parasitic infection. Here we further demonstrate that the somatostatin analogue SMS 201-995 as well as the SP receptor antagonist CP 96,345 can effectively decrease the inflammation and lost lymphocyte function seen in the jejunum of T. spiralis-infected mice. Again, both intestinal morphology and myeloperoxidase levels were shown to return to normal values upon treatment. The above results suggest that SP is an important modulator of gastrointestinal inflammation.

Hormones and local immunity.

The modulatory role of hormones in the regulation of the immune response has been well documented. Here, we present some thoughts on how sex hormones affect immunity, particularly at mucosal sites. We further discuss the possible pitfalls and difficulties associated with analysis of the data.