SummaryBeginning at the time of insulitis (7 wk of age), CD4 + and CD8 + mature thymocytes from nonobese diabetic (NOD) mice exhibit a proliferative unresponsiveness in vitro after T cell receptor (TCR) crosslinking. This unresponsiveness does not result from either insulitis or thymic involution and is long lasting, i.e., persists until diabetes onset (24 wk of age). We previously proposed that it represents a form of thymic T cell anergy that predisposes to diabetes onset. This hypothesis was tested in the present study by further investigating the mechanism responsible for NOD thymic T cell proliferative unresponsiveness and determining whether reversal of this unresponsiveness protects NOD mice from diabetes. Interleukin 4 (IL-4) secretion by thymocytes from >7-wk-old NOD mice was virtually undetectable after treatment with either anti-TCR c~/B, anti-CD3, or Concanavalin A (Con A) compared with those by thymocytes from age-and sexmatched control BALB/c mice stimulated under identical conditions. NOD thymocytes stimulated by anti-TCR o~/B or anti-CD3 secreted less IL-2 than did similarly activated BALB/c thymocytes. However, since equivalent levels of IL-2 were secreted by Con A-activated NOD and BALB/c thymocytes, the unresponsiveness of NOD thymic T cells does not appear to be dependent on reduced IL-2 secretion. The surface density and dissociation constant of the high affinity IL-2 receptor of Con A-activated thymocytes from both strains are also similar. The patterns of unresponsiveness and lymphokine secretion seen in anti-TCR/CD3-activated NOD thymic T cells were also observed in activated NOD peripheral spleen T cells. Exogenous recombinant (r)IL-2 only partially reverses NOD thymocyte proliferative unresponsiveness to anti-CD3, and this is mediated by the inability of IL-2 to stimulate a complete IL-4 secretion response. In contrast, exogenous rlL-4 reverses the unresponsiveness of both NOD thymic and peripheral T cells completely, and this is associated with the complete restoration of an IL-2 secretion response. Furthermore, the in vivo administration of rlL-4 to prediabetic NOD mice protects them from diabetes. Thus, the ability of rlL-4 to reverse completely the NOD thymic and peripheral T cell proliferative defect in vitro and protect against diabetes in vivo provides further support for a causal relationship between this T cell proliferative unresponsiveness and susceptibility to diabetes in NOD mice.

Swab cultures are valuable in identifying pathogens in diabetic foot wounds when bone is not involved. When surgical debridement is contraindicated or delayed, swab cultures can be used to select appropriate antibiotic therapy.

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SummaryThymic T cell anergy, as manifested by thymocyte proliferative unresponsiveness to antigens expressed in the thymic environment, is commonly believed to mediate the acquisition of immunological self-tolerance. However, we previously found that thymic T cell anergy may lead to the breakdown of tolerance and predispose to autoimmunity in nonobese diabetic (NOD) mice. Here, we show that NOD thymic T cell anergy, as revealed by proliferative unresponsiveness in vitro after stimulation through the T cell receptor (TCR), is associated with defective TCRmediated signal transduction along the PKC/p21~'qp42m~p k pathway of T cell activation. PKC activity is reduced in NOD thymocytes. Activation of p21 ~' * is deficient in quiescent and stimulated NOD T cells, and this is correlated with a significant reduction in the tyrosine phosphorylation of p42maP k, a serine/threonine kinase active downstream of p21 ~'s. Treatment of NOD T cells with a phorbol ester not only enhances their p21 r~s activity and p42m~p k tyrosine phosphorylation but also restores their proliferative responsiveness. Since p42m'p k activity is required for progression through to S phase of the cell cycle, our data suggest that reduced tyrosine phosphorylation of p42m'v k in stimulated NOD T cells may abrogate its activity and elicit the proliferative unresponsiveness of these cells. Functional inactivation or anergy of a T cell is manifested by a long-lasting proliferative unresponsiveness, and may occur as a consequence of an interaction between an Ag or mitogen with the CD3-TCR complex in the absence of a second non-Ag-specific costimulator signal provided by an APC (1). T cell anergy in the thymus and/or periphery generally results in immunological self-tolerance (2-4). In contrast, we have found that beginning at the time of insulitis (7 wk of age), mature CD4 * 8-and CD4-8 + thymic T cells from prediabetic NOD mice are anergic as assessed by stimulation of proliferation in vitro after TCR cross-linking with either an anti-TCR mAb, anti-CD3 mAb, or Con A. This anergy is not due to the inability of thymic APCs to provide costimulation (5, 6, and Rapoport, M., A. Jaramillo, D. Zipris, A. Lazarus, D. Serreze, E. Leiter, P. Cyopick, and T. Delovitch, manuscript submitted for publication), but rather arises predominantly from the inability of these NOD thymic T cells to be stimulated to produce sufficient amounts of IL-4 to support their proliferation (6, and Rapoport, M., et al., manuscript submitted for publication). IL-4 completely reverses this thymic T cell anergy in vitro and when administered in vivo, prevents the onset of diabetes in NOD mice (Rapoport, M. et al., manuscript submitted for publication). These studies raise the possibility that thymic T cell anergy might influence susceptibility to diabetes in NOD mice. Elucidation of the biochemical mechanisms of this NOD thymic T cell anergy may further unravel the basis of the polygenic control of susceptibility to type I diabetes.In many types of cells, interactions between membrane rece...

The nonuniform skeletal involvement in osteoporosis argues for multi-site evaluation. The Sunlight Omnisense (Sunlight Ultrasound Technologies, Israel) is a multi-site device that measures speed of sound (SOS) at the appendicular skeleton. We report the reference database for SOS at the radius (RAD), tibia (TIB), metatarsus (MTR) and phalanx (PLX). The database was obtained from 1521 healthy Israeli women (age 20-90 years) out of 2051 respondents. SOS was determined in 97.6% of the participants at the PLX, 96.4% at the TIB, 93.6% at the RAD and 85.1% at the MTR; it was not measurable in 0.5%. Short-term coefficient of variation was lowest at the RAD and always less than 1%. Maximal SOS was noted at 35-45 years of age in three of the sites (RAD 4169 m/s, MTR 3663 m/s, PLX 4047 m/s, respectively) but 10 years earlier at the TIB (3939 m/s). In the perimenopausal period (age 46-55 years), SOS was always lower in post- as compared with premenopausal women (p<0.05). Immediately following the menopause, SOS annually declined close to the short-term CV: 16, 34, 37 and 13 m/s at the RAD, PLX, MTR and TIB, respectively. The average age-stratified SOS values at various measurement sites were highly correlated at the population level (0.96-0.99), but less so at the individual level (0.40-0.57). Therefore, multi-site SOS measurements are better than single-site assessment. After 79 years of age, the average T-score at the RAD and PLX was <--2.5. This is similar to that of dual-energy X-ray absorptiometry (DXA)-determined spine bone mineral density (BMD) and somewhat lower than hip BMD. Equivalent T-score curves obtained by percentile adjustment of SOS at various sites to that of the RAD (at age group 60-69 years) reveal convergence and indicate that 52-68% of women older than 79 years are osteoporotic. In conclusion, multi-site peripheral SOS measurements reveal age-dependent bone changes with a high degree of measurement precision and indicate a prevalence of osteoporosis similar to that obtained by DXA.

Optimal T cell responsiveness requires signaling through the T cell receptor (TCR) and CD28 costimulatory receptors. Previously, we showed that T cells from autoimmune nonobese diabetic (NOD) mice display proliferative hyporesponsiveness to TCR stimulation, which may be causal to the development of insulin-dependent diabetes mellitus (IDDM). Here, we demonstrate that anti-CD28 mAb stimulation restores complete NOD T cell proliferative responsiveness by augmentation of IL-4 production. Whereas neonatal treatment of NOD mice with anti-CD28 beginning at 2 wk of age inhibits destructive insulitis and protects against IDDM by enhancement of IL-4 production by islet-infiltrating T cells, administration of anti-CD28 beginning at 5-6 wk of age does not prevent IDDM. Simultaneous anti-IL-4 treatment abrogates the preventative effect of anti-CD28 treatment. Thus, neonatal CD28 costimulation during 2-4 wk of age is required to prevent IDDM, and is mediated by the generation of a Th2 cell-enriched nondestructive environment in the pancreatic islets of treated NOD mice. Our data support the hypothesis that a CD28 signal is requisite for activation of IL-4-producing cells and protection from IDDM. ( J.

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PPAR-gamma activation by rosiglitazone resulted in decreased manifestation of inflammatory hallmarks, including inhibition of mesangial cell proliferation, downregulation of apoptosis and blunted responsiveness to A-II. These anti-inflammatory renoprotective effects were maximally expressed in cultures from pregnant diabetic animals. The therapeutic relevance of these observations is a matter of further investigations.