Targeting interleukin-4 in asthma: lost in translation?

The first discovery that interleukin-4 (IL-4) is crucial in the development of allergic airway inflammation originates from the early 1990s. Whereas initial studies in experimental animal models provided the community with the optimistic view that targeting IL-4 would be the ultimate solution for treating asthma, the translation of these findings to the clinic has not been evident and has not yet fulfilled the expectations. Many technical challenges have been encountered in the attempts to modulate IL-4 expression or activity and in transferring knowledge of preclinical studies to clinical trials. Moreover, biological redundancies between IL-4 and IL-13 have compelled a simultaneous blockade of both cytokines. A number of phase I/II studies are now providing us with clinical evidence that targeting IL-4/IL-13 may provide some clinical benefit. However, the initial view that asthma is a purely Th2-mediated disease had to be revised. Currently, different asthma phenotypes have been described, implying that blocking specifically Th2 cytokines, such as IL-4, IL-5, and IL-13, should be targeted to only a specific subset of patients. Taking this into consideration, IL-4 (together with IL-13) deserves attention as subject of further investigations to treat asthma. In this review, we will address the role of IL-4 in asthma, describe IL-4 signaling, and give an overview of preclinical and clinical studies targeting the IL-4 Receptor pathway.     

Nine novel single-nucleotide polymorphisms in the integrin β4 (ITGB4) gene in the Japanese population

We identified nine single-nucleotide polymorphisms (SNPs) in the human integrin β4 (ITGB4) gene (17q24–q25), which encodes a cell-surface receptor, by screening all exons and exon-intron boundaries. Seven of these SNPs were present in coding regions and two in intronic sequences; four of the coding SNPs involved amino-acid substitutions. As the gene is implicated in the tumorigenesis of breast cancers, the polymorphic sites will serve as useful markers not only for distinguishing alleles in loss of heterozygosity (LOH) analyses but also for studying genetic susceptibility to malignancies in humans. Received: September 13, 2000 / Accepted: October 6, 2000     

Thymosin ß4 expression in colorectal polyps and adenomas

OBJECTIVE:

Thymosin beta 4 (Tβ4) is a ubiquitous peptide that plays pivotal roles in the cytoskeletal system and in cell differentiation. Recently, a role for Tβ4 has been proposed in experimental and human carcinogenesis, including gastrointestinal cancer. This study was aimed at evaluating the relationship between Tβ4 immunoreactivity and the initial steps of carcinogenesis.

METHODS:

In total, 60 intestinal biopsies, including 10 hyperplastic polyps, 10 sessile serrated adenomas/polyps, 15 colorectal adenomas with low-grade dysplasia, 15 adenomas with high-grade dysplasia, 15 adenocarcinomas and 10 samples of normal colon mucosa, were analyzed for Tβ4 expression by immunohistochemistry.

RESULTS:

Weak cytoplasmic reactivity for Tβ4 was detected in the normal colon mucosa. No reactivity for Tβ4 was found in hyperplastic and sessile serrated polyps/adenomas. Tβ4 expression was observed in 10/15 colorectal adenocarcinomas. In adenomas with low-grade dysplasia, Tβ4 immunoreactivity was mainly detected in dysplastic glands but was absent in hyperplastic glands. Tβ4 immunoreactivity was characterized by spot-like perinuclear staining. In high-grade dysplastic polyps, immunostaining for Tβ4 appeared diffuse throughout the entire cytoplasm of dysplastic cells. Spot-like perinuclear reactivity was detected in adenocarcinoma tumor cells.

CONCLUSIONS:

Our study shows for the first time that Tβ4 is expressed during different steps of colon carcinogenesis. The shift of Tβ4 immunolocalization from low-grade to high-grade dysplastic glands suggests a role for Tβ4 in colorectal carcinogenesis. However, the real meaning of Tβ4 reactivity in dysplastic intestinal epithelium remains unknown.     

IgG4-positive plasma cells in Hashimoto thyroiditis: IgG4-related disease or inflammation-related IgG4-positivity?

Despite the interest of researchers in IgG4-related disease (IgG4-RD), many questions still remain unanswered regarding the thyroid gland. We aimed to clarify the relationship between IgG4-positive plasma cells and the histopathological pattern in the Hashimoto thyroiditis (HT) in a Finnish series. HT specimens (n = 280) were retrieved from the Department of Pathology, Fimlab Laboratories. After re-evaluation, 82 (29%) cases (72 females and 10 males, 52 ± 17 years) with significant fibrosis were selected. CD38, IgG and IgG4 positivity in plasma cells was evaluated by immunohistochemistry. Adjusted IgG4-positive plasma cells per HPF > 20 and IgG4- to IgG-positive plasma cell ratio > 30% were adopted as threshold criteria and related to other morphological features. IgG4-positive HT group included 13 cases (15% from fibrotic HT, 4.6% from all HT, 50 ± 15 years, 11 females) with adjusted HPF count 30 ± 5 (23–40) IgG4-positive cells. IgG4-positivity significantly correlated with the presence of lobulation, oncocytic metaplasia and certain type of fibrosis, fibrosis spread outside the gland, lymphocytes/plasma cells epithelial penetration, the predominance of microfollicles and follicular atrophy in the present study. Despite the persisting uncertainty whether HT is IgG4-RD, HT with IgG4-positive plasma cells is histopathologically distinct entity with some geographic variability.     

HLA Class I: An unexpected role in integrin β4 signaling in endothelial cells

The production of anti-donor antibodies to HLA class I and class II antigens following transplantation is associated with development of transplant vasculopathy and graft loss. Antibodies against HLA class I (HLA-I) molecules are thought to contribute to transplant vasculopathy by triggering signals that elicit the activation and proliferation of endothelial cells. The proximal molecular events that regulate HLA-I dependent signal transduction are not well understood. We demonstrated a mutual dependency between HLA-I and integrin β4 to stimulate signal transduction and cell proliferation. Similarly, we found that integrin β4-mediated cell migration was dependent upon its interactions with HLA-I molecules. Since integrin β4 has been implicated in angiogenesis and tumor formation, associations between integrin β4 and HLA-I may play an important role in cancer. Further characterization of interactions between HLA-I and integrin β4 may lead to the development of therapeutic strategies for the treatment and prevention of chronic allograft rejection and cancer.     

Characterization of the human β4 nAChR gene and polymorphisms in CHRNA3 and CHRNB4

Most neuronal nicotinic acetylcholine receptors are heteropentamers, composed of α and β subunits. Mice lacking the α3 subunit and mice lacking both the β2 and β4 subunits, but not mice lacking the β2 or β4 subunits alone, have a severe phenotype characterized by megacystis, failure of bladder strips to contract in response to nicotine, widely dilated ocular pupils, growth failure, and perinatal mortality. The deficit in bladder contraction was also found in mice lacking only the β4 subunit, although they did not develop megacystis. The major bladder phenotype resembles the human autosomal recessive disorder of megacystis-microcolon-hypoperistalsis syndrome (MMIHS). Based on the similarity of the mouse and human phenotypes, we initiated mutation analyses in the α3 and β4 genes in MMIHS families. The human gene encoding the β4 subunit was fully characterized, including refinement of its mapping. Analysis of disease families and controls identified numerous genetic variants, including high-frequency polymorphisms in both CHRNA3 and CHRNB4. Although no loss-of-function mutations have been identified to date, these genes remain strong candidates for involvement in MMIHS, because various mutations might be obscured within the complex cluster of genes. Some of the markers presented here are valuable tools for analysis of the role of genetic variation in responses to nicotine and for characterization of various dysautonomic abnormalities. Received: February 19, 2001 / Accepted: March 16, 2001     

Anti-integrin immunotherapy in rheumatoid arthritis: protective effect of anti-α4 antibody in adjuvant arthritis

Conclusions The current treatment of RA does not provide acceptable control of the inflammatory process due to either the onset of adverse effects or the lack of efficacy. RA is a T-cell mediated process, in which activated T cells must migrate through the blood vessels to reach the synovium. Anti-adhesion therapies designed to block the interaction of T cells with activated endothelial cells could be of great interest to control the disease. Flow cytometry analysis, immunohistochemical and functional studies cell adhesion in vitro have shown that the interaction between VLA-4 on T cells and VCAM-1 on endothelial cells could play a relevant role in the onset and perpetuation of RA. Here we show that the treatment with HP2/1, an mAb directed against 4 subunit of VLA-4, prevents adjuvant arthritis in Lewis rats. Data suggest that treatment with anti-4 antibodies could be of value in RA.     

Can variation in aquaporin 4 gene be associated with different outcomes in traumatic brain edema?

In traumatic brain injury (TBI), cerebral edema and hemorrhage are factors involved in the determination of the clinical presentation and outcome. The aquaporin 4 (AQP4) water channel is abundant in mammalian brain and there is a growing body of evidence suggesting that this protein plays a major role in the control of water flow within the central nervous system. Previous studies examined the influence of genetic variants in cerebral edema of TBI. However, to our knowledge, there are no previous studies of molecular variations of the AQP4 gene and its association with TBI. Thus, we sought to investigate if the clinical presentation and outcome of TBI could be influenced by the presence of mutations on exon 4 of the AQP4 gene. One hundred and two patients were enrolled in this study. A neurologist assessed the clinical severity at admission according to the GCS followed by a brain computer tomography (CT) scan. Then, DNA was extracted from blood cells and exon 4 of the AQP4 gene amplified by the polymerase chain reaction and directly sequenced. On discharge, GOS was assigned by a neurologist blind to the CGS on admission. We did not find any variation in exon 4 of the AQP4 gene in our considerable large sample. Despite this negative result, there is a strong biological rationale for the involvement of AQP4 gene in brain edema regulation and, as consequence, in TBI. Therefore, further studies should be performed, including the assessment of the other three exons of the AQP4 gene.     

Targeting Integrin α4β7 in Steroid-Refractory Intestinal Graft-versus-Host Disease

Steroid refractory acute graft-versus-host-disease of the gut is a serious complication associated with high mortality after allogeneic stem cell transplantation. Treatment options are limited and not predictably effective. We describe the treatment of steroid-refractory acute graft-versus-host-disease with vedolizumab, an antibody directed against integrin α4β7, in 6 patients. All patients responded, and 4 of 6 patients are alive with a median follow-up of 10 months.     

4-Aminopyridine-sensitive outward currents in preBötzinger complex neurons influence respiratory rhythm generation in neonatal mice

We measured a low-threshold, inactivating K⁺ current, i.e. A-current ( I _A), in respiratory neurons of the preBötzinger complex (preBötC) in rhythmically active slice preparations from neonatal C57BL/6 mice. The majority of inspiratory neurons (21/34 = 61.8%), but not expiratory neurons (1/8 = 12.5%), expressed I _A. In whole-cell and somatic outside-out patches I _A activated at −60 mV (half-activation voltage measured −16.3 mV) and only fully inactivated above −40 mV (half-inactivation voltage measured −85.6 mV), indicating that I _A can influence membrane trajectory at baseline voltages during respiratory rhythm generation in vitro . 4-Aminopyridine (4-AP, 2 m m ) attenuated I _A in both whole-cell and somatic outside-out patches. In the context of rhythmic network activity, 4-AP caused irregular respiratory-related motor output on XII nerves and disrupted rhythmogenesis as detected with whole-cell and field recordings in the preBötC. Whole-cell current-clamp recordings showed that 4-AP changed the envelope of depolarization underlying inspiratory bursts (i.e. inspiratory drive potentials) from an incrementing pattern to a decrementing pattern during rhythm generation and abolished current pulse-induced delayed excitation. These data suggest that I _A opposes excitatory synaptic depolarizations at baseline voltages of approximately −60 mV and influences the inspiratory burst pattern. We propose that I _A promotes orderly recruitment of constituent rhythmogenic neurons by minimizing the activity of these neurons until they receive massive coincident synaptic input, which reduces the periodic fluctuations of inspiratory activity.     

Expression of thymosin β4 in odontoblasts during mouse tooth development

Thymosin β4 (Tβ4) is expressed in developing tissue, where it stimulates cell differentiation and migration. Further, Tβ4 is expressed during molar development in mice, but the expression and function of Tβ4 in odontoblasts during mammalian tooth development have not yet been reported. Therefore, this study examined the expression and function of Tβ4 in differentiating odontoblasts during tooth development. As observed by immunohistochemistry, Tβ4 was expressed in the oral epithelium and inside cells of the tooth bud on embryonic day 15 (E15). Further, on E17, Tβ4 was expressed strongly in the dental lamina and oral epithelium, but only expressed in part of the cells in the outer and inner dental epithelium. Tβ4 was strongly expressed in the entire cytoplasm of odontoblasts on postnatal day 1 (PN1) and expressed intensively in the apical area of odontoblasts on PN4. Further, expression of Tβ4 was increased gradually in odontoblasts from PN1 to PN21. In an odontoblast cell line, MDPC-23, expression of Tβ4 mRNA and protein was increased strongly on day 4 and gradually decreased from day 14. The gene expression of dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), osteocalcin (OCN), osteonectin (ON), and collagen type I, related with mineralization, was significantly decreased in si-Tβ4/MDPC-23 during differentiation compared to that in MDPC-23 cells. Taken together, our results suggest that Tβ4 may be involved in oral epithelial cell proliferation at the initial stage of tooth development and regulates the expression and secretion of proteins during odontoblast differentiation.     

Acute peritoneal tuberculosis in HIV-infected patients. Study of 4 cases in Abidjan, Côte-d'Ivoire

This paper presents 4 cases of histologically verified peritoneal tuberculosis in HIV-infected patients followed in a 18 month-period. The patients were admitted in emergency and were suspected of present acute appendiceal peritonitis. There were 3 females of 18, 22 and 27 years old, and a 41-year-old male. The main symptoms were acute abdominal pain (4 cases), fever superior to 38 degrees C (4 cases) and abdominal defence (4 cases). Laboratory findings were hyperleucocytosis with lymphocytic predominance, anemia and CD4+ rate variable from 250 to 460/mm3. They underwent emergency laparotomy which led to diagnosis of peritoneal tuberculosis by histopathological analysis of peritoneal biopsies. Two patients died from surgery at days 3rd and 10th. The 2 remaining patients were successfully treated by tuberculostatic tritherapy with rifampicin, isoniazid, and pirazinamid. Acute peritoneal tuberculosis in HIV-infected patients is not to be missed in our practice. It must be considered in differential diagnosis of acute abdomens.     

CTLA-4 in autoimmune diseases--a general susceptibility gene to autoimmunity?

For most autoimmune disorders, the pattern of inheritance is very complex. The major histocompatibility complex (MHC) gene complex has been implicated as the major genetic component in the predisposition to these diseases but other genes are likely to be involved. Based on function and experimental data, the gene encoding cytotoxic T lymphocyte-associated antigen 4 (CTLA4) has been suggested as a candidate gene for conferring susceptibility to autoimmunity. In this review, we critically evaluate the evidence for pathogenetical involvement of CTLA-4 in the different autoimmune diseases with focus on the possible role of genetic variation of the CTLA4 locus.     

Changes in the expression of CD31 and CXCR3 in CD4+ naïve T cells in elderly persons

So far, very few studies exist on the na?ve T cell population of elderly persons. Only recently an increase in the percentage of long lived CD4(+)CD31(-) na?ve T cells has been claimed to occur with aging. We, therefore, characterised CD31(+) and CD31(-) CD45RA(+) CD4(+) T cells in young and healthy elderly persons. The production of IL-2 and IFN-gamma by the different subpopulations was studied following stimulation with PMA and Ionomycin. The expression of CD28, CD11a, CD62L, CXCR3 and CCR7 was also analysed. The results of this study demonstrate a pronounced increase in the percentage of CD31(-) CD45RA(+) T cells within the CD4 subpopulation of elderly persons. Both, CD31(-) and CD31(+) CD45RA(+) cells expressed CD28, CD62L, were CD11a (dim) and produced IL-2 but no IFN-gamma. This phenotype confirms that they were na?ve T cells. IL-2 production by na?ve T cells was not impaired in elderly persons. Interestingly, CD31(+) as well as CD31(-) na?ve T cells contained a subpopulation of CXCR3(+) cells in elderly individuals, but not in young ones. In spite of expressing this chemokine receptor that enables the cells to migrate into inflammatory tissues, they were still CCR7(+) and CD62L(+). We speculate that due to previous contact with local environmental factors, this subset of na?ve T cells acquires a different chemokine receptor phenotype, resulting in an altered migratory capacity in old age. Aberrant contact with antigen and effector cell differentiation in unorthodox locations may be the consequence. This could also affect Th1/Th2 polarisation, which is known to be impaired in elderly persons.     

Defects in acute responses to TLR4 in Btk-deficient mice result in impaired dendritic cell-induced IFN-γ production by natural killer cells

This study defines a critical role for Btk in regulating TLR4-induced crosstalk between antigen presenting cells (APCs) and natural killer (NK) cells. Reduced levels of IL-12, IL-18 and IFN-γ were observed in Btk-deficient mice and ex vivo generated macrophages and dendritic cells (DCs) following acute LPS administration, whilst enhanced IL-10 production was observed. In addition, upregulation of activation markers and antigen presentation molecules on APCs was also impaired in the absence of Btk. APCs, by virtue of their ability to produce IL-12 and IL-18, are strong inducers of NK-derived IFN-γ. Co-culture experiments demonstrate that Btk-deficient DCs were unable to drive wild-type or Btk-deficient NK cells to induce IFN-γ production, whereas these responses could be restored by exogenous administration of IL-12 and IL-18. Thus Btk is a critical regulator of APC-induced NK cell activation by virtue of its ability to regulate IL-12 and IL-18 production in response to acute LPS administration.     

The GLUT4 density in slow fibres is not increased in athletes. How does training increase the GLUT4 pool originating from slow fibres?

The influence of training on GLUT4 expression in slow- and fast-twitch skeletal muscle fibres was studied in male endurance-trained athletes and control subjects. The trained state was ensured by elevated maximal oxygen uptake (29%), as well as citrate synthase (60%) and 3-hydroxy-acyl-CoA dehydrogenase (38%) activities in muscle biopsy samples of the vastus lateralis. GLUT4 densities in slow- and fast-twitch fibres were measured by the use of a newly developed, sensitive method combining immunohistochemistry with morphometry, and no effect of training was found. GLUT4 density was higher in slow-twitch fibres compared to fast-twitch fibres (P<0.05) when biopsy samples from untrained subjects were examined. In athletes GLUT4 density was identical in slow- and fast-twitch fibres. Slow-twitch fibre diameters were 10% larger in the athletes (P<0.01), and slow-twitch fibre fractions were 140% of the fraction in the control group. Thus, GLUT4 originating from slow-twitch fibres was increased by 30% (P<0.02) in athletes. We conclude that long-lasting endurance training increases slow-twitch fibre GLUT4 expression by means of an elevated slow-twitch fibre mass in human skeletal muscle.