Nils Boehm

Proinflammatory cytokine profiling of tears from dry eye patients by means of antibody microarrays.

PURPOSE In the pathogenesis of keratoconjunctivitis sicca, immune processes are thought to play an important role. However, the exact details of the pathomechanisms are still unknown. In this study, the expression patterns of proinflammatory cytokines in the tears of patients with different subtypes of dry eye were analyzed. METHODS One hundred forty-three subjects subdivided into healthy controls (CTRL, n = 38), patients with aqueous-deficient dry eye (DRYaq, n = 35), patients with changes of the lipid layer (DRYlip, n = 36), and patients with a combination of both (DRYaplip, n = 34) were examined. Expression patterns of proteins (e.g., IL-1β, IL-6, ITNF-α, and IFN-γ) were examined using an advanced antibody microarray approach. RESULTS Several highly significant differences in the cytokine levels of dry eye patients compared with healthy controls were detected. Patients with DRYaq or those with DRYaplip showed elevated levels for most of the tested proteins. For example, IL-1β was found to be elevated 2.4-fold in DRYaq patients and 2.75-fold in DRYaqlip patients (both P < 8.00E-6). The detected amounts of protein in DRYlip patients and in healthy controls showed only minimal differences (fold increase/decrease for all proteins >1.2; P > 5.00E-1). CONCLUSIONS The similarity between the profiles of healthy controls and DRYlip patients justifies the assumption that the pathomechanism of this dry eye subtype is based on mechanisms other than inflammation, whereas it seems to be the case for DRYaq patients.

Enhanced Insight into the Autoimmune Component of Glaucoma: IgG Autoantibody Accumulation and Pro-Inflammatory Conditions in Human Glaucomatous Retina

Background There is accumulating evidence that autoimmune components, such as autoantibodies and autoantibody depositions, play a role in the pathogenesis of neurodegenerative diseases like Alzheimeŕs disease or Multiple Sclerosis. Due to alterations of autoantibody patterns in sera and aqueous humor, an autoimmune component is also assumed in the pathogenesis of glaucoma, a common reason for irreversible blindness worldwide. So far there has been no convincing evidence that autoantibodies are accumulated in the retina of glaucoma patients and that the local immune homeostasis might be affected. Methods and Results Six human glaucomatous donor eyes and nine samples from donors with no recorded ocular disease were included. Antibody microarrays were used to examine the patterns of pro-inflammatory proteins and complement proteins. Analysis of TNF-α and interleukin levels revealed a slight up-regulation exclusively in the glaucomatous group, while complement protein levels were not altered. IgG autoantibody accumulations and/or cellular components were determined by immunohistology (n = 4 per group). A significantly reduced number of retinal ganglion cells was found in the glaucomatous group (healthy: 104±7 nuclei/mm, glaucoma: 67±9 nuclei/mm; p = 0.0007). Cell loss was accompanied by strong retinal IgG autoantibody accumulations, which were at least twice as high as in healthy subjects (healthy: 5.0±0.5 IgG deposits/100 cells, glaucoma: 9.4±1.9 IgG deposits/100 cells; p = 0.004). CD27+ cells and CD27+/IgG+ plasma cells were observed in all glaucomatous subjects, but not in controls. Conclusion This work provides serious evidence for the occurrence of IgG antibody deposition and plasma cells in human glaucomatous retina. Moreover, the results suggest that these IgG deposits occurred in a pro-inflammatory environment which seems to be maintained locally by immune-competent cells like microglia. Thereby, glaucoma features an immunological involvement comparable to other neurodegenerative diseases, but also shows a multifactorial pathomechanism, which diverges and might be linked to the specific nature of both eye and retina.

New insights into autoantibody profiles from immune privileged sites in the eye: A glaucoma study

Glaucoma is a chronic neurodegenerative disease and one of the leading causes of blindness. Autoantibody based immune processes are assumed to be involved in its pathogenesis. However, it is still unclear to what extent autoantibody patterns found in the eye (aqueous humor) are congruent to systemic autoantibodies (blood). Consistency would underline the specificity of known serum antibody markers for glaucoma. In this study we used antigen microarrays to analyze autoantibody reactivities in sera and corresponding aqueous humor samples of primary open-angle glaucoma patients (N=37) and non-glaucomatous controls (N=31). Compared to control subjects several divergent immunoreactivities were identified for the glaucoma group in both body fluids. Interestingly, 20% of the tested antigens revealed increased immunoreactivities (e.g., against HSP27, MBP, and α-1-antitrypsin) and 7.5% decreased immunoreactivities (e.g., against GFAP and β-L-crystallin), thus demonstrating a significant alteration of the autoantibody profiles in glaucoma patients. Using an artificial neural network in combination with a unique serum autoantibody pattern on prospective sera we were able to detect glaucoma with a specificity and sensitivity of approximately 93%. The intraindividual comparison revealed a strong correlation of detected immunoreactivities in sera and comparative aqueous humor samples in both study groups. These results emphasize the specificity of immunoreactions found in blood samples of glaucoma patients. Furthermore they indicate the necessity of analyzing not only up-regulated but also down-regulated antibody reactivities, which might be likewise relevant for the understanding of other diseases.

Alterations in the Tear Proteome of Dry Eye Patients—A Matter of the Clinical Phenotype

PURPOSE Previous studies demonstrated alterations in the tear proteome of dry eye patients. The aim of the present study was to analyze tear protein patterns of dry eye patients considering different clinical phenotypes in order to examine their influence on tear film protein composition. METHODS We applied a surface-enhanced laser desorption/ ionization-time-of-flight (SELDI-TOF)/matrix-assisted laser desorption/ ionization-time-of-flight (MALDI-TOF)/TOF mass spectrometry (MS)-based strategy to detect/identify candidate biomarkers. Tear samples of 169 patients, enrolled in two independent studies, were analyzed. Patients were subdivided into healthy controls(CTRL: N = 39), aqueous-deficient dry eye (DRYaq: N = 40), lipid-deficient dry eye (DRYlip: N = 40), and a combination of the two (DRYaqlip: N = 40). RESULTS We uncovered six peptide/protein markers matching the stringent criteria applied for selection of reliable markers (P < 5.0E-03 in both studies). For example, proline-rich protein 4 was found to be diminished in DRYaq and DRYaqlip patients when compared to healthy subjects. Mammaglobin B and lipophilin A were found to be increased in these patients, as well as calgranulin S100A8. Remarkably, DRYlip patients revealed only slight alterations; these patients strongly deviated from the DRYaq or DRYaqlip group. With regard to classification of patients, we achieved discrimination from healthy subjects with a sensitivity and specificity ≈100% for DRYaq and DRYaqlip patients (receiver operating characteristic curve [ROC curve]: area under the curve [AUC] = 1) through use of the six-biomarker set. CONCLUSIONS This study demonstrates that different clinical phenotypes of dry eye are reflected by specific alterations of the tear film proteome. Especially a deficiency of the aqueous phase of the tear film seems to strongly influence the expression patterns of several proteins.

Comparison of tear protein levels in breast cancer patients and healthy controls using a de novo proteomic approach

Noninvasive biomarkers are urgently needed for early detection of breast cancer since the risk of recurrence, morbidity and mortality are closely related to disease stage at the time of primary surgery. In the past decade, many proteomics-based approaches were developed that utilize the protein profiling of human body fluids or identification of putative biomarkers to obtain more knowledge on the effects of cancer emergence and progression. Herein, we report on an analysis of proteins in the tear fluid from breast carcinoma patients and healthy women using a de novo proteomic approach and 25 mixed samples from each group. This study included 25 patients with primary invasive breast carcinoma and 25 age-matched healthy controls. We performed a MALDI-TOF-TOF-driven semi-quantitative comparison of tear protein levels in cancer (CA) and control (CTRL) using a de novo approach in pooled samples. Over 150 proteins in the tear fluid of CTRL and CA were identified. Using an in-house-developed algorithm we found more than 20 proteins distinctly upregulated or downregulated in the CTRL and CA groups. We identified several proteins that had modified expression in breast cancer patients. These proteins are involved in host immune system pathways (e.g., C1Q1 or S100A8) and different metabolic cascades (ALDH3A or TPI). Further validation of the results in an independent population combined with individual protein profiling of participants is needed to confirm the specificity of our findings and may lead to a better understanding of the pathological mechanism of breast cancer.

Effect of contact lenses on the protein composition in tear film: a ProteinChip study

BackgroundThe aim of this study was to analyze and compare the effects of rigid gas permeable and soft contact lenses on the protein composition in the tear film of contact lens wearers.MethodsWearers of soft contact lenses (CL_S, n = 13) and rigid gas permeable contact lenses (CL_H, n = 13) were recruited for this study. Thirteen non-contact lens wearers were also included as the control. Tears were collected using Schirmer strips and frozen until use. The tears were eluted and analyzed on ProteinChips SELDI-TOF (surface-enhanced laser desorption and ionization in time of flight mass spectrometry; Bio-Rad, USA) with different chromatographic surfaces (cationic and anionic exchanger and reversed phase surface). The SELDI spectra were analyzed by multivariate statistical analysis and artificial neural networks in order to find a biomarker panel which differentiates best between the groups. In order to identify protein/peptide peaks from SELDI spectra which showed a significant difference between groups, fractionated tear samples were analyzed using MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry). For validation of biomarkers, we used an antibody microarray approach.ResultsComplex patterns of tear proteins and peptides were detected in the control group and in both contact lens groups. The tear protein composition in both wearers of rigid gas permeable (CL_H) and soft contact lenses (CL_S) differed significantly from protein composition in non-contact lens wearers (p < 0.01). The identification of biomarkers revealed an increase of Protein S100 A8 in the group of wearers of soft contact lenses (CL_S) and a decrease of a main tear protein, lysozyme, in both contact lens groups. The identified biomarker cystatin was upregulated in the group of rigid gas permeable lens wearers (CL_H), whereas the protein intensity of secretoglobin was significantly reduced in this group. Using the microarray approach, detected alterations could be confirmed.ConclusionsContact lens wear alters the protein profiles in a complex manner. This study demonstrates that significant changes can be found in wearers of soft contact lenses (CL_S) and rigid gas permeable contact lenses (CL_H). Some biomarker intensities are significantly altered only in the group of rigid gas permeable lens wearers (CL_H).

Upregulation of Antibody Response to Heat Shock Proteins and Tissue Antigens in an Ocular Ischemia Model

PURPOSE The aim of this study was to characterize the serum antibody reactivities occurring after ocular ischemia reperfusion. The time course of serum antibody responses was examined. METHODS Wistar rats were exposed to transient ocular ischemia by elevating intraocular pressure to 130 mm Hg for 60 minutes. Axonal damage was evaluated on optic-nerve sections 2 and 4 weeks later. Blood samples collected before and several times after ischemia were used for antibody detection via customized protein microarrays. Different tissue antigens, including heat shock proteins (HSPs) and crystallins, were selected based on previous identification of antibody reactivities in studies on ischemic events or ophthalmic diseases associated with ischemia. Antibody reactivity was compared using multivariate statistical techniques. RESULTS Significant axonal damage was observed 2 and 4 weeks after ocular ischemia (P < 0.05). Animals showed certain immunoreactivities against antigens even before ischemia, whereas many reactivities increased afterward. Significantly different responses were detected 2, 3, and 4 weeks after ischemia (P < 0.05). Antibody reactivity against actin, glial fibrillary acidic protein, HSP 27, vimentin, or spectrin continually increased. CONCLUSIONS Ischemia induced by acute intraocular pressure elevation led to complex changes in antibody reactivities in sera of treated animals. Upregulation of serum autoantibodies, especially against heat shock and structural proteins, progressively increased throughout the 4-week follow-up period, whereas others such as ubiquitin decreased. The upregulation of anti-HSP 27 antibodies might be an attempt to protect the tissue from ischemic damage.

Antibody microarray analysis of the serum proteome in primary breast cancer patients.

Noninvasive biomarkers are urgently needed for detecting breast cancer as early as possible since the risk of recurrence, morbidity, and mortality is closely related to disease stage at the time of primary surgery. There are currently no such biomarkers in clinical use as a diagnostic tool. Proteomic analysis of protein expression patterns in body fluids has potential for use in identifying biomarkers of breast cancer. The aim of this study was to compare protein expression levels in the sera of primary breast cancer patients and healthy controls. An antibody microarray tool with 23 antibodies immobilized on nitrocellulose slides was used to determine the levels of acute phase proteins, interleukins, and complement factors in the sera of 101 study participants (49 women with primary breast cancer and 52 healthy age-matched controls). Statistical analysis of reaction intensities identified 6 proteins that showed significantly (p < 0.05) different levels in breast cancer patients vs. healthy subjects. The neural network distinguished cancer patients from controls with a sensitivity of 69% and a specificity of 76%. Thus, antibody microarray analysis could be used as a tool for the development of improved diagnostics and biomarker discovery for breast cancer patients. Further validation of the results and de novo screening of new biomarkers could facilitate the early diagnosis of breast cancer.

Effect of ischemia duration on autoantibody response in rats undergoing retinal ischemia-reperfusion.

Both the innate and the adaptive immune systems are involved in the pathogenic processes following ischemia-reperfusion injury. We analyzed the possible correlation between the duration of ischemia and autoantibody diversification in a model of ocular ischemia. Rats were subjected to 30, 45, or 90 min of ischemia, and retinal ganglion cell (RGC) density and antibody reactivity were analyzed via customized protein microarray slides. After ocular ischemia, significant alterations in antibody response were observed, while increasing exposure caused more severe RGC damage. Distinct antibody responses after ischemia were detected; these alterations comprised decreased reactivities against cyclophilin A and glyceraldehyde-3-phosphate dehydrogenase, possibly due to increased binding of circulating antibodies to debris material. Other antibodies, like those against α5β1-integrin or β2-adrenergic receptor, were upregulated after ischemia.

Reduced mRNA and Protein Expression of the Genomic Caretaker RAD9A in Primary Fibroblasts of Individuals with Childhood and Independent Second Cancer

Background The etiology of secondary cancer in childhood cancer survivors is largely unclear. Exposure of normal somatic cells to radiation and/or chemotherapy can damage DNA and if not all DNA lesions are properly fixed, the mis-repair may lead to pathological consequences. It is plausible to assume that genetic differences, i.e. in the pathways responsible for cell cycle control and DNA repair, play a critical role in the development of secondary cancer. Methodology/Findings To identify factors that may influence the susceptibility for second cancer formation, we recruited 20 individuals who survived a childhood malignancy and then developed a second cancer as well as 20 carefully matched control individuals with childhood malignancy but without a second cancer. By antibody microarrays, we screened primary fibroblasts of matched patients for differences in the amount of representative DNA repair-associated proteins. We found constitutively decreased levels of RAD9A and several other DNA repair proteins in two-cancer patients, compared to one-cancer patients. The RAD9A protein level increased in response to DNA damage, however to a lesser extent in the two-cancer patients. Quantification of mRNA expression by real-time RT PCR revealed lower RAD9A mRNA levels in both untreated and 1 Gy γ-irradiated cells of two-cancer patients. Conclusions/Significance Collectively, our results support the idea that modulation of RAD9A and other cell cycle arrest and DNA repair proteins contribute to the risk of developing a second malignancy in childhood cancer patients.