Oligoclonal T cells in histiocytic necrotizing lymphadenopathy are associated with TLR9+ plasmacytoid dendritic cells

Angiotensin type 1 receptor modulates macrophage polarization and renal injury in obesity

The mechanisms for increased risk of chronic kidney disease (CKD) in obesity remain unclear. The renin-angiotensin system is implicated in the pathogenesis of both adiposity and CKD. We investigated whether the angiotensin type 1 (AT(1)) receptor, composed of dominant AT(1a) and less expressed AT(1b) in wild-type (WT) mice, modulates development and progression of kidney injury in a high-fat diet (HFD)-induced obesity model. WT mice had increased body weight, body fat, and insulin levels and decreased adiponectin levels after 24 wk of a high-fat diet. Identically fed AT(1a) knockout (AT1aKO) mice gained weight similarly to WT mice, but had lower body fat and higher plasma cholesterol. Both obese AT1aKO and obese WT mice had increased visceral fat and kidney macrophage infiltration, with more proinflammatory M1 macrophage markers as well as increased mesangial expansion and tubular vacuolization, compared with lean mice. These abnormalities were heightened in the obese AT1aKO mice, with downregulated M2 macrophage markers and increased macrophage AT(1b) receptor. Treatment with an AT(1) receptor blocker, which affects both AT(1a) and AT(1b), abolished renal macrophage infiltration with inhibition of renal M1 and upregulation of M2 macrophage markers in obese WT mice. Our data suggest obesity accelerates kidney injury, linked to augmented inflammation in adipose and kidney tissues and a proinflammatory shift in macrophage and M1/M2 balance.

Immunohistochemical discrimination of plasmacytoid dendritic cells from myeloid dendritic cells in human pathological tissues

Until now, no method has been available to discriminate mature plasmacytoid DC (pDC) from myeloid DC (mDC) immunohistochemically. In this study, we report that these DC-subsets can be distinguished in routine pathological sections. Immature and mature monocyte-derived DCs (MoDCs) were S100 calcium binding protein B (S100B)+, while pDCs generated from pDC-precursors were S100B-. In contrast, both mature MoDC and pDC were fascin+. Epidermal Langerhans cells (LCs) were S100B+/fascin-. Although the majority of DCs were S100B+/fascin+ in the dermis with nonspecific inflammation, dermal DCs were mostly S100B-/fascin+ in psoriasis vulgaris, in which type I interferon secreted by pDC-precursors is thought to play a major role. S100B+/fascin+ DCs were accumulated in the superficial lymph node (LN), while they were scarce in the deep LN. In the superficial LN with dermatopathic lymphadenitis, a large number of S100B+/fascin+ DCs were accumulated in the T-zones, where numerous LC-derived DCs are accumulated. In contrast, almost all DCs were S100B-/fascin+ in the superficial LN with Kikuchi's lymphadenitis, in which numerous pDC-precursors are known to be present. In contrast to the superficial LN, the deep LN contained numerous S100B-/fascin+ DCs and a few S100B+ DCs. Thus, the distributions of S100B+ DC or S100B-/fascin+ DC correspond to the putative distribution of mDC or mature pDC, respectively.

Human matrix metalloproteinases: characteristics and pathologic role in altering mesangial homeostasis

Matrix metalloproteinases are zinc dependent endopeptidases belonging to the M10 family of the metalloproteinase superfamily. They are ubiquitous enzymes, structurally and functionally related, with a high degree of sequence homology. They are primarily involved in extracellular matrix (ECM) turn-over and cell migration through their expanding repertoire of substrate affinities. Twenty three different forms of human MMPs have been described to be arranged in eight distinct structural classes. Their interactions with tissue inhibitors of metalloproteinases (TIMPs), and other indigenous inhibitors have been well documented. This manuscript reviews pertinent information available on matrix metalloproteinases and TIMPs in the literature. Light chain-mediated glomerular injury represents an excellent example of how metalloproteinases participate in altering mesangial homeostasis. Investigations regarding these conditions have shown that the physico-chemical characteristics of the light chains govern the pattern of renal damage that will ensue with the mesangium representing the critical site where pathological alterations are centered. The mesangium is either replaced or expanded depending on the light chains involved in the pathologic process.

Different T-bet expression patterns characterize particular reactive lymphoid tissue lesions

AIMS

To investigate T-bet expression profiles in various lymphoid tissue diseases caused by intracellular pathogens and to compare them in disorders without an infective aetiology. Murine and in vitro experiments have shown that the expression/induction of T-bet, the master regulator of Th1 differentiation, can be achieved by obligate intracellular pathogens and high interferon (IFN)-gamma levels.

METHODS

Lymph node biopsies were analysed immunohistochemically employing single and double labelling for T-bet and CD20, CD4, CD8 and CD30 detection.

RESULTS

In disorders associated with high IFN-gamma levels and intracellular pathogens (infectious mononucleosis, HIV-associated lymphadenopathy, cat-scratch disease, and toxoplasmic lymphadenitis), T-bet-expressing CD4 cells were accompanied by significant numbers of T-bet-positive CD8 and B cells. A similar profile was also found in histiocytic necrotizing (Kikuchi) lymphadenitis, a disease of unknown cause. In contrast, T-bet expression in disorders without an infective aetiology was observed in only a small portion of lymphocytes.

CONCLUSIONS

Increased T-bet expression does not only identify intracellular infections in lymphoid tissue associated with high IFN-gamma levels, but also implies that, under these conditions, it becomes induced in B cells, which apparently support the Th1 response. T-bet expression in Kikuchi lymphadenitis underscores the hypothesis that it is caused by an intracellular microorganism.