Protein biochip array technology to monitor rituximab in rheumatoid arthritis.

In rheumatoid arthritis (RA) there are currently no good indicators to predict a clinical response to rituximab. The purpose of this study was to monitor and determine the role of peripheral blood cytokine profiling in differentiating between a good versus poor response to rituximab in RA. Blood samples were collected at baseline and at 3 months from 46 RA patients who were treated with rituximab. Responders are defined by the presence of three of four American College of Rheumatology criteria: >or=20% decrease in C-reactive protein, visual analogical score of disease activity, erythrocyte sedimentation rate and improvement of the disease activity score (28) (four values) by >or=1.2 obtained at 3 months. Twelve cytokines were measured from serum collected on days 0 and 90 by proteomic array, including interleukin-6 (IL-6), tumour necrosis factor-alpha, IL-1a, IL-1b, IL-2, IL-8, interferon-gamma, IL-4, IL-10, monocyte chemoattractant protein-1, epidermal growth factor and vascular growth factor. We showed that C-reactive protein and IL-6 levels decrease significantly at 3 months in the responder group compared with baseline. At day 90 we identified a cytokine profile which differentiates responders and non-responders. High serum levels of two proinflammatory cytokines, monocyte chemoattractant protein-1 and epidermal growth factor, were significantly higher in the responder group at day 90 compared with non-responders. However, we were not able to identify a baseline cytokine profile predictive of a good response at 3 months. These findings suggest that cytokine profiling by proteomic analysis may be a promising tool for monitoring rituximab and may help in the future to identify responder RA patients.

Expression of matrix-degrading enzymes in pulmonary vascular remodeling in the rat.

Exposure of rats to hypoxia causes pulmonary arterial remodeling, which is partly reversible after return to air. We hypothesized that degradation of excess collagen in remodeled pulmonary arteries in the posthypoxic period is mediated by endogenous matrix metalloproteinases (MMPs). Total proteolytic, collagenolytic, and gelatinolytic activities, levels of stromelysin-1 and tissue inhibitor of metalloprotease-1 (TIMP-1), and immunolocalization of stromelysin-1 in main pulmonary arteries were determined after exposure of rats to 10% O2 for 10 days followed by normoxia. We observed transient increases in total proteolytic, collagenolytic, and gelatinolytic activities and expression of approximately 72-, 68-, and 60-kDa gelatinases by zymography within 3 days of cessation of hypoxic exposure. The level of TIMP-1 increased as the stromelysin-1 level increased. Immunoreactive stromelysin-1 was localized predominantly in the luminal region of normal and hypertensive pulmonary arteries. These results are consistent with the notion that endogenous MMPs may mediate the breakdown of excess collagen in remodeled pulmonary arteries during the early posthypoxic period.

Role of in situ IL-2r and TGF-beta expression in tolerant vascularized bone marrow (limb) transplant chimeras.

We hypothesized that an increase in IL-2 activated T cells in situ within the marrow component of a transplanted limb may adversely affect development of tolerance, while increased TGF-beta expression locally would facilitate tolerance induction and/or maintenance. Digital image analysis of cellular expression of IL-2r in the bone marrow was significantly increased in the CON and TXP limbs for both GVHD and tolerant recipients as compared to normal limb marrow (P < .02). The amount of cellular expression of TGF-beta was significantly increased in the GVHD animals, both CON and TXP, as compared to the tolerant animals (43.2 +/- 3.1 vs 10.6 +/- 2.6; P < .000001). Our results show that increased IL-2r and TGF-beta expression in situ within the bone marrow is an important effect common to both alloimmune tolerance and GVHD induction with VBMT chimeras. The dramatic increase in the expression of TGF-beta in the GVHD transplanted limbs may explain the profound immunosuppression that results. Additionally, moderate expression of TGF-beta in situ in tolerant chimeras may represent a mechanism for the induction and maintenance of tolerance.

Graft-versus-host disease in limb transplantation: digital image analysis of bone marrow and TGF-beta expression in situ using a novel 3-D microscope.

A subpopulation of parental to hybrid VBMT recipients developed characteristic clinical and histopathologic manifestations of GVHD. These changes are similar to those seen in human GVHD secondary to bone marrow transplantation. Human GVHD also manifests itself in an acute and chronic manner. Only a minority (30% to 40%) of animals developed lethal GVHD in our model. Those animals developing GVHD had a significantly (P < .0001) higher expression of TGF-beta in situ compared to the tolerant subpopulation. The differential expression of TGF-beta may represent an important mechanism of immune dysregulation associated with GVHD in CTA recipients.

Graft-versus-host disease in extremity transplantation: digital image analysis of bone marrow in situ.

The development of either unstable immune chimerism and lethal graft-versus-host disease or stable immune chimerism and alloimmune tolerance can result from extremity transplantation. LBN rats served as recipients of Lewis vascularized extremity (limb) transplants. Recipients received no immune suppression and were immunologically unmodified. The bone marrow of transplanted and contralateral limbs was analyzed in situ for distribution of nuclei, nuclear area, and staining intensity by digital image analysis and computerized morphometry. Cellularity was significantly increased, and fat content was significantly decreased in the graft-versus-host disease animals' marrow versus the tolerant animals' marrow for both the transplanted and contralateral limbs. Tolerant animals demonstrated significantly increased nuclear staining compared with graft-versus-host disease animals for both transplanted and contralateral limbs. Additionally, there were significant changes between the host and the transplanted limbs for marrow intensity and cellularity within tolerant and graft-versus-host disease groups. The significant differences in the graft-versus-host disease-positive recipients suggested that both autoimmune dysregulation and alloimmune reactions were in effect for both donor and host bone marrow compartments. Cellular alterations in the tolerant recipients' marrow were suggestive of subtle subclinical graft-versus-host responses.