Bacterial flora in psoriasis

The Role of Epigenetic Factors in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease, the prevalence of which is increasing. Genetic, genomic, and epigenetic changes play a significant role in the pathogenesis of psoriasis. This review summarizes the impact of epigenetics on the development of psoriasis and highlights challenges for the future. The development of epigenetics provides a basis for the search for genetic markers associated with the major histocompatibility complex. Genome-wide association studies have made it possible to link psoriasis to genes and therefore to epigenetics. The acquired knowledge may in the future serve as a solid foundation for developing newer, increasingly effective methods of treating psoriasis. In this narrative review, we discuss the role of epigenetic factors in the pathogenesis of psoriasis.

The causal relationship between psoriasis and artificial joint re-operation after arthroplasty: A two-sample Mendelian randomization study

BACKGROUND

Psoriasis is observationally associated with a higher risk of complications of arthroplasty; however, the causal effects of psoriasis on complications of arthroplasty are yet to be established. This study was to explore the causal effect of psoriasis on artificial joint re-operation after arthroplasty through two-sample Mendelian randomization (MR).

METHODS

In the MR analysis, psoriasis was selected as the exposure in this study while single-nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS) were selected as the instrumental variables (IVs). Summary statistics data on artificial joint re-operation was extracted from publicly available GWAS data, including 218 792 European descent individuals. MR analysis was performed using the standard inverse variance weighted method (IVW). Furthermore, MR Egger, weighted median, simple mode, weighted mode, and the MR-PRESSO (Mendelian Randomization Pleiotropy Residual Sum and Outlier) test were also done to verify the results. Finally, the sensitivity analysis was executed.

RESULTS

The IVW showed that psoriasis increases the risk of artificial joint re-operation (OR = 1.12; 95% CI = (1.01, 1.25); p = 0.036). This outcome was also verified by other methods including weighted median (OR = 1.16; 95% CI = (1.03, 1.31); p = 0.015), MR Egger (OR = 1.22; 95% CI = (1.03, 1.44); p = 0.038), and weighted mode (OR = 1.16; 95% CI = (1.03, 1.30); p = 0.025). No heterogeneity and directional pleiotropy were observed upon sensitivity analysis.

CONCLUSION

The present study showed that psoriasis has a potential causal effect on artificial joint re-operation after arthroplasty. Further studies are warranted to elucidate the underlying mechanisms of causal associations between psoriasis on re-operation.

The effect of autoimmune skin disorders on post-operative outcomes following arthroplasty

INTRODUCTION

The impact of autoimmune skin disorders on post-operative outcomes after TJA is conflicting and studies are limited by small sample sizes. The purpose of this study is to analyze a range of common autoimmune skin disorders and identify whether an increased risk of post-operative complication exists after total joint arthroplasty.

METHODS

Data was collected from NIS database for patients diagnosed with autoimmune skin disorder (psoriasis, lupus, scleroderma, atopic dermatitis) and who underwent total hip arthroplasty (THA), total knee arthroplasty (TKA), or other TJA (shoulder elbow, wrist, ankle) between 2016 and 2019. Demographic, social, and comorbidity data was collected. Multivariate regression analyses were performed to assess the independent influence of autoimmune skin disorder on each post-operative outcome including implant infection, transfusion, revision, length of stay, cost, and mortality.

RESULTS

Among 55,755 patients with autoimmune skin disease who underwent TJA, psoriasis was associated with increased risk of periprosthetic joint infection following THA (odds ratio 2.44 [1.89-3.15]) and increased risk of transfusion following TKA (odds ratio 1.33 [1.076-1.64]). Similar analyses were performed for systemic lupus erythematosus, atopic dermatitis, and scleroderma, however no statistically significant associations were observed in any of the six collected post-operative outcomes.

CONCLUSION

This study suggests psoriasis is an independent risk factor for poorer post-operative outcomes following total joint arthroplasty, however similar risk was not observed for other autoimmune skin disorders such as lupus, atopic dermatitis, or scleroderma.

Psoriasis and Post-Surgical Infections in Primary Total Knee Arthroplasty: An Analysis of 10,727 Patients

BACKGROUND

Psoriasis is a dermatologic condition characterized by erythematous plaques that may increase wound complications and deep infections following total knee arthroplasty (TKA). There is a paucity of evidence concerning the association of this disease and complications after TKA. This study aimed to determine if patients who have psoriasis vs non-psoriatic patients have differences in demographics and various comorbidities as well as post-operative infections, specifically the following: (1) wound complications; (2) cellulitic episodes; and (3) deep surgical site infections (SSIs).

METHODS

We identified 10,727 patients undergoing primary TKA utilizing an institutional database between January 1, 2017 and April 1, 2019. A total of 133 patients who had psoriasis (1.2%) were identified using International Classification of Diseases, Tenth Revision codes and compared to non-psoriatic patients. The rate of wound complications, cellulitic episodes, and deep SSIs were determined. After controlling for age and various comorbidities, multivariate analyses were performed to identify the associated risks for post-operative infections.

RESULTS

Psoriasis patients showed an increased associated risk of deep SSIs (3.8%) compared to non-psoriasis patients (1.2%, P = .023). Multivariate analyses demonstrated a significant associated risk of deep SSIs (odds ratio 7.04, 95% confidence interval 2.38-20.9, P < .001) and wound complications (odds ratio 4.44, 95% confidence interval 1.02-19.2, P = .047).

CONCLUSION

Psoriasis is an inflammatory dermatologic condition that warrants increased pre-operative counseling, shared decision-making, and infectious precautions in the TKA population given the increased risk of wound complications and deep SSIs. Increased vigilance is required given the coexistence of certain comorbidities with this population, including depression, substance use disorder, smoking history, gastroesophageal reflux disease, and inflammatory bowel disease.

Risks for Staphylococcus aureus colonization in patients with psoriasis: a systematic review and meta-analysis

Evidence on whether patients with psoriasis have a higher risk for staphylococcal colonization than healthy controls remains controversial. To synthesize the current literature, we performed a systematic review on the prevalence and relative risk (RR) of Staphylococcus aureus colonization in patients with psoriasis. We modified the QUADAS-2 instrument to assess the reporting quality of individual studies and applied random-effects models in meta-analysis. Overall we identified 21 eligible studies, of which 15 enrolled one or more comparison groups. The pooled prevalence of staphylococcal colonization in patients with psoriasis was 35·3% [95% confidence interval (CI) 25·0-45·6] on lesional skin and 39·2% (95% CI 33·7-44·8) in the nares. Patients with psoriasis were 4·5 times more likely to be colonized by S. aureus than healthy controls were on the skin (RR 5·54, 95% CI 3·21-9·57) and 60% more in the nares (RR 1·60, 95% CI 1·11-2·32). Cutaneous and nasal colonization by meticillin-resistant S. aureus also appeared higher in patients with psoriasis (pooled prevalence 8·6%) than in healthy controls (2·6%), yet the difference was not statistically significant (P = 0·74). In contrast, despite of a similar risk for nasal staphylococcal colonization (RR 0·67, 95% CI 0·38-1·18), patients with psoriasis were less likely to carry S. aureus on lesional skin than atopic patients (RR 0·64, 95% CI 0·40-1·02). In summarizing the current literature, we found that patients with psoriasis were at an increased risk for staphylococcal colonization compared with healthy individuals. Prospective studies on how bacterial loads correlate with disease activity can guide the clinical management of bacterial colonization while preventing the emergence of drug-resistant strains.

Complications of Primary Total Knee Arthroplasty Among Patients With Rheumatoid Arthritis, Psoriatic Arthritis, Ankylosing Spondylitis, and Osteoarthritis

BACKGROUND

Although several studies have reported outcomes of primary total knee arthroplasty (TKA) in patients with rheumatoid arthritis, very little has been reported on the outcomes of this procedure in patients with other inflammatory arthritides.

METHODS

This study used a national database to evaluate 90-day postoperative complication rates, readmission rates, and revision rates after TKA in patients with inflammatory arthritis. Patients with rheumatoid arthritis (n = 153,531), psoriatic arthritis (n = 7,918), and ankylosing spondylitis (n = 4,575) were compared with patients with osteoarthritis (n = 1,751,938) who underwent TKA from 2005 to 2012.

RESULTS

The rates of systemic complications, infection, revision, and 90-day readmission after TKA in patients with different types of inflammatory arthritis were significantly higher than those in control patients with osteoarthritis (P < 0.0001). No differences were found in the rates of systemic or local complications, revision, or readmission among the types of inflammatory arthritis.

CONCLUSION

Inflammatory arthritis is associated with increased rates of perioperative complications, revision, and 90-day readmission after primary TKA.

LEVEL OF EVIDENCE

Level III.

A systematic review and meta-analysis on Staphylococcus aureus carriage in psoriasis, acne and rosacea

Staphylococcus aureus might amplify symptoms in chronic inflammatory skin diseases. This study evaluates skin and mucosal colonization with S. aureus in patients with psoriasis, acne and rosacea. A systematic literature search was conducted. Both odds ratios (OR) for colonization in patients versus controls and the prevalence of colonization in patients are reported. Fifteen articles about psoriasis and 13 about acne (12 having a control group) were included. No study in rosacea met our inclusion criteria. For psoriasis, one study out of three controlled studies showed increased skin colonization (OR 18.86; 95 % confidence interval [CI] 2.20-161.99). Three out of the five studies that reported on nasal colonization showed significant ORs varying from 1.73 (95 % CI 1.16-2.58) to 14.64 (95 % CI 2.82-75.95). For acne one of the three studies that evaluated skin colonization reported a significant OR of 4.16 (95 % CI 1.74-9.94). A relation between nasal colonization and acne was not found. Limitations in study design and low sample sizes should be taken into consideration when interpreting the results. Colonisation with S. aureus seems to be increased in patients with psoriasis. This bacterial species, known for its potential to induce long-lasting inflammation, might be involved in psoriasis pathogenesis. Information on acne is limited. Prospective controlled studies should further investigate the role of S. aureus in chronic inflammatory skin diseases.

Nonrheumatoid Inflammatory Arthroses of the Hand and Wrist

Various inflammatory and autoimmune conditions affecting joints of the hand and wrist can present with symptoms similar to those of rheumatoid arthritis. The most common of these nonrheumatoid arthroses are psoriatic arthritis, systemic lupus erythematosus, and systemic sclerosis. Management of these and several other conditions is typically medical in nature and continues to evolve with the development of biologically targeted medications. Surgical treatment is not frequently used but can be efficacious for severe cases to alleviate symptoms and correct deformities.

Prevention of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) has moved into the first place as the cause of failure following total knee arthroplasty (TKA). Recent studies have shown that PJI results in higher mortality in patients than many cancers. The economic burden of treating PJI is likely to exceed $1 billion this year in the US. Thus, it is paramount that all efforts are invested to prevent this dreaded complication after total joint arthroplasty (TJA). This article summarizes some of the most effective and proven strategies for prevention of PJI. It is hoped that the article will be of benefit to the readers of the journal.

Staphylococcus aureus inhibits terminal differentiation of normal human keratinocytes by stimulating interleukin-6 secretion

BACKGROUND

Staphylococcus aureus (S. aureus) is found on the skin of approximately 90% of patients with atopic dermatitis and approximately 20% of apparently healthy subjects. S. aureus induces keratinocytes and immune cells to secrete immunoregulatory factors that cause epidermal barrier dysfunction in atopic skin.

OBJECTIVE

This study examined factors that cause epidermal permeability barrier dysfunction in skin colonized by S. aureus.

METHODS

We examined the effect of S. aureus on keratinocyte differentiation in the stratum corneum (SC) of in vivo skin, normal human keratinocytes (NHKs) and a reconstructed human epidermis (RHE) model. The fold change in expression of the terminal differentiation markers and the level of secreted cytokines were investigated.

RESULTS

The SC displayed decreased expression of keratin 10 (KRT 10). NHKs treated with S. aureus extracts increased expression of interleukin (IL)-6 and significantly reduced expression of the terminal differentiation markers KRT 1, KRT 10, loricrin (LOR), and filaggrin (FLG); however, the expression of basal layer markers (KRT 5, KRT 14) remained unchanged. Treatment of NHKs with an anti-IL-6 antibody in combination with IL-6 or the S. aureus extracts inhibited the decrease in KRT 10 mRNA or protein expression. After the RHEs were exposed to the S. aureus extracts, KRT 1 and KRT 10 protein levels decreased.

CONCLUSIONS

These findings suggest that S. aureus inhibits the terminal differentiation of keratinocytes by stimulating IL-6 secretion.

Microbial ecology of the skin in the era of metagenomics and molecular microbiology

The skin is the primary physical barrier between the body and the external environment and is also a substrate for the colonization of numerous microbes. Previously, dermatological microbiology research was dominated by culture-based techniques, but significant advances in genomic technologies have enabled the development of less-biased, culture-independent approaches to characterize skin microbial communities. These molecular microbiology approaches illustrate the great diversity of microbiota colonizing the skin and highlight unique features such as site specificity, temporal dynamics, and interpersonal variation. Disruptions in skin commensal microbiota are associated with the progression of many dermatological diseases. A greater understanding of how skin microbes interact with each other and with their host, and how we can therapeutically manipulate those interactions, will provide powerful tools for treating and preventing dermatological disease.

Bacterial skin flora and contamination of blood components: do we defer blood donors wisely?

BACKGROUND AND OBJECTIVES

Bacterial infection through contaminated blood is currently the greatest infection risk in relation to a transfusion. Deferral of prospective blood donors with a skin disorder is a common practise, because bacteria usually originate from the donor's skin. The effectiveness of current deferral guidelines to prevent the bacterial contamination of blood has not been assessed.

MATERIALS AND METHODS

We recruited 55 blood donors with a skin disorder that prevented donation, and matched three controls for each case. The donors filled out a questionnaire and one bacterial culture sample was taken from venepuncture forearm skin.

RESULTS

The median total number of colony forming skin bacteria was significantly higher in the cases (224 CFUs per sample) than controls (105 CFU per sample). Staphylococcus aureus was significantly more often present on the skin in cases (49%) as compared to controls (7%). Regarding other bacterial genera, no difference between cases and controls was found.

CONCLUSIONS

This study shows that our current guidelines for deferral of blood donors with skin disorders effectively identifies individuals with a high number of bacteria on their skin, as well as S. aureus carriers. However, deferral due to skin disorders had only a minor impact on blood product contamination when compared to other actions.

Comparison of bacterial microbiota in skin biopsies from normal and psoriatic skin

Microorganisms have been implicated in the pathogenesis of psoriasis. Previous studies of psoriasis and normal skin have used swabs from the surface rather than skin biopsies. In this study, biopsies were taken from 10 patients with psoriasis and 12 control subjects from unmatched sites. Samples were analysed with massive parallel pyrosequencing on the 454 platform targeting the 16S rRNA gene and the variable regions V3-V4. The samples grouped into 19 phyla, 265 taxon and 652 operational units (OTUs) at 97% identity. A cut-off abundance level was set at 1%. The three most common phyla in both normal and psoriasis skin were Firmicutes (39% psoriasis, 43% normal skin), Proteobacteria (38% psoriasis, 27% normal skin) and Actinobacteria (5% psoriasis, 16% normal skin, p = 0.034). In trunk skin, Proteobacteria were present at significantly higher levels in psoriasis compared to controls (52 vs. 32%, p = 0.0113). The commonest genera were Streptococci in both psoriasis (32%) and normal skin (26%). Staphylococci were less common in psoriasis (5%) than in controls (16%), as were Propionibacteria (psoriasis 0.0001669%, controls 0.0254%). Both Staphylococci and Propionibacteria were significantly lower in psoriasis versus control limb skin (p = 0.051, 0.046, respectively). This study has shown some differences in microbiota between psoriasis and normal skin. Whether these are of primary aetiological significance, or secondary to the altered skin of psoriasis remains to be determined.

The Human Lung Microbiome

The human lower respiratory tract is considered sterile in normal healthy individuals (Flanagan et al., 2007; Speert, 2006) despite the fact that every day we breathe in multiple microorganisms present in the air and aspirate thousands of organisms from the mouth and nasopharynx. This apparent sterility is maintained by numerous interrelated components of the lung physical structures such as the mucociliary elevator and components of the innate and adaptive immune systems (discussed below) (reviewed in (Diamond et al., 2000; Gerritsen, 2000)). However, it is possible that the observed sterility might be a result of the laboratory practices applied to study the flora of the lungs. Historically, researchers faced with a set of diseases characterized by a changing and largely cryptic lung microbiome have lacked tools to study lung ecology as a whole and have concentrated on familiar, cultivatable candidate pathogens.

Mechanical and metabolic injury to the skin barrier leads to increased expression of murine β-defensin-1, -3, and -14

Protection of the skin against microbiological infection is provided by the permeability barrier and by antimicrobial proteins. We asked whether the expression of murine β-defensins (mBDs)-1, -3, and -14-orthologs of human β-defensins hBD-1, -2, and -3, respectively--is stimulated by mechanically/physicochemically (tape stripping or acetone treatment) or metabolically (essential fatty acid-deficient (EFAD) diet) induced skin barrier dysfunction. Both methods led to a moderate induction of mBD-1 and mBD-14 and a pronounced induction of mBD-3 mRNA. Protein expression of the mBDs was increased as shown by immunohistology and by western blotting. Artificial barrier repair by occlusion significantly reduced the increased expression of mBD-14 after mechanical injury and of all three mBDs in EFAD mice, supporting an interrelationship between permeability and the antimicrobial barrier. mBD-3 expression was stimulated in vitro by tumor necrosis factor-α (TNF-α), and a neutralizing anti-TNF-α antibody significantly reduced increased mBD-3 expression after barrier injury in mouse skin, indicating that induction of mBD-3 expression is mediated by cytokines. The expression of mBD-14 was stimulated by transforming growth factor-α and not by TNF-α. In summary, we demonstrated upregulation of mBD1, -3, and -14 after mechanically and metabolically induced skin barrier disruption, which may be an attempt to increase defense in the case of permeability barrier dysfunction.

Expression of Toll-like Receptor 2 in Cultured Human Keratinocytes: The Effect of Bacterial Antigens, Cytokines and Calcium Concentration

BACKGROUND

Toll-like receptors (TLRs) are expressed by human epidermal keratinocytes and are involved in immune responses.

OBJECTIVE

The goal of this was to investigate the expression of TLR2 in response to bacterial antigens, cytokines, and different calcium concentrations.

METHODS

The expression of TLR2 was assessed after stimulation by lipoteichoic acid (LTA) and streptolysin O (SLO). In addition, TLR2 expression was evaluated after treatment with IFN-gamma and TNF-alpha, and different concentrations of calcium. The expression levels of TLR2 mRNA and protein were studied using RT-PCR and Western blot analysis.

RESULTS

Cultured human epidermal keratinocytes constitutively expressed TLR2 and the expression was stimulated by LTA and SLO; in addition, IFN-gamma and TNF-alpha upregulated TLR2 expression. However, the changes in TLR2 expression associated with the calcium concentrations were insignificant.

CONCLUSION

TLR2 expression increased with the concentration and duration of bacterial pathogens and this increase was amplified by several cytokines, from activated keratinocytes and other cells.

Serum and tissue expression of transforming growth factor beta 1 in psoriasis

BACKGROUND

In psoriasis, keratinocyte hyperplasia may be explained by imbalance of growth factors responsible for epidermal proliferation and altered metabolism of their receptors. Transforming growth factor-beta 1 (TGF-beta1) implications in the pathogenesis of psoriasis can be attributed to several mechanisms besides keratinocyte cell cycle inhibition.

OBJECTIVES

To evaluate the relation between serum and tissue levels of TGF-beta1 in psoriasis and their correlation with disease parameters.

PATIENTS AND METHODS

Serum and punch biopsy of involved and non-involved skin of 22 patients with psoriasis vulgaris and 10 controls were collected for quantification of TGF-beta1 by enzyme-linked immunosorbent assay kit.

RESULTS

Serum level of TGF-beta1 in psoriatic patients was higher than controls in a statistically non-significant manner. Correlations between serum level of TGF-beta1 and extent of the disease (P = 0.007) and Psoriasis Area and Severity Index (PASI) score (P = 0.005) were observed. Mean tissue levels of TGF-beta1 were highest in psoriatic lesions in contrast to normal skin of psoriatic patients and healthy controls, but not statistically significant. Correlation between tissue levels of TGF-beta1 in non-involved skin and extent of the disease (P = 0.007) and PASI score (P = 0.013) was detected. Correlation was detected between levels of TGF-beta1 in psoriatic plaques and serum of patients (P = 0.035), but not between levels of TGF-beta1 in non-involved skin and serum.

CONCLUSIONS

Tissue expression of TGF-beta1 in psoriasis may be affected by the stage of development of the lesion. The direct relation between TGF-beta1 in psoriatic plaques and serum imply that the mechanisms for TGF-beta1 production and release in both these compartments may be related.

Effects of antikeratin 16 antibodies on the expression of Toll-like receptors 2 and 4 in keratinocytes

Innate immunity plays an important role in psoriasis. The possible role of Toll-like receptors (TLRs) in the activation of innate immunity in psoriasis remains unknown. Serum antikeratin 16 (anti-K16) autoantibody levels are raised in patients with psoriasis. The aim of this study was to investigate the effects of anti-K16 antibodies on TLR2 and TLR4 expression in keratinocytes. Keratinocytes were incubated with mouse anti-K16 monoclonal antibodies. Levels of TLR2 and TLR4 were measured by quantitative real-time PCR and flow cytometry. TLR2 mRNA level was increased by 1.73-fold, 1.60-fold and 2.52-fold at 6, 24 and 36 h after incubation, respectively. TLR4 mRNA level was increased by 3.62-fold and 2.21-fold at 12 and 36 h, respectively. TLR2 protein expression was increased by 1.73-fold on the cell membrane and 2.22-fold in cell membrane and intracytoplasmic locations. There was no change in TLR4. The results of this study indicate that anti-K16 antibodies may be a modulator of TLRs.

Innate immune modulation of keratinocytes by antikeratin 16 antibodies

BACKGROUND

Chronic inflammation of psoriatic lesions may be due to an exaggerated innate immune response. Toll-like receptors (TLRs) are expressed by keratinocytes in psoriasis. Antikeratin 16 autoantibodies (AK16 autoAbs) are increased in serum from patients with psoriasis. Whether the elevated AK16 autoAbs play a role in psoriasis by exaggerating innate immune response is still unknown.

OBJECTIVE

To prove that AK16 autoAbs are involved in psoriasis, by exaggerating the innate immune response of keratinocytes.

METHODS

Keratinocytes were incubated with mouse antikeratin 16 monoclonal antibodies (AK16 mAbs) for a given length of time. Levels of TLR2, TLR4, involucrin and nascent polypeptide-associated complex (NACA) mRNA were measured by quantitative RT-PCR. Levels of TLR2, TLR4, involucrin, NF-kappaB and actin-related protein 2 (ARP2) protein were measured by flow cytometry or Western blot. Effects of the mAbs on keratinocytes were studied using DNA synthesis and cell cycle analysis.

RESULTS

TLR2 mRNA increased 1.73-, 1.60- and 2.52-fold at 6, 24 and 36 h after incubation, respectively. TLR4 mRNA increased 3.62- and 2.21-fold after 12 and 36 h. Involucrin mRNA increased 2.33- and 2.0-fold after 12 and 36 h. NACA mRNA increased 5.93-, 3.35- and 3.54-fold after 12, 24 and 36 h. TLR2 protein increased 1.73-fold on the cell membrane and 2.22-fold on membrane plus intracytoplasm. NF-kappaB increased 2.64-fold after 6 h. Involucrin protein increased 4.5-fold, whereas Arp2 protein decreased 1.82-fold, after 36 h. The mAbs had an inhibitory effect on cultured keratinocytes.

CONCLUSION

AK16 autoAbs may be involved in the chronic inflammation of psoriasis lesions by promoting TLR expression.

Peptidoglycan and peptidoglycan-specific Th1 cells in psoriatic skin lesions

We have previously demonstrated, in psoriatic skin lesions, the presence of a subset of dermal CD4+ T cells that produce interferon-gamma (IFN-gamma) in response to a mixture of cell wall proteins extracted from group A streptococci. However, the identity of the antigen(s) involved is unknown. To investigate the hypothesis that peptidoglycan (PG), the major constituent of the streptococcal cell wall, acts as a T cell activator in psoriasis, we performed in situ analysis to detect antigen-presenting cells containing PG in lesional versus non-lesional skin, and determined proliferation and IFN-gamma responses of lesional skin T cells. Increased numbers of PG-containing cells were detected in the dermal papillae and cellular infiltrates of guttate and chronic plaque skin lesions compared with normal and non-lesional psoriatic skin. A varying proportion of these were CD68+ macrophages, but the remaining cells did not double stain for either Langerhans' or dendritic cell markers. Psoriatic dermal streptococcal-specific CD4+ T cell lines proliferated and produced IFN-gamma in a self HLA-DR allele-restricted manner in response to streptococcal PG, excluding mitogenic or superantigenic stimulation, but were unresponsive to staphylococcal PG. Similarly, psoriatic staphylococcus-specific T cell lines recognized staphylococcal, but not streptococcal, PG by IFN-gamma production. The presence of PG-containing macrophages in close association with PG-specific CD4+ T cells in lesional skin suggests that PG may be responsible, at least in part, for T cell activation in psoriasis.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Normal keratinocytes express Toll-like receptors (TLRs) 1, 2 and 5: modulation of TLR expression in chronic plaque psoriasis

BACKGROUND

Toll-like receptors (TLRs) are part of the innate immune system involved in the response to microbial pathogens. TLR2 recognizes various ligands expressed by Gram-positive bacteria, while TLR3, TLR4 and TLR5 are specific for double-stranded RNA, Gram-negative lipopolysaccharides and bacterial flagellin, respectively.

OBJECTIVES

To determine, firstly, whether epidermal keratinocytes of normal skin express TLRs and, secondly, whether modulation of TLR expression occurs in psoriasis, an inflammatory skin disease associated with certain microorganisms such as streptococci, staphylococci and yeasts.

METHODS

Eight samples of normal, and 15 samples of lesional and nonlesional psoriatic skin were stained with polyclonal antibodies specific for TLR1-5 using an avidin-biotin-peroxidase technique.

RESULTS

Epidermal keratinocytes in normal skin constitutively expressed TLR1, TLR2 and TLR5, while TLR3 and TLR4 were, in most cases, barely detectable. Cytoplasmic TLR1 and TLR2 were expressed throughout the epidermis, with higher staining of the latter on basal keratinocytes, while TLR5 expression was concentrated in the basal layer. In contrast, in lesional epidermis from patients with psoriasis, TLR2 was more highly expressed on the keratinocytes of the upper epidermis than on the basal layer, while TLR5 was downregulated in basal keratinocytes compared with corresponding nonlesional psoriatic epidermis. In addition, nuclear TLR1 staining was observed in the upper layers of both nonlesional and lesional psoriatic epidermis, but not in that of normal skin.

CONCLUSIONS

These findings suggest that TLRs expressed by epidermal keratinocytes constitute part of the innate immune system of the skin. The relevance of altered keratinocyte TLR expression in psoriasis remains to be determined.

Microbiology of infected pustular psoriasis lesions

BACKGROUND

Bacterial infections can occur in lesions of pustular psoriasis (PP). The objective of this study was to establish the aerobic and anaerobic microbiology of secondarily infected PP.

METHODS

A retrospective 10-year review was carried out of clinical and microbiology laboratory records from patients with secondarily infected PP lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria.

RESULTS

Bacterial growth was noted in 23 specimens. Aerobic or facultative anaerobic bacteria only were present in 12 patients (52%), anaerobic bacteria only in four (17%), and mixed anaerobic-aerobic flora was present in seven (30%). Thirty-six isolates were recovered (1.6 per specimen), 23 aerobic or facultative bacteria and 13 strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (15 isolates), Group D Enterococcus (two isolates), and Escherichia coli (two isolates). The predominant anaerobes were Peptostreptococcus spp. (six isolates) and Bacteroides fragilis group, Propionibacterium acnes, and pigmented Prevotella spp. in two each. Single bacterial isolates were recovered in 14 patients (61%), 11 of which were S. aureus. Nineteen of the organisms isolated from 18 patients (78%) produced the enzyme beta-lactamase. S. aureus was isolated from all body sites. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric Gram-negative rods and Bacteroides fragilis group predominated in lesions on the legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Fusobacterium spp. were most frequently recovered in lesions of the hand.

CONCLUSIONS

The polymicrobial etiology of secondarily infected PP lesions and the association of bacterial flora with the anatomic site of the lesions were demonstrated.

Risk factors for colonization or infection due to methicillin-resistant Staphylococcus aureus in HIV-positive patients: a retrospective case-control study

OBJECTIVE

To determine the risk factors for colonization or infection with methicillin-resistant Staphylococcus aureus in human immunodeficiency virus (HIV)-infected patients.

DESIGN

Retrospective matched-pair case-control study.

SETTING

Continuity clinic and inpatient HIV service of a university medical center.

POPULATION

Patients with HIV infection from the general population of eastern and coastal Texas and from the Texas Department of Criminal Justice.

DATA COLLECTION

Patient charts and the AIDS Care and Clinical Research Program Database were reviewed for the following: age, race, number of admissions, total hospital days, presence of a central venous catheter, serum albumin, total white blood cell count and absolute neutrophil count, invasive or surgical procedures, any cultures positive for S. aureus, and a history of opportunistic illnesses, diabetes, or dermatologic diagnoses. Data also were collected on the administration of antibiotics, antiretroviral therapy, steroids, cancer chemotherapy, and subcutaneous medications.

RESULTS

In the univariate analysis, the presence of a central venous catheter, an underlying dermatologic disease, lower serum albumin, prior steroid therapy, and prior antibiotic therapy, particularly antistaphylococcal therapy or multiple courses of antibiotics, were associated with increased risk for colonization or infection with methicillin-resistant S. aureus. Multivariate analysis yielded a model that included presence of a central venous catheter, underlying dermatologic disease, broad-spectrum antibiotic exposure, and number of hospital days as independent risk factors for colonization or infection with methicillin-resistant S. aureus.

CONCLUSIONS

In our HIV-infected patient population, prior hospitalization, exposure to broad-spectrum antibiotics, presence of a central venous catheter, and dermatologic disease were risk factors for acquisition of methicillin-resistant S. aureus.

Insights into the pathogenesis of psoriasis and psoriatic arthritis

Psoriasis and its related arthritis are chronic inflammatory disorders affecting predominantly the skin and synovium. Although their etiology remains to be established, multiple factors seem to play important roles in their pathogenesis. These environmental (eg, infectious agents and trauma), genetic, and immunologic factors are reviewed in this article.

Interactions between non-immune host cells and the immune system during periodontal disease: role of the gingival keratinocyte

Periodontal disease and inflammatory dermatoses, such as psoriasis, are characterized by the accumulation of dense inflammatory infiltrates immediately beneath the epithelial cell layer of the gingiva and skin, respectively. Dermatologists are increasingly aware that the epidermal keratinocyte probably contributes to inflammatory disease progression by secreting a number of pro-inflammatory cytokines and expressing various adhesion molecules. In psoriatic lesions, it is now believed that epidermal keratinocytes may also act as antigen-presenting cells and participate directly in the superantigenic activation of T-cell clones, some of which may initiate, contribute to, or maintain the disease process. Although the role of the host response in periodontal disease has been extensively studied over the years, very little is known about the contribution of the gingival keratinocyte to the inflammatory response. The available published information is discussed in this review, and we suggest that, like its epidermal counterpart, the gingival keratinocyte may participate actively in the pathogenesis of periodontal disease.

Effect of an ointment containing boric acid, zinc oxide, starch and petrolatum on psoriasis

A randomized double-blind controlled trial was undertaken to study the efficacy of a cow udder ointment versus petroalatum alone. A total of 30 patients participated in the study. Sixteen patients completed the trial with 8 of 9 patients improving in the active group and 6 of 7 patients improving in the placebo group. This difference was not statistically significant. The use of a cow udder ointment for psoriasis cannot be supported, particularly with the potential for side effects.

Infectious complications of erythrodermic psoriasis

Severe morbidity and mortality may be associated with erythrodermic psoriasis, especially when complicated by septicemia. We describe five patients with erythrodermic psoriasis complicated by staphylococcal septicemia. In two, concurrent infection with HIV increased vulnerability to bacteremia.

Staphylococcal sepsis in HIV antibody seropositive psoriasis patients

The cases of three HIV-positive men with generalized psoriasis and staphylococcal sepsis are reported. In each case the skin appeared to be the source of infection. While the patients received antibiotic therapy, the psoriatic plaques resolved despite minimal or no topical treatment.

Staphylococcus aureus in atopic dermatitis and in nonatopic dermatitis

Skin colonization with Staphylococcus aureus (S. aureus) was examined in 30 patients with atopic dermatitis (AD), in 25 patients with nonatopic eczema (NAE) and in 30 individuals as healthy controls (HC). Bacteria growth was examined in aerobic cultures and the population densities per dish were estimated; S. aureus colonization was found in the eczematous skin of 24 of 30 (80%) AD patients and in 13 of 25 (52%) NAE patients (NS, p greater than 0.1). In nonaffected skin S. aureus colonization was found in 19 of 30 (63%) of all AD patients compared with 6 of 25 (24%) in NAE patients and 1 of 30 (3%) in HC, respectively (p less than 0.05). In nonaffected skin, coagulase negative strains of staphylococcus were found in 25 of 30 (84%) controls and in 18 of 25 (72%) NAE patients compared with 12 of 30 (40%) patients with AD. It seems that colonization with S. aureus is not a characteristic feature for atopic dermatitis but is a frequent event in damaged skin; significantly elevated values were also observed in nonatopic eczema. The degree of colonization may depend on the severity and duration of the eczematous lesions.

Microbiology of the skin: resident flora, ecology, infection

Humans exist in an environment replete with microorganisms, but only a few become resident on the skin surface. The skin possesses protective mechanisms to limit colonization, and the survival of organisms on the surface lies in part in the ability of the organisms to resist these mechanisms. Microbial colonization on the skin adds to the skin's defense against potentially pathogenic organisms. Although microbes normally live in synergy with their hosts, occasionally colonization can result in clinical infection. Common infections consist of superficial infections of the stratum corneum or appendageal structures that can respond dramatically to therapy but commonly relapse. In rare circumstances, these infections can be quite severe, particularly in immunocompromised patients or in hospitalized patients with indwelling foreign devices. These infections are often resistant to conventional antibiotics and can result in infection with other opportunistic pathogens.

Extractable immune complex in soluble substances from psoriatic scales

Soluble substances of psoriatic scales (Pso-exts) were analysed immunologically to detect immune complex (IC) related to the immune reactions in psoriatic lesions and compared with extracts of scales from a patient with erythroderma due to pityriasis rubra pilaris (PRP-exts) as control. Immunoelectrophoretically IgG, IgA and C3 were detected in Pso-exists, but in PRP-exists only IgG was seen as immunological reactive substances. When analysed by Sephadex G-200 column chromatography, IgG and IgA eluates were found in Pso-exts with a molecular weight of more than 200,000 daltons. By Raji cell assay, the IgG and IgA eluates were shown to have IC characteristics and they were the IC composed of IgG-IgA, which was also confirmed using anti-IgG affinity chromatography. The IC seemed to be binding the epidermal proteins as antigen. These findings suggest that deposits of immunoglobulins and complement in the stratum corneum of psoriatic lesions are not just secondary to the underlying inflammation in the dermis but that the IC detected is related to the immune reactions in psoriatic lesions.

Migration-stimulating effect of psoriatic scales on polymorphonuclear leukocytes

Several previous studies have demonstrated a chemotactic factor for white blood cells in extracts from psoriatic scales. In the present work, the question was studied whether chemotaxis is a primary or a secondary event in the development of a psoriatic lesion. The migration-stimulating properties of polymorphonuclear leukocytes of different extracts were determined by means of a modified Boyden technique. Aqueous extracts of psoriatic scales were good stimulators of migration of both autologous and homologous leukocytes. Uninvolved skin adjacent to psoriatic plaques (perilesional skin) has previously been shown to differ from control skin in various respects. Extracts of such perilesional skin of psoriatic patients did not have migration-stimulating properties. This result indicates that chemotaxis is a secondary event in the pathogenesis of psoriasis.

Chemokinetic and chemotactic factors in psoriasis scale extracts

Soluble solutions of psoriasis scale were prepared by extracting scales in 6 m urea and removing urea by dialysis. Extracts were tested for chemokinetic and chemotactic activity for human polymorphonuclear leukocytes and mononuclear cells in vitro using the migration under agarose assay. Five of 6 extracts demonstrated significant chemotactic activity for polymorphonuclear leukocytes, and 4 or 6 were also chemotactic for mononuclear cells. All extracts augmented random migration of polymorphonuclear leukoyctes (chemokinesis). Checkerboard epxeriments showed extracts were truly chemotactic as well as chemokinetic. The kinetics of polymorphonuclear leukocyte and mononuclear cell chemotaxis toward psoriasis scale extracts were similar to kinetics of chemotaxis toward a bacteria-derived chemotactic factor and zymosan-activated serum. Since zymosan-activated serum and purified C5a were not chemokinetic, psoriasis scale extract was more like a bacteria-culture supernate than these complement factors in augmenting random migration of polymorphonuclear leukocytes. Substances in psoriasis scale may be capable of influencing the inflammatory response.