Abnormalities of B-cell activation and immunoregulation in patients with Crohn's disease

IgA nephropathy associated with Crohn's disease

The relationship between IgA nephropathy (IgAN) and Crohn’s disease was reported. IgAN is the most common primary glomerulonephritis and one of the leading causes of chronic kidney disease and end-stage renal failure, and up to 50% of cases progressed to end-stage renal disease within 25 years after IgAN diagnosis. However, specific and effective therapeutic strategies are still lacking. In this review, we discuss the possibility of the mechanism involved in IgAN associated with Crohn’s disease based on the findings of basic and clinical studies. Although the etiology of IgAN associated with Crohn’s disease is not permanent and various factors are thought to be involved, the stabilization of the disease condition of Crohn’s disease is believed to help treat IgAN.

Salivary IgA and IgG Antibody Responses against Periodontitis-Associated Bacteria in Crohn's Disease

Elevated serum immunoglobulin (Ig) antibody levels are observed in Crohn's disease patients. The aim of this study was to evaluate the salivary IgA and IgG antibody levels against Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia in Crohn's disease patients. Eighty-eight participants (47 Crohn's disease patients and 41 systemically healthy age- and gender-matched controls) were included in the study. Oral and medical health statuses were recorded and salivary samples were collected. Salivary P. gingivalis, T. forsythia, A. actinomycetemcomitans, and P. intermedia carriage were analyzed with DNA sequencing technique, salivary levels of IgG1, IgG2, IgG3, IgG4, and IgM were measured with the Luminex^® xMAP™ technique, and salivary IgA and IgG antibody levels against P. gingivalis, T. forsythia, A. actinomycetemcomitans, and P. intermedia were detected by ELISA. As result, higher salivary IgG2 (p = 0.011) and IgG3 (p = 0.006), P. gingivalis IgA (p < 0.001), A. actinomycetemcomitans IgG (p = 0.001), and P. intermedia IgG (p < 0.001) antibody levels were detected in the Crohn's disease group compared to the controls. Salivary P. gingivalis carriage was lower in the Crohn's disease group in comparison to the controls (p = 0.024). In conclusion, salivary IgA antibody responses against P. gingivalis and IgG antibody responses against P. intermedia have independent associations with Crohn's disease.

Crohn's disease may promote inflammation in IgA nephropathy: a case-control study of patients undergoing kidney biopsy

Intestinal immunity has been closely associated with the pathogenesis and progression of renal diseases, a relationship known as the "gut-kidney axis." To determine the association between immunoglobulin A nephropathy (IgAN) and Crohn's disease (CD), a clinico-pathological study was performed on patients who had IgAN with CD (CD-IgAN) and without CD (NOS-IgAN). We enrolled 29 patients diagnosed with IgAN via renal biopsy at the Tokyo Yamate Medical Center from 2009 to 2017. The patients were divided into CD-IgAN (n = 18) and NOS-IgAN (n = 11) and evaluated for clinical and pathological findings. IgA subclasses and galactose-deficient IgA1 (Gd-IgA1) were examined via immunohistochemistry using formalin-fixed paraffin-embedded sections from renal biopsy. Our results showed no significant difference in the extent of mesangial IgA subclasses or Gd-IgA1 deposition according to the presence or absence of CD. Pathologically, however, those with CD-IgAN had remarkably higher percentage of global glomerulosclerosis and extent of interstitial fibrosis and tubular atrophy (IF/TA) compared to those with NOS-IgAN. Moreover, the extent of macrophage infiltration in the glomerulus and interstitium was significantly higher in CD-IgAN than in NOS-IgAN. Clinically, the CD-IgAN group had significantly worse responsiveness to steroid treatment compared to the NOS-IgAN group. In conclusion, the similar immunological characteristics of deposited IgA molecules in the glomeruli between the CD-IgAN and NOS-IgAN groups might suggest their etiological similarity. However, a renal pathology showing advanced glomerular and tubulointerstitial sclerosis accompanying increased macrophage infiltration and highly resistant clinical features in patients with CD-IgAN suggests that some pathophysiological factors in CD, including abnormal intestinal immunity, may promote and activate the inflammatory process in IgAN via undetermined mechanisms.

Crohn's Disease Patients in Remission Display an Enhanced Intestinal IgM⁺ B Cell Count in Concert with a Strong Activation of the Intestinal Complement System

Inflammatory bowel disease (IBD) is an umbrella term that comprises Crohn’s disease (CD) and ulcerative colitis (UC). Both entities are characterized by a disturbed mucosal immune response and an imbalance of intestinal microbiota composition. The complement system (C) plays a critical role in the detection, and clearance of bacteria and dysregulation of single complement components has been linked to IBD. Here, we asked if the C contributes to distinct subtypes of inflammation observed in CD and UC. We performed systematical expression analyses of the intestinal C in IBD patients and controls. Immunohistochemistry or immunoblot experiments were performed to verify qPCR data. Activity of the three activation pathways of C was studied in sera samples. In CD patients a strong upregulation of the C was observed enabling the definition of unique expression patterns being associated either with remission or active disease. These data were reflected by an enhanced C activation in sera and fecal samples. An excessive mucosal presence of immunoglobulin M (IgM) and CR2/CD21 positive B cells in concert with decreased fecal IgA level was identified in CD patients in remission. These findings point to an exacerbated induction of the intestinal C that may potentially be involved in the etiology of CD.

Oral manifestations as the first presenting sign of Crohn's disease in a pediatric patient

Crohn’s disease (CD) is a chronic inflammatory disorder affecting the gastrointestinal (GI) tract. Although the GI tract is the primary site of involvement, many patients, particularly in pediatric cases, first present with non-intestinal manifestations, including oral lesions. Oral manifestations of CD in children occur in around 50-80% of cases, and about 30% of CD cases in children occur first in the mouth. Recognizing such oral lesions in the pediatric population, and requesting a biopsy, may expedite the diagnosis of CD. We describe a 15 year old male who presented with oral findings of multiple aphthous ulcers and plaques of pink papules of the buccal vestibule. We highlight the initial pathology findings, including non-caseating granulomas, sialadenitis, and a notable plasmacytosis, from biopsy of the left retromolar pad area, which triggered further testing for CD. We provide discussion of how CD was eventually diagnosed and treated and highlight the significance of the pathological findings in this case as they relate to the pathogenesis of CD.

Key words:Crohn’s disease, Inflammatory bowel disease, Oral manifestations, Pediatric, Granulomatous inflammation, Monotypic plasma cells.

B-Cell Dysregulation in Crohn's Disease Is Partially Restored with Infliximab Therapy

BACKGROUND

B-cell depletion can improve a variety of chronic inflammatory diseases, but does not appear beneficial for patients with Crohn's disease.

OBJECTIVE

To elucidate the involvement of B cells in Crohn's disease, we here performed an 'in depth' analysis of intestinal and blood B-cells in this chronic inflammatory disease.

METHODS

Patients with Crohn's disease were recruited to study B-cell infiltrates in intestinal biopsies (n = 5), serum immunoglobulin levels and the phenotype and molecular characteristics of blood B-cell subsets (n = 21). The effects of infliximab treatment were studied in 9 patients.

RESULTS

Granulomatous tissue showed infiltrates of B lymphocytes rather than Ig-secreting plasma cells. Circulating transitional B cells and CD21low B cells were elevated. IgM memory B cells were reduced and natural effector cells showed decreased replication histories and somatic hypermutation (SHM) levels. In contrast, IgG and IgA memory B cells were normally present and their Ig gene transcripts carried increased SHM levels. The numbers of transitional and natural effector cells were normal in patients who responded clinically well to infliximab.

CONCLUSIONS

B cells in patients with Crohn's disease showed signs of chronic stimulation with localization to granulomatous tissue and increased molecular maturation of IgA and IgG. Therapy with TNFα-blockers restored the defect in IgM memory B-cell generation and normalized transitional B-cell levels, making these subsets candidate markers for treatment monitoring. Together, these results suggest a chronic, aberrant B-cell response in patients with Crohn's disease, which could be targeted with new therapeutics that specifically regulate B-cell function.

On the role of tumor necrosis factor and receptors in models of multiorgan failure, rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease

The specific role of the tumor necrosis factor (TNF)/TNF receptor (TNFR) system in disease pathogenesis still remains an unresolved puzzle. Recent studies in transgenic and knockout animals, where the pathogenic influence of genetically perturbed TNF expression has been evaluated, indicate that several pathways of TNF/TNFR action may contribute independently or in concert to initiate, promote or downregulate disease pathogenesis. Evidently, organ-specific inflammatory or autoimmune pathology may ensue due to sustained activation by TNF of innate immune cells and inflammatory responses, which may consequently lead to tissue damage and to organ-specific chronic pathology. However, more cryptic functions of this molecule may be considered to play a significant part in the development of TNF-mediated pathologies. Direct interference of TNF with the differentiation, proliferation or death of specific pathogenic cell targets may be an alternative mechanism for disease initiation or progression. In addition to these activities, there is now considerable evidence to suggest that TNF may also directly promote or downregulate the adaptive immune response. It is therefore evident that no general scenario may adequately describe the role of TNF in disease pathogenesis. In this article, we aim to place these diverse functions of TNF/TNFRs into context with the development of specific pathology in murine models of multiorgan failure, rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease.

Circulating soluble factor-inhibiting natural killer (NK) activity of fresh peripheral blood mononuclear cells (PBMC) from inflammatory bowel disease (IBD) patients

This study was performed in order to assess the cytotoxic activity, both natural (NK) and antibody-dependent (ADCC), of PBMC from 38 IBD patients and correlate it with their clinical features. Cytotoxicity assays were performed using sensitive target cells for NK and ADCC activities. In some experiments, highly purified NK cells, obtained both by Percoll density gradient and by co-culturing non-adherent PBMC with RPMI 8866 feeder cells, were used as effector cells. Furthermore, we evaluated NK cell parameters such as number, surface expression of adhesion molecules (CD11a/CD18, CD49d and CD54) and response to different stimuli. We observed a decreased NK cytotoxicity of PBMC from IBD patients, both in ulcerative colitis (UC) and Crohn's disease (CD), independently of the clinical activity of disease. In contrast, the ADCC lytic activity was within normal range. The lower NK cytotoxic activity observed in our IBD patients cannot be related to a decreased number of NK cells, surface expression of adhesion molecules, defective response to IL-2 and maturative defect. Decreased NK activity was induced in PBMC of controls when serum of patients was added and this was unrelated to monocyte-derived modulating factor(s). Our data show a decreased natural killing by fresh PBMC from IBD patients. This lower activity seems to be unrelated to a primary NK cell defect, since purified NK cells exhibited normal levels of killing. It might be hypothesized that serum factors, possibly derived from lymphocytes, with inhibitory properties on NK activity, might be functionally active in the blood of IBD patients, thus modulating NK activity.

Crohn's disease and myasthenia gravis: a possible role for thymectomy

A female patient with a three year history of Crohn's disease of the colon developed myasthenia gravis. Despite diversion of the faecal stream by an ileostomy, and total colectomy, the patient had continuing problems with perineal and perianal abscesses and fistulas. Her myasthenia gravis became unresponsive to anti-cholinergics so a thymectomy was performed. The perineal and perianal disease improved subsequently. This case supports the theory that functional disturbances of the thymus may have a role in the pathogenesis of inflammatory bowel disease.

New insights into the pathogenesis of appendicitis based on immunocytochemical analysis of early immune response

Although appendicitis is the most common condition requiring emergency surgery, the pathogenesis of this disease is poorly understood. In this study, local immune responses in acute appendicitis were investigated, using an experimental rabbit model, as well as in different grades of appendicitis in humans. Polymorphonuclear leukocyte (PMN) and plasma cell isotypes infiltration was measured in 24 New Zealand-bred white rabbits following experimental obstruction of the appendiceal lumen for periods ranging from 30 minutes to 24 hours. Significant infiltration of PMNs, IgM, and IgG plasma cells was noted at 30 minutes following obstruction, and IgA plasma cells were noted at 2 hours after obstruction. The immunopathological features observed in the study of human appendicitis clearly demonstrated the role of plasma cell infiltration in the immunopathogenesis of appendicitis. IgA and IgG plasma cells were significantly increased in the lamina propria of both focal and acute suppurative appendicitis, compared with controls (P less than .001). In focal appendicitis, in which the focus of inflammation is confined to only a few serial sections, the increased IgA and IgG plasma cell infiltration was present throughout the entire length of the resected organ. The possibility, as seen in this study, that antigen stimulation of the effector immune system could give rise to appendicitis, provides new insights into the diversity of inflammatory responses contributing to diseases of the intestinal tract. This previously unrecognised concept in the pathogenesis of appendicitis requires further elucidation of the stimulating agent, and in particular the T-cell recognition process.

A limiting-dilution analysis of activated circulating B cells in Crohn's disease

In the present study the spontaneous in vitro production of immunoglobulins G, A, and M by peripheral mononuclear cells was evaluated, in patients with Crohn's disease, in relation to the state of B-cell activation and further characterized by limiting-dilution analysis. A total of 25 patients with Crohn's disease and 10 healthy controls was studied. The proportion of the transferrin receptor-bearing cells in the B7+ subset was higher in active Crohn's disease patients than in either those with quiescent disease or controls. There was a significant rise in the in vitro IgG, IgM, and IgA production in patients with untreated active Crohn's disease compared to either those with untreated quiescent disease or controls. When patients were followed up from the active phase to clinical remission, a significant decrease in the production of IgG and IgM was observed. IgA levels also showed a decrease, although not reaching statistical significance. When the Ig production was analyzed by limiting dilution, no difference was observed between patients and controls in terms of either precursor frequency of Ig-producing cells or patterns of frequency distribution. In both patients and controls a biphasic limiting-dilution profile was observed. This study shows that a significant B-cell activation is present in Crohn's disease patients, which is accompanied by an increase in immunoglobulin production. This study also indicates that in Crohn's disease the increased immunoglobulin production is related to an augmented B-cell clone size rather than to an increased precursor frequency.

Crohn's disease and the mycobacterioses: a review and comparison of two disease entities

Crohn's disease is a chronic granulomatous ileocolitis, of unknown etiology, which generally affects the patient during the prime of life. Medical treatment is supportive at best, and patients afflicted with this disorder generally live with chronic pain, in and out of hospitals, throughout their lives. The disease bears the name of the investigator who convincingly distinguished this disease from intestinal tuberculosis in 1932. This distinction was not universally accepted, and the notion of a mycobacterial etiology has never been fully dismissed. Nevertheless, it was 46 years after the distinction of Crohn's disease and intestinal tuberculosis before research attempting to reassociate mycobacteria and Crohn's disease was published. Recently, there has been a surge of interest in the possible association of mycobacteria and Crohn's disease due largely to the isolation of genetically identical pathogenic Mycobacterium paratuberculosis from several patients with Crohn's disease in the United States, the Netherlands, Australia, and France. These pathogenic organisms have been isolated from only a few patients, and direct evidence for their involvement in the disease process is not clear; however, M. paratuberculosis is an obligate intracellular organism and strict pathogen, which strongly suggests some etiologic role. Immunologic evidence of a mycobacterial etiology, as assessed by humoral immune determinations, has been conflicting, but evaluation of the more relevant cellular immunity has not been performed. Data from histochemical searches for mycobacteria in Crohn's disease tissues have been equally conflicting, with acid-fast bacilli detected in 0 to 35% of patients. Animal model studies have demonstrated the pathogenic potential of isolates as well as elucidated the complexity of mycobacterial-intestinal interactions. Treatment of Crohn's disease patients with antimycobacterial agent has not been fully assessed, although case reports suggest efficacy. The similarities in the pathology, epidemiology, and chemotherapy of Crohn's disease and the mycobacterioses are discussed. The issue is fraught with controversy, and the data generated on the association of mycobacteria and Crohn's disease are in their infantile stages so that a general conclusion on the legitimacy of this association cannot be made. While no firm evidence clearly implicates mycobacteria as an etiologic agent of Crohn's disease, the notion is supported by suggestive and circumstantial evidence and a remarkable similarity of Crohn's disease to known mycobacterial diseases.

Abnormalities of B cell activation and immunoregulation in patients with chronic inflammatory liver diseases

The immunoglobulin production capacities of peripheral blood lymphocytes obtained from patients with various chronic inflammatory liver diseases and from normal individuals were compared. Using a reverse hemolytic plaque assay, immunoglobulin-secreting cells (ISC) were counted immediately after isolation (immediate ISC) and again after 6-day, in vitro cultivation without stimulant (spontaneous ISC) or in the presence of pokeweed mitogen, PWM (PWM-induced ISC). An increased number of immediate ISC were observed in patients with chronic active hepatitis (CAH) of the autoimmune type (n = 7) or with CAH type B (n = 32), probably reflecting a defect of the in vivo suppressor cell system as previously demonstrated. In vitro preincubation of cells with 5 x 10(-8) M prednisolone reduced the increase in the number of immediate ISC in patients with CAH of the autoimmune type. On the other hand, lymphocytes obtained from patients with CAH-type NANB (n = 9) and with primary biliary cirrhosis (PBC) (n = 12) showed an impaired capacity to generate ISC upon stimulation with PWM. Spontaneous ISC from patients' lymphocytes were not significantly different from those of normal individuals. Using allogeneic co-cultures with lymphocytes from normal individuals and from patients with CAH NANB hepatitis or primary biliary cirrhosis, we observed no increase in suppressor cell activity. Therefore, the diminished responses to PWM are probably attributable to an alteration in the peripheral helper T-cell compartment.

Abnormal lymphocyte profiles and leukotriene B4 status in a patient with Crohn's disease and severe periodontitis

THIS CASE REPORT DESCRIBES clinical and laboratory findings for a 60-year-old woman with recently diagnosed Crohn's disease and severe generalized periodontitis. Comparison of dental radiographs taken in 1975, in 1983, and at the time of our evaluation in 1986 revealed dramatic progression of alveolar bone loss over that period. Standard laboratory blood tests did not reveal any remarkable significant leukocyte abnormalities, but flow cytometric analysis of lymphocytes revealed a paucity of B cells stained with anti-light chain antibodies, and an increased proportion of T lymphocytes which were dully-stained with anti-CD5 monoclonal antibody. B cell function as determined by in vitro proliferative responsiveness to anti-IgM antibody was only about 50% of that observed with cells from two healthy normal subjects. Serum leukotriene B4 (LTB4) was elevated to 150% of normal values, in spite of the fact that the patient was taking a systemic anti-inflammatory drug which is known to reduce LTB4 levels. The microbial flora was highly mixed and included several putative periodontopathic bacteria. Therapy consisted of oral hygiene instruction, scaling and root planing, mucoperiosteal-flap curettage, extracoronal splinting, and selective extraction of three teeth. The periodontal status improved markedly with therapy. Possible relationships between the patient's immunological status, her Crohn's disease, and the severe periodontal breakdown are discussed.

Disordered regulation of the in vitro immunoglobulin synthesis by intestinal mononuclear cells in Crohn's disease

In vitro immunoglobulin synthesis by isolated intestinal mononuclear cells of macroscopically normal mucosa from patients with Crohn's disease has been studied and results compared with those obtained with cells from normal mucosa of resection specimens from patients with colonic carcinoma, or other intestinal disorders. The total lamina propria mononuclear cells (LPMC) in Crohn's disease produced spontaneously less IgA and more IgG than the control groups, but no difference was observed for IgM. An enriched lymphocyte fraction (LPL) of the Crohn's disease patients showed a higher spontaneous synthesis of IgA and IgG when compared with controls. In contrast, another fraction enriched for macrophages (LPM) produced spontaneously less IgA, IgG, and IgM in Crohn's, than in control patients. Incubation with pokeweed mitogen (PWM) decreased immunoglobulin synthesis by LPMC in Crohn's disease and controls, and this was enhanced by simultaneous incubation with concanavalin A. In controls PWM stimulation increased immunoglobulin synthesis by LPL and decreased immunoglobulin synthesis by LPM. In Crohn's disease, however, PWM had no effect on either fraction. This study shows major differences in the regulation of the immunoglobulin synthesis by intestinal cells between Crohn's disease and controls.

Modulation of immune functions by long-term treatment with recombinant interferon-alpha 2 in a patient with hairy-cell leukemia

Serial in vitro immune function studies of peripheral blood mononuclear cells (PBMC) were carried out during the long-term treatment with recombinant interferon-alpha 2 (IFN-alpha 2) in a patient with hairy-cell leukemia (HCL). Parameters of B- and T-cell functions as well as NK-cell activity were determined. Treatment with IFN-alpha 2 is associated with temporary and long-term depression of some immune functions, but can also normalize immune responses: in vitro-induced immunoglobulin synthesis, which was normal at diagnosis, was inhibited during the first weeks of IFN therapy but subsequently rose to normal levels. Lymphocyte proliferative responses to mitogens and antigens that were markedly reduced pretherapeutically were further depressed by IFN treatment but, with the exception of pokeweed mitogen (PWM)-induced responses, normalized completely by the 15th to 17th week of treatment. Cocultivation of PBMC with monocytes from normal individuals enhanced depressed lymphocyte proliferative responses. NK-cell activity, which was low at diagnosis, did not rise to the normal range during IFN treatment, but rapidly normalized when IFN therapy was stopped. A discussion is presented on the implications of the alteration of immune functions by treatment with IFN.

Absence of complement fixing antibodies against lipopolysaccharides from Escherichia coli in a subgroup of patients with Crohn's disease

Complement fixing antibodies against different Escherichia coli lipopolysaccharides were determined in patients with Crohn's disease and in healthy individuals and compared with antitetanus toxoid antibodies. All healthy individuals had antilipopolysaccharide antibodies, 10 of 27 patients with Crohn's disease had no antibodies and six had rapidly changing antibody titres. These abnormalities were found in patients with disease in the colon, with arthropathy and fistula. Antilipid A was found at lower titres in Crohn's disease. Neither antitetanus toxoid antibodies, nor immunoglobulin concentrations were different in patients with or without antilipopolysaccharide antibodies. There was no evidence for circulating immune complexes in patients lacking antilipopolysaccharide antibodies. Certain subgroups of patients with Crohn's disease have altered antibody levels to typical enteral antigens which most likely can be explained by local antibody binding to lipopolysaccharides at inflammatory sites, or by changes in immunoregulation in this disease.

Abnormalities of B-cell activation and immunoregulation in splenectomized patients

Using a reverse hemolytic plaque assay as the effector system, we studied B-lymphocyte function in 12 patients after posttraumatic splenectomy, as well as in 25 normal individuals. The time interval between the splenectomy and the immunological studies varied between 2 days and 7 years. Compared to normal individuals, the splenectomized patients had markedly elevated numbers of spontaneous immunoglobulin-secreting cells (ISC) and severely decreased responses to the polyclonal activator pokeweed mitogen. A tendency towards normalization of these abnormalities, especially the high spontaneous ISC levels, could be observed during the time interval extending up to 7 years after splenectomy. In order to characterize the mechanism responsible for the altered immune response in splenectomized patients, co-culture experiments with unseparated and separated lymphocytes were performed. These revealed an impaired T-helper cell capacity as well as an intrinsic B-cell defect. Marker analyses with monoclonal antibodies revealed normal proportions with the exception of OKT 4 positive and B 1 positive cells that identify T-helper/inducer and peripheral B-cells respectively. We conclude that immune dysfunction in peripheral blood lymphocytes of splenectomized patients involves mainly the B-cell as well as the T-helper/inducer-cell population.