Rom J Morphol Embryol 2012, 53(4):1037–1042 ISSN (print) 1220–0522 ISSN (on-line) 2066–8279 ORIGINAL PAPER Immunoexpression of alpha-SMA and CD68 in native kidney biopsies OFELIA JERCAN 1) , M. PENESCU 2) , D. GH. MĂLĂESCU 3) 1) University of Medicine and Pharmacy of Craiova 2) “Carol Davila” Nephrology Hospital, Bucharest 3) Faculty of Nursing, “Constantin Brâncuşi” University, Targu Jiu Abstract Introduction: The role for inflammation and fibrosis as predictive histopathological markers for renal function has been discussed in several studies. Aim of our investigation was to evaluate the clinico-pathological correlation of myofibroblasts expression as markers for initial development of fibrotic processes and macrophagic infiltration in a population with impaired renal function, in order to better understand their value in diagnostic biopsies. Materials, Methods and Results: We evaluated 20 consecutive native kidney biopsies performed for diagnostic purposes. Material remaining after routine light microscopy and immunofluorescence, was stained for α-SMA as myofibroblast marker and CD68 as macrophage infiltration marker. Quantitative evaluation was conducted by electronic image analysis on consecutive low power fields, avoiding glomeruli, and estimated as percentage of the total area or as number of positive cells/field for macrophage infiltration. The renal biopsies were also evaluated for histological characteristics such as percentual area of inflammation infiltration and fibrosis. Clinical and laboratory data were recorded at biopsy moment and followed-up on a period of 17±11 months after the renal biopsy. Interstitial α-SMA immunoexpression proved to be related with interstitial fibrosis (r=-0.47, p<0.001) and macrophage infiltration (r=0.21, p=0.03). Higher immunoexpression of α-SMA was related with renal function assessed by creatinine level at biopsy moment (r=0.32, p=0.002). Conclusions: In this study, detection of myofibroblast infiltration using α-smooth-muscle actin (α-SMA) proved to be a good marker in describing the initial phases of interstitial fibrosis development in early stages of chronic kidney dysfunction. Keywords: myofibroblast, fibrosis, macrophage infiltration, chronic kidney disease.  Introduction Chronic kidney disease is clinically characterized by a progressive deterioration in glomerular filtration rate and the histopathological findings of progressive interstitial fibrosis as well as tubular damage in the progression of renal impairment, regardless of the initiating cause for the renal pathology [1, 2]. The differentiation into myofibroblasts is considered one of the essential early cellular events that initiate the development of organ fibrosis [3, 4]. Myofibroblasts are considered to play an important role in tissue repair and in production of extracellular matrix, they are characterized by the presence of cytoplasmic microfilament bundles expressing α-smooth- muscle actin (α-SMA), the actin isoform characteristic for vascular smooth-muscle cells [5, 6]. Also, myofibro- blasts are observed to be important elements in organ remodeling through their function of extracellular matrix organization, due to these properties myofibro- blasts presence is described also in pathological processes as hypertrophic scars as well as fibrosis processes in kidney and heart tissue [7]. In an experimental model of obstructive nephropathy induced by unilateral ureteral obstruction has been observed the presence of multiple cells that showed co- expression of both α-SMA and tubular markers, indicating that these cells are in a transitional stage between epithelium and mesenchyma [8, 9]. Fibroblasts renal origin remains controversial, currently the most common theory prioritizes local interstitial cells but other authors claim that migrated leukocytes derived from local fibroblasts may be responsible for the fibroblasts expression and extra- cellular matrix deposition [10]. Nevertheless, processes as infiltration of blood mononuclear cells and macro- phage recruitment, proliferation of interstitial mesen- chymal cells and apoptosis of tubular epithelial cells represent important steps in renal fibrosis development [11]. The aim of this study was to evaluate the immuno- expression of myofibroblasts and macrophage infiltra- tion in early stages of fibrosis development and their prognostic value for the progression of chronic kidney disease.  Materials and Methods The study was performed in kidney tissues obtained from 20 patients that underwent a biopsy procedure during 2009–2011. The protocol was approved by the Ethic Committees of “Carol Davila” Nephrology Hospital and University of Medicine and Pharmacy of Craiova, and was conducted according to the ethical principles of the Helsinki Convention. Medical history, physical examination and laboratory data recorded during the hospitalization period were retrieved from the patient files and the informed consent R J M E Romanian Journal of Morphology & Embryology http://www.rjme.ro/