Overexpression of IL-9 receptor in diffuse large B-cell lymphoma

Interleukin-9 (IL-9) is initially described as a growth factor secreted by helper T cells. It acts on a variety of immune cells via its receptor (IL-9R). Recently, the oncogenic activities of IL-9 and IL-9R were reported in some lymphomas but not diffuse large B-cell lymphoma (DLBCL). The purpose of the present study is to investigate the expression of IL-9R in pathological tissues from patients with DLBCL and to evaluate its correlation with clinical characteristics. Tissue samples from patients with DLBCL and reactive lymphoid hyperplasia were analyzed using RT-PCR, western blot and immunohistochemical staining. There was a higher expression of IL-9R within DLBCL tissues compared with hyperplasic lymph nodes. Immunohistochemical analysis indicated membrane localization of IL-9R in 22 of 36 (61.1%) DLBCL cases. The upregulated IL-9R was correlated to the serum levels of β2 microglobulin and albumin, International Prognostic Index (IPI) score as well as Ki-67 expression within tumor tissues. Our findings suggest that overexpression of IL-9R may contribute to the pathogenesis of DLBCL and is associated with some adverse prognostic parameters.

Expression of IL-9 receptor alpha chain on human germinal center B cells modulates IgE secretion

BACKGROUND

IL-9 has been shown to affect the differentiation pathway of different cell types. However, its potential role in the maturation pathway of antigen-driven B-cell differentiation and its functional effects remain unknown.

OBJECTIVE

To characterize IL-9 receptor alpha chain (IL-9R alpha) expression on human tonsillar B cells at different maturational stages, and to assess its effect on IgE production.

METHODS

Freshly purified human tonsillar B cells were fractionated into 3 populations: low-density (LD), medium-density, and high-density cells. Expression levels of IL-9R alpha were determined by using immunohistochemistry and flow cytometry. IL-9R alpha(high)-expressing cells were stimulated with IL-9 in the presence or absence of IL-4, and IgE release was measured by ELISA.

RESULTS

IL-9R alpha was expressed on human LD tonsillar B cells, with an ability to transduce signals through activation of signal transducer and activator of transcription 3 and 5. Although IL-9 was unable to induce IgE secretion by itself, it potentiated IL-4-mediated IgE production from LD cells. Moreover, increased IgE was paralleled by an upregulation of IL-9R alpha and CD27, with the latter a memory B-cell marker implicated in increased IgE secretion.

CONCLUSION

These results highlight a crucial role for IL-9 in modulating T-cell-dependent B-cell differentiation and establish a new paradigm for understanding the synergistic role of T(H)2 cytokines and their modulatory effect on B-cell maturation and IgE production.

CLINICAL IMPLICATIONS

IL-9 appears to be involved in memory B-cell differentiation and T(H)2-mediated allergic diseases such as asthma.

A specific cadherin phenotype may characterise the disseminating yet non-metastatic behaviour of pseudomyxoma peritonei

Pseudomyxoma peritonei (PMP) is a rare neoplasm of mainly appendiceal origin, characterised by excess intra-abdominal mucin production leading to high morbidity and mortality. While histological features are frequently indolent, this tumour disseminates aggressively throughout the abdominal cavity, yet seldom metastasises. This study determined the expression of several markers of colorectal differentiation (carcinoembryonic antigen (CEA), cytokeratins (CK20 and CK7), epithelial membrane antigen), mucin production (MUC-2, interleukin-9 (IL-9), IL-9 receptor (IL-9Rα)), and cell adhesion (N- and E-cadherin, vimentin) in PMP tissue (n=26) compared with expressions in normal colonic mucosa (n=19) and colorectal adenocarcinoma (n=26). Expressions of CEA and cytokeratins were similar for PMP as those in colorectal adenocarcinomas with the exception that the CK20−/CK7− pattern was rare in PMP (Fisher's exact test: P=0.001). Similarly, expressions of mucin-related proteins were comparable for adenocarcinoma and PMP, with the exception that IL-9 expression was uncommon in adenocarcinoma (P=0.009). Pseudomyxoma peritonei demonstrated a specific pattern of adhesion-related protein expressions of increased N-cadherin, reduced E-cadherin, and increased vimentin (P=0.004), a phenotype suggesting a possible epithelial–mesenchymal transition state. Primary PMP cell cultures were successfully maintained and demonstrated marker expressions similar to those seen in in vivo tissues. These early characterisation studies demonstrate similarities between PMP and colorectal adenocarcinoma, but also reveal a specific cadherin phenotype that may characterise the distinct non-metastasising behaviour of PMP, and form the basis for future mechanistic and therapy-targeting research.