The chondrocyte channelome: A narrative review

Chondrocytes are the main cells in the extracellular matrix (ECM) of articular cartilage and possess a highly differentiated phenotype that is the hallmark of the unique physiological functions of this specialised load-bearing connective tissue. The plasma membrane of articular chondrocytes contains a rich and diverse complement of membrane proteins, known as the membranome, which defines the cell surface phenotype of the cells. The membranome is a key target of pharmacological agents and is important for chondrocyte function. It includes channels, transporters, enzymes, receptors, and anchors for intracellular, cytoskeletal and ECM proteins and other macromolecular complexes. The chondrocyte channelome is a sub-compartment of the membranome and includes a complete set of ion channels and porins expressed in these cells. Many of these are multi-functional proteins with “moonlighting” roles, serving as channels, receptors and signalling components of larger molecular assemblies. The aim of this review is to summarise our current knowledge of the fundamental aspects of the chondrocyte channelome, discuss its relevance to cartilage biology and highlight its possible role in the pathogenesis of osteoarthritis (OA). Excessive and inappropriate mechanical loads, an inflammatory micro-environment, alternative splicing of channel components or accumulation of basic calcium phosphate crystals can result in an altered chondrocyte channelome impairing its function. Alterations in Ca²⁺ signalling may lead to defective synthesis of ECM macromolecules and aggravated catabolic responses in chondrocytes, which is an important and relatively unexplored aspect of the complex and poorly understood mechanism of OA development.     

The influence of glucocorticoid receptor single nucleotide polymorphisms on outcome after haematopoietic stem cell transplantation

Haematopoietic stem cell transplantation (HSCT) remains the only cure for most haematological malignancies, however, the mortality rate remains high. Complications after HSCT include relapse, graft versus host disease (GvHD), graft rejection and infection. Over the last few years several groups, have demonstrated that non‐HLA gene polymorphisms can be predictive of outcome after HSCT. Since the glucocorticoid cortisol is pivotal in the regulation of the immune system, we decided to examine single nucleotide polymorphisms (SNPs; rs6198, rs33388 and rs33389) within the glucocorticoid receptor (GR) and correlate with HSCT outcome. The training set consisted of patients (n = 458) who underwent HSCT for acute leukaemia between 1983 and 2005. In the recipients, the absence of the ACT haplotype and absence of the T allele of rs33388 were associated with decreased OS and the absence of the ACT haplotype, the absence of the T allele of rs33388 and the presence of the ATA haplotype were associated with increased risk of relapse. In addition, the presence of the ACT haplotype in the recipient showed a trend to be associated with increased risk of chronic graft versus host disease (cGvHD). The patients in this cohort received mainly myeloablative conditioning (n = 327). The SNPs in the glucocorticoid receptor were then investigated in a validation set (n = 251) of HSCT patients transplanted for acute leukaemia from 2006. This cohort contained significantly more patients that had received reduced intensity conditioning (RIC). Some of the results could be validated in these patients. However, contrary to the training set, the absence of the haplotype ACT in the donor in this cohort was associated with increased risk of cGvHD. Differences in the conditioning were shown to influence the results. These results are the first to associate GR SNPs with HSCT outcome and demonstrate the inherent problems of replicating SNP association studies in HSCT, due to different pre‐transplant regimens.     

Midline anterior neck inclusion cyst: A novel superficial congenital developmental anomaly of the neck

Background/Objectives

A variety of congenital developmental anomalies arise on the neck because of the many fusion planes and complex embryologic structures in this region. We describe a series of seven patients with a novel type of superficial midline congenital anomaly.

Methods

Retrospective case series. Clinical and histopathologic features were compared and used to describe this entity.

Results

Seven patients with nearly identical clinical findings were identified. In all cases, a small superficial cyst resembling a giant milium was observed at birth. There were no significant changes during infancy and no evidence of underlying abnormalities. The histopathologic findings were identical to those of an infundibular follicular cyst.

Conclusion

We have termed this entity midline anterior neck inclusion cyst. We believe it is a superficial developmental anomaly, probably a forme fruste of a midline fusion developmental defect, which has not to our knowledge, previously been described.     

Two distinct non-T helper type 2 interleukin-4 cell subsets in mice as revealed by single-cell cytokine analysis

We have previously defined four murine CD4⁺ peripheral T cell subsets, fractions (Fr.) I – IV, based on expression of the 6C10 and 3G11 determinants (Hayakawa, K. and Hardy, R. R., J. Exp. Med. 1988. 168: 1825). These subsets also show distinctive levels of other cell surface markers: the two minor subsets, Fr. III and Fr. IV, are both CD45RB^low/-, L-selectin (Mel-14)^? and CD44^hi, characteristic of secondary T cells. The patterns and levels of cytokine production by individual cells in each subset were determined by bioassay for interleukin (IL)-2/IL-4 or IL-4/interferon (IFN)-γ production after anti-CD3 stimulation. Our data revealed that these four phenotypically defined subsets largely coincide with clusters of cells showing uniform distinctive cytokine profiles, i.e. IL-2⁺/IFN-γ^?/IL-4^? (Fr. I and Fr. II, L-selectin⁺), IL-2⁺/IFN-γ⁺/IL-4⁺ (Fr. III, L-selectin^?), and IL-2^?/IFN-γ^low/-/IL-4⁺ (Fr. IV, L-selectin^?). Besides these subsets, an L-selectin-negative cell subfraction within Fr. II appears to represent a transitional population between the IL-2⁺/IFN-γ^?/IL-4^? stage and the IL-2⁺/IFN-γ⁺/IL-4⁺ stage. Taken together, these results demonstrate the presence of two IL-4⁺ secondary T cell subsets with distinct cytokine production patterns, and show that the majority of IL-4⁺ cells found in healthy adult laboratory mice co-produce IFN-γ, and thus are not typical T helper type 2 cells.     

High expression of the RNA-binding protein RBPMS2 in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and are often associated with KIT or PDGFRA gene mutations. GIST cells might arise from the interstitial cells of Cajal (ICCs) or from a mesenchymal precursor that is common to ICCs and smooth muscle cells (SMCs). Here, we analyzed the mRNA and protein expression of RNA-Binding Protein with Multiple Splicing-2 (RBPMS2), an early marker of gastrointestinal SMC precursors, in human GISTs (n = 23) by in situ hybridization, quantitative RT-PCR analysis and immunohistochemistry. The mean RBPMS2 mRNA level in GISTs was 42-fold higher than in control gastrointestinal samples (p < 0.001). RBPMS2 expression was not correlated with KIT and PDGFRA expression levels, but was higher in GISTs harboring KIT mutations than in tumors with wild type KIT and PDGFRA or in GISTs with PDGFRA mutations that were characterized by the lowest RBPMS2 levels. Moreover, RBPMS2 levels were 64-fold higher in GIST samples with high risk of aggressive behavior than in adult control gastrointestinal samples and 6.2-fold higher in high risk than in low risk GIST specimens. RBPMS2 protein level was high in 87% of the studied GISTs independently of their histological classification. Finally, by inhibiting the KIT signaling pathway in GIST882 cells, we show that RBPMS2 expression is independent of KIT activation. In conclusion, RBPMS2 is up-regulated in GISTs compared to normal adult gastrointestinal tissues, indicating that RBPMS2 might represent a new diagnostic marker for GISTs and a potential target for cancer therapy.     

Olanzapine vs. haloperidol in the treatment of elderly chronic schizophrenia patients

OBJECTIVE: Most of the data supporting the use of atypical antipsychotics (AA) is based on studies in young adult patients. The present study is an open-label naturalistic follow-up study of olanzapine treatment vs. haloperidol for elderly chronic schizophrenia patients. MEHTOD: 20 patients (mean age 72.7+/-5.9 years, mean disease duration 33.1+/-12.0 years) who met the DSM-IV criteria for schizophrenia were randomly assigned to olanzapine (n=10) or haloperidol (n=10) treatment during acute exacerbation. Primary outcome measure was rating on the Clinical Global Impression (CGI) scale and the Positive and Negative Symptom Scale (PANSS). RESULTS: Between-group differences were computed using analysis of covariance. PANSS Total score decreased from 84 at baseline to 65 after treatment with olanzapine while decreased only from 79 to 74 with haloperidol treatment (F= 6.66, P=.02). PANSS Negative subscale decreased from 19 at baseline to 15 with olanzapine treatment while increased (deteriorated) from 18 to 20 with haloperidol treatment (F=23.37, P=.0003). CGI decreased from baseline with both olanzapine and haloperidol treatments (1.1 vs. 0.4) but the decrease in the olanzapine group was significantly greater (F=4.63, P=.05). Mean weight increased in both groups but without statistical difference between groups. CONCLUSIONS: In elderly chronic schizophrenia patients, olanzapine treatment is superior to haloperidol in reducing negative symptoms as well as less induction of extrapyramidal symptoms (EPS).     

Prenatal exposure to morphine alters brain μ opioid receptor characteristics in rats

Prenatal morphine exposure alters neither the binding capacity nor the affinity of ligand binding to μ opioid receptors of adult male brains. However, males have significantly higherB_max in the hypothalamus than ovariectomized females. In females, prenatal exposure to morphine reduces theB_max of μ opioid receptors 25% in the hypothalamus and preoptic area. Estrogen treatment increases theB_max of μ opioid receptors in the striatum of all ovariectomized females but in the hypothalamus only of morphine-exposed females, thereby eliminating the sex difference observed in control animals.     

Sex dimorphic alterations in postnatal brain catecholarnines after gestational morphine

The concentration of brain catecholamines was measured in the hypothalamus, preoptic area (POA), frontal cortex, cerebellum, and striatum of rats exposed in utero to morphine (5–10 mg/kg/twice daily) during gestation days 11–18. Prenatal morphine induced regionally specific, sexually dimorphic alterations in male and female norepinephrine (NE), and dopamine (DA) content at different postnatal ages. Prenatal morphine significantly increased NE content in the hypothalamus of both sexes at postnatal day (PND) 23. In the POA, on the other hand, morphine increased NE content in exposed males at PND 23 and in females at PND 33. In the cerebellum, the NE content of both sexes was significantly elevated at PND 45. In the striatum, NE content was increased by the prenatal morphine only in females at PND 16. The concentration of DA was also affected in a sexually dimorphic manner. At PND 16, prenatal morphine increased the levels of hypothalamic DA only in males, and it reduced the content of DA in female but not male PDA. At PND 45, prenatal morphine increased DA in the hypothalamus of females and decreased it in males. In the cerebellum of 16-day-old morphine-exposed animals, DA levels were increased only in males; at PND 45, the levels of DA were still increased in males but had not changed in females. In the striatum, the DA content was reduced only in males at PND 16. Thus, prenatal morphine alters the development of both NE and DA neurotransmitter systems in the hypothalamus, POA, striatum, and cerebellum in a sexually dimorphic manner.