Smriti K. Raychaudhuri

Effect of nerve growth factor on endothelial cell biology: proliferation and adherence molecule expression on human dermal microvascular endothelial cells.

Abstract In addition to its effect on the central nervous system, nerve growth factor (NGF) appears to play a key role in the initiation and maintenance of inflammation in many organs. NGF degranulates mast cells, recruits inflammatory cellular infiltrates and activates T cells. Extravascular migration of leukocytes is initially controlled by the interaction of cell surface adhesion molecules of leukocytes and endothelial cells. A marked upregulation of NGF in keratinocytes is also observed in conditions characterized by angiogenesis such as psoriasis and wound healing. In this study we investigated the role of NGF in inflammation by studying its effects on endothelial cell proliferation and intracellular adhesion molecule expression by endothelial cells. The effect of NGF on human dermal microvascular endothelial cell (HDMEC) proliferation was measured using the hexosaminidase assay. ICAM-1 expression on HDMEC was measured by ELISA. The function of ICAM-1 was assessed by adherence of peripheral blood mononuclear cells (PBMC) to HDMEC using 51 Cr-labeled PBMC. There was a significant increase in proliferation of HDMEC stimulated with NGF as compared to unstimulated HDMEC ( P < 0.001). NGF-neutralizing antibody decreased the mitogenic effect of NGF significantly ( P < 0.05). NGF also increased ICAM expression on HDMEC as compared to unstimulated HDMEC ( P < 0.05). NGF-neutralizing antibody decreased ICAM expression on NGF-stimulated HDMEC ( P < 0.05). The percentage of PBMC adherence was higher in NGF-stimulated HDMEC ( P < 0.001). Anti-ICAM antibody decreased PBMC adherence. In the study reported here, the role of NGF in two important aspects of inflammation, i.e. angiogenesis and inflammatory cell recruitment at the site of inflammation, was investigated.

Diagnosis and classification of psoriasis.

Psoriasis is a chronic inflammatory multi organ disease with well characterized pathology occurring in the skin and often the joints. Although the disease has many characteristic and even pathognomonic features, no established diagnostic criteria exist for cutaneous psoriasis and there is no unified classification for the clinical spectrum of the disease. Prior approaches that have been taken to classify psoriasis include age of onset, severity of the disease, and morphologic evaluation. The latter has yielded plaque, guttate, pustular, and erythrodermic as subtypes of psoriasis. Unlike other autoimmune diseases, histopathological examination and blood tests are generally not valuable tools in making the diagnosis of psoriasis. However, on occasion, dermatopathologic evaluation may be helpful in confirming the diagnosis of psoriasis. Thus, in most cases the diagnosis of psoriasis is dependent primarily on pattern recognition that is morphologic evaluation of skin lesions and joints.

Role of NGF and neurogenic inflammation in the pathogenesis of psoriasis.

A contributing role of neurogenic inflammation has provided a new dimension in understanding the pathogenesis of various cutaneous and systemic inflammatory diseases such as atopic dermatitis, urticaria, rheumatoid arthritis, ulcerative colitis and bronchial asthma. Several critical observations, such as (i) psoriasis resolves at sites of anaesthesia, (ii) neuropeptides are upregulated, and (iii) there is a marked proliferation of terminal cutaneous nerves in psoriatic plaques, encouraged us to search for a mechanism of neural influence in inflammation and inflammatory diseases. In immunohistochemical studies, we found that keratinocytes in lesional and nonlesional psoriatic tissue express high levels of nerve growth factor (NGF) and that there is a marked upregulation of NGF receptors, p75 neurotrophin receptor (p75NTR) and tyrosine kinase A (TrkA), in the terminal cutaneous nerves of psoriatic lesions. As keratinocytes of psoriatic plaques express increased levels of NGF, it is likely that murine nerves will promptly proliferate into the transplanted plaques on a severe combined immunodeficient mouse. Indeed, we have noted marked proliferation of nerve fibers in transplanted psoriatic plaques compared with the few nerves in transplanted normal human skin. By double label immunofluorescence staining, we have further demonstrated that in these terminal cutaneous nerves there is a marked upregulation of neuropeptides, such as substance P and calcitonin gene-related protein. These observations, as well as recent findings about NGF-induced chemokine expression in keratinocytes, further substantiate a role of the NGF-p75NTR-TrkA system in the inflammatory process of psoriasis. Currently, we are evaluating antagonists to selected neuropeptides and NGF/receptors, with the expectation of identifying pharmacological agents to counter neurogenic inflammation in psoriasis.

Mast cell density and IL-8 expression in nonlesional and lesional psoriatic skin.

Abstract

Revisiting the Koebner phenomenon: Role of NGF and its receptor system in the pathogenesis of psoriasis

Nerve growth factor (NGF) influences the key pathological events of psoriasis: keratinocyte proliferation, angiogenesis, and T-cell activation. We have systematically examined the kinetics of NGF expression, keratinocyte proliferation, and migration of T lymphocytes in the epidermis in Koebner-induced developing psoriatic plaques. In skin traumatized by the tape-stripping method (n = 12), a marked up-regulation of NGF in Koebner-positive lesions (n = 7) was observed 24 hours after trauma. Synthesis of NGF reached its maximum level in the 2nd week. Furthermore, cultured keratinocytes from nonlesional skin of psoriasis patients produced 10 times higher levels of NGF compared with keratinocytes from healthy individuals. To substantiate the in vivo effect of NGF secreted by keratinocytes in psoriatic plaques, we studied psoriatic plaques and normal human skin in a SCID-human skin xenograft model. The transplanted psoriatic plaques demonstrated marked proliferation of NGF-R (p75)-positive nerve fibers compared with only a few nerves in the transplanted normal human skin. Our results demonstrate that 1) in a developing psoriatic lesion, up-regulation of NGF together with keratinocyte proliferation are early events and precede epidermotropism of T lymphocytes; 2) keratinocytes in patients with psoriasis are primed to produce elevated levels of NGF; and 3) NGF synthesized by these keratinocytes is functionally active.

Clinical course of psoriasis during pregnancy

Background Since the landmark study on rheumatoid arthritis, many reports have suggested that physiological changes during pregnancy often induce remission of systemic and cutaneous inflammatory diseases. In this study we investigated the clinical course of psoriasis during pregnancy.

IL-22 induced cell proliferation is regulated by PI3K/Akt/mTOR signaling cascade.

OBJECTIVE Interleukin 22 (IL-22), a relatively new cytokine has been found to induce significant proliferation of human keratinocytes and fibroblast like synoviocytes (FLS) and thus plays an important role in the pathogenesis of autoimmune diseases like psoriasis and rheumatoid arthritis (RA) which are characterized by hyperproliferation of keratinocytes and FLS respectively. PI3K/Akt/mTOR signaling cascade plays crucial role in cell growth and survival. Therefore our objective was to see the regulatory role of PI3K/Akt/mTOR signaling cascade in IL-22 induced proliferation of keratinocytes and FLS. METHODS Normal human epidermal keratinocytes (NHEK) and FLS were isolated from skin of healthy volunteers undergone plastic surgery and synovial tissue of psoriatic arthritis (PsA) and RA patients respectively. IL-22 induced proliferation of NHEK and FLS was measured by MTT assay. Phosphorylation of Akt/mTOR was determined by western blot assay and further confirmed by real time polymerase chain reaction (RT-PCR). RESULTS We observed that IL-22 induced significant proliferation of NHEK and FLS which was effectively inhibited by dual kinase (PI3K/mTOR) inhibitor, NVP-BEZ235 and specific mTOR inhibitor, Rapamycin. In NHEK and FLS, IL-22 significantly induced phosphorylation of Akt and mTOR which was effectively blocked by Rapamycin and NVP-BEZ235. Further we did RT-PCR in NHEK and found that IL-22 significantly upregulated AKT1 and MTOR gene. CONCLUSION These results show that IL-22 induced proliferation of NHEK and FLS is dependent on PI3K/Akt/mTOR signaling pathway. This novel observation provides the scope to develop new therapeutics targeting PI3K/Akt/mTOR signaling pathway in autoimmune diseases like psoriasis and rheumatoid arthritis.

Functional role of IL-22 in psoriatic arthritis

IntroductionInterleukin-22 (IL-22) is a cytokine of IL-10 family with significant proliferative effect on different cell lines. Immunopathological role of IL-22 has been studied in rheumatoid arthritis (RA) and psoriasis. Here we are reporting the functional role of IL-22 in the inflammatory and proliferative cascades of psoriatic arthritis (PsA).MethodFrom peripheral blood and synovial fluid (SF) of PsA (n = 15), RA (n = 15) and osteoarthritis (OA, n = 15) patients, mononuclear cells were obtained and magnetically sorted for CD3+ T cells. Fibroblast like synoviocytes (FLS) were isolated from the synovial tissue of PsA (n = 5), RA (n = 5) and OA (n = 5) patients. IL-22 levels in SF and serum were measured by enzyme linked immunosorbent assay (ELISA). Proliferative effect of human recombinant IL-22 (rIL-22) on FLS was assessed by MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole) and CFSE dilution (Carboxyfluorescein succinimidyl ester) assays. Expression of IL-22Rα1 in FLS was determined by western blot.ResultsIL-22 levels were significantly elevated in SF of PsA patients (17.75 ± 3.46 pg/ml) compared to SF of OA (5.03 ± 0.39 pg/ml), p < 0.001. In MTT and CFSE dilution assays, rIL-22 (MTT, OD: 1.27 ± 0.06) induced significant proliferation of FLS derived from PsA patients compared to media (OD: 0.53 ± 0.02), p < 0.001. In addition, rIL-22 induced significantly more proliferation of FLS in presence of TNF-α. IL-22Rα1 was expressed in FLS of PsA, RA and OA patients. Anti IL-22R antibody significantly inhibited the proliferative effect of rIL-22. Further we demonstrated that activated synovial T cells of PsA and RA patients produced significantly more IL-22 than those of OA patients.ConclusionSF of PsA patients have higher concentration of IL-22 and rIL-22 induced marked proliferation of PsA derived FLS. Moreover combination of rIL-22 and TNF-α showed significantly more proliferative effect on FLS. IL-22Rα1 was expressed in FLS. Successful inhibition of IL-22 induced FLS proliferation by anti IL-22R antibody suggests that blocking of IL-22/IL-22R interaction may be considered as a novel therapeutic target for PsA.

Increased Prevalence of the Metabolic Syndrome in Patients with Psoriatic Arthritis

OBJECTIVES Psoriasis (PsO) is a common chronic T cell-mediated inflammatory disorder traditionally thought to manifest in the skin and joints (psoriatic arthritis, PsA). Recently, it has been shown that these patients have an increased risk for myocardial infarction and this was greater with increasing severity of psoriasis. Patients with psoriasis have reported to have cardiometabolic disturbances including obesity, insulin resistance, and dyslipidemia. This constellation of risk factors, referred to as the metabolic syndrome, increases the risk for atherosclerotic cardiovascular disease (ASCVD) and type 2 diabetes mellitus. The aim of this study was to determine the prevalence of metabolic syndrome in PsA. METHODS In our study, we examined the records of 105 patients with PsA to determine the prevalence of metabolic syndrome in PsA. This was a retrospective analysis of the Sacramento Veterans Affairs database. RESULTS Our results demonstrated an increased prevalence of the metabolic syndrome in patients with PsA (61/105 patients or 58.1%) compared to the 35.2 % reported for the Third National Health and Nutrition Examination Survery (NHANES III) data. CONCLUSIONS Thus, patients with PsA have a very high prevalence of metabolic syndrome, which predisposes them to an increased risk of both diabetes and ASCVD.

Inflammation, Atherosclerosis, and Psoriasis

Increasing evidence supports an important role for inflammation in all phases of atherosclerosis, from initiation of the fatty streak to final culmination in acute coronary syndromes. Numerous inflammatory biomarkers including cell adhesion molecules, cytokines, chemokines, and acute-phase reactants such as fibrinogen, serum amyloid A, and C-reactive protein (CRP) have been shown to predict cardiovascular (CVD) events. Several prospective studies have shown a consistent and robust relationship between levels of high-sensitivity CRP and the risk of future CVD events. Toll-like receptors are pattern recognition receptors and members of the innate immune system that contribute to inflammation and appear to play key roles in atherosclerosis. Lipoprotein-associated phospholipase A2 may also be an independent CVD risk factor. Psoriasis has been associated with an increasing risk for atherosclerosis, including coronary artery disease and stroke. Patients with psoriasis have a 5-year shorter life expectancy, most frequently due to CVD. Psoriasis is associated with a chronic inflammatory state and with elevated levels of CRP and other inflammatory cytokines and these may play a causative role in the increased risk of psoriatic patients for CVD. Patients with psoriasis may represent an emerging risk population and patients with moderate to severe psoriasis should be screened and aggressively treated for CVD risk factors.