Identification and characterization of pro-interleukin-16 from mud crab Scylla paramamosain: The first evidence of proinflammatory cytokine in crab species.

IL-16 is a pro-inflammatory cytokine originally designated as a lymphocyte chemoattractant factor. In mammal and avian, it has been characterized as an essential regulator of various cellular processes including cell recruitment and activation against pathogen invasion. So far, neither of the full-length of IL-16 homologue nor the response mechanism against pathogen was reported in crab species. In the present study, the pro-IL-16 homologue was firstly cloned and characterized from mud crab Scylla paramamosain. The full-length Sp-pro-IL-16 consisted of 4107 bp with an opening reading frame encoding 1369 amino acids. Multiple alignment analysis showed the putative amino acid sequence of Sp-pro-IL-16 had about 73.86% identity with Litopenaeus vannamei pro-IL-16. Additionally, two conserved PDZ domains and protein binding sites were found in Sp-pro-IL-16 and showed high similarities about 94.19% and 51.14% with their Litopenaeus vannamei and Mus musculus counterparts. RT-PCR analysis indicated that Sp-pro-IL-16 transcripts were constitutively expressed in all tissues examined with an extreme high level in hepatopancreas. Moreover, Sp-pro-IL-16 transcripts in hepatopancreas were significantly up-regulated 15-fold at 72 h after Vibrio alginolyticus challenge and 3.5-fold at 12 h after virus-analog Poly (I:C) challenge. The Western blot analysis revealed that Sp-pro-IL-16 can be cleaved to its bioactive form, an approximately 35 kDa mature IL-16, and the protein levels of both pro-IL-16 and mature IL-16 increased after Vibrio alginolyticus challenge. It is the first experimental identification of pro-inflammatory cytokine IL-16 in arthropods. This study could shed new light on further understanding of the response mechanism of pro-inflammatory cytokine IL-16 in Scylla paramamosain against pathogens. Meanwhile, it brought new insight into the origin and evolution of IL-16 in crab species.

Emerging role of IL-16 in cytokine-mediated regulation of multiple sclerosis.

Cytokines are pleiotropic soluble mediators of cellular functions. Cytokines are critical in immune pathogenesis of human diseases, including autoimmune CD4(+) T cell mediated chronic inflammatory, demyelinating and neurodegenerative diseases of the central nervous system (CNS), multiple sclerosis (MS). In MS and its experimental model, experimental autoimmune encephalomyelitis (EAE), chronic persistence and/or reoccurrence of inflammation in the CNS causes chronic progressive or relapsing disease, accompanied with demyelination and damage to axons and oligodendrocytes, which ultimately leads to paralysis and disability. As opposed to other cytokines, whose effects are not limited to the CD4(+) T cell subset, IL-16 exerts its biological properties by exclusive binding and signaling through CD4 receptor. IL-16 selectively regulates migration of all CD4 expressing T cells regardless of their activation state, which is of critical importance for immune modulation and potential therapy of MS. Other major biological properties of IL-16 essential for the function of CD4(+) T cells include regulation of: T cell activation, CD25 expression, MHC class II expression, dendritic cell (DC)-T cell cooperation, B cell-T cell and T cell-T cell cooperation, inflammatory cytokine production and modulation of chemokine regulated T cell chemo-attraction. In this article we outline immune pathogenesis of the disease necessary to understand significance of cytokines and IL-16 in MS regulation. We revisit cytokine regulation with emphasis on involvement of IL-16 mechanisms, implicated in MS progression and important for development of new therapies. We emphasize the significance of similar IL-16 mechanisms for other chronic inflammatory CNS diseases.

CCR4+T cell recruitment to the skin in mycosis fungoides: potential contributions by thymic stromal lymphopoietin and interleukin-16.

Mycosis fungoides (MF) is characterized by skin accumulation of CCR4+CCR7- effector memory T cells; however the mechanism for their recruitment is not clearly identified. Thymic Stromal Lymphopoietin (TSLP) is a keratinocyte-derived cytokine that triggers Th2 immunity and is associated with T cell recruitment to the skin in atopic dermatitis. Interleukin-16 (IL-16) is a chemoattractant and growth factor for CD4+T cells. We hypothesized that TSLP and IL-16 could contribute to recruitment of malignant T cells in MF. We found elevated TSLP and IL-16 in very early stage patients' plasma and skin biopsies, prior to elevation in CCL22. Both TSLP and IL-16 induced migratory responses of CCR4+TSLPR+CD4+CCR7-CD31+cells, characteristic of malignant T cells in the skin. Co-stimulation also resulted in significant proliferative responses. We conclude that TSLP and IL-16, expressed at early stages of disease, function to recruit malignant T cells to the skin and contribute to their enhanced proliferation.

Therapeutic Effect and Mechanism of Chaige Qinlian Tang on Young Mouse MRSA Pneumonia Model / 中国实验方剂学杂志

Objective::To explore the therapeutic effect and mechanism of Chaige Qinlian Tang on pneumonia in young mice. Method::The pneumonia model was duplicated by slowly dripping Staphylococcus aureus into the nasal cavity of mice.After successful modeling, the mice were randomly divided into model group, clindamycin group, and high and low-dose Chaige Qinlian Tang groups, with sham operation group as negative control group.The rats were given 200 mg·kg-1 high-dose Chaige Qinlian Tang, 100 mg·kg-1 low-dose Chaige Qinlian Tang and 120 mg·kg-1 clindamycin.The mice were observed every day.Colonies were counted in the lungs of each group five days later.The expression levels of interleukin(IL)-16, tumor necrosis factor (TNF)-α in lung lavage fluid of each group were determined by enzyme linked immunosorbent assay (ELISA). Real-time fluorescent quantitative polymerase chain reaction (Real-time PCR) and Western blot were used to measure the expression levels of IL-16, TNF-α in lung lavage fluid of each group.The expressions of tumor necrosis factor receptor (TNFR) 1, Caspase-3 and Caspase-7 in lung and the pathological changes of lung were observed. Result::Compared with the sham operation group, the respiratory state and the activity state of the model mice were worse, and the survival rate was higher in the high-dose Chaige Qinlian Tang group.Compared with the sham operation group, the pulmonary colony counts in the model group and treatment groups were increased, compared with the model group, the lung colony counts in clindamycin group and high-dose Chaige Qinlian Tang group were improved significantly (P<0.05, P<0.01). Compared with the control group, the expression levels of IL-16, TNF-α, TNFR1, Caspase-3, Caspase-7 mRNA and protein in the lung of model group and treatment groups were significantly increased (P<0.01). Compared with model group, the expression levels of IL-16, TNF-α and TNFR1, Caspase-3, Caspase-7 in the lung of clindamycin group and high and low-dose Chaige Qinlian Tang groups were significantly increased (P<0.01). The expression levels of protein and mRNA were significantly decreased (P<0.05, P<0.01), and the pathological changes of lung were improved, especially in clindamycin group and high-dose Chaige Qinlian Tang group. Conclusion::Chaige Qinlian Tang has a certain therapeutic effect on Staphylococcus aureus pneumonia in young mice.This effect may be related to regulating TNFR1, Caspase-3 and Caspase-7 pathways, reducing the secretion of IL-16 and TNF-alpha, and enhancing the clearance of staphylococcus aureus.