Addition of zinc and manganese to a biological dressing

BACKGROUND

Zinc and manganese, which are used in vivo because of their healing properties, have been shown to modulate in vitro integrin expression and to enhance keratinocyte migration. In addition, at the clinical level, a dressing of keratinocytes suspended in a fibrin glue has been proposed for the treatment of chronic wounds.

OBJECTIVE

To investigate whether the addition of trace elements to this dressing could modulate the migratory phenotype of keratinocytes via the modulation of integrin expression in a manner similar to an in vitro model and thus increase the healing properties of this dressing.

METHODS

Keratinocytes were mixed with Tissucol and maintained in culture for 12 days in a medium either supplemented or not with zinc or manganese. Then, integrin expression was studied by immunohistochemistry on fibrin clot cryosections.

RESULTS

We observed a significant increase of alpha5beta1 with zinc compared to the control medium. Zinc also enhanced alphaVbeta6 expression and manganese alpha5beta1, alphaVbeta5 and alphaVbeta6 expression, however without reaching a significant level.

CONCLUSION

By modulating integrin expression, trace elements can improve the efficiency of a biological dressing made of keratinocytes in a fibrin glue matrix and, thus, it appears beneficial to add them to this biological dressing for the treatment of skin defects.

Large scale expansion of gamma 9 delta 2 T lymphocytes: Innacell gamma delta cell therapy product

gamma9delta2 T lymphocytes are non-conventional lymphocytes presenting a direct cytotoxic effect against a broad range of tumour targets. These cells also secrete inflammatory cytokines that can boost the other components of the immune system. In contrast to conventional CD8(+) T cells, the cytotoxic effect of gamma9delta2 T lymphocytes does not depend on the expression of major histocompatibility complex molecules by target tumour cells. INNACELL gammadeltatrade mark is a cell therapy product obtained by ex vivo amplification of mononuclear cells. The stimulation is achieved by a specific synthetic agonist of gamma9delta2 T lymphocytes, bromohydrin pyrophosphate (BrHPP). After a single stimulation with BrHPP, gamma9delta2 T lymphocytes are expanded for 2 weeks in a closed system in culture medium with interleukin-2 (IL-2). On day 15, cells are washed and harvested in 4% human serum albumin. In this manufacturing process, the total cell population is expanded by approximately 10-fold and gamma9delta2 T lymphocytes undergo a specific 1000-fold expansion, corresponding to a gamma9delta2 T lymphocyte enrichment of more than 70% at the end of the culture. This manufacturing process is much simpler than most current cellular therapy approaches using conventional CD8(+) T-cell lines or clones: there is no final or initial separation, no purification step and no use of feeder cells; the specific T-cell receptor-mediated signal provided by BrHPP is sufficient to trigger the IL-2-dependent expansion of the gamma9delta2 subset, which then becomes predominant in the cell culture in large amounts.

In vitro modulation of TLR-2, CD1d and IL-10 by adapalene on normal human skin and acne inflammatory lesions

The anti-inflammatory mechanisms of adapalene, a synthetic retinoid used for the treatment of acne patients, are partially understood. They seem particularly related to the modulation of the non-specific immunity. Recent studies have shown that Toll-like receptor (TLR)-2 expression, a receptor of the innate immune system, was increased in acne lesions and could play an essential role in acne-linked inflammation. The aim of our study was to investigate the new mechanisms of the anti-inflammatory activity of adapalene in vitro, and more specifically the modulatory effect of adapalene on the expression of TLR-2, CD1d, a cell surface glycoprotein that plays a role as antigen-presenting molecules and is responsible for the development of cutaneous inflammation, and also on the expression and the secretion of the anti-inflammatory interleukin (IL)-10 cytokine. Both explants of normal human skin and explants of acne patients were incubated with adapalene (10(-7) or 10(-6) M) or the control medium for 24 h. Evaluation of epidermal expression by immunohistochemistry showed a decreased expression of TLR-2 and IL-10 in explants of normal skin and explants of acne with adapalene. On the contrary, adapalene increased CD1d expression in explants of acne patients. Thus, adapalene can modulate the epidermal immune system by increasing the CD1d expression and by decreasing the IL-10 expression by keratinocytes. Moreover, these modulations could increase the interactions between dendritic cells and T lymphocytes and could strengthen the antimicrobial activity against Propionibacterium acnes. The decreased expression of TLR-2 by the keratinocytes can contribute to explain the anti-inflammatory activity of adapalene observed in clinical practice.

Induction of toll-like receptors by Propionibacterium acnes

BACKGROUND

The bacterium Propionibacterium acnes is involved in the induction and maintenance of the inflammatory phase of acne. Recent studies have found that keratinocytes express toll-like receptors (TLRs) implicated in immediate immunity. No studies have, to date, been carried out on the action of P. acnes upon TLR activation in keratinocytes.

OBJECTIVES

Focusing on the inflammatory phase of acne, to clarify the role of P. acnes in immediate immunity by inducing expression of TLR-2 and TLR-4 by keratinocytes. We also studied how the secretion and expression of matrix metalloproteinase (MMP)-9 is induced by P. acnes.

METHODS

The work was carried out on two levels: in vivo with the study of the expression of TLR-2 and TLR-4 proteins in biopsies of acne lesions and in vitro on cultured keratinocyte monolayers to study the modulating effects of P. acnes on the expression of TLR-2 and TLR-4 and also on the expression and secretion of MMP-9.

RESULTS

Our findings reveal that in vivo TLR-2 and TLR-4 expression is increased in the epidermis of acne lesions. In vitro, an increase in TLR-2 and TLR-4 expression by human keratinocytes occurred in the first hours of incubation with bacterial fractions as well as an increase of the expression and secretion by the keratinocytes of MMP-9, which plays a role in inflammation.

CONCLUSIONS

This work demonstrates that P. acnes induces TLR expression and that this mechanism could play an essential role in acne-linked inflammation. These receptors could be involved notably in acute acne.

Modulation in vitro of keratinocyte integrins by interferon-alpha and interferon-gamma

BACKGROUND

Interferon-alpha and -gamma are glycoproteins with antiviral and immunoregulatory properties. In vitro studies have shown a role for these cytokines in the regulation of epidermal keratinocyte growth and differentiation. In the same way, integrins are adhesion molecules which regulate keratinocyte proliferation and differentiation.

AIM

To determine whether the regulatory activity of interferons on keratinocyte proliferation and differentiation is related to a modulation of keratinocyte integrins.

METHODS

Two different methods were used: monolayers and reconstituted skin, incubated either with 1,200 U/mL interferon-alpha or 500 U/mL interferon-gamma or control medium for 48 h. The integrin expression was assessed by flow cytometry and immunohistochemistry.

RESULTS

In monolayers, only the alpha3 subunit was significantly inhibited by interferon-gamma. In reconstituted skin, where keratinocytes are differentiated, both interferons had an inductive effect on beta1 expression and interferon-alpha had an inhibitory effect on alpha6 expression.

CONCLUSION

Interferon-alpha and -gamma induce a modulatory effect on alpha3, alpha6 and beta1 which appears to be related to the state of differentiation. Moreover, the decreased expression of alpha6 and alpha3 could be one of the mechanisms involved in the formation of bullous lesions during long-term interferon therapy.

Interleukin-15 expression in cutaneous T-cell lymphoma (mycosis fungoides and Sezary syndrome)

BACKGROUND

Cytokines are of potential importance in the pathogenesis of cutaneous T-cell mediated disorders, including cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To compare interleukin (IL)-15 expression in certain inflammatory cutaneous diseases, with that in CTCL (mycosis fungoides and Sézary syndrome).

METHODS

IL-15 mRNA and protein expression were examined by in situ hybridization and immunohistochemistry, respectively, on formalin-fixed, paraffin-embedded biopsies of normal human skin, atopic dermatitis, psoriasis, parapsoriasis and CTCL.

RESULTS

Despite similar expression of IL-15 mRNA, we found differences in IL-15 protein expression between normal human skin, atopic dermatitis and psoriasis on the one hand, and parapsoriasis and CTCL on the other. IL-15 protein expression was not detected in normal human skin, atopic dermatitis or psoriasis, but was detected, mainly at low levels but in a few patients at higher levels, in epidermal keratinocytes in parapsoriasis, mycosis fungoides and Sézary syndrome.

CONCLUSIONS

Induction of keratinocyte IL-15 expression appears to be a feature of CTCL. The factors stimulating such an expression remain unknown.

Zinc, copper and manganese enhanced keratinocyte migration through a functional modulation of keratinocyte integrins

The migration of keratinocytes plays an important role in the re-epithelialization of cutaneous wounds. Zinc, copper and manganese are used in vivo for their healing properties and their mechanism of action is still only partially known. Thus, they have been shown both to promote keratinocyte proliferation and to modulate integrins expression. The aim of this study was to determine if trace elements induce an increase of the migration of keratinocytes and if this effect is related to the modulation of integrins. Two independent migration assays were used to study keratinocyte migration: the scratch assay using normal human keratinocytes and the modified Boyden chamber using HaCaT cells. Inhibition studies using function-blocking antibodies directed to alpha3, alpha6, alpha(v) and beta1 subunits were performed to investigate the modulator effect of trace elements on integrin function. In this way, zinc and copper gluconates increased alpha3, alpha(v) and beta1 function whereas manganese gluconate seems mainly able to modulate the function of alpha3 and beta1. The stimulating effect of these trace elements on keratinocyte migration does not appear related to alpha6 subunit. Thus, zinc, copper and manganese enhanced keratinocyte migration and one of the mechanisms was going through a modulation of integrin functions.

Minocycline modulation of alpha-MSH production by keratinocytes in vitro

The anti-inflammatory mechanisms of minocycline, an antibiotic used in the treatment of the inflammatory component of acne, are only partially understood. In addition to inflammation due to cytokines (IL-1, IL-6, TNF-alpha, etc.), recent studies have shown that neuropeptide-mediated neurogenic inflammation may play an important role in cutaneous inflammation. The purpose of this study was to investigate minocycline-induced modulation of cutaneous production of alpha-melanocyte-stimulating hormone (alpha-MSH), a neuropeptide with known anti-inflammatory activity. Two different skin models were used: explants of inflammatory skin and reconstituted skin, both incubated with minocycline at different concentrations and for different time periods. Epidermal production of alpha-MSH, as evaluated by immunofluorescence and immunoperoxidase techniques, showed increased expression in both models. This neuropeptide, which has an anti-inflammatory activity (notably through production of IL-10, antagonism of IL-1 and inhibition of the chemotaxis of polymorphonuclear leukocytes), thus plays a role in the anti-inflammatory action of minocycline.

In vitro modulation of keratinocyte wound healing integrins by zinc, copper and manganese

Although the trace elements zinc, copper and manganese are used in vivo for their healing properties, their mechanism of action is still only partially known. Some integrins expressed by basal layer keratinocytes play an essential part in healing, notably alpha2beta1, alpha3beta1, alpha6beta4 and alphaVbeta5, whose expression and distribution in epidermis are modified during the re-epithelialization phase. This study demonstrates how the expression of these integrins are modulated in vitro by trace elements. Integrin expression was studied in proliferating keratinocytes in monolayer cultures and in reconstituted skin that included a differentiation state. After 48 h incubation with zinc gluconate (0.9, 1.8 and 3.6 microg/mL), copper gluconate (1, 2 and 4 microg/mL), manganese gluconate (0.5, 1 and 2 microg/mL) and control medium, integrin expression was evaluated by FACScan and immunohistochemistry. Induction of alpha2, alpha3, alphaV and alpha6 was produced by zinc gluconate 1.8 microg/mL in monolayers, of alpha2, alpha6 and beta1 by copper gluconate 2 and 4 microg/mL and of all the integrins studied except alpha3 by manganese gluconate 1 microg/mL. Thus, alpha6 expression was induced by all three trace elements. The inductive effect of zinc was particularly notable on integrins affecting cellular mobility in the proliferation phase of wound healing (alpha3, alpha6, alphaV) and that of copper on integrins expressed by suprabasally differentiated keratinocytes during the final healing phase (alpha2, beta1 and alpha6), while manganese had a mixed effect.

Comparative study of the in vitro inflammatory activity of three nickel salts on keratinocytes

Nickel, the allergen of contact dermatitis, induces the in vitro production of inflammation markers such as intracellular adhesion molecule-1, interleukin-1 and tumour necrosis factor-alpha by keratinocytes. The purpose of our study was to compare the effect in vitro of different nickel salts on keratinocyte activation in order to determine whether this process depends on the nature of the salt used. Cultured keratinocytes were incubated with three nickel salts for 24 h in MCDB153 medium without hydrocortisone. Nickel gluconate, nickel sulphate and nickel chloride were each used at four concentrations: 5.10(-5) M, 1.10(-4) M and 1.10 (-3) M. Keratinocyte activation was studied through the production of three inflammation markers: intracellular adhesion molecule-1, tumour necrosis factor-alpha and very late antigen-3 (an integrin with increased expression during contact dermatitis). Marker production was detected by immunocytochemistry and flow cytometry. Tumour necrosis factor-alpha production and intracellular adhesion molecule-1 and very late antigen-3 expression increased with addition of the three nickel salts, becoming maximal for nickel gluconate 1.10(-4) M. In a subsequent experiment, zinc gluconate (an anti-inflammatory molecule) at 9 micrograms/ml reduced the very late antigen-3 expression induced by nickel gluconate 1.10(-4) M. Therefore, this study enabled us to determine the concentration of a nickel salt (nickel gluconate) inducing optimal keratinocyte activation in our culture conditions and also indicated the potential interest of very late antigen-3 as an inflammation marker.

Control of growth and differentiation of normal human epithelial cells through the manipulation of reactive nitrogen species

In this work, we addressed the issue of whether exogenous NO and ONOO- (peroxynitrite) are able to alter growth, viability and/or differentiation of normal epithelial cells using cultured normal human keratinocytes as a model. 3-Morpholino-sydnonimine (SIN-1), a donor of both NO and O2(-)., leading to the production of ONOO-, dose-dependently inhibited growth of human keratinocytes without loss of viability. This inhibitory effect was lowered when SIN-1 was transformed into a pure NO donor by scavenging O2(-). with superoxide dismutase/catalase. Finally, scavenging NO release from SIN-1 with carboxy-1H-imidazol-1-yloxy,2-(4-carboxyp henyl)-4,5-dihydro-4,4,5,5 -tetramethyl-3-oxide (PTIO) resulted in a loss of the inhibitory effect of SIN-1. Together these findings suggest that both ONOO- and NO exert a growth inhibitory effect on human keratinocytes without cytotoxicity. Further support for this conclusion came from the treatment of human keratinocytes with the NO. donor propanamine 3-(2-hydroxy-2-nitroso-1-propyl hydrazino) or with authentic peroxynitrite. Moreover, only SIN-1 or peroxynitrite, and not NO, was able to trigger the expression of markers of terminal differentiation in human keratinocytes. From a physiological perspective, the ability of peroxynitrite, a known genotoxic and potentially carcinogenic agent, to direct proliferating keratinocytes towards terminal differentiation may be crucial to protect the genomic stability of this barrier epithelium.