Inflammatory stimuli

A Inflammatory stimuli induce accumulation of MHC class II complexes on dendritic cells. Nature 1997 388 782-787. 

S, Reis e Sousa C, Germain RN, Mellman I, Steinman 48 RM The formation of immunogenic major histocompatibility complex class Il-peptide ligands in lysosomal compartments of dendritic cells is regulated by inflammatory stimuli. J Exp Med 2000 191 927-936. 49... 

It has been well documented that the anaemia of chronic disease, ACD, results in a lowering of various haematological parameters. Several mediators are involved, among them histamine, serotonin, bradykinin, prostaglandins and, as found more recently, cytokines and nitric oxide. ACD is a parameter of systemic autoimmune disorders. The severe inflammatory stimuli lead to several systemic changes, mediated by inflammation-associated cytokines, e.g. IL-6, IL-1 TNFa, TGF beta that regulate hepatic synthesis of the acute phase proteins. 

COXs thus catalyze the same first committed step of the AA cascade (Fig. 33-2). COX-2, however, is expressed in response to mitogenic and inflammatory stimuli and encoded by an early-response gene. To date we do not understand how COX-3 expression is regulated. In contrast, COX-1 expression is not subject to short-term regulation. Neurons in the hippocampus, as well as in a few other brain regions, are unlike other cells in that they display basal COX-2 expression [36]. This expression is modulated by synaptic activity, such as long-term potentiation, and involves the NMDA glutamate receptors [36,40]. 

The putative role of angiogenesis in chronic inflammatory diseases is the maintenance of the inflammatory state by allowing ongoing recruitment of inflammatory cells and by supplying nutrients and oxygen to proliferating inflamed tissue. The increased endothelial surface creates an enormous capacity for the production of cytokines, adhesion molecules, and other inflammatory stimuli [35]. 

As stated earlier, activation of endothelial cells by pro-inflammatory stimuli leads to the expression of cell adhesion molecules and cytokines such as IL-6 and IL-8. The expression and hence modulation of surface expressed adhesion molecules by e.g. targeted delivery of inhibitors of NFkB, can be measured using flow cytometric analysis or whole cell ELISA techniques. Cytokine production can be measured in the supernatant of cultured cells or in biological fluids. Furthermore, competitive or quantitative RT-PCR analysis of mRNA levels of cell adhesion molecules or cytokines, allows the transcriptional activity of the genes of interest to be estimated. 

The viability and function tests described above are used to evaluate the hepatocytes within the slice. Up to now, tests to measure the viability of the non-parenchymal cells have not been reported. The presence of the latter cell types is one of the conceptual advantages of slices as compared to isolated hepatocytes. As some drug targeting devices are designed to target non-parenchymal cells in the liver, the development of tests for the sinusoidal cell types deserves more attention. For example, the uptake of substrates such as succinylated human serum albumin (Suc-HSA,which is specifically endocytosed by endothelial cells [79]), or hyaluronic acid [80], can be used to assess the functionality of endocytotic pathways in the endothelial cells in the liver [81]. Other modified proteins that are specifically taken up by Kupffer cells such as mannosylated HSA, may be used to assess the functionality of the endocytotic pathway in Kupffer cells [79]. Another parameter which can be used to assess the functionality of these non-parenchymal liver cells, is the excretion of cytokines in response to pro-inflammatory stimuli. Non-parench5mal cell function in liver slices will be described in more detail in the Section 12.7. 

Two COX isoenzymes have been identified COX-1 and COX-2. Inhibition of COX-1 activity is considered a major contributor to NSAID Gl toxicity. The function of the COX-2 isoenzyme is induced during pain and inflammatory stimuli. 

The COX enzyme exists in at least two isoforms. COX-1 is a constitutive or housekeeping isoform that is responsible for the basal production of prostaglandins, prostacyclins, and thromboxanes. COX-2 is inducible by cytokines and other inflammatory stimuli and is believed to predominate during chronic inflammation. The final product of the COX pathway is tissue specific. For example, platelets produce thromboxane A2 (TXA2) vascular endothelial cells produce prostacyclin (PGI2) mast cells produce prostaglandin Dj (PGD2) ... 

Halichlorine (1) (Fig. 11.1) is an alkaloid which was isolated from the marine sponge H. okadai Kadota (Kuramoto et ah, 1996). This compound was revealed to be a novel alkaloid containing an azaspiro[4.5]decane skeleton clarified by detailed spectroscopic analyses. The absolute stereostructure was confirmed by many synthetic studies (Arimoto et ah, 1998 Clive et ah, 2005 Liu et ah, 2009 Trauner et ah, 1999). Halichlorine was shown to inhibit the induction of vascular cell adhesion molecule-1 (VCAM-1) in cultured human umbilical vein endothelial cells. Drugs that block the inflammatory stimuli-induced expression of VCAM-1 may be useful for treating atherosclerosis, coronary artery diseases, angina, and noncardiovascular inflammatory diseases (Kock et ah, 1995). We introduce here the recent aspects of the biological and physiological activities of halichlorine. 

Various adhesion molecules are reported to be expressed on vascular endothelial cells at sites of inflammation (Libby, 2002). In fact, VCAM-1, expressed on the surface of vascular endothelial cells in response to inflammatory stimuli, is suggested to play an important role in leukocyte recruitment (Gerrity et al, 1979). The adhesion of monocytes to vascular endothelial cells is the first critical step in the induction of atherosclerosis (Glass and Witztum, 2001). Supportively, the expression of VCAM-1 is reported to increase in atherosclerosis lesions (Cybulsky and Gimbrone,... 

Idanpaan, J. J., Kalso, E. A., Seppala, T.. Antinociceptive actions of dexmedetomidine and the K-opioid agonist U-50488H against noxious thermal, mechanical and inflammatory stimuli, J. Pharmacol. Exp. Ther. 1994, 271, 1306-1313. 

Further experimental evidence for the involvement of SP in pain perception came from knock-out animals. Mice, in which the preprotachykinin A gene was disrupted, showed significantly reduced responses in tests that involved more intense noxious stimuli (Cao et al., 1998). De Felipe et al. (1998) disrupted the N receptor, and found the characteristic amplification ( wind up ) and intensity coding of nociceptive reflexes to be absent. NK receptor knockout mice show no changes in acute nociception tests. In contrast, SP and NKi receptor knock-out mice show reduction in responses to inflammatory stimuli. Nerve injury-induced mechanical but not thermal hyperalgesia is attenuated in NKi receptor knock-out mice, when inducing chronic neuropathic pain by unilateral ligation of the L5 spinal nerve (Mansikka et al., 2000). 

This test, performed in rats, is the classical model of inflammatory pain. Intraplantar injection of inflammatory stimuli such as carrageenan, kaolin, or complete Freund adjuvants (CFA) induces paw swelling and increased pain sensitivity. As pain stimulus pressure is applied on the inflammed paw and gradually increased until the animal responds by vocalisation or withdrawal of the paw. Analgesics increase the pressure threshold (Randall and Selitto, Arch. Int. Pharmacodyn. 1957, 111, 409-419). 

The relevance of the A3 receptor over the other adenosine subtypes in immature human dendritic cells is attested to by different studies demonstrating a role for this receptor in the increase of intracellular calcium, actin polymerization and chemot-axis (Panther et al. 2001 Fossetta et al. 2003) (Fig. 12.5). However a loss of the A3 and an increase of the A2A receptor has been reported during maturation of dendritic cells. This switch has been interpreted as a protective effect of adenosine in the context of tissue injury as A2A activation plays an inhibitory role on dendritic cells migration. In this way adenosine could counterbalance inflammatory stimuli by delaying the arrival of mature dendritic cells to lymph nodes, thereby impairing the... 

McDonald PP, Bald A, Cassatella MA. 1997. Activation of the NF-kB pathway by inflammatory stimuli in human PMN. Blood. 89 3421-3433. 

Figure 15.3 Resveratrol modulation of pro-inflammatory signaling pathways. Resver-atrol represses transcriptional activation of various pro-inflammatory genes by inhibiting pro-inflammatory stimuli-induced activation of upstream kinases, such as MAP kinases, PI3K/Akt, IKK, PKC, etc., and blocking the DNA binding of eukaryotic transcription factors, such as NF-kB, AP-1, and STAT3.

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