A recombinant adeno-associated virus (rAAV) virion comprising a modified capsid protein and a promoter operably linked to a nucleotide sequence encoding a gene product of interest, wherein the rAAV virion is for use in treating or preventing an arthritic disease or for use in treating or preventing a symptom associated with an arthritic disease, wherein the symptom is joint pain or the inflammation of one or more arthritic joints, wherein (i) the gene product of interest is an IL-6 inhibitor; and (ii) the modified capsid protein comprises in the C-terminal part of the protein an amino acid sequence Z, residues of which are exposed on the surface of the capsid protein, and wherein the amino acid sequence Z: a. comprises or consists of a sequence of amino acid residues of the formula I: y-G-Q-x-G-(x) 3 -R-(x) 3 -y-A-Q-A-A wherein x represents a single amino acid residue and wherein y represents 0, 1 or 2 amino acid residues; b. is present at a location corresponding to a position 130 - 170, preferably 140 - 160 amino acid residues from the C terminus of a wild-type AAV capsid protein; and c. the amino acid sequence Z has at least 90% sequence identity with an amino acid sequence selected from the group consisting of SEQ ID NOs: 8-12, and wherein the modified capsid protein provides for an at least two-fold increase in expression in comparison to an unmodified capsid protein having SEQ ID NO: 19 when tested under the same conditions. wherein the symptom is joint pain or the inflammation of one or more arthritic joints, wherein (i) the gene product of interest is an IL-6 inhibitor; and (ii) the modified capsid protein comprises in the C-terminal part of the protein an amino acid sequence Z, residues of which are exposed on the surface of the capsid protein, and wherein the amino acid sequence Z: a. comprises or consists of a sequence of amino acid residues of the formula I: y-G-Q-x-G-(x) 3 -R-(x) 3 -y-A-Q-A-A wherein x represents a single amino acid residue and wherein y represents 0, 1 or 2 amino acid residues; b. is present at a location corresponding to a position 130 - 170, preferably 140 - 160 amino acid residues from the C terminus of a wild-type AAV capsid protein; and c. the amino acid sequence Z has at least 90% sequence identity with an amino acid sequence selected from the group consisting of SEQ ID NOs: 8-12, (i) the gene product of interest is an IL-6 inhibitor; and (ii) the modified capsid protein comprises in the C-terminal part of the protein an amino acid sequence Z, residues of which are exposed on the surface of the capsid protein, and wherein the amino acid sequence Z: a. comprises or consists of a sequence of amino acid residues of the formula I: y-G-Q-x-G-(x) 3 -R-(x) 3 -y-A-Q-A-A wherein x represents a single amino acid residue and wherein y represents 0, 1 or 2 amino acid residues; b. is present at a location corresponding to a position 130 - 170, preferably 140 - 160 amino acid residues from the C terminus of a wild-type AAV capsid protein; and c. the amino acid sequence Z has at least 90% sequence identity with an amino acid sequence selected from the group consisting of SEQ ID NOs: 8-12, a. comprises or consists of a sequence of amino acid residues of the formula I: y-G-Q-x-G-(x) 3 -R-(x) 3 -y-A-Q-A-A wherein x represents a single amino acid residue and wherein y represents 0, 1 or 2 amino acid residues; b. is present at a location corresponding to a position 130 - 170, preferably 140 - 160 amino acid residues from the C terminus of a wild-type AAV capsid protein; and c. the amino acid sequence Z has at least 90% sequence identity with an amino acid sequence selected from the group consisting of SEQ ID NOs: 8-12, and wherein the modified capsid protein provides for an at least two-fold increase in expression in comparison to an unmodified capsid protein having SEQ ID NO: 19 when tested under the same conditions.